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Comparison of anti-glycation capacities of several herbal infusions with that of green tea
Abstract
Advanced glycation end-products (AGEs) are implicated in the pathogenesis of diabetic microvascular complications and microvascular complications of the aged. Dietary compounds that can reduce glycation may reasonably serve as valuable adjuvants, promoting the health of the aged and diabetics. This work evaluates and compares the anti-glycation activities of different herbal infusions with that of green tea, a well-documented anti-glycation beverage. The anti-glycation activity of herbal infusions were determined based on the ability of an infusion to attenuate the formation of fluorescent AGEs in glucose- and methylglyoxal-mediated protein glycation systems. All of the tested herbs except for lemongrass and rosemary—balm, mint, black tea, sage and common verbena—had potent anti-glycation abilities that exceeded or equalled that of green tea. Additionally, the amounts of phenolics and flavonoid in the herbal infusions were highly correlated with their anti-glycation activity, revealing that the anti-glycation activity of herbal infusions was primarily attributable to phenolics, particularly flavonoids.
... Protein glycation is the key molecular basis of diabetic complications. Therefore, inhibiting any step of the glycation process, preventing the formation of intermediate and end products and reversing the already formed AGEs are considered as effective approaches in preventing diabetic complications (Ho et al., 2010;Kaewnarin et al., 2013). The findings of the present study revealed antiglycation and glycation reversing activities of Ravi, Rawana and Oshadha finger millet varieties while indicating the potential of preventing AGEs-mediated diabetic complications. ...
... Besides, significant negative correlations were observed between EC 50 values of glycation reversing activities and total phenolic contents (r = − 0.630, P < 0.01) and total flavonoid contents (r = − 0.524, P < 0.05) of all extracts indicating the contribution of phenolic compounds including flavonoids which are present in Ravi, Rawana and Oshadha finger millet varieties in reversing the protein glycation process. Aforementioned correlations were consistent with the previous studies reported by Ho et al. (2010), Kaewnarin et al. (2013) and Younus and Anwar (2016) on the correlation of the antiglycation activities and the total phenolic and flavonoid contents of plant extracts. ...
... Free radicals are generated during the glycation process as glycation intermediates and hydroxyl radicals are involved in the rearrangement of Schiff bases to form Amadori products through oxidation reactions (Mattson, 2001;Ho et al., 2010;Kaewnarin et al., 2013). IC 50 values of antiglycation activities of all extracts showed strong positive correlations with IC 50 values of DPPH (r = 0.836, P < 0.05) and ABTS (r = 0.699, P < 0.05) radical scavenging activities of the extracts. ...
Introduction
Finger millet is considered as a therapeutic food for diabetes mellitus. However, there is a lack of scientific evidence on the antidiabetic potential of the finger millet varieties which are commonly cultivated in Sri Lanka.
Materials and methods
This study was focused on determining anti-α-amylase, anti-α-glucosidase, antiglycation, glycation reversing and radical scavenging activities and total phenolic and flavonoid contents of Ravi, Rawana and Oshadha finger millet varieties, using ethanolic and methanolic extracts of whole grain flours, in view of their antidiabetic potential.
Results and discussion
The findings revealed anti-α-amylase, anti-α-glucosidase, antiglycation and glycation reversing activities of Ravi, Rawana and Oshadha finger millet varieties while indicating their potential of decreasing the postprandial hyperglycemia and preventing advanced glycation end products-mediated diabetic complications. Ethanolic extract of Oshadha indicated the highest anti-α-amylase activity (IC50 value: 1.62 ± 0.04 mg/ml), methanolic extract of Oshadha indicated the highest antiglycation (IC50 value: 79.42 ± 4.46 µg/ml) and glycation reversing (EC50 value: 411.76 ± 5.91 µg/ml) activities and methanolic extract of Ravi indicated the highest anti-α-glucosidase activity (IC50 value: 47.96 ± 0.79 µg/ml). Anti-α-amylase and anti-α-glucosidase activities of the finger millet varieties can be attributed to their phenolic and flavonoids contents and antiglycation and glycation reversing activities can be attributed to the radical scavenging potential of their phenolic compounds including flavonoids.
Conclusion
These findings scientifically proved the efficacy of using Ravi, Rawana and Oshadha varieties in prevention and dietary management of diabetes mellitus and its complications and reinforced the traditional recommendation of finger millet-based foods for diabetic patients.
... Therefore, it can be deduced that antiglycative compounds are promising options to prevent Biomolecular damages in such conditions [4]. A number of glycation inhibitors have been studied such as amino guanidine, pyridoxamine and phenyl thiazolium bromide, and some of them have ameliorated diabetes complications in animal models; however, potential toxicity has limited their clinical application [10,11]. Although free radicals have an undeniable role in living organisms [12], several studies have shown that diabetes is associated with increased production of free radicals [13]. ...
... After 24 hours, the suspensions were filtered through Whatman filter paper 1 and completely dried in an incubator (37°C) [15]. Eventually, three concentrations (0.5 ، 0.25 and 0.12 g/dl) were prepared from each extract in distilled water and were used for subsequent measurements [10]. ...
... Correlative analysis also indicated a significant association between the antioxidant capacity and the content of phenolic (r= -0.853, p = 0.000) and flavonoid compounds (r= -0.844, p = 0.001) in the extracts (Table 5). Several studies showed that antioxidant properties of plants are directly correlated with phenolic and flavonoid compounds [5,10]. ...
Aims: Both glycation and oxidative stress play a critical role in the incidence of diabetic
complications. Plants with antioxidative and antiglycative properties may attenuate such
pathological conditions. The aim of this study is comparing the antiglycative and antioxidative
effects of Vaccinium arctostaphylos, Plantago ovata, Securigera securidaca and Rhus coriaria on
albumin glycation for the first time.
Methodology: Antiglycative property of methanolic extract (75%) of these plants was evaluated by
co-incubation of extracts with bovine serum albumin and glucose. Various stages were assessed
by measuring different markers of glycation (fructosamine, protein carbonyls and amyloid cross-β
structure aggregation). Total phenolic and flavonoid contents as well as antioxidant capacity of
extracts were determined. Finally, the correlations between antiglycation property, total phenol and
flavonoid content and antioxidant capacity of extracts were evaluated.
Results: The results demonstrated that the extracts exert inhibitory effects on various stages of
glycation and V. arctostaphylos showed maximum attenuating effect. A significant correlation was
found between antiglycation and antioxidant properties of extracts with total phenolic and flavonoid
content. In addition, the antioxidant capacity of extracts correlated with their antiglycation
properties.
Conclusion: Our findings revealed that antioxidative and antiglycative activities of extracts may be
related to their phenolic and flavonoid contents. These findings support the viewpoint that the
medicinal plants with anti-diabetic properties may be beneficial resources for inhibition of glycation
and oxidative stress in diabetic patients.
... (2010) 43 who reported higher levels of total phenolics, flavonoids and proanthocyanidins in green tea than in black tea by 1.08-, 1.28-and 2.54-fold, respectively. Using the same tea cultivar that was grown under the same conditions, Carloni and co-workers (2013) 11 have attributed the low phenolic and flavonoid profiles in black tea to manufacturing processes. ...
... Ribose results in glycation at a faster rate compared to glucose 55 as the aldofuranose ring of ribose is unstable which makes the latter susceptible to reaction with amino acids while glucose has a stable aldopyranose ring. 32 As demonstrated by Ho et al. (2010), 43 black and green teas had comparable inhibitory activity against glucose-and MGO-induced fluorescent AGE formation. Tea polyphenols, such as gallic acid, kaempferol, rutin, (+)-catechin, (−)-epicatechin, ECG, EGC, EGCG and quercetin, have previously been shown to inhibit fluorescent AGE production induced by glucose, ribose or MGO. ...
... Ribose results in glycation at a faster rate compared to glucose 55 as the aldofuranose ring of ribose is unstable which makes the latter susceptible to reaction with amino acids while glucose has a stable aldopyranose ring. 32 As demonstrated by Ho et al. (2010), 43 black and green teas had comparable inhibitory activity against glucose-and MGO-induced fluorescent AGE formation. Tea polyphenols, such as gallic acid, kaempferol, rutin, (+)-catechin, (−)-epicatechin, ECG, EGC, EGCG and quercetin, have previously been shown to inhibit fluorescent AGE production induced by glucose, ribose or MGO. ...
This study aimed at investigating and comparing the anti-diabetic potential of black and green teas. Biochemical analyses indicate higher antioxidant potency, significantly correlated to phytochemicals present, in green teas compared to black teas. Both extracts afforded similar level of protection to erythrocytes against peroxyl radical-induced lysis. Non-cytotoxic concentration of green and black tea extracts significantly reduced reactive oxygen species (ROS) production (P<0.01), lowered oxidation of proteins (P<0.05) and decreased IL-6 secretion (P<0.01) induced by AGEs or H2O2 in 3T3-L1 preadipocytes. Both teas also inhibited the decline in enzymatic activities of superoxide dismutase, catalase and glutathione peroxidase induced by the pro-oxidants. The teas further suppressed glycation of BSA mediated by glucose, ribose and MGO by reducing fluorescent AGEs, fructosamine, protein carbonyl and AOPP levels. Black and green teas also inhibited activities of α-amylase (AA50: 589.86 ± 39.51 and 947.80 ± 18.20 µg/mL respectively) and α-glucosidase (AA50: 72.31 ± 4.23 and 100.23 ± 8.10 µg/mL respectively). The teas afforded comparable level of protection at cellular level and against glycation while black tea exerted highest carbohydrate hydrolysing enzymes inhibitory activity. Our results clearly show that black and green teas represent an important source of antioxidants with anti-diabetic potential.
... This spontaneous non-enzymatic reaction occurs in hyperglycemia and in diabetic individuals and is the main factor of complication in diabetes [3]. During the early stages of glycation, reversible Schiff bases and Amadori products can be formed, and further complex rearrangements ultimately lead to the irreversible formation of heterogeneous, toxic, fluorescent, and cross-linked products known as advanced glycation end products (AGE) [4][5][6]. The glycation of proteins and AGEs can induce radical production that may damage cellular and extracellular proteins and biomolecules [7]. ...
... Even though various synthetic drugs and chemical agents such as amino guanidine have been tested for glycation inhibition, most of them had numerous side effects and low efficacy, which limited their practical application in clinical trials [4,16,17]. Natural agents, namely numerous medical herbs and dietary plants, have recently received more attention in this field because of their various biological properties [4,12]. ...
... Even though various synthetic drugs and chemical agents such as amino guanidine have been tested for glycation inhibition, most of them had numerous side effects and low efficacy, which limited their practical application in clinical trials [4,16,17]. Natural agents, namely numerous medical herbs and dietary plants, have recently received more attention in this field because of their various biological properties [4,12]. ...
This study investigated the effects of the ethanolic extract of propolis (EEP) in the absence and presence of aspirin on the glycation-induced structural changes of human hemoglobin (Hb). Hb samples were incubated in the presence and absence of glucose (40 mM) for 5 weeks in the absence and presence of various concentrations of EEP and aspirin. Sampling was conducted at the end of each week, and the extent of glycation was evaluated by spectrophotometry, Thioflavin-T test, and by measuring free amino group contents and heme degradation products. Results showed that Hb was glycated by glucose after various incubation times reduced free amino group content, downturn absorption of and induced blue shifting in the UV–visible spectrum of Hb as well as increased amyloid structures and heme degradation. EEP prevented these changes and decreased the extent of glycation in a concentration-dependent manner. Aspirin also prevented glycation with the same efficacy as EEP (20 μg/ml). Surprisingly, the simultaneous presence of aspirin and EEP resulted in the extensive inhibition of glycation; in the 40 μg/ml concentration of EEP and aspirin, glycation was fully prevented in a synergic way. It is probable that EEP exerts its anti-glycation effect via its potent antioxidant and radical scavenging properties which decrease glycation-produced oxidative stress. In conclusion, EEP is to be introduced as an anti-glycation agent for the first time in this study. It could be developed as a natural agent for the design of new anti-glycation drugs aimed at reducing protein glycation as well as diabetic complications.
... Several studies previously pointed out the antioxidant and antiglycation capacities of herbal infusions, such as black and green tea (Camellia sinensis), balm (Melissa officinalis), sage (Salvia officinalis), common verbena (Verbena officinalis), some Thai herbal teas, and mate tea (Ilex paraguariensis). 67,68 The inhibitory effects on AGEs registered for dittany infusion are similar to those reported in particular for black and green tea in BSA-GLC and BSA-MGO systems by Ho et al. 67 and for Guava tea in BSA-GLC, 69 and the activity values are higher than those registered for sage, common verbena and lemon grass (Cymbopogon citratus) herbal tea. 67,68 Moreover, the antiglycative activity of dittany is higher than that of mate tea in the BSA-MGO system 70 and mate tea and coffee in the BSA-FRU system. ...
... Several studies previously pointed out the antioxidant and antiglycation capacities of herbal infusions, such as black and green tea (Camellia sinensis), balm (Melissa officinalis), sage (Salvia officinalis), common verbena (Verbena officinalis), some Thai herbal teas, and mate tea (Ilex paraguariensis). 67,68 The inhibitory effects on AGEs registered for dittany infusion are similar to those reported in particular for black and green tea in BSA-GLC and BSA-MGO systems by Ho et al. 67 and for Guava tea in BSA-GLC, 69 and the activity values are higher than those registered for sage, common verbena and lemon grass (Cymbopogon citratus) herbal tea. 67,68 Moreover, the antiglycative activity of dittany is higher than that of mate tea in the BSA-MGO system 70 and mate tea and coffee in the BSA-FRU system. ...
... 67,68 The inhibitory effects on AGEs registered for dittany infusion are similar to those reported in particular for black and green tea in BSA-GLC and BSA-MGO systems by Ho et al. 67 and for Guava tea in BSA-GLC, 69 and the activity values are higher than those registered for sage, common verbena and lemon grass (Cymbopogon citratus) herbal tea. 67,68 Moreover, the antiglycative activity of dittany is higher than that of mate tea in the BSA-MGO system 70 and mate tea and coffee in the BSA-FRU system. 71 The antiglycative activity is generally correlated with the polyphenolic composition of the extracts. ...
