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Abstract

Bitter leaf is a popular vegetable commonly consumed and which has been employed in traditional medicine for the prevention/management of diabetes and hypertension for centuries in the tropical Africa. However, possible mechanism underlining its hypoglycemic and antihypertension is not clear. Therefore, this study sought to investigate the inhibitory effect of free and bound phenol extracts of bitter leaf on key enzymes linked to type-2 diabetes (α-glucosidase and α-amylase) and hypertension (angiotensin-I converting enzyme [ACE]). The free and bound phenol extracts significantly (P < 0.05) inhibited α-amylase and α-glucosidase activities in vitro in a dose-dependent pattern (4–16 µg/mL). However, the α-glucosidase inhibitory activity of the extracts were significantly (P < 0.05) higher than their α-amylase inhibitory activity. Furthermore, the ACE inhibitory activity of the extracts also followed a dose-dependent pattern (5–20 µg/mL), and the bound phenol extract significantly (P < 0.05) inhibited ACE more than the free phenol extract. However, there exists a strong correlation between the enzyme inhibitory activities and the phenol content of the extracts. Therefore, the inhibition of α-amylase, α-glucosidase and ACE, coupled with the antioxidant activities of bitter leaf phenolic-rich extracts, could be a possible mechanism through which Vernonia amygdalina exert its antidiabetes and antihypertension properties. This manuscript deals with the possibilities of using phenolic extracts of bitter leaf as a nutraceutical source for the management of diabetes and hypertension.

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... e sterilized water was added for residue analysis in UVspectrophotometer, calibration, and absorbance recorded at a wavelength of 228 nm. e results were plotted as % inhibition. 50 . ...
... at closely resembles previous literature [40,[49][50][51][52]. e total antioxidant potential or capacity results are in Table 1 and are determined via standard mmol trolox/100 g; the species Veronica biloba possesses higher potential in both cases of free and bound phenolics, 12.21 ± 1.5 and 16.09 ± 1.2, than Schoenoplectus triqueter which showed 9.8 ± 0.05 and 11.03 ± 0.1, respectively, as mean having P significantly < 0.05, and the higher antioxidant potential is due to phenol content in the plants [24,48]. ...
... phenolics were lower. However, previous studies showed that phytochemicals have lower α-amylase inhibition than α-glucosidase inhibition [49,50,70,71]. e antidiabetic and acarbose possess excess α-amylase inhibition which would avoid the side effects [72]. us, plant phenolics with high α-glucosidase and mild α-amylase inhibitory activities have been suggested as suitable substitutes for the clinician to the analogous synthetic inhibitors [67]. ...
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Veronica (Plantaginaceae) and Schoenoplectus have a unique chemotaxonomic and phytochemical importance and are widely utilized in Turkish and Traditional Chinese Herbal Medicine (TCM) for treating tonics, influenza, diuretics, expectorants, restoratives, and respiratory diseases, and both are very useful in treating infectious and metabolic disorders as well. This study evaluates two medicinal plant species, Veronica biloba and Schoenoplectus triqueter (L.) Palla; extraction was performed through Soxhlet and maceration methods as well as determination of free and bound phenolics. Evaluated biological screening of (extracts and phenolics) angiotensin-I converting enzyme (ACE), Type-II diabetes (α-glucosidase and α-amylase), and antioxidants potential was performed using modified assays. The angiotensin-I converting enzyme (ACE) 50% inhibition potential in Veronica biloba was found at IC50 = 210.68 μg/mL and in Schoenoplectus triqueter (L.) Palla at IC50 = 229.40 µg/mL, respectively. Meanwhile Type-II diabetes with α-amylase 50% inhibition shown by bound phenolics of Veronica biloba at IC50 = 219.66 µg/mL and its water extract at IC50 = 110.09 µg/mL possesses higher potential, and α-glucosidase potential by free phenolics was found to be active at IC50 = 469.56 µg/mL, while water and ethyl acetate extracts showed higher potential, IC50 = 78.65 µg/mL and IC50 = 97.03 µg/mL, than the standard acarbose, recorded lower. In case of amylase, α-glucosidase showed IC50 = 88.73 μg/mL. Our results showed that both plants possess a direct relationship with the increase in the concentration of extracts and inhibited very strongly angiotensin-I converting enzyme (ACE) and Type-II diabetes (α-glucosidase and α-amylase). The properties of enzyme hindrance may be associated with phenolic compounds and rich phenolic plant antioxidant potential provides a route to the elucidation of natural antihypertension and antidiabetes.
... Several studies have reported its antioxidant (Adesanoye & Farombi, 2010), anti-obesogenic (Adaramoye, Akintayo, Achem, & Fafunso, 2008, antidiabetic (Saliu, Ademiluyi, Akinyemi, & Oboh, 2012), antihypertensive (Saliu et al., 2012), andanti-sickling (Afolabi et al., 2012) effects. These activities can be attributed to the reported phytochemical constituents of the leaves such as the polyphenols, steroidal saponins and glucosides, and terpenes (Farombi & Owoeye, 2011;Ijeh & Ejike, 2011;Saliu et al., 2012). ...
... Several studies have reported its antioxidant (Adesanoye & Farombi, 2010), anti-obesogenic (Adaramoye, Akintayo, Achem, & Fafunso, 2008, antidiabetic (Saliu, Ademiluyi, Akinyemi, & Oboh, 2012), antihypertensive (Saliu et al., 2012), andanti-sickling (Afolabi et al., 2012) effects. These activities can be attributed to the reported phytochemical constituents of the leaves such as the polyphenols, steroidal saponins and glucosides, and terpenes (Farombi & Owoeye, 2011;Ijeh & Ejike, 2011;Saliu et al., 2012). ...
... Several studies have reported its antioxidant (Adesanoye & Farombi, 2010), anti-obesogenic (Adaramoye, Akintayo, Achem, & Fafunso, 2008, antidiabetic (Saliu, Ademiluyi, Akinyemi, & Oboh, 2012), antihypertensive (Saliu et al., 2012), andanti-sickling (Afolabi et al., 2012) effects. These activities can be attributed to the reported phytochemical constituents of the leaves such as the polyphenols, steroidal saponins and glucosides, and terpenes (Farombi & Owoeye, 2011;Ijeh & Ejike, 2011;Saliu et al., 2012). While in folk medicine, its medicinal properties are attributed to its characteristic bitter taste. ...
... Nevertheless, the determined α-amylase inhibitory activity of the vegetable agreed with some earlier reports where plant phytochemicals from pepper inhibited saliva α-amylase activity and inhibitory effects of Allium spp. on α-amylase activity (Nickavar and Yousefian, 2009). This also agreed with a recent worked where with bitter leaf inhibited α-amylase activity in vitro (Saliu et al., 2012). ...
... The determined α-glucosidase inhibitory activity follows the same pattern as observed in Figure 1. This result is in agreement with a recent work reported by Saliu et al. (2012) where bitter leaf inhibited α-glucosidase activity in vitro. ...
... This agrees with the finding on eggplant phenolics, which have been recommended as a choice diet for the management of type 2 diabetes (Pinto et al., 2009). Also, this agrees with Saliu et al. (2012) for bitter leaf extract. The result of the total phenol and flavonoid content of A. cruentus leaf revealed that there was a significant (P < 0.05) difference between the total phenol and flavonoid contents of unprocessed A. cruentus leaf and blanched A. cruentus leaf. ...
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This study investigated the inhibitory effect of Amaranthus cruentus leaf on key enzyme linked to type-2 diabetes (α-amylase and α-glucosidase) as well as assessing the effect of blanching (a commonly practiced food processing technique) of the vegetable on these key enzymes. Fresh leaves of A. cruentus were blanched in hot water for 10 min, and the ethanolic extracts of both the fresh and blanched vegetables were prepared and used for subsequent analysis. The inhibitory effect of the extract on α-amylase and α-glucosidase activities as well as some antioxidant parameter was determined in vitro. The result revealed that extract of unprocessed A. cruentus leaf reduce Fe 3+ to Fe 2+ and also inhibited α-amylase and α-glucosidase activities in a dose dependent manner. However, blanching of the leafy vegetables caused a significant (P < 0.05) increase in the antioxidant properties but decreased their ability to inhibit α-amylase and α-glucosidase activities. This antioxidant properties and enzyme inhibition could be part of the mechanism by which they are used in the treatment/prevention of type-2 diabetes. However, the blanched vegetable reduced their ability to inhibit both α-amylase and α-glucosidase activity in vitro.
... It is a common leafy vegetable in West Africa where it is consumed as food and employed in folkloric medicine (Farombi & Owoeye, 2011;Ijeh & Ejike, 2011). The leaves have been widely studied for their medicinal properties which include antidiabetes (Ong et al., 2011;Saliu et al., 2012), antioxidant (Adesanoye & Farombi, 2010;Iwalokun et al., 2006), antihypertensive (Ajibola et al., 2011;Saliu et al., 2012), anti-sickling (Afolabi et al., 2012;Chikezie, 2006), and anti-obesogenic (Adaramoye et al., 2008) activities. These studies correlated the biological activities with the phytochemical constituents notably stigmastane-type and steroidal saponins, steroid glucosides, flavonoids, sesquiterpene lactones, polyphenols, and terpenes (Farombi & Owoeye, 2011;Ijeh & Ejike, 2011;Saliu et al., 2012;Yeap et al., 2010). ...
... It is a common leafy vegetable in West Africa where it is consumed as food and employed in folkloric medicine (Farombi & Owoeye, 2011;Ijeh & Ejike, 2011). The leaves have been widely studied for their medicinal properties which include antidiabetes (Ong et al., 2011;Saliu et al., 2012), antioxidant (Adesanoye & Farombi, 2010;Iwalokun et al., 2006), antihypertensive (Ajibola et al., 2011;Saliu et al., 2012), anti-sickling (Afolabi et al., 2012;Chikezie, 2006), and anti-obesogenic (Adaramoye et al., 2008) activities. These studies correlated the biological activities with the phytochemical constituents notably stigmastane-type and steroidal saponins, steroid glucosides, flavonoids, sesquiterpene lactones, polyphenols, and terpenes (Farombi & Owoeye, 2011;Ijeh & Ejike, 2011;Saliu et al., 2012;Yeap et al., 2010). ...
... The leaves have been widely studied for their medicinal properties which include antidiabetes (Ong et al., 2011;Saliu et al., 2012), antioxidant (Adesanoye & Farombi, 2010;Iwalokun et al., 2006), antihypertensive (Ajibola et al., 2011;Saliu et al., 2012), anti-sickling (Afolabi et al., 2012;Chikezie, 2006), and anti-obesogenic (Adaramoye et al., 2008) activities. These studies correlated the biological activities with the phytochemical constituents notably stigmastane-type and steroidal saponins, steroid glucosides, flavonoids, sesquiterpene lactones, polyphenols, and terpenes (Farombi & Owoeye, 2011;Ijeh & Ejike, 2011;Saliu et al., 2012;Yeap et al., 2010). ...
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The ethyl acetate, ethanol, and aqueous extracts sequentially obtained from the leaves of Vernonia amygdalina were investigated for their antidiabetic and antioxidant protective effect in oxidative hepatic injury. The extracts showed significant (p < .05) free radical scavenging and reducing power activities. They significantly (p < .05) elevated reduced glutathione level, superoxide dismutase, and catalase activities, with concomitant depletion of malondialdehyde level. The ethanol and aqueous extracts caused a removal of oxidative-included chemical functional group at 1,500–1,200 (amide II)/cm region, with the inclusion of a functional group at 3,000–2,800 (carboxylic acid)/cm region. The extracts significantly (p < .05) inhibited the activities of α-glucosidase and α-amylase and stimulated glucose uptake in rat muscles. Gas chromatography-mass spectrometric (GC-MS) analysis revealed phytol as the predominant compound, with ethanol having the highest concentration. Based on the IC50 values, the ethanol extract exhibited the best activities, followed by the ethyl acetate extract, while the aqueous extract was the least. These results suggest the antioxidative and antidiabetic properties of V. amygdalina as evident by their modulation of antioxidant biomarkers and oxidative-induced chemistry changes and stimulate muscle glucose uptake. Practical applications Vernonia amygdalina (bitter leaf) is amongst the common leafy vegetables in West Africa reported for its various medicinal and nutritional properties. It is utilized as a food ingredient as well as supplement for the treatment and management of type 2 diabetes. The ability of its extracts to stimulate glucose uptake and protect against diabetic-induced changes in the chemical functional groups of the liver gives more credence to its reported antidiabetic properties. Being a common leafy vegetable, V. amygdalina can be a cheap source of nutraceutical for the treatment and management of type 2 diabetes and its complications.