Accumulation of advanced glycation end products (AGEs) in vivo is associated with many chronic disorders such as diabetes, renal failure, aging, and Alzheimer’s disease. The aim of this study was to expand the knowledge about the functional properties of Origanum dictamnus L. beverage (Cretan tea) by an investigation about the inhibitory effects on the formation of AGEs and the capacity to trap dicarbonyl compounds. Dittany infusion was characterized in its polyphenolic composition by RP-HPLC-DAD-ESI-MSn and twenty compounds were detected. Antiglycative property was evaluated by in vitro BSA-sugars (glucose, fructose, and ribose) and BSA-methylglyoxal (MGO) assays, formation of Amadori products and dicarbonyl compounds tests, direct glyoxal (GO) and MGO trapping capacity. The infusion showed the highest inhibitory effect on the formation of dicarbonyl compounds and of AGEs (activity values range 72-100%) and only a weak effect on the formation of Amadori products, indicating that the antiglycative action occurred primarly during the last two phases of the non-enzymatic glycation reaction. These activities are partially correlated with the antioxidant/antiradical activity, as demonstrated by the scavenger capacity against ABTS cation and DPPH stable radicals, and the reducing power. The registered high anti-AGEs capacity could probably be ascribed to dittany polyphenolic composition particularly rich in flavone derivatives. These findings support further investigations to study the feasibility of dittany as antiglycative agents in food or cosmetic preparation.
... A previous study on the effect of extraction temperature on polyphenol yield of papaya leaves aqueous extracts showed that the extraction yield of polyphenols increased when the extraction temperature increased from 50 to 70 • C. The yield however decreased when the temperature was raised to 100 • C, a result that may be linked to thermally-induced decomposition [30]. Vuong et al. explained the effect of elevated temperatures on the decrease of total phenolic content by trigger competing processes (decomposition and epimerization) [31]. Additionally, the vaporization of water at boiling point, by increasing the temperature, affects the ability of extraction of some phenolic compounds [32]. ...
... This correlation is also in line with Jimenez-Zamora et al., who studied antioxidant capacity and total phenolic content of chamomile and sage as infusions [28]. Other studies on herbal aqueous extracts also indicated that antioxidant activity was positively correlated with total phenolic content [5,13,18,[29][30][31][32][33]. However, according to Rivas Romero et al., the total content of antioxidants of an herbal extract, including aqueous extracts of chamomile and sage, is not bi-univocally related to its antioxidant capacity, because the distinct components of the extracts can have very different antioxidant capacities [16]. ...
Chamomile and sage are common herbs that are mostly used as infusions due to their beneficial properties. The aims of this study were to determine the total phenolic content, antioxidant activity, and potential toxicity of chamomile and sage aqueous extracts prepared at three different temperatures (25, 80, 100 °C) and finally, to detect their phenolic profiles at the optimum temperature. In order to measure the total phenolic content and antioxidant capacity, Folin–Ciocalteu and 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) assays were applied, respectively. The extraction temperature at 80 °C was the optimum, with maximal antioxidant activity and the highest total phenolic content for both herbs. Luminescence-based assay demonstrated that all the examined aqueous extracts possessed toxicity towards Vibrio fischeri. Microtox assay demonstrated no correlation with the other two assays, which were positively correlated. The major phenolics of chamomile were rutin trihydrate, ferulic acid, chlorogenic acid, and apigenin-7-O-glucoside; and major phenolics of sage were rosmarinic acid, salvianolic acid K, and luteolin-7-O-glucuronide, as defined by LC-MS of aqueous extracts at 80 °C. It can be concluded that the extraction of herbal aqueous extracts at 80 °C can provide significant bioactive and antioxidant compounds, but their consumption must be in moderation.
... In order to benchmark the SPPE beverage, statistics from data on the phenolic content, antioxidant activity and soluble solids of commercial and laboratory prototype beverages from scientific journals were computed. The commercial antioxidant beverages considered were fruit juices (Pellegrini et al. 2003;Pulido et al. 2003;Seeram et al. 2008;de Beer et al. 2012 (Pellegrini et al. 2003;Bravo et al. 2007;Ho et al. 2010) and teas (Pulido et al. 2003;Bravo et al. 2007;Ho et al. 2010). Three laboratory beverages were also used for comparison, a plum peel enriched nectar (de Beer et al. 2012), a cardio protection fruit beverage (Gunathilake et al. 2013) and a nutraceutical fruit juice (Lawless et al. 2012). ...
... In order to benchmark the SPPE beverage, statistics from data on the phenolic content, antioxidant activity and soluble solids of commercial and laboratory prototype beverages from scientific journals were computed. The commercial antioxidant beverages considered were fruit juices (Pellegrini et al. 2003;Pulido et al. 2003;Seeram et al. 2008;de Beer et al. 2012 (Pellegrini et al. 2003;Bravo et al. 2007;Ho et al. 2010) and teas (Pulido et al. 2003;Bravo et al. 2007;Ho et al. 2010). Three laboratory beverages were also used for comparison, a plum peel enriched nectar (de Beer et al. 2012), a cardio protection fruit beverage (Gunathilake et al. 2013) and a nutraceutical fruit juice (Lawless et al. 2012). ...
A beverage benchtop prototype related to oxidative stress protection was developed based on sweet potato peels phenolics. Formula components were sweet potato peel (Ipomoeas batatas L.) aqueous extract (SPPE), sweet potato leaves water extract (SPLE) and honey solution (HonS). According to linear squares regression (LSR) models, SPLE presented higher additive effect on total phenolic content (TPC), FRAP and DPPH than the other components. All antagonist interactions were not significant. The optimum formula obtained by artificial neural networks (ANN) analysis was 50.0% of SPPE, 21.5% of SPLE and 28.5% of HonS. Predicted responses of TPC, FRAP, DPPH and soluble solids were 309 mg GAE/L, 476 mg TE/L, 1098 mg TE/L and 12.3 °Brix, respectively. Optimization with LSR models was similar to ANN. Beverage prototype results positioned next to commercial vegetable and fruit beverages, thus it has an interesting potential to the market of health and wellness.
... It is also claimed that the floral beverage of various types illustrates anti-carcinogenic effect, which is most likely related to free radical scavenging activity [23]. Ho et al. [24] reported that herbal tea infusions contained anti-glycation activity that involved in aging and diabetics problems was due to phenolics and flavonoids. Nonetheless, the reports on nutritional properties from edible flowers especially those from wild habitats are lacking. ...
... NFS Journal 24 (2021)[15][16][17][18][19][20][21][22][23][24][25] ...
In this research, 4 wild flowers of Thailand were initially analysed for phytochemicals, nutritional compositions as well as their antioxidants properties. Bauhinia variegata L. (BV), Gmelina arborea Roxb. (GA), Shorea roxburghii G. Don (SR) and Viburnum inopinatum Craib (VI) were collected from Queen Sirikit Botanic Garden (QSBG) edible collection. VI contained the highest dietary fiber (25.26%), vitamin C (3.47 mg/100 g) as well other minerals including calcium (790 mg/100 g), potassium (2370 mg/100 g). SI, on the other hand had higher fat (32.30%) and iron (7.53 mg/100 g) to the others. Protein was maximum in BV (10.26 g/100 g), while GA contained the highest values carbohydrate (68.43%) and sodium (14.07 mg/100 g). Screening tests for bioactive compounds showed that flavonoids and saponins were mostly found in both water and ethanolic extracts of flowers. Tannin and polyphenols were detected in flowers of SR and VI. Moreover, terpenoids were detected only in ethanolic extracts of SR and VI. Thereafter, quantitative measurements of antioxidative compounds from the water and ethanolic extracts of these flowers were compared. Total phenolic contents were the highest in both extracts of BV and GG. GA gave the highest total flavonoid content and anti-oxidative properties by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays. The phenolic compounds were also characterised using High Performance Thin Layer Chromatography (HPTLC) and Thin Layer Chromatography/ Compact Mass Spectrometer (TLC/ CMS). The QSBG tea products that incorporated these wild flowers were formulated. The total phenolic contents, total flavonoid contents and antioxidants of these formulations were also reported.
... mediated protein glycation inhibitors[4,27,28]. Thus, the antioxidant activity of OP grade tea is likely to play a crucial role in inhibiting the MGO mediated protein glycation in this study. ...
... Thus, the antioxidant activity of OP grade tea is likely to play a crucial role in inhibiting the MGO mediated protein glycation in this study. Several studies have revealed that a strong relationship exists between phenolic content and MGO mediated protein glycation inhibitory activity[28,29]. However, surprisinglyin this study, no strong positive linear correlations were evident between MGO mediated protein glycation inhibition and TPC, TFC (indirect measures of antioxidant activity), or ABTS, DPPH and FRAP (direct measures of antioxidant activity) antioxidant activities. ...
Objective: To evaluate inhibitory activity of methylglyoxal (MGO) mediated protein glycation
and ability to potentiate its reversing activity and range of antioxidant properties of Sri Lankan
low grown orthodox orange pekoe grade black tea.
Methods: Freeze dried black tea brew (BTB) was used as the sample in this study. Antiglycation and glycation reversing activity was studied in bovine serum albumin (BSA)-MGO
model. Antioxidant properties were studied using total polyphenolic content, total flavonoid
content, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid, 1,1-diphenyl-2-picrylhydrazine
and ferric reducing antioxidant power in vitro antioxidant assays.
Results: The results demonstrated significant (P < 0.05) and dose dependant inhibition of
BSA-MGO glycation [IC50: (164.30 ± 4.85) µg/mL], potentiating of its reversing activity [EC50:
(235.39 ± 5.37) µg/mL] and marked antioxidant properties [total polyphenolic content: (119.55
± 9.97) mg gallic acid equivalents/g BTB; total flavonoid content: (6.04 ± 1.26) mg quercetin
equivalents/g BTB; 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid, 1,1-diphenyl-2-
picrylhydrazine and ferric reducing antioxidant power: (3.29 ± 0.06), (1.95 ± 0.15) and (1.31
± 0.19) mmol Trolox equivalents/g BTB, respectively]. No correlations were observed between
antioxidant activity and BSA-MGO glycation.
Conclusions: The novel properties observed for Sri Lankan orange pekoe grade black tea
indicate its usefulness as a supplementary beverage in managing MGO and advanced glycation
end products related diseases and ailments.
... During hot aqueous extraction, the action of heat causes the hydrolysis of sucrose which produces reducing sugars; this hydrolysis is less in absence of heat in cold aqueous extraction. These intrinsic carbohydrates may indirectly induce fluorescence [37] . According to Arhab R., (2007) [38] , the total sugar content varies depending on the climate, season and stage of plant development. ...
... The results of research showed that glycation acts synergistically with oxidative stress generating diabetes complications. In addition, several studies have shown a relationship between antioxidant activity and anti-glycation MAPs extracts [37] . In fact, it has been demonstrated the ability to inhibit glycation induced by methylglyoxal and glyoxal by antioxidants [69] . ...
Antioxidant and anti-glycation properties of nine Moroccan plants of the Lamiaceae family used in
traditional medicine, has been evaluated by after extraction by hot (HAE) or cold (CAE) maceration and
by ethanol (EE). Anti-glycation activity was performed on BSA-Methylglyoxal system and was
measured by fluorescence and native electrophoresis.
The EE yielded the highest levels of polyphenols and flavonoids at Origanum Compactum. The same
extract showed a strong antioxidant activity with IC50 = 75.5±0.63 µg/ml, followed by Rosmarinus
officinalis with IC50 = 99.7±0.47 µg/ml, and Calamintha officinalis with IC50 = 111±0.5 µg/ml. All plants
studied showed dose dependent anti-glycation activity, with a pronounced effect recorded in Thymus
satureioides. The aqeous extracts showed a correlation between polyphenols and flavonoids witch was in
turn correlated with antioxidant activity. No correlation was observed between anti-glycation and antioxidation/polyphenol
content. The Lamiaceae family is therefore a rich promoter source in phenolic
compounds, and presents both an antioxidant and anti-glycation activity.
... Too much attention has been addressed to dietary phytochemicals like catechins, proanthocyanidins, anthocyanin and flavonols (Dearlove, 2008;Ho et al., 2010;Lavelli et al., 2011;Hou et al., 2014;Harsha et al., 2014) as active substances able to inhibit AGEs formation and glycation process (Kazeem et al.,2012).Various in vitro and in vivo studies suggested that the inhibitory mechanism of polyphenols against glycation is due in part to their antioxidant properties that prevent a further oxidation of Amadori product and metal-catalyzed glucose oxidation (Ramkissoon et al., 2013;Daiponmak et al.,2014). In fact, the total phenolics, flavonoids and total anthocyanins inred grape skin extract (RGSE), and B-type procyanidin Figure 1. ...
The diet polyphenols are a secondary metabolites of plants able to act on inflammation process. Their anti-inflammatory activity is articulated through several mechanisms that are related to their antioxidative and radical scavengers properties. Our work is focused on a novel approach to inflammatory disease management, based on anti-glycative and matrix metalloproteinases (MMPs) inhibition effects, as a connected phenomena. To better understand these correlation, polyphenols Structure–Activity Relationship (SAR) studies were also reported. The antioxidant polyphenols inhibit the AGEs at different levels of the glycation process in the following ways: (1) prevention of Amadori adduct oxidation; (2) trapping reactive dycarbonyl compounds; (3) attenuation of receptor for AGEs (RAGE) expression. Moreover, several flavonoids with radical scavenging property showed also MMPs inhibition interact directly with MMPs or indirectly via radical scavengers and AGEs reduction. The essential polyphenols features involved in these mechanisms are C2-C3 double bond and number and position of hydroxyl, glycosyl and O-methyl groups. These factors induce a change in molecular planarity interfering with the hydrogen bond formation, electron delocalization and metal ion chelation. In particular, C2-C3 double bond improve the antioxidant and MMPs inhibition, while the hydroxylation, glycosylation and methylation induce a positive and negative correlation, respectively.
... In a previous study, condensed tannin content could not be determined rosemary tea, too. Also, the condensed tannin content of balm, mint, black tea, sage and common verbena was reported between 0.02 ± 0.00 and 2.11 ± 0.18 mg CEs/ml [20]. ...
Some non-wood forest products are brewed and consumed as tea. Among the reasons for the consumption of herbal tea, digestive problems are located in the first row. Antioxidants help to human body for arranging digestive and immune system. Herbal tea is brewed in various ways such as boiling at different durations or waiting in hot water at different temperatures etc. Type of brewing can affect to bioactive properties of herbal tea. In this study, it was investigated the bioactive properties (total phenolic content, total flavonoid content, condensed tannin content and antioxidant properties) of some herbals brewed (Green tea / Camellia sinensis., senna / Cassia sp., corn silk / Zea mays, rosemary / Rosmarinus officinalis) at different temperature. These herbs were brewed for 10 minutes at 60 o C, 80 o C and 100 o C temperatures. After cooling, total phenolic, flavonoid content, total condensed tannin content and antioxidant properties of these herbs were determined. Consistently, the highest results were found in the tea brewed at 100 o C. The highest total flavonoid (0.305 ± 0.005 mg QE/g) and ferric reducing ability (670.150 ± 2.121 µmol FeSO47H2O/g) was in Rosmarinus officinalis. The highest condensed tannin (9.443 ± 0.524 mg CE/g) and the highest total phenolic content (4.872 ± 0.005 mg GAE/g) was in Camellia sinensis and Cassia sp., respectively.
... In a previous study, condensed tannin content could not be determined rosemary tea, too. Also, the condensed tannin content of balm, mint, black tea, sage and common verbena was reported between 0.02 ± 0.00 and 2.11 ± 0.18 mg CEs/ml [20]. ...
Some non-wood forest products are brewed and consumed as tea. Among the reasons for the consumption of herbal tea, digestive problems are located in the first row. Antioxidants help to human body for arranging digestive and immune system. Herbal tea is brewed in various ways such as boiling at different durations or waiting in hot water at different temperatures etc. Type of brewing can affect to bioactive properties of herbal tea. In this study, it was investigated the bioactive properties (total phenolic content, total flavonoid content, condensed tannin content and antioxidant properties) of some herbals brewed (Green tea / Camellia sinensis., senna / Cassia sp., corn silk / Zea mays, rosemary / Rosmarinus officinalis) at different temperature. These herbs were brewed for 10 minutes at 60 o C, 80 o C and 100 o C temperatures. After cooling, total phenolic, flavonoid content, total condensed tannin content and antioxidant properties of these herbs were determined. Consistently, the highest results were found in the tea brewed at 100 o C. The highest total flavonoid (0.305 ± 0.005 mg QE/g) and ferric reducing ability (670.150 ± 2.121 µmol FeSO47H2O/g) was in Rosmarinus officinalis. The highest condensed tannin (9.443 ± 0.524 mg CE/g) and the highest total phenolic content (4.872 ± 0.005 mg GAE/g) was in Camellia sinensis and Cassia sp., respectively.
... In a previous study, condensed tannin content could not be determined rosemary tea, too. Also, the condensed tannin content of balm, mint, black tea, sage and common verbena was reported between 0.02 ± 0.00 and 2.11 ± 0.18 mg CEs/ml [20]. ...
... According to latest research conducted by Harris et al. (2011) andPeng, Ma, Chen, andWang (2011), plant extracts, which are good source of antioxidant polyphenols, could contribute to the reduction of AGE formation by preventing oxidative damage of proteins. Green tea and tea infused with selected herbs (Ho, Wu, Lin, & Tang, 2010), tomato paste (Kiho et al., 2004) or spices (Tosun & Khan, 2015) were highlighted as potential inhibitors of AGE formation. Therefore, the positive correlation between antiglycation potential and antioxidant properties in herbs was observed (Ramkissoon, Mahomoodally, Ahmed, & Subratty, 2013). ...
Glycation is known to be related with several pathophysiological complications. Several chemical and natural compounds had been tested on different systems to prevent glycation-related complications. Though they show a promising result initially, but often fail to succeed in preclinical trials. In this paper, we try to demonstrate how syringic and chlorogenic acids, two largely consumed natural products bind with BSA to prevent glycation-associated complications. Biochemical (glucose estimation) and biophysical (CD, MALDI, MS/MS) techniques have been used to demonstrate the antiglycating mechanism. We have calculated binding constant 3.07 ± 0.42 × 10− 4 and 2.67 ± 0.28 × 10− 4 M− 1 for syringic and chlorogenic acids respectively. Further we have successfully purified BSA–phenolic acid conjugates by chromatographic methods. Molecular modeling and mass spectrometric studies suggested that Lys 93,261,232, Arg 194 and Lys 93, Arg 194 are the responsible binding residues for syringic and chlorogenic acids respectively.
... The reactive carbonyl species can also be produced from sugar glyoxidation contributing to the AGE formation [14][15]. AGE products can cross-link with long-lived proteins such as collagen, lens crystallins, and other biological molecules---haemoglobin, lowdensity lipoprotein---leading to the altered structures and functions of these proteins in vivo [16][17]. Ahmed [18] reported that the glycation of lens crystallins has been considered as one of the major factors in causing diabetic cataracts. ...
Protein glycation and oxidative stress caused by chronic hyperglycemia are the major factors in diabetic complications. In the attempt to search for natural remedies, ethyl acetate and ethanol extracts from twenty Thai edible and medicinal plants were assessed in terms of their phenolic and flavonoid contents as well as their antioxidant and antiglycation activities. The highest amounts of phenolic and flavonoid compounds were found in the ethanolic extract of the young leaves of Punica granatum followed by those of Dimorcarpus longan and Mangifera indica, respectively. These three plant extracts also exhibited the highest antioxidant activity. A high correlation between the antiglycation activity and the phenolic and flavonoid contents was observed in all extracts. In addition, five ethanolic extracts-from Tamarindus indica, Psidium guajava, Mangifera indica, Dimocarpus longan and Punica granatum young leaves-were determined for their concentrations required to inhibit 50% (IC50) of either glucose or methyl glyoxal-derived glycation. P.granatum, M.indica and P.guajava extracts showed high antiglycation activity in the BSA-glucose model, with IC50 values of 110.4, 214.4 μg/mL and 243.3 μg/mL, respectively. The IC50 values of antiglycation activity in the BSA-methylglyoxal model of M.indica (54.1 μg/mL), P.granatum (69.1 μg/mL) and D.longan (74.2 μg/mL) were higher than that of the standard AGE inhibitor, aminoguanidine (91.2 μg/mL). These results indicated that some Thai edible and medicinal plants possessed high contents of phenolic and flavonoid and have potential applications towards the prevention of glycation-associated diabetic complications.
... Table 2, the total catechin content of green tea made from purple-colored-leaf tea cultivars (TTES No.113 & 117) were higher than that of from green-coloredleaf tea cultivar (TTES No.18). As expected, due to oxidation and polymerization into theafl avins and thearubigins, the Table 4, fructosamine formation was inhibited by all tea infusions in a dose-dependent manner at dilutions from 2-fold [ [25][26][27] The inhibitory mechanism of phenolics and fl avonoids against glycation was partly due to their scavenging effect on free radicals derived from the glycoxidation process. [28] Moreover, anthocyanin-rich extract from berries, red grape skin and butterfl y pea fl ower petals have also been reported to exhibit anti-glycation capacity, and total phenolics rather than anthocyanins seems to be primarily responsible for the anti-glycation capacity. ...
p>The special tea varieties with purple- or red-colored leaves have been successfully bred in Taiwan and their health benefits are needed to be evaluated. The aim of this study was to evaluate the phytochemical content, the antioxidant properties, and the anti-glycation capacities of two new purple-colored-leaf tea cultivars (TTES No.113 & 117) and one of the most cultivated teas in Taiwan (TTES No.18). Green tea made from the two purple-colored-leaf tea cultivars, especially the TTES No.117 had significantly higher phenolic, flavonoid, anthocyanin, and catechin content than the TTES No.18. The purple-colored-leaf tea also had higher antioxidant activities including ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC). The formation of fluorescent advanced glycation end products (AGEs) and non-fluorescent AGEs (Nɛ-carboxymethyllysine; CML) in a glucose/ BSA system were significantly inhibited by teas. The inhibitory capacities of teas on fluorescent AGEs and CML were correlated with phenolics or flavonoids, rather than catechins or anthocyanins. These results implied that the potent antiglycation capacity of purple-colored-leaf tea was primarily attributed to the total phenolics. These findings highlight that the potential use of purple-colored-leaf tea bred in Taiwan as a functional beverage for preventing diabetic complications.</p
... RA and CA are antioxidants that can mitigate diabetes in animals (Sedighi, Zhao, Yerke, & Sang, 2015;Vanithadevi & Anuradha, 2008;Zhao, Sedighi, Chen, Zhu, & Sang, 2015), and infusions of green tea with rosemary have been shown to exhibit antiglycation activity (Ho, Wu, Lin, & Tang, 2010). Thus, RA and CA may inhibit AGEs formation. ...
This work aimed to investigate the effect of the two main components of rosemary extracts, namely rosmarinic acid (RA) and carnosic acid (CA), on the formation of advanced glycation end-products (AGEs) in vitro. In the bovine serum albumin (BSA)/glucose model, addition of RA and CA at 400 μg/mL inhibited fluorescent AGEs by more than 90%, and carboxymethyl lysine (CML) and carboxyethyl lysine (CEL) by 82.7% and 75.2%, and 71.4% and 64.2%, respectively. Moreover, the addition of RA and CA at 400 μg/mL inhibited fluorescent AGEs by more than 90% both in the BSA/glyoxal (GO) and BSA/methylglyoxal (MGO) models, the formation of CML by 64.9% and 53.9% in BSA/GO model, and CEL by 28.9% and 24.3% in BSA/MGO model, respectively. RA and CA also significantly decreased the concentration of MGO and protein carbonylation.
... Accordingly, comparing the antiglycation capacities of different herbal infusions based on the experimental results obtained from a 40-fold dilution seems logical. At a 40-fold dilution, the antiglycation capacity of herbal infusions followed the order, balm (89.8%) >mint (47.8%) >black tea (38.0%) >green tea (35.4%), sage (33.4%) and common verbena (30.4%) >rosemary (18.8%) >lemongrass (3.0%) [236]. ...
First described in the context of diabetes, advanced glycation end products (AGEs) are formed through a type of non-enzymatic reaction called glycation. Protein glycation and formation of advanced glycation end products (AGEs) play an important role in the pathogenesis of diabetic complications like retinopathy, nephropathy, neuropathy, cardiomyopathy along with some other diseases such as rheumatoid arthritis, osteoporosis, and, recently, skin aging. Glycation of proteins interferes with their normal functions by disrupting molecular conformation, altering enzymatic activity, and interfering with receptor functioning. AGEs form intra- and extracellular cross linking not only with proteins, but with some other endogenous key molecules including lipids and nucleic acids to contribute in the development of diabetic complications. Recent studies suggest that AGEs interact with plasma membrane localized receptors for AGEs (RAGE) to alter intracellular signaling, gene expression, release of pro-inflammatory molecules and free radicals. Characteristic findings of aging skin, including decreased resistance to mechanical stress, impaired wound healing, and distorted dermal vasculature, can be in part attributable to glycation. Multiple factors mediate cutaneous senescence, and these factors are generally characterized as endogenous (e.g., telomere shortening) or exogenous (e.g., ultraviolet radiation exposure). Interestingly, AGEs exert their pathophysiological effects from both endogenous and exogenous routes. The former entails the consumption of sugar in the diet, which then covalently binds an electron from a donor molecule to form an AGE. The latter process mostly refers to the formation of AGEs through cooking. Results of several studies in animal models and humans show that the restriction of dietary AGEs has positive effects on wound healing, insulin resistance and cardiovascular diseases. Recently, the effect of restriction in AGEs intake has been reported to increase the lifespan in animal models. Recent studies have revealed that certain methods of food preparation (i.e. grilling, frying, and roasting) produce much higher levels of AGEs than water-based cooking methods such as boiling and steaming. Moreover, several dietary compounds have emerged as promising candidates for the inhibition of glycation-mediated aging. In this chapter, we summarize the evidence supporting the critical role of glycation in skin aging and highlight preliminary studies on dietary strategies that may be able to combat this process.
... Lu, Lee, Mau, and Lin (2010) observed also similar 450 results upon the antioxidant properties of green tea sponge cake. 451 Fig. 2A ) and higher formation of Ama- 481 dori compounds (Fig. 2BHo et al., 2010; Mesias 499 et al., 2014; Zhang et al., 2014). Vuong, Bowyer, & Roach, 2011). ...
The antiglycoxidative properties of theanine (TEF) and polyphenols enriched fractions (PEF) prepared from tea dust were tested in a model system composed of bovine serum albumin (BSA) and methylglyoxal (MGO). PEF caused a decrease in available free amino groups of BSA in presence and absence of MGO, suggesting the simultaneous occurrence of glycoxidation reaction and phenols-protein interaction. The presence of PEF and TEF inhibited formation of fluorescent advanced glycation end-products (AGEs). Moreover, theanine (TB) and polyphenol-enriched bread (PB) were formulated. A significant increase in free amino groups was observed in TBs with a dose-response effect, while addition of PEF in bread produced a significant decrease (p < 0.05). PEF efficiently reduced fluorescent AGE formation in breads compared with TEF. The results are in line with the simplified model systems. PEF used as food ingredient allows obtaining a tasty food possessing health promoting properties and lower content of potential harmful compounds (AGEs).
... Several evidences have demonstrated that their antiglycating potential is correlated significantly with the total phenolics present in their extracts. (115)(116)(117)(118)(119) Methanol extracts of whole plants of Calendula officinalis and fruits of Juglans regia have shown antiglycating activity with respect to bovine serum albumin (BSA) in vitro, and their antiglycating potential is comparable to that of AG on the weight concentration basis. (120) During in vitro conditions, ethyl acetate extracts of Erigeron annuus inhibited glycation of BSA, prevented opacification of lenses and inhibited aldose reductase. ...
Non-enzymatic glycosylation (glycation) plays an important role in the development of physiological and pathophysiological processes such as aging, diabetes, atherosclerosis, neurodegenerative diseases and chronic renal failure. Preventing glycation can minimize diabetic complications. Glycation can be prevented by the natural defence system in the body, synthetic inhibitors and natural inhibitors. Synthetic inhibitors may prevent glycation through several possible mechanisms. They might inhibit the glycation by interfering with the attachment of sugars with proteins, by inhibiting the late stage of glycation or by preventing Amadori product formation. Furthermore, their ability to scavenge free radicals and to break cross-links might be other mechanisms responsible for their potential to inhibit glycation. Naturally occurring phytochemicals/products have been found to be relatively non-toxic as compared to synthetic compounds, and are inexpensive and available in an ingestible form. A large number of plants and natural biomolecules have been shown to have antidiabetic effects. Several hypoglycaemic compounds have anti-oxidant properties. The present review describes the various ways in which glycation can be prevented.