... It is consumed as a food and employed in traditional medicine in the treatment of various ailments including diabetes, hypertension, and infertility Ijeh and Ejike 2011). Its folkloric medicinal claims have been authenticated by several studies which includes anti-obesogenic (Adaramoye et al. 2008), antioxidant (Adesanoye and Farombi 2010;Iwalokun et al. 2006), anticancer (Howard et al. 2003;Yedjou et al. 2008), antidiabetes (Ong et al. 2011;Saliu et al. 2012), anti-sickling (Afolabi et al. 2012;Chikezie 2006) and antihypertension (Ajibola et al. 2011;Saliu et al. 2012). Its protective effects against brain degeneration as well as in improving learning have also been reported (Ebuehi and Ajagun-Ogunleye 2017;Farombi and Owoeye 2011;Owoeye et al. 2011). ...
... It is consumed as a food and employed in traditional medicine in the treatment of various ailments including diabetes, hypertension, and infertility Ijeh and Ejike 2011). Its folkloric medicinal claims have been authenticated by several studies which includes anti-obesogenic (Adaramoye et al. 2008), antioxidant (Adesanoye and Farombi 2010;Iwalokun et al. 2006), anticancer (Howard et al. 2003;Yedjou et al. 2008), antidiabetes (Ong et al. 2011;Saliu et al. 2012), anti-sickling (Afolabi et al. 2012;Chikezie 2006) and antihypertension (Ajibola et al. 2011;Saliu et al. 2012). Its protective effects against brain degeneration as well as in improving learning have also been reported (Ebuehi and Ajagun-Ogunleye 2017;Farombi and Owoeye 2011;Owoeye et al. 2011). ...
... Its protective effects against brain degeneration as well as in improving learning have also been reported (Ebuehi and Ajagun-Ogunleye 2017;Farombi and Owoeye 2011;Owoeye et al. 2011). Its reported phytochemical constituents include steroid glucosides, sesquiterpene lactones, stigmastane-type and steroidal saponins, terpenes, and polyphenols Ijeh and Ejike 2011;Saliu et al. 2012;Yeap et al. 2010). ...
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Brain glucose uptake is usually reduced in type 2 diabetes owing to downregulation of brain glucose transporters. The ability of Vernonia amygdalina to stimulate glucose uptake as well as ameliorate glucose-induced oxidative stress and proinflammation were investigated in rat brain. Hot infusion of V. amygdalina leaves was incubated with rat brain tissues for 2 h in the presence of glucose. Another incubation with glucose only, served as negative control while metformin served as positive control. Incubation of brain tissues with V. amygdalina led to significant (p < 0.05) increase in glucose uptake, reduced glutathione, nitric oxide and non-thiol proteins levels, superoxide dismutase, catalase and ATPase activities, while concomitantly decrease in myeloperoxidase activity and malondialdehyde level compared to the negative control. Incubation with glucose only, led to the development of nitrate, amide II and amide I functional groups which were removed on incubation with the infusion. LC-MS analysis revealed depletion of oxidative stress-induced 2-keto-glutaramic acid and cysteinyl-tyrosine metabolites in brain tissues, with concomitant generation of S-formylglutathione and adenosine tetraphosphate by the infusion. Pathway analysis of the metabolites revealed an activation of pyruvate metabolism pathway in the negative control, with the infusion reducing the intensity fold. LC-MS analysis of the infusion revealed the presence of l–serine, l-cysteine, l-proline, nicotinic acid, cumidine, salicylic acid, isoquinoline, 3-methyl-, and γ-octalactone. Except for l–serine, l-cysteine and l-proline, the other compounds were predicted to be permeable across the blood brain barrier. These results indicate the brain glucose uptake stimulatory and neuroprotective effect of V. amygdalina.
... 28,29 Phenolic compounds have been reported to inhibit aamylase and a-glucosidase inhibitory activities and exhibit antioxidant properties which are essential in the prevention and management of T2DM. 12 The use of medicinal plants which are rich in polyphenols are often advocated for the management of T2DM Fig. 1. Representative high performance liquid chromatography profile of Raffia palm (R. Hookeri) extract. ...
... owing to their possible lower risk of side effects compared to contemporary antidiabetic drugs such as acarbose. 12 Therefore, the potential antidiabetic properties of Raffia palm leaf extract observed in this study as a result of their inhibitory effect on major carbohydrate catabolizing enzymes as well as their antioxidant effect could be largely linked to their constituent phenolic phytochemicals. Rutin and chlorogenic acid were the predominant phenolic compounds that was identified in Raffia leaf. ...
Article
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This study sought to investigate the effects of Raffia palm (Raphia hookeri) leaf extract on enzymes linked to type-2 diabetes mellitus (T2DM) and pro-oxidant induced oxidative stress in rat pancreas. The extract was prepared and its α-amylase and α-glucosidase inhibitory effects were determined. Radical [2,2-diphenyl-1-picrylhydrazyl (DPPH)] scavenging and Fe²⁺-chelating abilities, and inhibition of Fe²⁺-induced lipid peroxidation in rat pancreas homogenate were assessed. Furthermore, total phenol and flavonoid contents, reducing property, and high performance liquid chromatography diode array detector (HPLC-DAD) fingerprint of the extract were also determined. Our results revealed that the extract inhibited α-amylase (IC50 = 110.4 μg/mL) and α-glucosidase (IC50 = 99.96 μg/mL) activities in concentration dependent manners which were lower to the effect of acarbose (amylase: IC50 = 18.30 μg/mL; glucosidase: IC50 = 20.31 μg/mL). The extract also scavenged DPPH radical, chelated Fe²⁺ and inhibited Fe²⁺-induced lipid peroxidation in rat pancreas all in concentration dependent manners with IC50 values of 402.9 μg/mL, 108.9 μg/mL and 367.0 μg/mL respectively. The total phenol and flavonoid contents were 39.73 mg GAE/g and 21.88 mg QAE/g respectively, while the reducing property was 25.62 mg AAE/g. The HPLC analysis revealed the presence of chlorogenic acid (4.17 mg/g) and rutin (5.11 mg/g) as the major phenolic compounds in the extract. Therefore, the ability of the extract to inhibit carbohydrate hydrolyzing enzymes and protect against pancreatic oxidative damage may be an important mechanisms supporting its antidiabetic properties and could make Raffia palm leaf useful in complementary/alternative therapy for management of T2DM. However, further studies such as in vivo should be carried out.
... The seed and the leaf had the least inhibitory strength against α-amylase and α-glucosidase respectively. This research is in agreement with a recent work where red and white ginger inhibited α-amylase and α-glucosidase in vitro (Oboh et al., 2010) and the inhibition of saliva α-amylase activity by plant phytochemicals gotten from pepper (Aguilar-Santamaria et al., 2009;Oboh et al., 2011;). The free and bound phenol extracts of Vernonia amygdalina del significantly (P < 0.05) inhibited α-amylase and α-glucosidase activities in vitro in a dose-dependent pattern although the α-glucosidase inhibitory activity of the extracts were significantly (P < 0.05) higher than their α-amylase inhibitory activity (Saliu et al., 2011). ...
... This research is in agreement with a recent work where red and white ginger inhibited α-amylase and α-glucosidase in vitro (Oboh et al., 2010) and the inhibition of saliva α-amylase activity by plant phytochemicals gotten from pepper (Aguilar-Santamaria et al., 2009;Oboh et al., 2011;). The free and bound phenol extracts of Vernonia amygdalina del significantly (P < 0.05) inhibited α-amylase and α-glucosidase activities in vitro in a dose-dependent pattern although the α-glucosidase inhibitory activity of the extracts were significantly (P < 0.05) higher than their α-amylase inhibitory activity (Saliu et al., 2011). This result also supports another where the seaweeds aqueous extracts in the order of Gracilaria edulis > Sargassum polycystum > Ulva lactula > Gracilaria corticata exhibited significant (P < 0.05) inhibitory activity against α-amylase and α-glucosidase enzymes (Palanisamy & Sellappa, 2012). ...
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ABSTRACT Introduction The use of natural products for the management of diseases had been established in folk medicine. Avocado pear (Persea americana) is used in traditional medicine to manage type 2 diabetes mellitus. Therefore, the focus of this study was to investigate the mechanism behind its antidiabetic prowess by accessing the inhibitory activities of aqueous extract of leaves and fruit parts of avocado on α-amylase, α-glucosidase and malondialdehyde (MDA) produced by sodium nitropruside-induced lipid peroxidation in rats’ pancreas in vitro. Methods The inhibitory effect was assessed using 5mg/ml aqueous extracts on α-amylase and α-glucosidase activities, ABTS (2, 2’-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid)) radical, NO. radical scavenging abilities and SNP-induced malondialdehyde produced after which the types and quantity of phenolics in the leaves and fruit parts of Persea americana were characterized. Results The leaves, peel, flesh and seed extracts inhibited α-amylase, α-glucosidase and the production of malondialdehyde in a dose dependent pattern. The minimum extract concentration that will inhibit 50% enzyme activity (IC50) revealed that the peel showed the highest significant (P < 0.05) α-amylase and α-glucosidase inhibitory activities while the seed revealed the highest MDA inhibition, NO. and ABTS radical scavenging abilities. Syringic acid, eugenol, vnillic acid, isoeugenol, guaiacol, phenol, kaempherol, catechin, ρ-hydroxybenzoic acid, ferulic acid, apigenin, naringenin, epigallocatechin, lupeol and epigallocatechin-3-O-gallate were revealed when the aqueous extracts of avocado pear leaf and fruit parts was characterized. Conclusions This work unravel the possible mechanisms (inhibition of α-amylase and α-glucosidase) used by avocado pear leaves and fruit parts to manage/treat diabetes type 2 and the bioactive phenolics that may take part in the process. KEYWORDS: Type 2 diabetes, Malondialdehyde, Persea americana, α-amylase, α-glucosidase
... Therefore, inhibition of ACE by phenolics of the sea buckthorn juice can be considered as an unusual and beneficial treatment of hypertension. The findings of the current study of selected sea buckthorn juice agreed with earlier reports on the inhibition of ACE by phenolic extracts of bitter leaf [64], soybean [65] and Allium sativum from garlic [66]. exhibited a high ACE inhibitory activity, showing the lowest IC50 value of 222.87 ± 3.59 µ g/mL. ...
... Therefore, inhibition of ACE by phenolics of the sea buckthorn juice can be considered as an unusual and beneficial treatment of hypertension. The findings of the current study of selected sea buckthorn juice agreed with earlier reports on the inhibition of ACE by phenolic extracts of bitter leaf [64], soybean [65] and Allium sativum from garlic [66]. ...
Article
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Sea buckthorn is a temperate bush plant native to Asian and European countries, explored across the world in traditional medicine to treat various diseases due to the presence of an exceptionally high content of phenolics, flavonoids and antioxidants. In addition to the evaluation of nutrients and active compounds, the focus of the present work was to assess the optimal levels for L. plantarum RM1 growth by applying response surface methodology (RSM), and to determine the impact of juice fermentation on antioxidant, anti-hypertension and anticancer activity, as well as on organoleptic properties. Sea buckthorn berries were shown to contain good fiber content (6.55%, 25 DV%), high quality of protein (3.12%, 6.24 DV%) containing: histidine, valine, threonine, leucine and lysine (with AAS 24.32, 23.66, 23.09, 23.05 and 21.71%, respectively), and 4.45% sugar that provides only 79 calories. Potassium was shown to be the abundant mineral content (793.43%, 22.66 DV), followed by copper and phosphorus (21.81 and 11.07 DV%, respectively). Sea buckthorn juice exhibited a rich phenolic, flavonoid and carotenoid content (283.58, 118.42 and 6.5 mg/g, respectively), in addition to a high content of vitamin C (322.33 mg/g). The HPLC profile indicated that benzoic acid is the dominant phenolic compound in sea buckthorn berries (3825.90 mg/kg). Antioxidant potentials (DPPH and ABTS) of sea buckthorn showed higher inhibition than ascorbic acid. Antimicrobial potentials were most pronounced against Escherichia coli BA12296 (17.46 mm). The probiotic growth was 8.5 log cfu/mL, with juice concentration, inoculum size and temperature as the main contributors to probiotic growth with a 95% confidence level. Fermentation of sea buckthorn juice with L. plantarum RM1 enhanced the functional phenolic and flavonoid content, as well as antioxidant and antimicrobial activities. The fermentation with L. plantarum RM1 enhanced the anti-hypertension and anticancer properties of the sea buckthorn juice and gained consumers’ sensorial overall acceptance.
... In folk medicine, the aerial organs of G. amygdalinum are mainly used as an antipyretic, laxative, antimalarial and anthelmintic (Igile et al., 1994;Vigneron et al., 2005;Agra et al., 2008;Georgewill, Georgewill, 2010). Studies of different extracts have shown antioxidant (Igile et al., 1994;Farombi, Owoeye, 2011), antimicrobial (Erasto, Grierson, Afolayan, 2006;Okigbo, Mmeka, 2008), antiparasitic (Tadesse et al., 1993;Ademola, Eloff, 2011;Adiukwu, Amon, Nambatya, 2011), antidiabetic (Akinola et al., 2011;Ong et al., 2011) and antihypertensive (Ajibola, Eleyinmi, Aluko, 2011;Saliu et al., 2011) properties. ...