... It was suggested that the glycation in the model was inhibited by the addition of resveratrol. The inhibition capability of resveratrol could be attributed to its function of scavenging free radicals, chelating metals and trapping carbonyls as phenolic compounds (Ho, Wu, Lin, & Tang, 2010). Also, resveratrol could protect BSA against glycation through hydrogen bonds and electrostatic interactions. ...
Glycation can generate advanced glycation end products (AGE) and its intermediates methylglyoxal (MGO) and glyoxal in foods, which increase the risk of developing diabetes diseases. In this study, the effect of resveratrol against AGE formation, carbohydrate-hydrolyzing enzyme activity and trapping MGO capability were evaluated. Resveratrol showed a significant inhibition capability against AGE formation in bovine serum albumin (BSA)-fructose, BSA-MGO and arginine-MGO models with inhibition percentages of 57.94, 85.95 and 99.35%, respectively. Furthermore, resveratrol acted as a competitive inhibitor for α-amylase with IC50 3.62 μg/ml, while it behaved in an uncompetitive manner for α-glucosidase with an IC50 of 17.54 μg/l. A prevention of BSA protein glycation was observed in the BSA-fructose model with addition of resveratrol. Three types of resveratrol-MGO adducts were identified in the model consisting of MGO and resveratrol. The results demonstrated that resveratrol has potential in reducing glycation in foods and retarding carbohydrate-hydrolyzing enzyme activities.
... RA and CA are antioxidants that can mitigate diabetes in animals (Sedighi, Zhao, Yerke, & Sang, 2015;Vanithadevi & Anuradha, 2008;Zhao, Sedighi, Chen, Zhu, & Sang, 2015), and infusions of green tea with rosemary have been shown to exhibit antiglycation activity (Ho, Wu, Lin, & Tang, 2010). Thus, RA and CA may inhibit AGEs formation. ...
This study evaluated the protective effects of two rosemary components, namely, rosmarinic acid and carnosic acid against hypoglycemia, hyperlipidemia, oxidative stress and an imbalanced architecture of gut microbiota in diabetic rats. The treatment with rosmarinic acid and carnosic acid (30 mg/Kg) decreased the levels of fasting plasma glucose (23.7%, 15.6%), total cholesterol (30.4%, 14.1%), and triglyceride (65.7%, 47.8%) at 15 weeks. Rosmarinic acid and carnosic acid also exhibited antioxidative and anti-glycative effect by lowering the formation of MDA and advanced glycation end-products. In addition, they showed protective effects against tissue damage and inflammation in the abdominal aorta based on microscopic observation and the analysis of protein expression. Finally, their prebiotic effects on gut microbiota were demonstrated by increasing the population of diabetes-resistant bacteria and decreasing the amount of diabetes-sensitive bacteria. Overall, rosmarinic acid showed stronger protective effect than carnosic acid in mitigating the diabetic symptoms in rats.
... Glycation is a chaotic process which can take place endogenously (Kellow and Savige, 2013) and modifies biomolecules (Misciagna and Michele, 2007). The process is a nonenzymatic reaction of proteins with sugars (Ho et al., 2010). These modifications lead to impaired protein functions (Goodarzi et al., 2010) and perhaps contributes to microvascular diseases that slows down wound healings of diabetic patients, associated complications and aging-related sicknesses for instance cataracts, retinopathy, renal dysfunction and arteriosclerosis (Rodriguez and Jarvis, 2012;Anguizola et al., 2013;Akash, et al., 2013). ...
Benzimidazole derivatives 1–20 were synthesized and evaluated for antiglycation and antioxidant potentials. Among the series some analogs showed antiglycating potential ranging in between 182.30 ± 1.20 and 473.51 ± 2.17 when compared with standard rutin (IC50 value 295.09 ± 1.04 µM) and for antioxidant potential ranging between 22.42 ± 0.26 and 82.30 ± 1.33 when compare with standard Propyl gallate (IC50 value 29.20 ± 1.25). Compound 2, 6, 10 and 19 showed potent antioxidant and antiglycation inhibitory potentials. Compounds 7, 11, 13, 15 and 20 showed moderate antiglycating potential with IC50 values 473.51 ± 2.17, 325.20 ± 1.70, 440.0 ± 3.60, 370.60 ± 2.80 and 415.20 ± 3.20 μM, and these compounds also showed excellent antioxidant potential with IC50 values 73.51 ± 1.17, 45.63 ± 0.92, 82.30 ± 1.33, 75.41 ± 1.51, 40.60 ± 0.80 and 64.92 ± 1.41 μM respectively. The remaining compounds 1, 3, 4, 5, 8, 9, 12, 14, 16, 17and 18 were found inactive.
... Shen, Zhou & Wang, 2019;Yilmaz et al.,2018;Yeh, Hsia, Lee & Wu , 2017;Crasci, Lauro, Puglisi & Panaico, 2018;Perron & Brumaghim. 2009;Hou, Wang, Liu, Song, & Liu, 2014;Nagasawa et al., 2003 ;Liu, et al., 2013;Seo et al., 2014;Dearlove, Greespam, Hartle, Swanson, & Hargrove J, 2008;Ho, et al., 2010;Lavelli, Corey, Kerr, & Vantaggi 2011;Harsha, Lavelli , & Scarafoni, 2014;Kazeem, Akanji, Hafizur, & Choundhary, 2012;Sadowska-Bartosz, Galiniak, & Bartosz 2014, Wu & Yen, 2005. ...
The formation of advanced glycation end-products (AGEs) is a key pathophysiological event linked not only to the onset and progression of diabetic complications, but also to neurodegeneration, cardiovascular diseases, cancer, and others important human diseases. AGEs contributions to pathophysiology are mainly through the formation of cross-links and by engaging the receptor for advanced glycation end-products (RAGE). Polyphenols are secondary metabolites found largely in fruits, vegetables, cereals, and beverages, and during many years, important efforts have been made to elucidate their beneficial effects on human health, mainly ascribed to their antioxidant activities. In the present review, we highlighted the beneficial actions of polyphenols aimed to diminish the harmful consequences of advanced glycation, mainly by the inhibition of ROS formation during glycation, the inhibition of Schiff base, Amadori products, and subsequent dicarbonyls group formation, the activation of the glyoxalase system, as well as by blocking either AGEs-RAGE interaction or cell signaling.
... In the protein cross assay the inhibition competency of chloroform extract is ascribed to its role of metal chelation, scavenging free radicals, chelating metals and trapping of carbonylic compounds as phenolics. 25 The standard drug rutin on the other hand showed a comprehensive antiglycation potential (65%) that could be attributed to quenching of dicarbonyl compounds. 26 Overall the chloroform fraction presented significantly high levels inhibition of cross link formation. ...
Objective:
To investigate the inhibitive efficacy of Nymphoides Indica (L.) Kuntze rhizome extract on α-glucosidase and on cross-link formation of advanced glycation end products (AGEs).
Methods:
The plant extracts were prepared by cold maceration and fractionated in solvents of diverse polarity. The in vitro α-glucosidase inhibition assay, fluorescence spectrometry and SDS-PAGE analysis was performed for antiglycation assays.
Results:
During α-glucosidase inhibition assay significant inhibition by chloroform (0.43 mg/mL) and methanol fractions (0.66 mg/mL) was noticed. During the AGEs inhibition assay, both oxidative (BSA-MGO) and non-oxidative (BSA-glucose) modes were employed. The inhibition of AGEs by total extract was considered moderate (IC50 0.10 mg/mL) as a result of non-oxidative mode, whereas in case of oxidative mode (BASA-MGO) no activity was recorded. Among fractions the methanolic fraction presented significant results both in oxidative (IC50 0.01 mg/mL) and non-oxidative modes (IC50 0.3 mg/mL). Likewise the ethyl acetate fraction was more active in non-oxidative mode (IC50 0.04 mg/mL) compared to oxidative mode (IC50 0.32 mg/mL). During assay for inhibition of cross-link formation, the chloroform fraction significantly inhibited cross-link formation in a dose dependent mode.
Conclusion:
It was finally concluded that N. Indica rhizome extract possesses significant properties that inhibit α-glucosidase, and AGEs cross-link formation.
... Previous studies also confirmed that the strong correlation between phenolic contents and Anti-AGE formation activities in natural products [22]. The prevention of further oxidation of Amadori product and metal-catalyzed glucose oxidation are the main mechanisms involved with retardation of AGE synthesis by the natural anti-oxidative agents [46]. ...
Background: The excessive formation of Advanced Glycation End-products (AGEs) by non-enzymatic glycation mediates many health complications in the human body and the formation of AGEs largely accelerated under the hyperglycaemic condition. Objective: The prospect of the study to assess the strength of inhibiting the rapid AGE formations in four Ayurvedic medicinal plants, namely; Salacia reticulata (stems), Syzygium cumini (barks), Artocarpus heterophyllus (mature leaves) and, Cassia auriculata (flowers). Materials and methods: Herbal decoctions of four medicinal plant materials were prepared by simmering with hot water as prescribed by the Ayurvedic medicine. The effectiveness of the decoctions was analyzed in vitro based on their Anti-AGE formation activity, glycation reversing, and anti-oxidant potentials. Results: According to the results, the decoctions of S. reticulata, A. heterophyllus and C. auriculata indicated the strong Anti-AGE forming (IC 50 : 23.01 ± 2.70, 32.01 ± 2.09, 43.66 ± 2.11 mg/mL, respectively), glycation reversing (EC 50 : 183.15 ± 7.67, 91.85 ± 1.93, 252.35 ± 4.03 mg/mL, respectively) and antioxidant potentials in terms of total polyphenol content (TPC), total flavonoid content (TFC), ferric ion reducing power (FRAP), ABTS and DPPH radical scavenging activities. However, the decoction of S. cumini reported the significantly high (p < 0.05) Anti-AGE forming, (IC 50 : 9.75 ± 0.32 mg/mL), glycation reversing (EC 50 : 66.45 ± 4.51 mg/mL), and antioxidant potentials against the decoctions of the other three plant materials. Conclusion: S. cumini bark extract was identified as the best source in controlling the formation of AGEs excessively. Further, the other three plant extracts can also be effectively used as potential therapeutic agents to control the pathological conditions associated with AGEs-mediated health complications.
... Previous studies also confirmed that the strong correlation between phenolic contents and Anti-AGE formation activities in natural products [22]. The prevention of further oxidation of Amadori product and metal-catalyzed glucose oxidation are the main mechanisms involved with retardation of AGE synthesis by the natural anti-oxidative agents [46]. ...
... The higher levels of total phenolics and flavonoids in green tea than black tea is in accordance to literature data (Ho et al., 2010;Carloni et al., 2013) and is attributed to the manufacturing processes. As such, increased levels of (+)-catechin, (-)-epicatechin, EGC, EGCG, ECG, quercetin glycosides and kaempferol glycosides occur in green tea compared to black tea as the fermentation process during black tea manufacturing oxidises most of the catechins, resulting in formation of theaflavins and thearubigins (Paquay et al., 2000;Del Rio et al., 2004). ...
About 6,800 island angiosperms are globally threatened by extinction, yet the causes behind their decline remain largely elusive. Here, an endangered Mauritius endemic scrambler was used as a model island plant to understand the factors driving its decline. A series of observational and manipulative experiments were carried out to determine its distribution, pollination biology, pollinator effectiveness and temporal impact of invasive ants on its gecko- plant pollination mutualism. Over the last 80 years, its population has declined drastically, previously unknown flower visitors were revealed and the once thought major threat was proven to be negligible in absence of invasive plants. Conservation managers should exercise a more holistic approach including the spatio-temporal scale, synergy and antagonism between threats when devising plant conservation measures.
... The polyphenols that can be used in AGEs inhibition are mainly about flavonoids and phenolic acids (Chen et al., 2019). Ho et al. analyzed the inhibitory effects of different kinds of herbal extracts on AGEs, such as lemon grass, green tea, sage, mint and verbena etc., suggesting that the active ingredients that can inhibit the AGEs formation are mainly polyphenol compounds, especially flavonoids (Ho & Wu & Lin and Tang, 2010). Matsuda et al. systematically examined the ability of 62 flavones to inhibit AGEs in a glucose-BSA system, and got good inhibition effects. ...
... A marked inhibition of the formation of AGE and CML was demonstrated in in vitro model systems, which was associated with the presence of caffeic acid and chlorogenic acid (93) . Moreover, chlorogenic acid may interfere with glucose absorption (94) . It was also shown that extracts of Ilex paraguariensis were able to inhibit AGE-precursor formation in a similar way as synthetic AGE inhibitors, including aminoguanidine or carnosine (61) . ...
This review aims to give dietary recommendations to reduce the occurrence of the Maillard reaction in foods and in vivo to reduce the body’s AGE/ALE pool. A healthy diet, food reformulation and good culinary practices may be feasible for achieving the goal. A varied diet rich in fresh vegetables and fruits, non-added sugar beverages containing inhibitors of the Maillard reaction, and foods prepared by steaming and poaching as culinary techniques is recommended. Intake of supplements and novel foods with low sugars, low fats, enriched in bioactive compounds from food and waste able to modulate carbohydrate metabolism and reduce body’s AGE/ALE pool is also recommended. In conclusion, the recommendations made for a healthy eating by the Spanish Society of Community Nutrition (SENC) and Harvard University seem to be adequate to reduce dietary AGE/ALE, body’s AGE/ALE pool and to achieve a sustainable nutrition and health.
... A strong correlation (r=0.964, p<0.05) existed between phenolic and flavonoid, which indicate flavonoid may contribute to most of the phenolic in the tea which in agreement with previous study [18] on various herbal tea. ...
... For instance, dihydrochalcones from Malus leaves (De Bernonville et al., 2010); flavan-3-ols from green tea and Procyanidins from cinnamon have shown antiglycation effects . A multitude of research studies have previously established a correlation between PC with the antiglycation activity (Deetae, Parichanon, Trakunleewatthana, Chanseetis, & Lertsiri, 2012;Ho, Wu, Lin, & Tang, 2010;Ramkissoon et al., 2013). ...
Chronic hyperglycemia presents the major etiology of diabetes mellitus and related complications mainly Alzheimer's disease, via the protein glycation and toxic products generated. In the current study, we investigated the eventual protective effect of the methanolic extract of Ceratonia siliqua L. (CsME) against glucose‐mediated glycation in serum bovine albumin. The multi‐stage glycation markers, namely fructosamines and advanced glycation end products (AGEs) levels were monitored along with measurement of thiol groups; moreover, the in vitro acetylcholinesterase (AChE) inhibition potential was carried out. HPLC was also assessed. Rutin was the main phenolic compound found in CsME. CsME showed a good capacity to inhibit AGEs, fructosamines and protected thiol groups against glycation. CsME exhibited a great AChE inhibition activity. In the present study, CsME prevented glucose‐induced protein glycation, it also exhibited a good inhibition of AChE, suggesting its DM complications such as memory troubles related to AD.
Practical applications
Neurodegenerative disorders ranging from memory troubles to Alzheimer's disease present the most diabetes mellitus complications and mainly attributed to protein glycation process. Currently, there is a strong trend to search for efficient natural sources of glycation and acetylcholinesterase inhibitors to replace the synthetic ones, whose secondary effects were shown. The present article tries to justify scientifically the wide use of Ceratonia siliqua L. in Moroccan folk medicine, demonstrating that the methanolic extract of leaves from this species presents a promising source of new natural compounds inhibiting acetylcholinesterase and acting in vitro against glycation generated compounds. Furthermore, for the first time, Rutin was the main phenolic compound found in this extract, these encouraging results should be coupled with further studies to integrate it in pharmaceutical formulations. As such, this paper should be of interest to a broad readership, including those interested in Biochemistry, Phytochemistry, pharmacology, and neurosciences.
... The green tea was ranked at 3 rd position after rosemary and lavender with total flavonoid content as 44.9±1.3 mg Catechin Equivalent (CE)/g of extract. Later, Ho et al. [66] measured flavonoids in green tea as 0.68±0.03 mg CEs/mL i.e. higher than black tea 0.53±0.00 ...
The incorporation of plant originated non-nutritive components named as phytonutrients in dietary approaches has upgraded the evolving theory of designer foods in terms of health assistance and disease modulatory potential. In this regard, previous researchers developed green tea (Camellia sinensis) extract enriched dietary prototypes such as candies, meat & fish products, crackers, cakes & breads and oil & juices that have shown improvement in shelf -stability of products especially against microbial attack. For enrichment, such components are often extracted using optimized extraction procedures either conventional like solvents extraction or advanced such as supercritical fluid extraction. There are certain health concerns associated with solvent extraction procedure as in this process some residual effects of solvents may sustain declining the consumer acceptability based on religious or cultural norms. On the other hand supercritical fluid extraction is considered as a green extraction method based on safety concerns. Though, the extract achieved via supercritical fluid extractor is costly as compared to conventional extracts still this amount is far lesser than cost expanded to fight against lifestyle related disorders. The green tea possesses varied catechin such as epicatechin (EC), epigallocatechin (EGC), epicatechin gallat (ECG), and epigallocatechin gallate (EGCG). Previous researchers have worked on different extraction methods, solvents and their ratios, time, temperature and pressure conditions for optimized extraction of polycatechin from green tea. The galloyl group of green tea has proven their ability to capture free radicals, involved in oxidative stress. Various researchers are working on affirmative participation of phytonutrients in physiological activities of the body. Such therapies have shown their potential to address metabolic aliments and immune dysfunction. In this connection , epigallocatechin-3-gallate (EGCG) has defensive aptitude to fight against free radical mediated lipid peroxidation especially in liver and renal tissues besides, it modulates the glycemic index as well as serum lipid profile hence protects against obesity and associated chronic maladies. Besides, it has highlighted the ideology of immunonutrition in down-regulating oncogenic events by inducing apoptosis and inhibiting cell proliferation & angiogenesis.
KEYWORDS: Green tea, Nutraceutics, Nutrification, Designer foods, Polycatechins, Epigallocatechins-3-gallate (EGCG), Epigallocatechin (EGC), epicatechin gallate (ECG), Epicatechin (EC), Conventional solvents extraction (CSE), Supercritical fluid extraction (SFE), Nephrotoxicity, Oncogenic event.
... The green tea was ranked at 3 rd position after rosemary and lavender with total flavonoid content as 44.9?1.3 mg Catechin Equivalent (CE)/g of extract. Later, Ho et al. [66] measured flavonoids in green tea as 0.68?0.03 mg CEs/mL i.e. higher than black tea 0.53?0.00 mg CEs/mL. ...
The incorporation of plant originated non-nutritive components named as phytonutrients in dietary approaches has upgraded the evolving theory of designer foods in terms of health assistance and disease modulatory potential. In this regard, previous researchers developed green tea (Camellia sinensis) extract enriched dietary prototypes such as candies, meat & fish products, crackers, cakes & breads and oil & juices that have shown improvement in shelf -stability of products especially against microbial attack. For enrichment, such components are often extracted using optimized extraction procedures either conventional like solvents extraction or advanced such as supercritical fluid extraction. There are certain health concerns associated with solvent extraction procedure as in this process some residual effects of solvents may sustain declining the consumer acceptability based on religious or cultural norms. On the other hand supercritical fluid extraction is considered as a green extraction method based on safety concerns. Though, the extract achieved via supercritical fluid extractor is costly as compared to conventional extracts still this amount is far lesser than cost expanded to fight against lifestyle related disorders. The green tea possesses varied catechin such as epicatechin (EC), epigallocatechin (EGC), epicatechin gallat (ECG), and epigallocatechin gallate (EGCG). Previous researchers have worked on different extraction methods, solvents and their ratios, time, temperature and pressure conditions for optimized extraction of polycatechin from green tea. The galloyl group of green tea has proven their ability to capture free radicals, involved in oxidative stress. Various researchers are working on affirmative participation of phytonutrients in physiological activities of the body. Such therapies have shown their potential to address metabolic aliments and immune dysfunction. In this connection , epigallocatechin-3-gallate (EGCG) has defensive aptitude to fight against free radical mediated lipid peroxidation especially in liver and renal tissues besides, it modulates the glycemic index as well as serum lipid profile hence protects against obesity and associated chronic maladies. Besides, it has highlighted the ideology of immunonutrition in down-regulating oncogenic events by inducing apoptosis and inhibiting cell proliferation & angiogenesis. KEYWORDS: Green tea, Nutraceutics, Nutrification, Designer foods, Polycatechins, Epigallocatechins-3-gallate (EGCG), Epigallocatechin (EGC), epicatechin gallate (ECG), Epicatechin (EC), Conventional solvents extraction (CSE), Supercritical fluid extraction (SFE), Nephrotoxicity, Oncogenic event.
In the recent years multifunctional biocompatible materials based on poly-lactic acid (PLA) have gain great interest in biomedical applications for its biocompatibility in the human body. However, some PLA properties have to be enhanced such as its low crystallinity and its mechanical properties. The introduction of other materials to reinforce PLA matrix as well as the addition of active additives to reduce the microorganism growth on the final material has been also suggested to obtain a final material with active properties. The addition of 25 wt% of poly-3-hydroxybutyrate (PHB) into PLA matrix has shown a positive reinforcement effect by maintaining the biocompatibility of the final formulation. The use of natural terpene D-(+)-limonene (D- (+)-Lim) to improve the compatibility between two polymer matrixes has been also proposed. The introduction of citrus essential oil as a component in biocompatible polymeric matrices opens new perspectives for biomedical applications.
N‐epsilon‐carboxymethyllysine (CML), as a potential glycotoxin and general marker for dietary advanced glycation end products (dAGEs), exists in raw food and is formed via various formation routes in food processing such as Maillard reaction between the reducing sugars and amino acids. Although comprehensive cause‐effect proof is not available yet, current research suggests a potential risk of chronic diseases such as diabetes is associated with exogenous CML. Thus, CML is causing public health concerns regarding its dietary exposure, but there is a lack of explicit guidance for understanding if it is detrimental to human health. In this review, inconsistent results of dietary CML contributed to chronic disease are discussed, available concentrations of CML in consumed foods are evaluated, measurements for dietary CML and relevant analytic procedures are listed, and the possible mitigation strategies for protecting against CML formation are presented. Finally, the main challenges and future efforts are highlighted. Further studies are needed to extend the dietary CML database in a wide category of foods, apply new identifying methods, elucidate the pathogenic mechanisms, assess its detrimental role in human health, and propose standard guidelines for processed food.
Water infusion of pan-fried minimally oxidized leaves of plant Camellia sinensis is recognized as green tea. This infusion is rich in catechins, the bioactive components responsible for its health-promoting potential. Herbal teas or tisanes are the infusion or decoction of plant parts other than Camellia sinensis. Tisanes are generally known for their refreshing taste, fragrance, tranquilizing, and antioxidant effects. These infusions are also loaded with different types of phenolic compounds and exhibit multiple health benefits. The popularity and consumption of green tea is on the rise world over, but herbal teas are underutilized. There is a need to explore more about herbal teas and their biological activities especially in comparison to green tea. This review provides an update on the comparative studies carried out between green tea and herbal teas for antioxidant, antidiabetic, antimicrobial and anticancer properties.
N-(carboxyethyl) lysine (CEL) is a kind of advanced glycation end-products (AGEs) derived from Maillard Reaction. The effect of four natural sources of antioxidants, including water-soluble antioxidant of bamboo leaves (AOB-w), water-soluble tea polyphenols (TP-w), oil-soluble antioxidant of bamboo leaves (AOB-ο) and oil-soluble tea polyphenols (TP-ο) on CEL formation in cookies were investigated and the optimal mitigation strategy was summarized. The cookie dough with or without addition of the selected antioxidants was all baked at 205°C for 11 min and the CEL contents in the final products were quantified by UPLC-MS/MS. The antioxidant activity, sensory evaluation and evaluation of other cookie quality attributes, including diameter, thickness, spread ratio, color, moisture content and texture were also performed. The results showed that the CEL content in control cookies was 11.97±0.26 mg/kg. Four antioxidants at the addition level of 0.01~0.05% (m/m) effectively inhibited CEL formation with 7.29~67.25% inhibitory rates. And the ddition of 0.03% (m/m) AOB-ο induced the lowest CEL content (3.71±0.01 mg/kg) in cookie. Further experiments confirmed that 0.03% AOB-ο addition treatment significantly increased the antioxidant activity of cookies by DPPH and ABTS assays and kept the original quality attributes and sensory properties of cookies.
Natural and synthetic xanthone derivatives are well known for their ability to act as antioxidants and/or enzyme inhibitors. This paper aims to present a successful synthetic methodology toward xanthenedione derivatives and the study of their aromatization to xanthones. Additionally their ability to reduce Fe(III), to scavenge DPPH radicals, and to inhibit AChE was evaluated. The results demonstrated that xanthenedione derivative 5e, bearing a catechol unit, showed higher reduction capacity than BHT and, similar to quercetin, strong DPPH scavenging activity (EC50 = 3.79 ± 0.06 µM) and it was also shown to be a potent AChEI (IC50 = 31.0 ± 0.09 µM) compared to galantamine (IC50 = 211.8 ± 9.5 µM).
Tea is the second most consumed beverage aside from water, and has gained much attention due to its health-promoting benefits. Among the benefit effects include antimutagenic, anticancer and anti apoptotic, neuroprotective, hypoglycemic and antihyperglycemic, antioxidant, antimicrobial, and anti inflammatory. These biological activities are associated in part to the antioxidant activity of chemical compounds present in teas, especially flavonoids and phenolic compounds (Chapter 1). The aim of this study was to evaluate the phenolic
compounds and in vitro antioxidant activity of teas consumed in Brazil. In the Chapter 2, 51 Brazilian teas of eight different species (Camellia sinensis, Peumus boldus, Matricaria recutita, Baccharis trimera, Cymbopogon citratus, Pimpinella anisum, Mentha piperita and Ilex paraguariensis) were analyzed in terms of the phenolic compounds, color, and in vitro antioxidant activity using FRAP and DPPH. The dataset was analyzed using PCA, HCA, and LDA. Gallic acid, catechin, epicatechin, procyanidin B2, quercetrin, and caffeine displayed a significant correlation (p < 0.05) with antioxidant activity. Using the PCA was possible to have a suitable approach to check the similarities among tea samples, explaining up to 50% of data variability and four clusters were suggested by HCA. The overall classification of 82% was obtained by LDA, which 100% of samples from I. paraguariensis, C. citratus, M. recutita, and P. boldus were adroitly classified, while 60% of teas from P. anisum, 80% of M. piperita, and 88% of C. sinensis teas were correctly classified. Chapter 3 was modelled the extraction of phenolic compounds and in vitro antioxidant activity from mixtures of green, white, and black teas (Camellia sinensis) using a simplex-centroid design couple multiple regression analysis. All proposed models were significant (p < 0.05) and showed high determination coefficients (R2adj > 0.80). A simultaneous optimization was performed using the desirability function and optimum point to maximize the extraction of epicatechin, epigallocatechin gallate, epicatechin gallate, as well as the antioxidant activity (DPPH and FRAP) was suggested. Therefore, in the Chapter 3 the results showed up that white tea was the best solution for obtaining the higher content of antioxidant compounds, then the Chapter 4 was destined to optimize the extraction of antioxidant compounds from white tea by BoxBehnken design and the compounds were identified by LC-DAD-MS/MS. All mathematical
models proposed were able to explain up more that 85% of data variation and the optimization performed using DPPH, ABTS, FRAP, (-)-epigallocatechin gallate, and (-)-epicatechin gallate suggested the time of 10 min, temperature of 66 °C and the 30% ethanol solution as optimum point. The principal compounds identified in the optimum point by mass spectrometry were gallic acid, 5-galloylquinic acid, caffeine, theobromine, gallocatechin, epigallocatechin, epicatechin, epigallocatechin gallate, and epicatechin gallate. Nevertheless, this study showed that different analytical determination associated chemometrics tools can be used to explore and classify the samples, thus it can be used for extraction processes of bioactive compounds
of plant samples.