... Chemical analysis of the leaf and stem found different groups of metabolites, such as sesquiterpene lactones (Babalola, Anetor, Adeniyi, 2001;Erasto, Grierson, Afolayan, 2006;Luo et al., 2011), saponins (Adiukwu, Amon, Nambatya, 2011), polyphenols (Ong et al., 2011;Saliu et al., 2011) and flavonoids (Igile et al., 1994;Atangwho et al., 2009). ...
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Gymnanthemum amygdalinum (Delile) Sch.Bip. ex Walp. (Asteraceae), better known by its former name Vernonia amygdalina Delile, is a small shrub used in folk medicine as an antipyretic, laxative, antimalarial and anthelmintic. Studies have demonstrated that different vegetal extracts possess antioxidant, antimicrobial and antiparasitic activities. Among the bioactive metabolites, there are sesquiterpene lactones, saponins, polyphenols and flavonoids. This study investigated the leaf and stem microscopic characters of G. amygdalinum, aiming to expand the knowledge on this medicinal species and indicate anatomical structures. Plant material was fixed and sectioned by freehand and using a microtome. The sections were either stained or underwent standard histochemical tests. Scanning electron microscopy was performed to investigate epidermal relief. The leaf is amphistomatic with anomocytic stomata. There are striate cuticle, glandular and non-glandular trichomes and dorsiventral mesophyll. In transverse section, the midrib and the petiole have a plano-convex shape. Both show several collateral vascular bundles and few crystals of calcium oxalate. In the stem, the epidermis persists and the phellogen has a peripheral origin. It presents typical endodermis and sclerenchymatic caps adjoining the phloem. The aspects that contribute to characterizing the species are stomata on both leaf surfaces, midrib and petiole features, the endodermis and sclerenchymatic caps in the stem, as well as the different types of trichome on both aerial organs.
... Plant phenolics such as flavonoids have often been reported to be stronger inhibitors of α-amylase [20] which might explain the lower IC 50 value of methanol extract. Nevertheless, the inhibitory action of the extracts from G. kola seeds on α-amylase activity agreed with some earlier reports where plant phytochemicals from Telfairia occidentalis inhibited saliva á-amylase activity and inhibition of pancreatic α-amylase activity by red and white ginger [21] grapefruits and orange peels [22,23], pepper and bitter leaf [24,25]. ...
... 10,49 Polyphenol-rich extracts from C. olitorius and V. amygdalina exhibited marked inhibitory effects on key enzymes linked to type 2 diabetes ( -amylase and -glucosidase) and hypertension (angiotensin I converting enzyme), providing a possible mechanism for reducing the risk of type 2 diabetes and hypertension. 50,51 Similarly, antioxidant properties and enzyme inhibition could be part of the mechanism by which T. occidentalis and S. sparganophora reduce blood sugar and the risk of type 2 diabetes. 52,53 Other African traditional leafy vegetables that have exhibited significant (>70%) inhibition of -amylase activity that could result in reduced blood glucose levels and reduced risk of diabetes include Centella asiatica, C. tribola, C. monophylla, A. hybridus, J. flava, C. album and P. oleracea. ...
Article
There are hundreds of traditional leafy vegetables and wild food plants of horticultural and nutritional significance in Africa. These lesser-known crops and wild food plants that are highly adapted to harsh growing conditions thrive with little care and are available when other sources of food fail or are out of season. They are rich in micronutrients and are often the cheapest sources of many essential vitamins and minerals in many localities. Many of them are very important functional foods in the traditional African diets and are rich in nutraceuticals including polyphenols, tannins, flavonoids and flavonols that exert demonstrable antioxidant, free radical scavenging and enzyme inhibition activities and have antimicrobial properties that provide scientific justification and possible mechanisms for their use in the management of a wide range of ailments including diet-related, non-communicable diseases such as diabetes, hypertension and cardiovascular diseases. African traditional leafy vegetables are invaluable in promoting food security and wellness in Africa on account of their availability and affordability; their great nutritional value, chemotherapeutic and health promoting properties and other unique qualities. Long recognised by the rural populace as quality food items, they are becoming more popular even with the more affluent urban elites. There is the need to develop improved management practices for these super vegetables to promote their cultivation and boost their exploitation for food security and wellness in Africa.
... This could facilitate spermatogenic processes via signal transduction mechanistic pathway. Correspondingly, the HSD activation potentials of the PTSSBE agreed with earlier studies on plant foods [65]. D 5 -3b-HSD catalyzes the synthesis of progesterone from pregnenolone while D 5 -17b-HSD catalyzes the conversion of androstenedione to testosterone in the leydig cell of the males. ...
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Occupational and environmental exposure to mercury causes varieties of adverse reproductive disorders in mammals. The present study was designed to investigate the unsaturated fatty acids of Pteleopsis suberosa stem bark extract (PTSSBE), evaluate its antioxidant properties and examine its biochemical targets on sub-acute mercury-induced testicular dysfunctions. Rats were divided into five groups of 10 animals each. Group I was given distilled water; group II, III, IV and V was orally administered with mercury at a dose of 3.75 mg/kg body weight. Group III, IV and V were co-treated with PTSSBE of 25, 50 and 100 mg/kg body weight respectively, for 10 days. Rats exposed to mercury significantly decreased the activities of catalase (CAT), lactate dehydrogenase (LDH), and the level of reduced glutathione (GSH), while the formation of malondialdehyde (MDA) was increased. There was also a marked significant decrease (p < 0.05) in testicular activities of Δ⁵-3β-hydroxysteroid dehydrogenase and Δ⁵ 17β-hydroxysteroid dehydrogenase. Moreover, the activities of prostatic acid phosphatase, total acid phosphatase and prostatic alkaline phosphatase, were significantly (p < 0.05) elevated in mercury treated rats. These effects were prevented by co-treatment with PTSSBE in mercury-induced testicular toxicity in rats. Aphrosidiac effects of Pteleopsis suberosa, may find clinical application in reproductive abnormalities. Isolation and translation of individual active ingredient would help to find new drugs to cure and/or prevent male infertility among mercury exposed workers.
... 32,33 However, the ACE inhibitory activity of the differently dried mistletoe leaves extract is consistent with earlier studies on ACE inhibitory activity of plant phenolic extracts. 10,34 ACE is a known powerful vasoconstrictor that cleaves angiotensin-I to form angiotensin-II and has been identified as a major factor in hypertension. 35 As a result, ACE inhibitors have been widely developed to prevent angiotensin-II production in cardiovascular disease and utilized in clinical applications since the discovery of ACE inhibitor in snake venom. ...
Article
This study investigated the most appropriate drying method (sun drying, oven drying, or air drying) for mistletoe leaves obtained from almond tree. The phenolic constituents were characterized using high-performance liquid chromatography-diode array detector, while the inhibitory effect of the aqueous extracts of the leaves on angiotensin-I converting enzyme (ACE) was determined in vitro as also the antioxidant properties. Oven-dried extract (kidney [276.09 μg/mL] and lungs [303.41 μg/mL]) had the highest inhibitory effect on ACE, while air-dried mistletoe extract (kidney [304.47 μg/mL] and lungs [438.72 μg/mL]) had the least. Furthermore, the extracts dose-dependently inhibited Fe(2+) and sodium nitroprusside-induced lipid peroxidation in rat's heart and kidney. Also, all extracts exhibited antioxidative properties as typified by their radical scavenging and Fe-chelating ability. Findings from this study revealed that oven drying is the best of the 3 drying methods used for mistletoe obtained from almond host tree, thus confirming that diversity in drying methods leads to variation in phenolic constituents and biological activity of plants. © The Author(s) 2015.
... The results of the enzymes (α-amylase and αglucosidase) inhibitory assays agreed with the phenolic contents, flavonoids contents and reducing power activity of both extracts. Nevertheless, these extracts had higher inhibitory effect than that reported by on ethanolic extract of fluted pumpkin, also to what was reported on 80% acetone and ethyl acetate phenolics extract on bitterleaf (Saliu et al., 2011). ...
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This study sought to investigate the inhibitory effect of methanolic extract of different species of African eggplant (Solanum melongena L.) and (Solanum macrocarpon) on starch hydrolysing enzymes relevant to type-2 diabetes (α-amylase and α-glucosidase). The phenolic content and antioxidant properties of the eggplant varieties were also assessed. The results revealed that both extracts exhibited mild α-amylase and stronger α-glucosidase inhibitory activities in a dose dependent manner. Furthermore, S. macrocarpon exhibited stronger radicals (1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging ability, nitric-oxide (NO·) scavenging ability and ferric reducing antioxidant property (FRAP) than S. melongena, while S. melongena had stronger hydroxyl (OH·) radical ability. The inhibition of starch hydrolysing enzymes and antioxidant activities suggested the potential use of eggplants in the dietary management or control of postprandial hyperglycemia associated with type-2 diabetes. Key words: Antioxidant activity, diabetes, α-amylase, α-glucosidase, Solanum macrocarpon,Solanum melongena.
... Recently, extracts with high phenolic contents have shown a strong capacity to inhibit α-glucosidase activity [54][55][56] and to treat diabetic rats [57]. The same correlation is observed in our study, the most active extract (E14), obtained from N. diderrichii leaves, being also the richest in phenols. ...
Article
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Background Diabetes mellitus is a metabolic disorder which is rising globally in rich and developing countries. In the African region this rate is the highest, with 20 million diagnosed diabetics. Despite a noticeable progress in the treatment of diabetes mellitus by synthetic drugs, the search for new natural anti-diabetic agents is going on. Nauclea diderrichii (De Wild.) Merr. (ND) and Sarcocephalus pobeguinii Hua ex Pellegr. (SP) are used as traditional medicines in Gabon for the treatment of different diseases, especially in the case of diabetes. The aim of this study was to evaluate the antidiabetic potential of these two medicinal plants traditionally used in Gabon.Methods Pharmacological (inhibitory action on α and β-glucosidases) and toxicological (effect on human T cell proliferation) studies were conducted on aqueous extracts of ND (leaves and bark) and SP (bark) collected in Gabon. All raw extracts were analyzed by HPTLC and their content in phenolic compounds was determined by using standard method. The most active extracts were submitted to preparative HPLC in order to evidence the most efficient subfractions by biological evaluation.ResultsThe results showed that two extracts from ND were potent α-glucosidase inhibitors, the leaf extract being more active that the bark extract: the first one was more than 60 fold more active than Acarbose, which is an oral medication used to treat type 2 diabetes; the extract from SP bark was less efficient. The HPLC subfractions of the extracts of ND leaves and SP bark were tested in the same experimental conditions. In each case, the most active subfractions still show very potent inhibitory effect on α-glucosidase (80-90 % inhibition at 0.1 mg/mL). The most efficient extract, from ND leaves, was also characterized by the highest percentage of phenolic compounds, which suggests a relationship between its inhibitory potential on α-glucosidase and its content in phenolic compounds. Conversely, only a moderate inhibitory activity of the three extracts was observed on β-glucosidase.Conclusion These results clearly indicated that active compounds present in N. diderrichii and S. pobeguinii leaves or/and bark were selective and highly potent inhibitors of α-glucosidase and validate their popular use for the treatment of diabetes.
... Plant phenolics such as flavonoids have often been reported to be stronger inhibitors of α-amylase [20] which might explain the lower IC 50 value of methanol extract. Nevertheless, the inhibitory action of the extracts from G. kola seeds on α-amylase activity agreed with some earlier reports where plant phytochemicals from Telfairia occidentalis inhibited saliva á-amylase activity and inhibition of pancreatic α-amylase activity by red and white ginger [21] grapefruits and orange peels [22,23], pepper and bitter leaf [24,25]. ...
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The present study was carried out to evaluate the inhibitory effects of Garcinia kola seeds on key enzymes linked with diabetes mellitus and Phytochemical characterization of its bioactive constituents. Crude n-hexane, ethyl acetate and methanol extracts were prepared successively in a soxhlet apparatus at 50ºC. Subsequently, extraction of crude enzymes from porcine pancreas and rat intestine, thin layer chromatographic analysis, and inhibitory effects of the extracts on α-amylase and α-glucosidase were determined in vitro. The results reveal that G. kola seed extracts inhibited α-amylase (IC50= 4.89mg/ml, 3.44mg/ml, 0.78mg/ml) and α-glucosidase (IC50= 10.29mg/ml, 1.68mg/ml, 2.67mg/ml) corresponding to n-hexane, ethyl acetate, methanol gradient extracts. n-hexane extract had the highest inhibitory effect on α-amylase, while methanol extract was highest on α-glucosidase. Characterization of the bioactive constituents of the extracts using TLC analysis revealed the presence of steroids/triterpenes and phenolic compounds with phenolic compounds appearing in all extracts irrespective of the solvent polarity used for extraction. Anthraquinone and alkaloids were confirmed absent on TLC. This enzyme inhibition could be one of the possible pathways by which G. kola elicits its antidiabetic properties. Furthermore, the enzyme inhibitory properties of the extracts can be attributed to the presence of steroids/ triterpenes, phenolic compounds in the seeds of G. kola.