The insecticidal action of Citrus sinensis essential oil (EO) (LC50 = 3.9 mg/dm3) against the house fly Musca domestica is reviewed with special emphasis on the process of detoxification and on the actual intoxication of the insect once it is fumigated with the EO. The first metabolic pathway of terpenes is the oxidation by P450, followed by a neurotoxic effect with characteristic features that make flies sensitive to these compounds. The same response was observed for the most abundant terpene of the C. sinensis EO, the (4R)(+)-limonene (LC50 = 6.2 mg/dm3). By comparing the activity of the EO with (4R)(+)-limonene, we propose an explanation of the enhanced activity of the first with respect to the compound. The toxicity of C. sinensis EO showed a second order response with the temperature, with a maximum at 26°C. The neurotoxic effect of C. sinensis and (4R)(+)-limonene was assayed on the enzyme acetylcholinesterase (AChE) activity and the biogenic amines levels were determined. (4R)(+)-Limonene showed a low activity against AChE, with an inhibitory percentage of 22.6% at 0.61 M (equivalent to 84 mg/mL). The levels of tyrosine, dopamine, tyramine and octopamine in M. domestica head after fumigation with the EO or (4R)(+)-limonene were analyzed by HPLC and compared with the corresponding levels of untreated flies. Fumigation with C. sinensis EO or (4R)(+)-limonene increased 8 times the levels of dopamine but they did not affect the concentration of octopamine compared with control flies. The level of tyrosine, the precursor molecule of dopamine, was enhanced 3.3 and 3.6 times when flies were submitted to both fumigants, respectively, indicating that terpenes affect the chemistry of the neurological system.
The activities of four natural phenolics, kaempferol, galangin, carnosic acid and polydatin in scavenging free radicals, inhibiting advanced glycation end-product (AGE) formation, α-amylase and α-glucosidase and trapping methylglyoxal (MGO), were evaluated in this study. Carnosic acid and galangin had the highest activity in scavenging free radicals. Kaempferol and galangin had the greatest activity in preventing bovine serum albumin (BSA) against glycation and reducing glycated proteins. Polydatin had the greatest performance in trapping MGO to reduce glycation reaction. However, there was no significant difference for kaempferol, galangin and carnosic acid in inhibiting AGE formation by BSA-MGO reaction. Kaempferol, galangin and carnosic acid were the competitive inhibitors for α-amylase, while kaempferol and carnosic acid were noncompetitive inhibitors for α-glucosidase. However, polydatin showed as a mixed noncompetitive inhibitor for both α-amylase and α-glucosidase. The results indicated that the four natural phenolics have potential in inhibiting AGE production and the digestive enzymatic activity with different mechanisms.
ZET İleri glikasyon son ürünleri (AGE'ler) proteinler, lipidler ve nükleik asitlerin enzimatik olmayan glikasyonundan endojen olarak üretilen heterojen bileşiklerdir. Normal metabolizmanın bir parçası olan AGE'ler, ekzojen olarak da organizmaya alınabilmektedir. Besinlerin bileşimi, besinlere hazırlık ve pişirme sırasında uygulanan işlemler, nem ve pH gibi birçok etmen doğrudan veya dolaylı olarak AGE'lerin oluşumunu etkileyebilmektedir. Protein ve yağ içeriği yüksek besinler, karbonhidrat içeriği yüksek olan besinlere göre daha yüksek miktarda AGE'leri içerirler. Diyetle alınan AGE'ler genellikle Maillard reaksiyonu kaynaklıdırlar. Maillard reaksiyonunun hızını etkileyen etmenler dolayısıyla AGE'lerin oluşumunu ve alım miktarını etkilemektedir. Yapılan çalışmalarda günlük ortalama AGE'lerin alımının 16.000 kU olduğu saptanmıştır. Ekzojen AGE'lerin oluşumunu azaltmak amacıyla günümüzde farklı yöntemler kullanılmaktadır. Yüksek nem, daha kısa pişirme süresi, daha düşük pişirme sıcaklıkları veya limon suyu, sirke gibi asidik bileşenlerin kullanımı ile besinlerdeki AGE'lerin oluşumunun azaltılabileceği belirtilmektedir. Genel olarak yağ, yağlı kırmızı et, atıştırmalık besinler ve işlenmiş besin içeriğinin azaltıldığı, sebze ve meyve, tam tahıl, kurubaklagil, yağsız et ve balık gibi besinlerin artırıldığı bir diyetle sadece AGE'lerin alımı azaltılmaz aynı zamanda hastalık risklerine karşı da koruyucu etki sağlanabilir. Anahtar kelimeler: İleri glikasyon son ürünleri, Maillard reaksiyonu, Anti-AGE yöntemleri ABSTRACT Advanced glycation end products (AGEs) are heterogeneous compounds and produced endogenously from non-enzymatic glycation of the proteins, lipids and nucleic acids. AGEs are part of the normal metabolism however they can be taken to organisms exogenously. Many factors such as the composition of food, moisture, pH, processes applied to foods during preparation and cooking may affect the formation of AGEs directly or indirectly. Foods with high protein and fat content contain higher amount of AGEs compared to foods with high carbohydrate content. Dietary AGEs are generally derived from Maillard reaction. Factors affecting the rate of Maillard reaction also affect the formation and intake of AGEs. The studies have found that daily AGEs intake is about 16.000 kU. Nowadays different methods are used to reduce exogenous AGEs formation. It is stated that AGEs formation in foods may be reduced via high moisture, short cooking time, low cooking temperature or the use of acidic components such as vinegar and lemon juice. Increasing the consumption of vegetables, fruits, whole grains, legumes, lean meat and fish and reducing intake of fatty meats, snack foods and highly processed foods might not only reduce the AGEs intake but also provide a protective effect against chronic disease risks.
The study aimed to evaluate the inhibitory effects of Centella asiatica phenolics (CAP) on bovine serum albumin glycoxidation in a BSA-glucose model in vitro. The impact of the phenolic extract on the formation of total fluorescent advanced glycation end products (AGEs) and Amadori adducts were determined. Dityrosine, N-formylkynurenine, kynurenine and protein-carbonyls were quantified as markers of protein oxidation. Protein structural perturbations were determined by Congo red binding and FTIR analysis. Chemical characterization and CAP phytoconstituent profile was obtained by colorimetric and UHPLC-ESI-qTOF-MS analysis, respectively. Our data show that CAP attenuated the formation of fluorescent AGEs (38.5 %), Dityrosine (44.6 %), N-formylkynurenine (42.9 %), Amadori products, and resisted structural alterations of BSA subjected to glycation. These effects could be due to the antioxidant and radical scavenging activities of CAP mediated by the presence of phenolics and triterpenoids. The results collectively suggest that CAP possesses antiglycative properties with potentials for nutraceutical applications.
Objective: Diabetes mellitus (DM) is the most common metabolic disorder that defined by chronic hyperglycemia for the deficiency in insulin secretion or resistance. Hyperglycemia could induce non-enzymatic glycation of proteins. It has been suggested that some traditional plants can improve blood glucose and inhibit glycation process. This work evaluates and compares the anti-glycation activities of four Iranian plant extracts in vitro.
Methods: The methanolic extract of “Fumaria officinalis, Stachys lavandulifolia, Salvia hydrangea and Rosa Damascene” was prepared in three different concentrations. Phenolic, flavonoids content and antioxidant activity were evaluated. The multistage glycation markers- fructosamines (early stage), protein carbonyls (intermediate stage) and β aggregation of albumin were investigated in the bovine serum albumin (BSA)/ glucose systemt.
Results: All plants showed the high potency of scavenging free radicals and glycation inhibition in the following order: Fumaria officinalis> Rosa Damascene> Stachys lavandulifolia > Salvia hydrangea. There was a significant correlation between antioxidant and anti-glycation activity. Also, the antioxidant and anti-glycation capacity of extracts correlated with total phenolic and flavonoids content.
Conclusion: Our findings demonstrated that the studied plants are good sources of anti-glycation and antioxidant compounds and, these properties can primarily attributable to phenolics, particularly flavonoids.
The aim of the present study was to investigate the effects of microwave-assisted extraction parameters on total phenolic content (TPC), total flavonoid content (TFC), condensed tannins content (CTC), DPPH-scavenging activity, and colour attributes of aqueous green tea extracts and to optimise the microwaving conditions using response surface methodology. Microwave power (120–360–600 W) and irradiation time (1–3–5 min) were selected as independent variables. Statistical analysis revealed that all responses were significantly affected by extraction parameters. The optimum microwave-assisted extraction conditions were 350.65 W microwave power and 5 min irradiation time to maximise TPC, TFC, CTC, DPPH-scavenging activity, and L* values and to minimise a* and b* values of aqueous green tea extracts. The predicted TPC was 116.58 mg gallic acid equivalents/g (GAE/g), TFC was 49.33 mg catechin equivalents/g (CE/g), CTC was 9.89 mg catechin equivalents/g (CE/g), DPPH-scavenging activity (IC50) was 294.46 µg/mL, L* value was 12.31, a* value was 2.61 and b* value was 7.02 under optimum microwave-assisted extraction conditions. This study revealed that microwave extraction conditions should be controlled to obtain aqueous green tea extracts with both high bioactivity and acceptable colour quality.
Protein glycation and oxidative stress lead to severe health complications in various diseases including diabetes mellitus. The intake of flavonoid-rich foods has been confirmed previously to have a positive effect on human health. Ginger is an important source of flavonoids and is one of the most widely used traditional medicines in many Asian countries. The aim of this study was to verify the therapeutic potential of methanolic extract from ginger against glycation and other oxidative stress-induced complications using in vitro study. In this study, quantitative estimations of antioxidant components such as total phenolic and flavonoids were determined by UV-visible spectrophotometry. The anti-inflammatory action of the ginger extract was checked by determining its protective action against the denaturation of proteins, anti-proteinase activity and its membrane stabilization effect. The anti-inflammatory action of ginger extract was found to be comparable with reference standard drugs. The antiglycating effect of ginger extract was investigated by placing bovine serum albumin (BSA) with glucose in the presence and absence of ginger extract for two weeks at 37 • C. The incubated samples were analyzed for the number of glycation products, secondary structural changes, aggregation and advanced glycation end products (AGEs) formation by checking browning intensity, determination of aggregation index and Congo red assays. Our findings demonstrated that ginger extract (600 µg/mL) significantly reduced the browning, secondary structural changes, aggregation and AGEs formation. Thus, it can be concluded from these results that ginger extract is a wealthy source of antioxidants and can be used to prevent the glycation and oxidative stress-induced damage of biomolecules in various health complications including inflammation.
The allyl-substituted cysteine derivatives were major components of sulfur compounds in garlic. This study separated and identified 3 allyl-substituted cysteine derivatives, i.e. S-allyl-L-cysteine (SAC), S-allyl-L-cysteine sulfoxide (ACSO) and γ-L-glutamyl-S-allyl-L-cysteine (GSAC). Furthermore, scavenging ability of 1, 1-Diphenyl-2-picrylhydrazyl (DPPH) free radical and iron chelating ability were tested through comparing the compounds of SAC, ACSO and GSAC with glutathione (GSH) to evaluate the antioxidation. SAC, ACSO and GSAC were isolated from garlic bulbs using ion-exchange chromatography and pre-HPLC (high performance liquid chromatography). Their molecular structures were identified by high performance liquid chromatography-electrospray ionization-mass/mass spectrometry (HPLC-ESI-MS/MS), proton nuclear magnetic resonance (1H NMR), carbon-13 nuclear magnetic resonance (13C NMR) and specific rotatory power. SAC and ACSO which yielded the expected [M+H]+ of m/z 162.1 and 177.8 by the measurement of mass spectrometry under positive ion mode were conferred as S-allyl-L-cysteine (C6H11O2NS) and S-allyl-L-cysteine sulfoxide (C6H11O3NS) respectively compared with the data of corresponding standard. GSAC, showing the corresponding [M-H]- of m/z 288.8, was identified as γ-glutamyl-S-allyl-L-cysteine (C11H18O5N2S) by HPLC-MS. The 1H NMR spectrum of SAC and ACSO indicated the presence of the cysteinyl (δ 2.96 and 3.83, 3H) and (δ 3.26 and 4.13, 3H) moieties. The 13C NMR spectrum of compound SAC and ACSO showed the presence of the cysteinyl carboxyl (δ 175.6 and δ 188.0) carbons. Similarly, the 1H NMR spectrum of GSAC indicated the presence of the glutamyl (δ 2.32-2.43, 2.66 and 3.46, 5H) and cysteinyl (δ 2.75 and 4.76, 3H) moieties. The 13C NMR spectrum of GSAC revealed the presence of 11 magnetically nonequivalent carbon atoms, with three of them being the glutamyl carboxyl, glutamyl carbonyl and cysteinyl carboxyl (δ 182.5, 183.2 and 184.4) carbons. Meanwhile, the scavenging activity of DPPH free radical and the chelating activity of iron ion by allyl-substituted sulfides (SAC, ACSO and GSAC) were determined with reference to cysteine derivative of GSH. The scavenging activity of DPPH free radical had no significant difference between GSH (71.14%) and both of SAC (73.55%) and GSAC (72.68%). Iron ion is one of the main oxidizing auxiliaries which can initiate free radical in vitro and vivo, therefore, chelating with iron ion can remove the oxidizing auxiliaries effectively, and prevent the formation of free radicals. Likewise, no significant differences between GSH (81.21%) and both of SAC (79.18%) and ACSO (78.13%) were observed for the chelating activity of iron ion tested in this study. In particular, the chelating activity of iron ion of GSAC (92.76%) was greater than GSH. These results confirmed the antioxidant activity of these allyl-substituted cysteine derivatives. Garlic planting area in China accounted for a third of the world. At harvest time, garlic waste dumping in the field led to the waste of resource and the pollution of the environment, and these waste parts of garlic were also the sources of sulfur compounds. The processing in this experiment could make full use of garlic (edible part and non-edible part), and the study could provide some theoretical guidance for the industrialization of large-scale extraction of sulfur-containing products, and improve the level of deep processing of garlic. The work revealed the first evidence of antioxidant activity of GSAC, which could be involved in its chelating activity of iron ion. ©, 2015, Chinese Society of Agricultural Engineering. All right reserved.