... 32,33 However, the ACE inhibitory activity of the differently dried mistletoe leaves extract is consistent with earlier studies on ACE inhibitory activity of plant phenolic extracts. 10,34 ACE is a known powerful vasoconstrictor that cleaves angiotensin-I to form angiotensin-II and has been identified as a major factor in hypertension. 35 As a result, ACE inhibitors have been widely developed to prevent angiotensin-II production in cardiovascular disease and utilized in clinical applications since the discovery of ACE inhibitor in snake venom. ...
Conference Paper
African mistletoe (Loranthus bengwensis L.); a hemi-parasitic plant that commonly grows on trees which may eventually kill the host upon heavy infestation has been employed in sub-Sahara African folklore for the treatment of many degenerative diseases such as hypertension. Drying generally plays an important role in herbs production/preservation and it has been reported that drying methods affect the biological activity of herbs. This study sought to investigate the most appropriate drying method for mistletoe leaves by assessing the influence of the drying methods of these leaves on their antioxidant properties and inhibition of Angiotensin-I converting enzyme (ACE), a key enzyme linked to hypertension. Fresh leaves obtained from kolanut host trees were subjected to oven drying, sun drying and air drying respectively. The aqueous extracts of the samples were prepared (1:20 w/v) and then used for subsequent analysis. The extracts were characterized using HPLC-DAD; thereafter, the vitamin C, total phenol and flavonoid contents as well as the antioxidant properties were evaluated. Then, the inhibitory effect of the aqueous extracts of the leaves on ACE was determined in vitro. The vitamin C contents ranged from 10.01mg.AAE/100g (Oven dried) to 8.24mg.AAE/100g (Air dried). Also the total phenol ranged from 8.07mg.GAE/100g (Sun dried) to 6.19mg.GAE/100g (Air dried), while the flavonoid content ranged from 3.03mg.QUE/100g (Sun dried) to 2.61mg.GAE/100g (Air dried). In addition, all extracts scavenged DPPH, ABTS, NO, OH radicals in dose-dependent manner as well as reduced Fe3+ to Fe2+ and chelate Fe2+. Also, the extracts dose-dependently inhibited Fe2+ and sodium nitropruside induced lipid peroxidation in rat’s heart and kidney. Furthermore, sun dried mistletoe extract [kidney (281.86µg/mL), lungs (359.17µg/mL)] had the highest inhibitory effect on angiotensin-І converting enzyme while air dried [kidney (324.97µg/mL), lungs (458.21µg/mL)] had the least. This study revealed that sundried mistletoe leaves from kolanut host tree has more phenolic constituents and elicited higher biological activity than the oven dried and air dried ones. Thus, confirming that diversity in drying methods leads to variation in phenolic compounds, antioxidant property and anti-hypertensive potential.
... This ACE inhibitory property of the phenolic-rich extracts from the Allium sativum clearly showed that the extracts could inhibit ACE in vitro, and this could explain the possible mechanism for their use in the management/treatment of renal failure in folklore. The inhibition of ACE by the phenolic-rich extracts from the Allium sativum agreed with earlier reports on phenolic extracts of bitter leaf (26) and soyabean (27). ACE inhibitors have been widely developed to prevent angiotensin II production in renal dysfunction, and this have been utilized in clinical applications since the discovery of ACE inhibitors in snake venom (28). ...
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Allium sativum have been an important food ingredient in the management or treatment of renal disease. Therefore, this study sought to determine the inhibitory effect of phenolic-rich extract from A. sativum on angiotensin 1 converting enzyme (ACE) activity (key enzyme linked to renal dysfunction) and cisplatin-induced lipid peroxidation in rat kidney in vitro. The free phenolics were extracted with 80% acetone, while the bound phenolics were extracted from the alkaline and acid hydrolyzed residue with ethyl acetate. Thereafter, their inhibitory effect on angiotensin 1 converting enzyme (ACE) activity and cisplatin-induced lipid peroxidation in rat kidney were determined-in vitro. The results revealed that the free phenolics had significantly higher (P<0.05) inhibitory effect on ACE activity than the bound phenolics. Furthermore, incubation of rat kidney in presence of 1 mM cisplatin caused a significant increase (P<0.05) in the malondialdehyde (MDA) content, however, both extracts inhibited MDA produced in a dose dependent manner. The additive and/or synergistic action of the free and bound phenolics could have contributed to the observed medicinal properties of the spice. Therefore, inhibition of ACE activity and prevention of oxidative stress in the kidney could be some of the possible mechanism by which they exert nephroprotective properties. However, the bound phenolic extracts showed stronger inhibition on ACE activity in vitro.
... 11 Accordingly, phenolic extract of V. amygdalina Del was found to have significant effect on the key enzymes linked to type-2 diabetes thereby inhibiting the activities of αamylase and α-glucosidase in vitro in a concentrationdependent manner. 12 Okolie et al. (2008) 13 assessed the antidiabetic effect of V. amygdalina Del in human subjects using standard laboratory testing (fasting blood glucose, glucose tolerance test and postprandial blood glucose). It was found that V. amygdalina Del caused significant reductions in blood glucose levels atmost postprandial time points and for area-under-curve. ...
... In this context, the antioxidant capacity in vitro using ABTS, with a preliminary test to evaluate compounds having electron-donating and/or proton-free radical quenching properties and the inhibition of oxidative processes based on the above results (Table 1), it was possible to demonstrate that MEA may be a potential source of antioxidant compounds and these results suggest that this activity could inactivate the radicals generated in a body in the state of hyperglycemia. Studies suggest that antioxidant capacity contributes positively in the prevention and treatment of diabetes mellitus (DM) [16], making essential to know the content of phenolic compounds present in plants extracts to evaluate their hypoglycemic activity. ...
Article
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In Mexico one in 14 deaths are caused by diabetes mellitus (DM) or by the macro and microvascular disorders derived from it. A continuous hyperglycemic state is characteristic of DM, resulting from a sustained state of insulin resistance and/or a dysfunction of �-pancreatic cells. Acaciella angustissima is a little studied species showing a significant antioxidant activity that can be used as treatment of this disease or preventive against the complications. The objective of this study was to explore the effect of oral administration of A. angustissima methanol extract on physiological parameters of streptozotocin-induced diabetic rats. The results indicated a significant reduction in blood glucose levels, an increase in serum insulin concentration, a decrease in lipid levels and an improvement in the parameters of kidney damage by applying a concentration of 100 mg/Kg B.W. However, glucose uptake activity was not observed in the adipocyte assay. Moreover, the extract of A. angustissima displayed potential for the complementary treatment of diabetes and its complications likely due to the presence of bioactive compounds such as protocatechuic acid. This study demonstrated that methanol extract of Acacciella angustissima has an antidiabetic effect by reducing the levels of glucose, insulin and improved physiological parameters, hypolipidemic effect, oxidative stress and renal damage in diabetic rats.
... Plant foods and herbs have been used in folklore and traditional medicine to treat and manage hypertension (Saliu, Ademiluyi, Akinyemi, & Oboh, 2012). However, previous findings have revealed that these plant foods are rich sources of phytochemicals such as phenolics; with strong antioxidant properties and many researchers have attributed the health promoting effects of plant foods to its phenolic constituents (Oboh, Ademosun, et al., 2014). ...
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The erectogenic potential of alkaloids extracted from Bitter leaf (Vernonia amygdalina) and Black nightshade (Solanum nigrum) was investigated in this study. Fresh leaves obtained from Bitter leaf and Black night shade were air‐dried, pulverized, and extracted for alkaloids. The inhibitory potential of the alkaloid extracts on arginase and phosphodiesterase‐5 (PDE‐5) activities in rats penile tissue was determined in vitro. The antioxidant properties were also evaluated and the constituent alkaloids quantified using GC‐MS. The alkaloid extracts inhibited arginase (0–30.51 μg/ml) and PDE‐5 (0–133.69 μg/ml) activities in a concentration‐dependent pattern. Similarly, the alkaloid extracts inhibited Fe²⁺‐induced lipid peroxidation in rats penile tissues, scavenged DPPH, OH, and NO radicals as a function of concentration. GC‐MS characterization revealed over 20 alkaloid compounds. The inhibition of PDE‐5‐, arginase‐, pro‐oxidant‐induced lipid peroxidative‐, and free radicals‐scavenging activities by the alkaloids is suggestive of putative mechanisms underlying their therapeutic use for managing erectile dysfunction in folklore medicine. Practical applications Alkaloids extracted from Black nightshade (Solanum nigrum) and Bitter leaf (Vernonia amygdalina) were characterized and investigated by standard procedures for inhibitory action against key erectile dysfunction‐linked enzymes and antioxidant activity. The alkaloids inhibited erectile dysfunction‐linked enzymes (arginase and PDE‐5) and showed considerable antioxidant activity in a concentration‐dependent manner. In view of this, we suggest the application of these results in the development of erectile dysfunction drugs in the pharmaceutical industry, with probable minimal or no adverse effect.
... Bamboo shoots contain significant dietary fibre content as reported in current study and by several previous investigations (Ferreira et al. 1992;Bhatt et al.2005;Kumbhare and Bhargava 2007;Nirmala et al. 2007) (Table 2). Dietary fibre from bamboo shoot have been shown to impart several health benefits including prevention of intestinal diverticulum and hyperlipemia (Naito et al. 1980 (Puupponen-Pimiä et al. 2001;Mira et al. 2002;González-Gallego et al. 2007;Landet 2012;Saliu et al. 2012). However, the health benefit which has attracted the strongest interest of researchers during past few decades is their anti-cancerous property, probably owing to their strong anti-oxidant nature. ...
Conference Paper
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Cancer, the feared non-communicable disease, contributes a staggering 16% to total deaths worldwide. Despite the enormous advances in medical research, cancer continues to pose an impregnable challenge for global health care systems with its massive economic burden mounting to approximately US$ 1.16 trillion. However, about 30-50% cases of cancer remain preventable mainly through modification of our dietary patterns. Over the years it has been scientifically proven that plant based diet exert preventive and antagonistic effects on cancer incidences. These whole plants and other natural plant products have a plethora of bioactive phytochemicals embedded in them which actively functions towards prevention and treatment of varied cancer forms. Moreover, plant based cancer prevention therapy is considered safe largely because it lacks the side effects normally associated with other cancer treatment strategies like chemotherapy and radio therapy etc. Bamboo shoots, the highly palatable juvenile culms of bamboo plant which have proven nutritional credentials, possess rich repositories of several phytochemicals like phenolic compounds, dietary fibres, phytosterols and several other functional groups which are known to possess anti-cancerous properties. With its worldwide distribution, bamboo shoots represent a vast natural resource which can very effectively be promoted as a potential functional food in the form of a highly efficient, healthy and economic anticancer therapeutic system.
... They also have antibacterial, antihistamine, antihypertensive, cognitive improvement, and mood uplifting qualities. Studies have shown that flavonoid-rich foods, supplements, or herbal preparations may protect against and cure atherosclerosis and cardiovascular disorders (Schmeda-Hirschmann and Arias 1992;Hansen et al. 1996;Pinto et al. 2009;Oboh and Ademosun 2011;Saliu et al. 2012;Oboh et al. 2012). Flavonoids derived from plants have been widely used as herbal remedies to treat illnesses of the circulatory system. ...
Article
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The purpose of this research was to characterize and identify novel bioactive flavonoids in Rauvolfia serpentina roots as natural, safe, and efficacious angiotensin-converting enzyme (ACE) inhibitor for the management of antihypertension. Firstly, total flavonoids were extracted from Rauvolfia serpentina to evaluate the ACE inhibition potential. The extracted total flavonoids showed greater ACE inhibition potential (79.9 ± 0.42%) than the standard captopril (72.12 ± 0.35%) which is synthetic hypotensive drug. These flavonoids were further purified using column chromatography, and their potential to inhibit the angiotensin-converting enzyme was determined. Only the third fraction (F3) exhibited ACE inhibitory potential compared to the other seven purified fractions. The F3 fraction was analyzed with LC–ESI–MS/MS to determine which flavonoid compound inhibited ACE. The flavonoid compounds recognized as ACE inhibitors from Rauvolfia serpentina included pinocembrin, quercetin, galangin-5 methyl-ether, apigenin, pseudobaptigenin, quercetin dimethyl ether O-glucuronide, and myricetin 3 O-glucoside, luteolin 7-O glucuronyl, rutin, and quercetin -3- O hexose-pentose. The finding of this research indicates that the root of Rauvolfia serpentina contains several different medicinal flavonoids possessing the capacity to control hypertension through angiotensin-converting enzyme inhibition mode of action.