Nonenzymatic glycation, the reaction of glucose and other reducing sugars with protein, reversibly produces Amadori products and over a long period irreversible advanced glycation end products. In diabetes, these reactions are greatly accelerated and are important in the pathogenesis of diabetic complications.In vitro glycation was studied with bovine albumin as the model protein. A mixture of 25 mM glucose/fructose was used as the glycating agent. The Amadori product was quantitated by thiobarbituric acid colorimetry after hydrolysis. Advanced glycation end products were measured by their intrinsic fluorescence. A number of vitamins and nutrients were found to be potent inhibitors of both the glycation reaction and the subsequent end products. The nutrients were effective at physiological concentrations and exhibited dose-response relationships. The inhibitors included ascorbic acid, tocopherol, pyridoxal, niacinamide, sodium selenite, selenium yeast, and carnosine. A significant correlation was found between the inhibition of glycation and the inhibition of AGE formation (P < 0.001). One of the nutrients, ascorbic acid, was used in a pilot study. Eighteen normal subjects, 7 college age and 10 middle age, were supplemented with 1,000 mg of ascorbic acid in the form of Re-Natured Vitamin C® for a period of 4 weeks. Serum protein glycation was decreased an average of 46.8% (P < 0.01). These results underline the importance of nutrition in diabetes and indicate the possibility of therapeutic use of these nutrients for the prevention of diabetic complications.
The action of the phenolic compounds acetaminophen, salicylate, and 5-aminosalicylate (5-ASA) as inhibitors of lipid peroxidation was studied under conditions suitable for establishing their antioxidant potencies. These phenolic compounds react differently with diphenylpicrylhydrazyl (DPPH) and protect differently sarcoplasmic reticulum membranes against lipid peroxidation induced by Fe2+/ascorbate, as evaluated by the formation of thiobarbituric acid-reactive substances (TBARS) and by the loss of the polyunsaturated fatty acyl chains. 5-Aminosalicylate reacts promptly with DPPH, suggesting a potent radical scavenger activity and was found to be the most active in inhibiting Fe2+/ascorbate-induced lipid peroxidation. These compounds also exhibit peroxyl radical scavenging activity generated by the water-soluble 2,2'-azobis-(2-amidinopropane hydrochloride) azoinitiator of peroxyl radicals, as evidenced by the inhibition of cis-parinaric acid fluorescence decay or oxygen consumption. 5-ASA rapidly scavenges peroxyl radicals in the aqueous phase, producing a concentration-dependent inhibition period similar to Trolox or cysteine, suggesting an antioxidant activity of chain-breaking type. By comparison, the reactivities of acetaminophen and salicylate are significantly weaker, acting essentially as oxidation retardants. Although closely related in structure, the antioxidant efficiencies of the three phenolic compounds are significantly different. The higher antioxidant activity of 5-ASA is putatively related with the p-amine relative to the hydroxyl group, potentially increasing the stability of the phenoxyl radical. Such a stabilization is not possible with salicylate and is decreased in acetaminophen by an electron withdrawing effect of the p-acetyl.
The advanced glycation end-product (AGE) hypothesis proposes that accelerated chemical modification of proteins by glucose during hyperglycemia contributes to the pathogenesis of diabetic complications. The two most commonly measured AGEs, N(epsilon)-(carboxymethyl)lysine and pentosidine, are glycoxidation products, formed from glucose by sequential glycation and autoxidation reactions. Although several compounds have been developed as AGE inhibitors and are being tested in animal models of diabetes and in clinical trials, the mechanism of action of these inhibitors is poorly understood. In general, they are thought to function as nucleophilic traps for reactive carbonyl intermediates in the formation of AGEs; however alternative mechanisms of actions, such as chelation, have not been rigorously examined. To distinguish between the carbonyl trapping and antioxidant activity of AGE inhibitors, we have measured the chelating activity of the inhibitors by determining the concentration required for 50% inhibition of the rate of copper-catalyzed autoxidation of ascorbic acid in phosphate buffer. All AGE inhibitors studied were chelators of copper, as measured by inhibition of metal-catalyzed autoxidation of ascorbate. Apparent binding constants for copper ranged from approximately 2 mm for aminoguanidine and pyridoxamine, to 10-100 microm for carnosine, phenazinediamine, OPB-9195 and tenilsetam. The AGE-breakers, phenacylthiazolium and phenacyldimethylthiazolium bromide, and their hydrolysis products, were among the most potent inhibitors of ascorbate oxidation. We conclude that, at millimolar concentrations of AGE inhibitors used in many in vitro studies, inhibition of AGE formation results primarily from the chelating or antioxidant activity of the AGE inhibitors, rather than their carbonyl trapping activity. Further, at therapeutic concentrations, the chelating activity of AGE inhibitors and AGE-breakers may contribute to their inhibition of AGE formation and protection against development of diabetic complications.
Collagen crosslinking during aging in part results from Maillard reaction endproducts of glucose and oxoaldehydes. Because of the tight link between oxidative and carbonyl stress, we hypothesized that natural antioxidants and "nutriceuticals" could block collagen aging in C57BL/6 mice. Six groups of young and adult mice received vitamin C, vitamin E, vitamin C&E, blueberry, green tea extract (GTE), or no treatment for a period of 14 weeks. Body weights and collagen glycation were unaltered by the treatment. However, GTE or vitamin C&E combined blocked tendon crosslinking at 10 months of age (p < 0.05, adult group). GTE also blocked fluorescent products at 385 and 440 nm (p = 0.052 and < 0.05, respectively) and tended to decrease skin pentosidine levels. These results suggest that green tea is able to delay collagen aging by an antioxidant mechanism that is in part duplicated by the combination of vitamin C and E.
Several lines of evidence suggest that rutin, flavonoid in fruits and vegetables, or one of its metabolites may effectively modulate advanced glycation end product (AGE) formation. Following ingestion, rutin forms metabolites that include 3,4-dihydroxyphenylacetic acid (3,4-DHPAA), 3,4-dihydroxytoluene (3,4-DHT), m-hydroxyphenylacetic acid (m-HPAA), 3-methoxy-4-hydroxyphenylacetic acid (homovanillic acid, HVA) and 3,5,7,3',5'-pentahydroxyflavonol (quercetin). We studied the effects of rutin and its metabolites on the formation of AGE biomarkers such as pentosidine, collagen-linked fluorescence, N(epsilon)-carboxymethyllysine (CML) adducts, glucose autoxidation and collagen glycation, using an in vitro model where collagen I was incubated with glucose. Rutin metabolites containing vicinyl dihydroxyl groups, i.e., 3,4-DHT, 3,4-DHPAA and quercetin, inhibited the formation of pentosidine and fluorescent adducts, glucose autoxidation and glycation of collagen I in a dose-dependent manner, whereas non-vicinyl dihydroxyl group-containing metabolites, i.e., HVA and m-HPAA, were much less effective. All five metabolites of rutin effectively inhibited CML formation. In contrast, during the initial stages of glycation and fluorescent AGE product accumulation, only vicinyl hydroxyl group-containing rutin metabolites were effective. These studies demonstrate that rutin and circulating metabolites of rutin can inhibit early glycation product formation, including both fluorescent and nonfluorescent AGEs induced by glucose glycation of collagen I in vitro. These effects likely contribute to the beneficial health effects associated with rutin consumption.
We tested whether polyphenolic substances in extracts of commercial culinary herbs and spices would inhibit fructose-mediated protein glycation. Extracts of 24 herbs and spices from a local supermarket were tested for the ability to inhibit glycation of albumin. Dry samples were ground and extracted with 10 volumes of 50% ethanol, and total phenolic content and ferric reducing antioxidant potential (FRAP) were measured. Aliquots were incubated in triplicate at pH 7.4 with 0.25 M fructose and 10 mg/mL fatty acid-free bovine albumin. Fluorescence at 370 nm/440 nm was used as an index of albumin glycation. In general, spice extracts inhibited glycation more than herb extracts, but inhibition was correlated with total phenolic content (R(2) = 0.89). The most potent inhibitors included extracts of cloves, ground Jamaican allspice, and cinnamon. Potent herbs tested included sage, marjoram, tarragon, and rosemary. Total phenolics were highly correlated with FRAP values (R(2) = 0.93). The concentration of phenolics that inhibited glycation by 50% was typically 4-12 microg/mL. Relative to total phenolic concentration, extracts of powdered ginger and bay leaf were less effective than expected, and black pepper was more effective. Prevention of protein glycation is an example of the antidiabetic potential for bioactive compounds in culinary herbs and spices.
Several parameters of the vanillin assay were examined to determine which must be most closely controlled to ensure accuracy and reproducibility. A 20-min extraction in methanol was found to be adequate. When corrected for background color, the modified vanillin assay was found to give nearly identical values with those obtained with the regular vanillin assay, except with group II sorghum. The reactions of tannin and catechin, the usual standard, with vanillin were found to differ markedly in reaction kinetics. Assays of purified tannin showed that use of catechin equivalents overestimates tannin content The assay was found to be extremely temperature dependent. Revised procedures for the vanillin assay are presented which give excellent reproducibility.
The anti-glycation activity of four kinds of beans including mung bean, black bean, soybean and cowpea were evaluated. Aqueous alcohol extract of mung bean exhibited the strongest inhibitory activity against the formation of fluorescent advanced glycation endproducts (AGEs) in a bovine serum albumin (BSA)-glucose model, and the inhibitory activities of extracts of the four beans were found to be highly correlated with their total phenolic contents (R2 = 0.95). Subsequent HPLC analysis of mung bean extract revealed two major phenolics which were purified and identified as vitexin and isovitexin by spectral methods. In the anti-glycation assays, both vitexin and isovitexin showed significant inhibitory activities against the formation of AGEs induced by glucose or methylglyoxal with efficacies of over 85% at 100 μM. In another assay, vitexin and isovitexin failed to directly trap reactive carbonyl species, such as methylglyoxal, suggesting that their anti-glycation activities may mainly be due to their free radical scavenging capacity.
Flavonoid content of mulberry leaves of 19 varieties of species, determined spectrophotometrically in terms of rutin equivalent, varied from 11.7 to 26.6 mg g−1 in spring leaves and 9.84 to 29.6 mg g−1 in autumn leaves. Fresh leaves gave more extract than air-dried or oven-dried ones. HPLC showed that mulberry leaves contain at least four flavonoids, two of which are rutin and quercetin. The percentage superoxide ion scavenged by extracts of mulberry leaves, mulberry tender leaves, mulberry branches and mulberry bark were 46.5, 55.5, 67.5 and 85·5%, respectively, at a concentration of 5 μg ml−1. The scavenging effects of most mulberry extracts were greater than those of rutin (52.0%).
An important field of research today is the control of ‘redox’ status with the properties of food and food components. Natural antioxidants present in the diet increase the resistance toward oxidative damages and they may have a substantial impact on human health.Dietary antioxidants such as ascorbates, tocopherols and carotenoids are well known and there is a surplus of publications related to their role in health. Plant phenols have not been completely studied because of the complexity of their chemical nature and the extended occurrence in plant materials.Extensively studied sources of natural antioxidants are fruits and vegetables, seeds, cereals, berries, wine, tea, onion bulbs, olive oil and aromatic plants. Attempts are also made to identify and evaluate antioxidants in agricultural by-products, ethnic and traditional products, herbal teas, cold pressed seed oils, exudates resins, hydrolysis products, not evaluated fruits and edible leaves and other raw materials rich in antioxidant phenols that have nutritional importance and/or the potential for applications in the promotion of health and prevention against damages caused by radicals.
Oxidative stress caused by the production of excess nitric oxide (NO) during infection or inflammation has been implicated in the pathogenesis of several diseases, including cancer, diabetes and renal disease. Accordingly, the scavenging of NO radical or/and suppression of NO production by mitogen-activated cells may be promising indicators in screening healthy food. In this work, the NO-scavenging and NO-suppressing activities of different herbal teas were determined and compared with those of green tea. All of the tested herbal teas revealed NO-scavenging and NO-suppressing activities. The NO-scavenging activity of herbal teas can be ranked by the IC50, the concentration of the tested herbal tea required to quench 50% of NO radicals released by sodium nitroprusside. The activities follow the order: green tea > rosemary, sweet osmanthus, rose and lavender > jasmine, lemongrass and daisy. The NO-suppressing activity was evaluated, based on the suppressing effect of herbal teas on the production of NO by LPS-activated RAW 264.7 macrophages. Experimental results indicated that green tea and rosemary had IC50 values of less than 500 μg/ml, and were proven to be good NO-suppressors, whereas lavender, sweet osmanthus, lemongrass, rose, daisy and jasmine had IC50 values that exceeded 500 μg/ml, and were classified as rather poor NO-suppressors. In conclusion, consumption of herbal teas promotes the NO-scavenging and NO-suppressing activities of the diet, even though their activities are weaker than that of green tea.
The formation of advanced glycation end products (AGEs) leading to protein glycation and cross-linking is associated with the pathogenesis of diabetic complications. The inhibition of protein glycation by phenolic and flavonoid antioxidants demonstrates that the process is mediated, in part, by oxidative processes. In this study, the effects of seed and skin extracts of the muscadine grape on AGEs formation were examined. Seeds and skins were extracted (10% w/v) with 50% ethanol and incubated at 37 degrees C with a solution containing 250 mM fructose and 10 mg/ml albumin. After 72 h, fluorescence was measured at the wavelength pair of 370 and 440 nm as an index of the formation of AGEs. Both seed and skin extracts were found to be efficacious inhibitors of AGE formation. A 1:300 dilution of the seed extract decreased fluorescence by approximately 65%, whereas muscadine grape skin extract produced a 40% lowering. This difference correlates with the greater antioxidant activity found in muscadine seeds in comparison to skins, however, on a mass basis, the inhibitory activities of the seeds and skins were found to be nearly equivalent. Gallic acid, catechin and epicatechin, the three major polyphenols in the seeds, all significantly decreased the AGE product related fluorescence at a concentration of 50 microM. Neither muscadine seed extract nor skin extract inhibited the methylglyoxal-mediated glycation of albumin. These results suggest that consumption of the muscadine grape may have some benefit in altering the progression of diabetic complications.