... There is a strong correlation between plant phenol content and inhibitory activities of α-amylase and α-glucosidase. Polyphenols are considered as potent antioxidants due to their redox properties in their hydroxyl groups [14]. One of the important functions of polyphenols is to inhibit digestive enzymes, especially carbohydrate hydrolyzing enzymes such as α-amylase and α-glucosidase. ...
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Background Diabetes mellitus is a type of metabolic disease characterized by elevated blood sugar. The main strategy for its treatment is to inhibit carbohydrate-hydrolyzing enzymes, including α-amylase and α-glucosidase. The aim of the present study was to evaluate the efficacy of Salvia extracts in inhibiting diabetes marker enzymes. Materials and methods This experimental study was performed in vitro. The studied plants included Salvia mirzayanii , Salvia macilenta , Salvia officinalis and Salvia santolinifola and inhibitory effects of their methanolic and dichloromethane extracts were investigated. After calculating the percentage of α-amylase inhibition and IC 50 of the extracts, Km and Vmax were also determined using prism7.Statistical analysis was performed employing with Graph Pad instat3 software. Results The results here in revealed that methanol extracts of Salvia santolinifola (with IC 50 = 54.72 ± 9.6 μg / ml) and Salvia officinalis with (IC 50 = 54.87 ± 5.7 μg / ml) and dichloromethane extract of Salvia officinalis with (IC 50 = 71.20 ± 14.3 μg / ml) had the greatest inhibitory effect on α-amylase comparing to acarbose with (IC 50 = 42.94 ± 3.8 μg / ml) as a standard. Tukey test results showed that there is a significant difference between IC 50 of acarbose comparing to methanol extract of Salvia mirzayanii and dichloromethane extracts of Salvia mirzayanii and Salvia santolinifola with P value ˂0.001 in α-amylase inhibition. Conclusion The extracts had significant inhibitory effects on α-amylase inhibition. Among the extracts of the studied species, methanol extract of Salvia santolinifola demonstrated the greatest inhibitory effect on α-amylase.
... Phenolic compounds have diverse biological activities and have been reported to be effective in the treatment and management of degenerative diseases such as diabetes, hypertension and obesity (Graf et al., 2005 andArts et al., 2005) [9,4] . Phenolic compounds have been reported to inhibit α-amylase and α-glucosidase inhibitory activities and exhibit antioxidant properties which are essential in the prevention and management of type 2 diabetes (Saliu et al., 2012) [18] . The use of medicinal plants which are rich in polyphenols are often advocated for the management of type 2 diabetic owing to their possible lower risk of side effects compared to contemporary antidiabetic drugs such as acarbose (Felix et al., 2017) [8] . ...
Article
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Background: Oxidative stress has been demonstrated to participate in the progression of diabetes including impairment of insulin action and elevation of the complication incidences. Antioxidants have already shown to be prospective in the treatment of diabetes both type I and type II diabetes. Methods: The study was conducted to determine the total phenolic and flavonoid content of the ethanolic extracts of four Nepalese medicinal plants by the Folin Ciocalteu reagent and Aluminium chloride colorimetric method respectively. The antioxidant activity of the ethanolic extract was determined by the DPPH (2, 2-diphenyl-1-picryl-hydrazyl) radical scavenging method using ascorbic acid as the positive control was measured at different concentration (1, 10, 100 µg/mL). Results: The phytochemical analysis revealed presence of phenols and flavonoids in Magnolia grandiflora and Mangifera indica. The total phenolic content and flavonoid content were 353.81± 0.84 mgGAE/g and 310.54±0. 0 mgQE/g dry extract weight for unripe Mangifera indica respectively. The extracts of unripe Mangifera indica showed antioxidant activity with the IC 50 values of 3.87 μg/mL compared with the standard ascorbic acid IC 50 value of 4.22 μg/mL. Conclusion: In this study showed potential antioxidant, with present of Flavonoids and Phenols. These data are important because they contribute to the recording of traditional knowledge used for the antioxidant activities.
... V. amygdalina has been to possess antiviral activity (Momoh et al. 2012) and significantly inhibit ACE (Ajibola et al. 2011, Saliu et al. 2012, Abdulazeez Mansurah et al. 2013, which is a key mechanism for combating severe acute respiratory distress syndrome reported in the COVID crisis, besides its beneficial effect in decreasing blood pressure. This makes V. amygdalina a good candidate to combat metabolic syndrome and COVID co-morbidity. ...
Article
The global market for medicinal plants and herbs is on the increase due to their desirability, efficacy, and less adverse effects as complementary and alternative medications to the orthodox pharmaceuticals, perhaps due to their natural components and qualities. Metabolic syndromes are managed with changes in diet, exercise, lifestyle modifications and the use of pharmacological agents. Plants are now known to have potent antioxidant and cholinergic activities which are relevant to the management of several metabolic syndromes, which are unfortunately, co-morbidity factors in the coronavirus disease crisis. This review will focus on the biological activities of some plant products used as complementary and alternative medicines in the management of metabolic syndromes, and on their reported antiviral, antithrombotic, angiotensin-converting enzyme inhibitory properties, which are integral to their usage in the management of viral infections and may give an avenue for prophylactic and therapeutics especially in the absence of vaccines/formulated antiviral therapies.
... However, the IC50 value (Concentration of the extract at 50% inhibitory activity) of V. amygdalina leaf extract was 0.51 mg/mL which is lower to that of acarbose (0.56 mg/mL), indicating higher inhibitory activity of the extract. In a similar, the IC50 value of 8.4 µg/mL and 10.6 µg/mL have been reported for both free and bound phenol extract from V. amygdalina leaf grown in Nigeria [20]. Natural polyphenols have been reported to inhibit the activity of carbohydrate hydrolysing enzymes [21]. ...
... Therefore, this study buttress the claim that natural inhibitors from dietary plants have mild inhibitory effect on 毩-amylase activity but strong 毩-glucosidase inhibitory activity and could be used as effective therapy for the management of postprandial hyperglycemia with minimal side effects [3] this agrees with the finding on eggplant phenolics, which have been recommended as a choice diet for the management of type 2 diabetes [28] . Also agrees with Oboh et al. [27] for ginger varieties and Saliu et al. [29] for bitter leaf extract The result of the total phenol and flavonoid content of T. occidentalis leaf was observed as reported by Oboh et al. [30] . The result revealed that unprocessed T. occidentalis leaf had a significantly (P<0.05) ...
Article
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To investigate the inhibitory effect of Telfairia occidentalis Hook f. (Curcubitaceae) (T. occidentalis) leaf on key enzyme linked to type-2 diabetes (α - amylase and α - glucosidase) as well as assess the effect of blanching (a commonly practiced food processing technique) of the vegetable on these key enzymes. Fresh leaves of T. occidentalis were blanched in hot water for 10 minutes, and the extracts of both the fresh and blanched vegetables were prepared and used for subsequent analysis. The inhibitory effect of the extract on α - amylase and α - glucosidase activities as well as some antioxidant parameter was determined in vitro. The result revealed that unprocessed T. occidentalis leaf reduce Fe(3+) to Fe(2+) and also inhibited α - amylase and α - glucosidase activities in a dose dependent manner. However, blanching of the leafy vegetables caused a significant (P<0.05) increase in the antioxidant properties but decrease their ability to inhibit α - amylase and α - glucosidase activities. This antioxidant properties and enzyme inhibition could be part of the mechanism by which they are used in the treatment/prevention of type-2 diabetes. However, the blanched vegetable reduces their ability to inhibit both α - amylase and α - glucosidase activity in vitro.
... However, the IC50 value (Concentration of the extract at 50% inhibitory activity) of V. amygdalina leaf extract was 0.51 mg/mL which is lower to that of acarbose (0.56 mg/mL), indicating higher inhibitory activity of the extract. In a similar, the IC50 value of 8.4 µg/mL and 10.6 µg/mL have been reported for both free and bound phenol extract from V. amygdalina leaf grown in Nigeria [20]. Natural polyphenols have been reported to inhibit the activity of carbohydrate hydrolysing enzymes [21]. ...
... Zheng et al. [17] reported the total phytosterol content in the fresh bamboo shoot residue to be 523 mg/100g dry weight. These studies therefore support the fact that bamboo shoots contain very high quantities of major properties [19,20,21]. ...
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Food not only provides us with essential nutrients that are vital for normal functioning of the body, b u t a l s o serves as a source o f several active ingredients termed as bioactive compounds which play an active role in prevention and cure of chronic diseases. Emphasis on the utilization of food sources having balanced and optimum proportion of these nutrients and bioactive compounds globally might prove to be the most crucial factor in cutting the exorbitant costs of prevalent health care systems thereby bringing social and economic gains. Bamboo shoots, the young, aerial outgrowths of the bamboo plant, along with being rich repository of essential nutrient, also contain generous quantities of several bioactive compounds such as phytosterols, phenols and dietary fiber. These bioactive compounds have been proven to impart bamboo shoots with several health benefits such as reducing serum cholesterol, anti-inflammatory, anti-bacterial, antimicrobial and antioxidant properties, prevention of diabetes, obesity, metabolic disorders, cardiovascular diseases and even certain types of cancers. Therefore, with a plethora of bioactive compounds and associated health benefits, bamboo shoots represent an ideal functional food resource which if utilized to its full potential can prove to be a major ally in our quest for a healthy future.
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Functional foods describe the importance of foods in promoting health and preventing diseases aside their primary role of providing the body with the required amount of essential nutrients such as proteins, carbohydrates, vitamins, fats, and oils needed for its healthy survival. This review explains the interaction of functional food bioactive compounds including polyphenols (phenolic acids [hydroxybenzoic acids and hydroxycinnamic acids], flavonoids [flavonols, flavones, flavanols, flavanones, isoflavones, proanthocyanidins], stilbenes, and lignans), terpenoids, carotenoids, alkaloids, omega-3 and polyunsaturated fatty acids, among others with critical enzymes (α- amylase, α- glucosidase, angiotensin-I converting enzyme [ACE], acetylcholinesterase [AChE], and arginase) linked to some degenerative diseases (type-2 diabetes, cardiovascular diseases [hypertension], neurodegenerative diseases [Alzheimer's disease] and erectile dysfunction). Different functional food bioactive compounds may synergistically/additively confer an overwhelming protection against these degenerative diseases by modulating/altering the activities of these critical enzymes of physiological importance.
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The study evaluated the hypoglycemic effect of biscuits produced from flour blends of three medicinal foods (Unripe plantain fruits, Moringa seed, and pigeon pea) on high‐fat diet (HFD)/streptozotocin (STZ)‐induced (HFD/STZ) diabetic rats. The formulated biscuits were produced at different proportion of the flour blends and fed to HFD‐STZ‐induced diabetic rats for 14 days. The result showed that the formulated biscuits caused a significant increase in pancreas, liver, and kidney antioxidant molecules, decreased the production of thiobarbituric reactive acid species (TBARS) in pancreas, liver, and kidney homogenates, and reduced pancreatic α‐amylase and intestinal α‐glucosidase activities as against untreated diabetic rats. In conclusion, the use of formulated biscuits from the blends of flours from unripe plantain, Moringa seed, and pigeon pea could serve as functional food toward the treatment/management of diabetes and its possible complications such as diabetes‐induced liver and kidney damage. Practical applications The drug use in the management of diabetes such as acarbose have been reported to have side effects, while diet therapy is gaining much interest in the management of diabetes. Hence, there is a need for diets base therapy that will not only cure diabetes, but also combat its complications. In sight of this, unripe plantain, Moringa seed, and pigeon pea flours were blended and used to produce functional biscuits for diabetic rats. The biscuit could be produced on the large scale under hygienic and regulated condition.
Article
The study evaluated the hypoglycemic effect of biscuits produced from flour blends of three medicinal foods (Unripe plantain fruits, Moringa seed, and pigeon pea) on high-fat diet (HFD)/streptozotocin (STZ)-induced (HFD/STZ) diabetic rats. The formulated biscuits were produced at different proportion of the flour blends and fed to HFD-STZ-induced diabetic rats for 14 days. The result showed that the formulated biscuits caused a significant increase in pancreas, liver, and kidney antioxidant molecules, decreased the production of thiobarbituric reactive acid species (TBARS) in pancreas, liver, and kidney homogenates, and reduced pancreatic α-amylase and intestinal α-glucosidase activities as against untreated diabetic rats. In conclusion, the use of formulated biscuits from the blends of flours from unripe plantain, Moringa seed, and pigeon pea could serve as functional food toward the treatment/management of diabetes and its possible complications such as diabetes-induced liver and kidney damage.
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In the present study, ultrasonic extraction technique (UET) is used to improve the yield of polysaccharides from Laminaria japonica (LJPs). And their antioxidative as well as glycosidase inhibitory activities are investigated. Box-Behnken design (BBD) combined with response surface methodology (RSM) is applied to optimize ultrasonic extraction for polysaccharides. The optimized conditions are obtained as extraction time at 54 min, ultrasonic power at 1050 W, extraction temperature at 80°C and ratio of material to solvent at 1:50 (g mL−1). Under these optimal ultrasonic extraction conditions, an actual experimental yield (5.75% ± 0.3%) is close to the predicted result (5.67%) with no significant difference (P > 0.05). Vitro antioxidative and glycosidase inhibitory activities tests indicate that the crude polysaccharides (LJP) and two major ethanol precipitated fractions (LJP1 and LJP2) are in a concentration-dependent manner. LJP2 (30%–60% ethanol precipitated polysaccharides) possesses the strongest α-glucosidase inhibitory activity and moderate scavenging activity against hydroxyl radicals (66.09% ± 2.19%, 3.0 mg mL−1). Also, the inhibitory activity against α-glucosidase (59.08% ± 3.79%, 5.0 mg mL−1) is close to that of acarbose (63.99% ± 3.27%, 5.0 mg mL−1). LJP1 (30% ethanol precipitated polysaccharides) exhibits the strongest scavenging activity against hydroxyl radicals (99.80% ± 0.00%, 3.0 mg mL−1) and moderate α-glucosidase inhibitory activity (47.76% ± 1.92%, 5.0 mg mL−1). LJP shows the most remarkable DPPH scavenging activity (66.20% ± 0.11%, 5.0 mg mL−1) but weakest α-glucosidase inhibitory activity (37.77% ± 1.30%, 5.0 mg mL−1). However, all these LJPs exert weak inhibitory effects against α-amylase. These results show that UET is an effective method for extracting bioactive polysaccharides from seaweed materials. LJP1 and LJP2 can be developed as a potential ingredient in hypoglycemic agents or functional food for the management of diabetes. This study provides scientific evidence and advances in the preparation technology and a hypoglycemic activities evaluation method for seaweed polysaccharides, especially glycosidase inhibition in combination with an antioxidative activity evaluation method. © 2015, Science Press, Ocean University of China and Springer-Verlag Berlin Heidelberg.
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Using various chromatographic separations, four compounds, including one new steroid saponin named vernoamyoside E (1), were isolated from the leaves of the Vietnamese medicinal plant Vernonia amygdalina Delile (Asteraceae). Their structures were established by spectroscopic methods such as 1D- and 2D-NMR, HR-ESI-MS, and HPLC analysis. The inhibitory activities against α-glucosidase and α-amylase of the isolated compounds from V. amygdalina were reported for the first time. The results indicated that compound 1 significantly inhibited both against α-amylase and α-glucosidase activity.
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In all age groups globally, diabetes is a metabolic disease that is associated with oxidative stress caused by reactive free radicals in the human system. In folklore medicine, plants based diets such as unripe plantain, and water yam are used in management of diabetes. Hence, this study aimed to determine the antioxidant, α-amylase and α-glucosidase activities, glycemic index, blood glucose concentration and sensory attributes of dough meals developed from flour blends of unripe plantain, water yam and bitter leaf. A remarkable free radical scavenging activity and ferric ion reducing power was observed as the supplementation increased with water yam. The inhibition of α-amylase and α-glucosidase activities by the dough meal was dependent on the percentage inclusion of water yam and this indicates the antihyperglycemic potential of the dough meal. The glycemic index of rat fed with the dough meal was significantly low at 40% water yam supplementation compared to 100% unripe plantain dough meal. Hence, the study provides a rationale that dough meal from unripe plantain; water yam and bitter leaf have the potential to be used as functional foods to alleviate postprandial hyperglycemia.
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Background: Ethnopharmacological studies are relevant for sustaining and improving knowledge of traditional medicine within the framework of complementary/alternative therapeutic practices based solely on experience and observation across generations. Hypertension is a common cardiovascular disorder affecting more than 50% of older people in Africa (PLoS One. 2019; 14 (4): e0214934; published online on April 5, 2019, doi: 10.1371/journal.pone.0214934). Methods: We conducted a cross-sectional survey from October 2014 to August 2015 with 18 renowned traditional healers from the city of Bukavu to capture botanical plant species and remedies used by herbalists to manage hypertension in the Democratic Republic of Congo. Results: Respondents cited 41 plant species belonging to 25 botanical families. The ten most common plants are Allium sativum, Galinsoga ciliata, Moringa oleifera, Bidens pilosa, Persea americana, Piper capense, Catharanthus roseus, Rauvolfia vomitoria, Sida rhombifolia, and Vernonia amygdalina. The parts used are primary leaves (48.8%) formulated as oral decoctions (65.9%). Conclusion: The literature review validated the use of 73.2% of the plants listed. Plants of high local use-value not supported by other studies deserve in-depth chemical and pharmacological studies.
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This study focused on the effect of phenolic‐rich extracts of mistletoe from different host plants on key enzymes (α‐amylase, α‐glucosidase) linked to type‐2 diabetes (T2D) and hypertension (angiotensin‐I converting enzyme [ACE]), as well as Fe²⁺ and sodium nitroprusside (SNP)‐induced thiobarbituric acid reactive species (TBARS) production in rat pancreas in vitro. The phenolic‐rich extract was prepared using ethyl acetate and the effects on α‐amylase, α‐glucosidase, and ACE activities, and TBARS production was determined. The phenolic constituent of the extract was also determined. The results revealed that the extracts (CCT, KNT, AMT, BFT) inhibited α‐amylase (EC50 = 2.24, 2.59, 2.36, and 1.80 µg/mL, respectively), α‐glucosidase (EC50 = 1.94, 1.92, 1.96, and 8.59 µg/mL), and ACE (EC50 = 0.87, 0.67, 0.75, and 1.06 µg/mL) activities, and Fe²⁺ and SNP‐induced TBARS production. Therefore, inhibition of α‐amylase, α‐glucosidase, ACE, and oxidative stress by the phenolic‐rich extracts could be among the mode of actions of mistletoe toward the management of T2D and hypertension. Practical applications Dried mistletoe leaves are usually consumed as tea or decoction, and are often prescribed for hypertensive or diabetic patients while the wet leaves are used to cook soup. This study revealed the possible antidiabetic, antihypertensive, and antioxidant properties of mistletoe leaves from different host plants.
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Ethnopharmacological relevance: Sandpaper [Ficus exasperata Vahl (Moraceae)] leaf has been reportedly used in folklore for the management/treatment of cardiovascular diseases with little/or no scientific basis for their action. This study sought to investigate the effect of dietary supplementation of sandpaper leaf on angiotensin-I converting enzyme (ACE) activity in hypercholesterolemia as well as the effect of their phenolic extract on this enzyme in vitro. Materials and methods: The phenolic extract was prepared, then, the inhibitory effect of the leaf extract on ACE was determined in vitro. Thereafter, the effect of dietary supplementation of sandpaper leaf on angiotensin-I converting enzyme (ACE) activity in high cholesterol diet fed rats for 14 days was evaluated as well as some biochemical parameters. Results: The result revealed that under in vitro condition, the phenolic extract inhibited ACE (IC50=14.7µg/mL) in a dose-dependent manner (0-10µg/mL). Feeding high cholesterol diets to rats caused a significant (P<0.05) increase in the ACE activity. However, there was a significant (P<0.05) decrease in the ACE activity as a result of supplementation with the sand paper leaves. Furthermore, there was a significant (P<0.05) increase in the plasma lipid profile with a concomitant increase in malondialdehyde (MDA) content in rat liver and heart tissues. However, supplementing the diet with sandpaper leaf (either 10% or 20%) caused a significant (P<0.05) decrease in the plasma total cholesterol (TC), triglyceride (TG), very low density lipoprotein-cholesterol (VLDL-C), and low-density lipoprotein-cholesterol levels (LDL-C), and in MDA content in the tissues. Conversely, supplementation caused a significant (P<0.05) increase in plasma high-density lipoprotein-cholesterol level when compared with the control diet. Reversed phase HPLC analysis of the extract revealed Quercitrin (43.7mg/g), chlorogenic acid (42.8mg/g) and caffeic acid (33.9mg/g) as the major phenolics in the leaf. Conclusion: The inhibition of ACE activity and prevention of hypercholesterolemia by sandpaper leaf could be part of the possible mechanism underlying its anti-hypertensive property which could lay credence to its use in folk medicine. However, these activities may be directly/indirectly attributed to the polyphenolics present.
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Objective: To investigate the inhibitory effect of phenolic-rich extracts from Cola nitida (C. nitida) seeds on key enzymes linked with type-2 diabetes and Fe(2+) induced oxidative stress in rat pancreas. Methods: The phenolic extract was prepared with 80% acetone (v/v). Subsequently, the antioxidant properties and inhibitory effect of the extract on α - amylase and α - glucosidase as well as on Fe(2+) induced lipid peroxidation in rat pancreas were determined in vitro. Results: The result revealed that C. nitida extract inhibited α-amylase (EC50=0.34 mg/mL) and α-glucosidase (EC50=0.32 mg/mL) activities as well as Fe(2+) induced lipid peroxidation in rat pancreas in a dose dependent manner. In addition, the extract had high DPPH radical scavenging ability (EC50=2.2 mg/mL) and reducing power (8.2 mg AAE/g). Characterization of the main phenolic compounds of the extract using gas chromatography analysis revealed catechin (6.6 mg/100 g), epicatechin (3.6 mg/100 g), apigenin (5.1 mg/100 g) and naringenin (3.6 mg/100 g) were the main compounds in the extract. Conclusions: This antioxidant and enzyme inhibition could be some of the possible mechanism by which C. nitida is use in folklore for the management/treatment of type-2 diabetes. However, the enzyme inhibitory properties of the extract could be attributed to the presence of catechin, epicatechin, apigenin and naringenin.
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This study investigated the most appropriate drying method (sun drying, oven drying, and shade drying) for mistletoe leaves obtained from kolanut tree. The phenolic constituents were characterized using high performance liquid chromatography–diode array detector, while the inhibitory effect of the aqueous extracts of the leaves on cholinesterases and angiotensin-I converting enzyme (ACE) and antioxidant activities were determined in vitro. The extracts inhibited acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and ACE in dose-dependent manner. However, extract from sun-dried sample exhibited the highest AChE, BChE, and ACE inhibitory effect while extract from shade-dried sample had the least. Likewise, sun-dried sample exhibited the highest antioxidant properties as exemplified by Fe2+-chelating, 1,1-diphenyl-2 picrylhdrazyl, OH, and nitric oxide radical scavenging abilities. This study also revealed the presence of 20 phenolic compounds with caffeic acid being the most predominant. Conclusively, kolanut host tree mistletoe leaves can be used as therapeutic agent in the management of Alzheimer's disease and hypertension. The best drying method for mistletoe harvested from kolanut host tree was proposed in this study. Having identified the best drying method that retained phenolic constituents, antioxidant activities, anticholinesterase, and antihypertensive potential of kolanut host tree mistletoe leaves, this work maybe applicable in pharmaceutical industry for development of anticholinesterase and antihypertensive drugs with little or no side effect as well as in the food industry as complementary functional food/medicine in the management of Alzheimer's disease and hypertension.
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Abstract Ginger has reportedly been used in folk medicine for the management and prevention of hypertension and other cardiovascular diseases. Therefore, this study sought to investigate the inhibitory effect of aqueous extracts of two varieties of ginger on a key enzyme linked to hypertension (angiotensin I-converting enzyme [ACE]), and on pro-oxidants [Fe(2+) and sodium nitroprusside (SNP)] which have been shown to induce lipid peroxidation in the rat's isolated heart in vitro. Aqueous extracts (0.05 mg/mL) of red ginger (Zingiber officinale var. Rubra) and white ginger (Zingiber officinale Roscoe) were prepared and the ability of the extracts to inhibit ACE along with Fe(2+)- and SNP-induced lipid peroxidation was determined in rat's heart in vitro. Results revealed that both extracts inhibited ACE in a dose-dependent manner (25-125 μg/mL). However, red ginger extract (EC50=27.5 μg/mL) had a significantly (P<.05) higher inhibitory effect on ACE than white ginger extract (EC50=87.0 μg/mL). Furthermore, incubation of the rat's heart in the presence of Fe(2+) and SNP caused a significant increase (P<.05) in the malondialdehyde (MDA) content of the heart homogenates, while the introduction of the ginger extracts (78-313 μg/mL) caused a dose-dependent decrease in the MDA content of the stressed heart homogenates. This suggests that the possible mechanism through which ginger exerts its antihypertensive properties may be through inhibition of ACE activity and prevention of lipid peroxidation in the heart. Furthermore, red ginger showed stronger inhibition of ACE than white ginger. Additionally, it should be noted that these protective properties of the ginger varieties could be attributed to their polyphenol contents.