Tea is an important dietary source of flavonols in countries such as the Netherlands, the United Kingdom and Japan. Flavonols may have beneficial health effects because of their antioxidant properties and their inhibitory role in various stages of tumor development in animal studies. The association between flavonol intake and cancer risk was investigated in three prospective studies (Zutphen Elderly Study in the Netherlands, a Finnish cohort, and the Netherlands Cohort Study). Only one study (Finnish cohort) showed an inverse association with cancer mortality. The intake of flavonols with subsequent cardiovascular disease was studied in six prospective epidemiological studies. In some populations (Seven Countries Study, Zutphen Elderly Study, a Finnish cohort) a clear protective effect was observed. In a large US cohort, a protective effect was only found in a subgroup with previous history of coronary heart disease, whereas in Welsh men, flavonol intake, mainly from tea, was associated with an increased risk of coronary heart disease. These conflicting results may be due to confounding by coronary risk factors associated with tea consumption. The question of whether flavonols protect against cardiovascular disease remains still open; a protective effect of flavonols against cancer is less likely.
The present study concentrates on the evaluation of the anti-glycation effect of some bioactive substances present in yerba maté (Ilex paraguariensis): 5-caffeoylquinic acid, caffeic acid and a sapogenin (oleanolic acid). Bovine serum albumin and histones were incubated in the presence of methylglyoxal with or without the addition of 5-caffeoylquinic acid, caffeic acid and oleanolic acid. After the incubation period, advanced glycation end product (AGE) fluorescence spectra were performed and protein structural changes were evaluated by Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis. Chlorogenic acid, caffeic acid are the main substances responsible for the anti-glycation effect of maté tea.
Incubation of corneal collagen type I with glucose in the presence of transition metal ions (copper, iron) results in the formation of collagen aggregates insoluble in 6 M urea, and in 2% sodium dodecyl sulfate + 5% beta-mercaptoethanol. The reaction is mediated by hydrogen peroxide and transition metals since it is inhibited by catalase and by the chelating agent diethylenetriaminepentaacetic acid. Comparative studies showed that copper is more efficient than iron and that the reaction proceeds more rapidly with ribose than with glucose. The data support a mechanism involving transition metal ion catalyzed autoxidation of glucose (and possibly of Amadori products) with generation of superoxide radical. Superoxide dismutation produces hydrogen peroxide, which then generates hydroxyl radicals in the presence of transition metal ions (Fenton reaction). Hydroxyl radical attack is known to lead to cross-linking, which is enhanced in glycated proteins. The experimental data presented are consistent with in vivo alteration of collagen properties during normal aging and with the acceleration of similar changes in diabetes mellitus.
IN this seminar we review recent studies suggesting that the central pathologic features of diabetic complications are caused by the hyperglycemia-accelerated formation of nonenzymatic advanced glycosylation end products in tissue. We will emphasize new research findings with important clinical implications, since older information is available in previously published reviews.1 , 2 Other biochemical mechanisms by which hyperglycemia may contribute to the development of diabetic complications are not discussed here, since they are comprehensively reviewed elsewhere.3 4 5 6 7 8 Differences between Early and Advanced Glycosylation Products The central pathophysiologic features of diabetic vascular complications are an abnormal leakage of proteins from the circulation and a progressive . . .
The formation of alpha-dicarbonyl compounds seems to be an important step for cross-linking proteins in the glycation or Maillard reaction. To elucidate the mechanism for the cross-linking reaction, we studied the reaction between a three-carbon alpha-dicarbonyl compound, methylglyoxal, and amino acids. Our results showed that this reaction generated yellow fluorescent products as formed in some glycated proteins. In addition, three types of free radical species were also produced, and their structures were determined by EPR spectroscopy. These free radicals are 1) the cross-linked radical cation, 2) the methylglyoxal radical anion as the counterion, and 3) the superoxide radical anion produced only in the presence of oxygen. The generation of the cross-linked radical cations and the methylglyoxal radical anions does not require metal ions or oxygens. These results indicate that dicarbonyl compounds cross-link free amino groups of protein by forming Schiff bases, which donate electrons directly to dicarbonyl compounds to form the cross-linked radical cations and the methylglyoxal radical anions. Oxygen can accept an electron from the radical anion to generate a superoxide radical anion, which can initiate damaging chain reactions. Time course studies suggest that the cross-linked radical cation is a precursor of yellow fluorescent glycation end products.
The antioxidant enzyme superoxide dismutase (EC 1.15.1.1) (SOD) catalyzes the conversion of superoxide anion radical (O2.-) to hydrogen peroxide and molecular oxygen. SOD helps prevent tissue damage by O2.- and its metabolites, and augmentation of tissue SOD is a useful therapeutic strategy in certain diseases having an oxidative-injury component. Routine application of direct SOD assays is not technically facile, since the short half-life of the O2.- substrate and its free radical nature necessitate specialized analytical equipment to detect and measure O2.- chemically. Consequently, indirect SOD assays which monitor some change in an indicator substance reacting with O2.- are routinely used, particularly for biological samples. Limitations of indirect test systems utilizing heme-based indicators for the presence of O2.- and/or enzymatic O2.- generators led us to develop a SOD microassay based on spectrophotometric assessment of O2.- mediated nitro blue tetrazolium reduction by an aerobic mixture of NADH and phenazine methosulfate, which produces superoxide chemically at nonacidic pH (Rao, Free Radical Biol. Med. 7, 513-519, 1989). The proposed SOD assay system is formatted for use in an automated 96-well microplate reader and has the virtues of a nonheme indicator, a nonenzymatic O2.- source, physiological pH, and economy of time and materials. The assay has been applied to measure purified and tissue SOD (Cu,Zn- and Mn-types) activity as well as O2.- turnover by small-molecule "SOD mimetics."
Many antioxidants have been found in spices and herbs, and some of them are well known as strong scavengers of active oxygen radicals. We have isolated active products, which markedly inhibited the formation of malondialdehyde (MDA from 2-deoxyribose and the hydroxylation of benzoate with the hydroxyl radical, from methanol extracts of allspice and clove. Pimentol from allspice, and biflorin and its isomer, abbreviated as clove3, from clove were identified as the active principles. These revealed strong activity as hydroxyl radical scavengers at a concentration of 2.0 microM. The antioxidative activities in an in vitro model system involving the rabbit erythrocyte membrane ghost were as strong as those of alpha-tocopherol at 200 microM. Such advanced glycation end products (AGE) as pentosidine are biomarkers of diabetes mellitus, and active oxygens have been suggested to be involved in the formation of AGE. The above-mentioned free radical scavengers effectively inhibited the formation of pentosidine in a model system of N alpha-t-butoxycarbonyl-fructoselysine and N alpha-t-butoxycarbonyl-arginine.
The present study investigates the role of metal catalysed oxidation in the formation of Advanced Glycation End products (AGEs). Rat tail tendon collagen was incubated with glucose (250 mM) and increasing concentrations of copper ions (5-500 microM) under physiological conditions of temperature and pH. After 1 and 3 weeks of incubation the level of AGEs in collagen samples were estimated by enzyme linked immunoassay, using antibodies raised against AGE ribonuclease. It was observed that the presence of metal ions significantly increased the rate of accumulation of AGEs. The increase was dependent on the concentration of metal ions present in the incubation medium. Free radical scavengers such as mannitol, benzoate, catalase, and the antiglycating agent aminoguanidine almost completely inhibited the formation of AGEs. Incubation of collagen with copper ions alone did not show any increase in crosslinking, as detected by cyanogen bromide digestion, and AGEs formation. Further it was also noted that glycoxidation, i.e., oxidation of glycated collagen, was the major pathway that leads to increased formation of AGEs. These results indicate that metal-catalyzed oxidation and free radicals play a major role in the formation of AGEs. This work also strongly suggests that increased oxidative stress in diabetes may accelerate the formation of AGEs and thus contribute to the pathogenesis of diabetic complications.
Tea is an important dietary source of flavonols in countries such as the Netherlands, the United Kingdom and Japan. Flavonols may have beneficial health effects because of their antioxidant properties and their inhibitory role in various stages of tumor development in animal studies. The association between flavonol intake and cancer risk was investigated in three prospective studies (Zutphen Elderly Study in the Netherlands, a Finnish cohort, and the Netherlands Cohort Study). Only one study (Finnish cohort) showed an inverse association with cancer mortality. The intake of flavonols with subsequent cardiovascular disease was studied in six prospective epidemiological studies. In some populations (Seven Countries Study, Zutphen Elderly Study, a Finnish cohort) a clear protective effect was observed. In a large US cohort, a protective effect was only found in a subgroup with previous history of coronary heart disease, whereas in Welsh men, flavonol intake, mainly from tea, was associated with an increased risk of coronary heart disease. These conflicting results may be due to confounding by coronary risk factors associated with tea consumption. The question of whether flavonols protect against cardiovascular disease remains still open; a protective effect of flavonols against cancer is less likely.
Diabetes-specific microvascular disease is a leading cause of blindness, renal failure and nerve damage, and diabetes-accelerated atherosclerosis leads to increased risk of myocardial infarction, stroke and limb amputation. Four main molecular mechanisms have been implicated in glucose-mediated vascular damage. All seem to reflect a single hyperglycaemia-induced process of overproduction of superoxide by the mitochondrial electron-transport chain. This integrating paradigm provides a new conceptual framework for future research and drug discovery.
Protein oxidation and glycation are posttranslational modifications that are implicated in the pathological development of many age-related disease processes. This study investigated the effects of green tea extract, and a green tea tannin mixture and its components, on protein damage induced by 2,2'-azobis(2-amidinopropane) dihydrochloride (a free radical generator) and glucose in in vitro assay systems. We found that green tea extract can effectively protect against protein damage, and showed that its action is mainly due to tannin. In addition, it was shown that the chemical structures of tannin components are also involved in this activity, suggesting that the presence of the gallate group at the 3 position plays the most important role in the protective activity against protein oxidation and glycation, and that there is also a contribution by the hydroxyl group at the 5' position in the B ring and the sterical structure. These findings demonstrate the mechanisms of the usefulness of green tea in protein oxidation- and glycation-associated diseases.
Receptor for Advanced Glycation Endproducts (RAGE) is a multiligand member of the immunoglobulin superfamily of cell surface molecules with a diverse repertoire of ligands. These ligands include products of nonenzymatic glycation, the Advanced Glycation Endproducts (AGEs, enriched in the diabetic milieu), members of the S100/calgranulin family of proinflammatory mediators, beta-sheet fibrillar structures (characteristic of amyloid) and amphoterin (present at high levels in the tumor bed). Ligation of RAGE by its ligands upregulates expression of the receptor and triggers an ascending spiral of cellular perturbation due to sustained RAGE-mediated cellular activation. For example, in the setting of diabetes, a vascular environment rich in AGEs and S100/calgranulins accelerates atherogenesis in murine models, and this can be blocked by intercepting the interaction of ligands with RAGE. While RAGE is certainly not the cause of diabetes, it functions as a progression factor driving cellular dysfunction underlying the development of diabetic complications as the microenvironment becomes enriched in its ligands. Though further studies will be required to determine the importance of RAGE-mediated cellular activation to human chronic diseases, it represents a novel receptor-ligand system potentially impacting on a range of pathophysiologic conditions.
The oxygen radical absorbance capacity (ORAC) assay has been widely accepted as a standard tool to measure the antioxidant activity in the nutraceutical, pharmaceutical, and food industries. However, the ORAC assay has been criticized for a lack of accessibility due to the unavailability of the COBAS FARA II analyzer, an instrument discontinued by the manufacturer. In addition, the manual sample preparation is time-consuming and labor-intensive. The objective of this study was to develop a high-throughput instrument platform that can fully automate the ORAC assay procedure. The new instrument platform consists of a robotic eight-channel liquid handling system and a microplate fluorescence reader. By using the high-throughput platform, the efficiency of the assay is improved with at least a 10-fold increase in sample throughput over the current procedure. The mean of intra- and interday CVs was <or=15%, and the limit of detection and limit of quantitation were 5 and 6.25 microM, respectively.
Hyperglycaemia reduces proliferation of bovine aortic endothelial cells in vitro. A similar effect in vivo may contribute to long-term complications of diabetes such as impaired wound-healing and retinopathy.
We report the effect of increased glucose concentrations, glycated basic fibroblast growth factor (FGF-2) and bovine serum albumin-derived advanced glycation endproducts (BSA-AGE) on the proliferation of bovine aortic endothelial cells.
Glucose (30 and 50 mmol/l) had an antiproliferative effect on endothelial cells. This effect may be mediated through reduced mitogenic activity of FGF-2. The glycation of FGF-2 with 250 mmol/l glucose-6-phosphate led to reduced mitogenic activity compared to native FGF-2. BSA-AGE at concentrations of 10, 50 and 250 μg/ml had an antiproliferative effect on cultured endothelial cells.
Aminosalicylic acid at a concentration of 200 μmol/l proved to be more effective than equimolar concentrations of aminoguanidine in protecting endothelial cells against the antiproliferative effects of both high (30 mmol/l) glucose and 50 μg/ml BSA-AGE. FGF-2 glycated in the presence of 4 mmol/l aminosalicylic acid or aminoguanidine retained mitogenic activity compared to that glycated in their absence.
Compounds like aminoguanidine and, in particular, aminosalicylic acid protect endothelial cells against glucose-mediated toxicity and may therefore have therapeutic potential.
To clarify the structural requirements of flavonoids for formation of advanced glycation end-products (AGEs), various flavonoids were examined. The results suggested the following structural requirements of flavonoids for the inhibition of AGEs formation: (1). as the hydroxyl groups at the 3'-, 4'-, 5-, and 7-positions increased in number, the inhibitory activities became stronger; (2). the activities of flavones were stronger than those of corresponding flavonols, flavanones, and isoflavones; (3). methylation or glucosylation of the 4'-hydroxyl group of flavones, flavonols, and flavanones reduced activity; (4). methylation or glycosylation of the 3-hydroxyl group of flavonols tended to increase activity; (5). glycosylation of the 7-hydroxyl group of flavones and isoflavones reduced activity. In addition, various flavonoids with strong AGEs formation inhibitory activity tended to exhibit strong scavenging activity for 1,1-diphenyl-2-picrylhydrazyl and superoxide anion radicals, with several exceptions.
A water-soluble and low-molecular-weight fraction (SB) was obtained from tomato paste. The effects of SB on the formation of advanced glycation end-products (AGE) in protein glycation were studied by the methods of specific fluorescence, ELISA and a Western blot analysis, using the anti-AGE antibody after incubating protein with sugar. The