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Diabetes mellitus is one of the commonest diseases affecting the citizens of both developed and poor countries. In South Africa, the number of people suffering from diabetes is believed to be rising steadily. An ethnobotanical study of plants used by the traditional healers, herbalists and rural dwellers for the treatment of diabetes mellitus was conducted in the Eastern Cape Province. The study revealed 14 plant species belonging to six families namely; Asteraceae, Hypoxidaceae, Apocynaceae, Asphodelaceae, Apiaceae and Buddlejaceae. The use of infusions from plant leaves and roots was the commonest method of herbal preparation. In all cases, the treatment involved drinking the extracts for a long period of time. There was a general belief on the efficacy of the prepared extracts.
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Diabetes mellitus is a chronic disease which affects millions of people worldwide. The prevalence of this disease is increasing annually and the number of diabetics is projected to rise above 300 million before 2025. The growing number of diabetics, coupled with the harsh side effects of some synthetic drugs has led to the increasing search for more natural products of plant origin. Vernonia amygdalina Del. (Asteraceae) is one of the plants commonly used for the treatment of diabetes in Africa. This study evaluated the effect of leaf extracts of this plant on glucose utilization in 3T3-L1, C2C12 muscle, and Chang-liver cells. Treatment of the cells with the acetone, methanol, water, and n-hexane/isopropanol extracts of V. amygdalina leaves significantly increased glucose utilization in the C2C12 muscle and Chang-liver cells but showed no effect on the 3T3-L1 cells. The water and n-hexane/isopropanol extracts were the most active in the C2C12 cells with a response of 78.3 and 95.6% above the control, respectively, while in the Chang-liver cells, water and acetone extracts had a response of 65.8 and 59.6% above the control, respectively. The results, especially of the water extract, strongly corroborate the ethnomedical uses of V. amygdalina as an antidiabetic plant.
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Polyphenols exhibit a wide range of biological effects because of their antioxidant properties. The study sought to carry out a comparative studies on the protective ability of free and bound polyphenol extracts of red Capsicum annuum var. aviculare (Tepin) on brain and liver – in vitro. Free polyphenols of red Capsicum annuum var. aviculare (Tepin) were extracted with 80% acetone, while the bound polyphenols were extracted with ethyl acetate from acid and alkaline hydrolysed residue from free polyphenols extract. The phenol content, Fe(II) chelating ability, OH radical scavenging ability and protective ability of the extract against some pro-oxidant (25 μM Fe(II), 7 μM sodium nitroprusside and 1 mM quinolinic acid)-induced lipid peroxidation in brain and liver was subsequently determined. The results of the study revealed that the free polyphenols (218.2 mg/100 g) content of the pepper were significantly higher (PPCapsicum annuum var. aviculare (Tepin) contains 83.7% free soluble polyphenol and 16.3% bound polyphenols. In addition, both polyphenolic extracts inhibit the various pro-oxidant agents (Fe2+, sodium nitroprusside and quinolinic acid) induced lipid peroxidation in brain and liver tissues in a doe-dependent manner. However, the free polyphenols had higher protective ability than the bound polyphenols. The main mechanism through which they are carry out their protective effect against lipid peroxidation in the brain and the liver is by Fe(II) chelating ability, OH and NO radicals scavenging ability and inhibition of over-stimulation of NMDA receptor.
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Management of the blood glucose level is a critical strategy in the control of diabetes complications. Inhibitors of saccharide hydrolysing enzymes have been useful as oral hypoglycemic drugs for the control of hyperglycemia especially in patients with type-2 diabetes mellitus. This study compares the phenolic contents and antioxidant properties of two varieties of ginger, namely, Red (Zingiber offidnale var. Rubra) and white {Zingiber offidnale Roscoe), and their inhibitory effects on the activities of α-amylase and α-glucosidase (key enzymes linked to type-2 diabetes) using an in vitro model. The results show that the aqueous extracts of red ginger had significantly (P < 0.05) higher phenolic contents as well as higher antioxidant activities than the aqueous extracts of white ginger. However, contrary to the phenolic contents and antioxidant properties, white ginger had a significantly (P > 0.05) stronger inhibitory effect on a-amylase and α-glucosidase activities than red ginger. Furthermore, both extracts exhibited mild α-amylase and stronger α-glucosidase inhibitory activities, suggesting their potential use in dietary intervention in the management or control of postprandial hyperglycemia associated with type-2 diabetes. White ginger exhibited stronger enzyme inhibitory effects than red ginger.
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Undoubtedly medicinal plants are relevant in both developing and developed nations of the world as sources of drugs or herbal extracts for various chemotherapeutic purposes. Also the use of plant-derived natural compounds as part of herbal preparations as alternative sources of medicaments continues to play major roles in the general wellness of people all over the world. The African continent contains some of the richest biodiversity in the world, and abounds in plants of economic importance and plants of medicinal importance which when developed would reduce our expenditure on imported drugs to meet our health needs. Herbal-based and plant-derived products can be exploited with sustainable comparative and competitive advantage. This review presents some indigenous African plants with chemotherapeutic properties and possible ways of developing them into potent pharmacological agents using biotechnological approaches.
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Crude extracts from Inula aucherana, Fumaria officinalis, Crocus sativus, Vicum album, Tribulus terestris, Polygonatum multiflorum, Alkanna tinctoria and Taraxacum officinale were screened for their in vitro antioxidant and antimicrobial properties. Total phenolic content of extracts from these plants were also determined. beta-carotene bleaching assay and Folin-Ciocalteu reagent were used to determine total antioxidant activity and total phenols of plant extracts. Antimicrobial activity was determined by using disk diffusion assay. Antioxidant activity and total phenolic content varied among plants used and Viscum album and Crocus sativus had the highest antioxidant (82.23%) and total phenolic content (42.29 mgGAE/g DW), respectively. The methanol extracts from Vicum album and Alkanna tinctoria showed antimicrobial activity against 9 out of 32 microorganisms, however extract from Inula aucherana showed antimicrobial activity against 15 out of 32 microorganisms. The results provided evidence that the studied plant might indeed be potential sources of natural antioxidant and antimicrobial agents.
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A predominantly plant-based diet reduces the risk for development of several chronic diseases. It is often assumed that antioxidants contribute to this protection, but results from intervention trials with single antioxidants administered as supplements quite consistently do not support any benefit. Because dietary plants contain several hundred different antioxidants, it would be useful to know the total concentration of electron-donating antioxidants (i.e., reductants) in individual items. Such data might be useful in the identification of the most beneficial dietary plants. We have assessed systematically total antioxidants in a variety of dietary plants used worldwide, including various fruits, berries, vegetables, cereals, nuts and pulses. When possible, we analyzed three or more samples of dietary plants from three different geographic regions in the world. Total antioxidants was assessed by the reduction of Fe(3+) to Fe(2+) (i.e., the FRAP assay), which occurred rapidly with all reductants with half-reaction reduction potentials above that of Fe(3+)/Fe(2+). The values, therefore, expressed the corresponding concentration of electron-donating antioxidants. Our results demonstrated that there is more than a 1000-fold difference among total antioxidants in various dietary plants. Plants that contain most antioxidants included members of several families, such as Rosaceae (dog rose, sour cherry, blackberry, strawberry, raspberry), Empetraceae (crowberry), Ericaceae (blueberry), Grossulariaceae (black currant), Juglandaceae (walnut), Asteraceae (sunflower seed), Punicaceae (pomegranate) and Zingiberaceae (ginger). In a Norwegian diet, fruits, berries and cereals contributed 43.6%, 27.1% and 11.7%, respectively, of the total intake of plant antioxidants. Vegetables contributed only 8.9%. The systematic analysis presented here will facilitate research into the nutritional role of the combined effect of antioxidants in dietary plants.
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Levels of obesity-linked non-insulin-dependent diabetes mellitus (NIDDM) and hypertension are highest among indigenous communities in North America. This is linked to changes in dietary pattern towards high calorie foods such as sugar, refined grain flour, and sweetened beverages. Therefore, a return to traditional dietary patterns may help to reduce these disease problems because of better balance of calories and beneficial nutrients. Further protective non-nutrient phenolic phytochemicals against NIDDM and hypertension are potentially high in these foods but less understood. In this study antidiabetic- and antihypertension-relevant potentials of phenolic phytochemicals were confirmed in select important traditional plant foods of indigenous communities such as pumpkin, beans, and maize using in vitro enzyme assays for -glucosidase, alpha-amylase, and angiotensin I-converting enzyme (ACE) inhibitory activities. In vitro inhibitory activities of these enzymes provide a strong biochemical rationale for further in vivo studies and dietary management strategy for NIDDM through the control of glucose absorption and reduction of associated hypertension. These enzyme inhibitory activities were further compared to total soluble phenolic content and antioxidant activity of the above-targeted plant foods. Pumpkin showed the best overall potential. Among the varieties of pumpkin extracts P5 (round orange) and P6 (spotted orange green) had high content of total phenolics and moderate antioxidant activity coupled to moderate to high alpha-glucosidase and ACE inhibitory activities. Therefore this phenolic antioxidant-enriched dietary strategy using specific traditional plant food combinations can generate a whole food profile that has the potential to reduce hyperglycemia-induced pathogenesis and also associated complications linked to cellular oxidation stress and hypertension.
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In this study the interaction of free and bound phenolic-rich extracts from orange peels (a popular folklore for the management of diabetes & hypertension) with key enzymes linked to niddm (α-glucosidase and α-amylase) and hypertension [angiotensin i-converting enzyme (ace)] were assessed. The free phenolic extracts were extracted with 80% acetone, while the bound phenolics were extracted from the alkaline and acid hydrolyzed residue with ethyl acetate. The free and bound phenolic extracts inhibited α-amylase, α-glucosidase and ace activities in a dose-dependent manner; however, the extracts were stronger inhibitors of α-glucosidase [free (69.00%), bound (71.62%)] then α-amylase [free (57.39%), bound (24.32%)]. The extracts also, strongly inhibited (> 90%) angiotensin-i- converting enzyme and significantly inhibited sodium nitroprusside (anti-hypertensive drug) induced malondialdehyde (mda) production in the pancreas in dose-dependent manner. Therefore, the inhibition α-amylase, α-glucosidase, ace and oxidative stress by the orange phenolics could be part of the mechanism through which orange peels manage/prevent niddm and hypertension.
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Effect of crude aqueous extract of leaves of Vernonia amygdalina on blood glucose, serum albumin and cholesterol levels on alloxan induced diabetic albino rats was investigated. Blood glucose, serum albumin and cholesterol levels were significantly reduced. From 296.75 ± 9.0mg/dl to 179.0 ± 7.3mg/dl for blood glucose; 4.08 ± 0.4mg/dl to 0.93 ± 0.23mg/dl for serum albumin, while cholesterol level decreased from 280.33 ± 4.65mg/dl to 170.45 ± 4.52mg/dl. The effect was dose dependent, as the reduction followed increase in dose given to the animals. The biochemical implication of our findings are discussed.KEY WORDS: Blood glucose, serum albumin, Cholesterol, hypoglycemic, antilipolytic and lipogenic effects.Global Jnl Pure & Applied Science Vol.10(1) 2004: 189-194
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Over 11 million Americans have both diabetes and hypertension-comorbid diseases that strongly predispose people to both renal as well as cardiovascular (CV) injury. Hypertension substantially contributes to CV morbidity and mortality in people with diabetes. Diabetes is the most common cause of end-stage renal disease in the United States. Furthermore, hypertension and diabetes are particularly prevalent in certain populations, such as African-Americans and Native Americans. Since the 1994 Working Group Report on Hypertension and Diabetes, a large body of clinical trial data has affirmed the original blood pressure goal of less than 130/85 mmHg recommended to preserve renal function and reduce CV events in people with hypertension and diabetes. Data that are more recent have emerged, however, to support an even lower diastolic blood pressure goal, ie, 80 mmHg, in order to optimally preserve renal function and reduce CV events in people with diabetic nephropathy. A review of clinical trials indicates that more than 65% of people with diabetes and hypertension will require two or more different antihypertensive medications to achieve the new suggested target blood pressure of 130/80 mmHg. The purpose of this report is to update the previous recommendations with a focus on level of blood pressure control, proteinuria reduction, and therapeutic approaches to achieve these goals. We provide an evidence-based approach, integrating data from the major clinical trials that were designed as randomized prospective, long-term studies that had as a primary endpoint either progression of diabetic nephropathy or reduction in CV events. This report also addresses socioeconomic and cultural barriers that hinder achievement of blood pressure goals. Lastly, the report discusses approaches to resolve cultural barriers, both physician- and patient-derived, that interfere with achievement of lower blood pressure goals. (C) 2000 by the National Kidney Foundation, Inc.
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Diabetes mellitus is a debilitating and often life-threatening disease with increasing incidence in rural populations throughout the world. A scientific investigation of traditional herbal remedies for diabetes may provide valuable leads for the development of alternative drugs and therapeutic strategies. Alternatives are clearly needed because of the inability of current therapies to control all of the pathological aspects of diabetes, and the high cost and poor availability of current therapies for many rural populations, particularly in developing countries. This review provides information on more than 1200 species of plants reported to have been used to treat diabetes and/or investigated for antidiabetic activity, with a detailed review of representative plants and some of great diversity of plant constituents with hypoglycemic activity, their mechanisms of action, methods for the bioassay of hypoglycemic agents, potential toxicity problems, and promising directions for future research on antidiabetic plants. The objective of this work is to provide a starting point for programs leading to the development of indigenous botanical resources as inexpensive sources for standardized crude or purified antidiabetic drugs, and for the discovery of lead compounds for novel hypoglycemic drug development.
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Publisher Summary This chapter discusses the analysis of total phenols and other oxidation substrates and antioxidants by means of Folin-Ciocalteu reagent. Analyses of the Folin-Ciocalteu (FC) type are convenient, simple, and require only common equipment and have produced a large body of comparable data. Under proper conditions, the assay is inclusive of monophenols and gives predictable reactions with the types of phenols found in nature. Because different phenols react to different degrees, expression of the results as a single number—such as milligrams per liter gallic acid equivalence—is necessarily arbitrary. Because the reaction is independent, quantitative, and predictable, analysis of a mixture of phenols can be recalculated in terms of any other standard. The assay measures all compounds readily oxidizable under the reaction conditions and its very inclusiveness allows certain substances to also react that are either not phenols or seldom thought of as phenols (e.g., proteins). Judicious use of the assay—with consideration of potential interferences in particular samples and prior study if necessary—can lead to very informative results. Aggregate analysis of this type is an important supplement to and often more informative than reems of data difficult to summarize from various techniques, such as high-performance liquid chromatography (HPLC) that separate a large number of individual compounds .The predictable reaction of components in a mixture makes it possible to determine a single reactant by other means and to calculate its contribution to the total FC phenol content. Relative insensitivity of the FC analysis to many adsorbents and precipitants makes differential assay—before and after several different treatments—informative.
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The aqueous leaf extract of Vernonia amygdalina, Del, (Compositae) given i.p. produced a dose-related fall in blood sugar. A dose of 80 mg/kg body weight of adult rabbit produced a maximum lowering of blood sugar in both fasted normal and alloxanized rabbits. The fasting blood sugar in normoglycaemic rabbits was reduced from 96 mg% to 48 mg% in 4 h. In alloxanized rabbits, the blood sugar was reduced from the mean value of 520 mg% to 300 mg% in 8 h. The hypoglycaemic effects were compared with those of tolbutamide. Acute toxicity studies of the extract in mice gave LD50 value of 1122 mg/kg body weight when given i.p. The blood sugar lowering effect of Vernonia amygdalina extract may involve a mechanism not related to insulin secretion.
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The chemical composition and antioxidant properties of a water-soluble extract of Moldavian balm (Dracocephalum moldavica L., syn. Moldavian dragonhead) prepared by hydrodistillation are presented in this study. The total phenol content was estimated as gallic acid equivalents by the Folin-Ciocalteu reagent method, while the qualitative–quantitative composition of the extract was determined by high performance liquid chromatography coupled with photodiode array detection. The antioxidant properties assessed included iron(III) reduction and iron(II) chelation and 1,1-diphenyl-2-picrylhydrazyl, 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) and superoxide anion free radical scavenging. In addition, the ability of the extract to protect 2-deoxy-d-ribose and bovine brain-derived phospholipids against hydroxyl radical-mediated degradation was assessed. The extract principally contained polar compounds including hydroxycinnamic acids and flavonoids, with caffeic and ferulic acids, luteolin-7-O-glucoside, rosmarinic acid, luteolin and apigenin being identified from their chromatographic behavior and spectral characteristics. The Moldavian balm extract demonstrated activity in all the antioxidant assays; however, it was not as potent as the positive control except in the phospholipid-based assay where its hydroxyl radical scavenging activity was statistically indistinguishable from that demonstrated by Pycnogenol.
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In the current study, three different types of cheese, cheddar, feta, and Roquefort, were screened to determine the variations in phenolic-linked antioxidant activity and the potential to inhibit key enzymes relevant to type 2 diabetes and related hypertension. The cheese samples were assayed for total phenolic content, related antioxidant activity, and inhibition of alpha-glucosidase, pancreatic alpha-amylase inhibitory activity, and the angiotensin-converting enzyme (ACE)-I inhibitory activity. The three fungal-enriched Roquefort cheese samples had the highest total phenolic content. The phenolic content in the herb cheese was slightly but not significantly higher compared to plain cheese. Roquefort cheese samples had the highest antioxidant-linked DPPH (free radical) scavenging activity and as expected DPPH radical scavenging activity was higher in the herb cheese compared to plain cheese. All samples had some alpha-glucosidase and alpha-amylase inhibitory activities, with cranberry-enriched cheese having the highest activities. However, no correlation to soluble phenolic content was observed. All the cheese samples had very high anti-ACE-I inhibitory activity, indicating no correlation to phenolic content and activity was even high in I Ox diluted samples. The highest ACE-I inhibitory activity was observed in plain and herb-enriched cheddar cheese as well as cranberry-enriched cheese. These studies indicate that cranberry-enriched cheese had the best potential for inhibition of alpha-glucosidase and alpha-amylase relevant for type 2 diabetes management, whereas any cheese product had potential for ACE-I inhibition linked to hypertension management, indicating likely the role of other factors such as peptides from cheese fermentation. (c) 2006 Elsevier Ltd. All rights reserved.
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Several honey samples (27) from Burkina Faso were analyzed to determine their total phenolic, flavonoid and proline contents as well as their radical scavenging activity. These samples consisted of 18 multifloral, 2 honeydew and 7 unifloral honeys, derived in the latter cases from flowers of Combretaceae, Vitellaria, Acacia and Lannea plant species. The total phenolic contents varied considerably with the highest values obtained for honeydew honey. Similarly, much variation was seen in total flavonoid and proline content, with Vitellaria honey having the highest proline content. Vitellaria honey was also found to have the highest antioxidant activity and content. The correlation between radical scavenging activity and proline content was higher than that for total phenolic compounds. This suggests that the amino acid content of honey should be considered more frequently when determining its antioxidant activity.
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Iron is an essential metal for normal cellular physiology, but excess iron results in cell injury; it reacts with superoxide anions (O2) and hydrogen peroxide (H2O2) to produce the hydroxyl radical (OH) and other reactive oxygen species (ROS) which can cause damage to body cells. Free radical damage can be prevented by food rich in antioxidants such as fruit and vegetables. In the present study, the ability of aqueous extracts of ripe (red) and unripe (green) hot peppers [Capsicum annuum, Tepin (CAT) and Capsicum chinese, Habanero (CCH)] (3.3–16.7 mg/ml) to prevent 25 μM Fe2+-induced lipid peroxidation in Rat’s brain (In vitro) were assessed using TBARS (Thiobarbituric acid reactive species). The total phenol and vitamin C content, as well as Fe2+-chelating ability, and the ability of the pepper extracts to prevent Fe2+/H2O2-induced decomposition of deoxyribose was also determined. The results of the study revealed that incubating the brain tissues in the presence of 25 μM Fe2+ caused a significant increase (p < 0.05) in MDA (Malondialdehyde) production in the rat’s brain (260%) when compared with the basal (100%). However, the pepper extracts (unripe and ripe) caused a significant decrease (p < 0.05) in the MDA production in both the basal and the Fe2+-induced lipid peroxidation in the Rat’s brain. However, CAT [ripe and unripe] had a significantly (p < 0.05) higher inhibitory effect on both basal and Fe2+-induced lipid peroxidation in the brain tissues than that of CCH (ripe and unripe). In addition, CAT (ripe and unripe) had a significantly higher (p < 0.05) total phenol, vitamin C and Fe2+ chelating ability than CCH (ripe and unripe). The unripe CAT had a significantly (p < 0.05) higher total phenol, Fe2+ chelating ability and inhibitory effect on the basal and Fe2+-induced lipid peroxidation in the brain tissues than the ripe pepper, while the reverse is the case with CCH where the red pepper had a higher values for the same parameters. However, ripe CAT and CCH had a significantly higher (p < 0.05) vitamin C content than the unripe; meanwhile both ripe and unripe peppers (CAT&CCH) did not significantly inhibit (p < 0.05) Fe2+/H2O2-induced decomposition of deoxyribose (Fenton reaction). The inhibitory effect of the pepper on lipid peroxidation (basal and Fe2+ induced) and Fe2+ chelating effect of the extracts were dose dependent. It was therefore concluded that hot peppers prevent Fe2+-induced lipid peroxidation, however CAT (ripe and unripe) are more potent inhibitors of Fe2+-induced lipid peroxidation than CCH (unripe and ripe), meanwhile unripe CAT had the highest protective ability and this is probably due to its higher total phenol content and Fe2+ chelating ability.
Article
Diabetes mellitus is a metabolic disorder characterized by chronic hyperglycemia. The management of the blood glucose level is a critical strategy in the control of diabetes complications. Inhibitors of carbohydrate hydrolyzing enzymes have been useful as oral hypoglycemic drugs for the control of hyperglycemia especially in patients with type II disables mellitus. The goal of the present study was to investigate the inhibitory effects of six selected Allium species (A. akaka, A. ampeloprasum subsp. iranicum, A. cepa, A. hirtifolium, A. porrum and A. sativum) on α-amylase enzyme using an in vitro model. According to the results, ethanol extracts of A. akaka, A. sativum, A. porrum and A. cepa were found to have a favorable α-amylase inhibitory activity with IC50 values of 16.74, 17.95, 15.73 and 16.36 mg/ml, respectively and they did not reveal any significant differences in their IC50 values (p>0.05). However, the two other Allium species tested (A. ampeloprasum subsp. iranicum and A. hirtifolium) did not show valuable inhibitory activity
Article
The present study investigated the effects of Punica granatum aqueous extract (PgAq) on streptozotocin (STZ) induced diabetic rats by measuring fasting blood glucose, lipid profiles (atherogenic index), lipid peroxidation (LPO) and activities of both non-enzymatic and enzymatic antioxidants. Diabetes was induced by single intraperitoneal injection of STZ (60 mg/kg) to albino Wistar rats. The increase in blood glucose level, total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), very low density lipoprotein (VLDL), LPO level with decrease in high density lipoprotein cholesterol (HDL-C), reduced glutathione (GSH) content and antioxidant enzymes namely, glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT) were the salient features observed in diabetic rats. On the other hand, oral administration of PgAq at doses of 250 mg/kg and 500 mg/kg for 21 days resulted in a significant reduction in fasting blood glucose, TC, TG, LDL-C, VLDL-C and tissue LPO levels coupled with elevation of HDL-C, GSH content and antioxidant enzymes in comparison with diabetic control group. The results suggest that PG could be used, as a dietary supplement, in the treatment of chronic diseases characterized by atherogenous lipoprotein profile, aggravated antioxidant status and impaired glucose metabolism and also in their prevention.
Article
The role of active oxygen species in diabetes is discussed in this review. Type I diabetes is caused by destruction of the pancreatic beta cells responsible for producing insulin. In humans, the diabetogenic process appears to be caused by immune destruction of the beta cells; part of this process is apparently mediated by white cell production of active oxygen species. Diabetes can be produced in animals by the drugs alloxan and streptozotocin; the mechanism of action of these two drugs is different, but both result in the production of active oxygen species. Scavengers of oxygen radicals are effective in preventing diabetes in these animal models. Not only are oxygen radicals involved in the cause of diabetes, they also appear to play a role in some of the complications seen in long-term treatment of diabetes. Changes in antioxidants in the diabetic state and their consequences are discussed.
Article
In 219 patients with essential hypertension, aldosterone excretion and plasma renin activity were related to daily sodium excretion and compared to a nomogram drawn from 52 normal volunteers studied over the same continuous range of sodium balance. Plasma renin activity was subnormal in 27 per cent, normal in 57 per cent and elevated in 16 per cent. Further study showed eight patterns of renin and aldosterone secretion. Patients with normal or high renin had an 11 and 14 per cent frequency respectively of heart attacks or strokes. However, during a similar period of observation, none of 59 low renin patients had any of these complications. They appear protected despite similar hypertension, similar left ventricular enlargement, and despite higher mean age. Plasma renin activity emerges as a potential risk factor for patients with essential hypertension — useful for identifying etiologies, determining prognosis and applying therapy.
Article
A sensitive, fixed-time, spectrophotometric assay for angiotensin-converting enzyme measures the rate of production of hippuric acid from hippuryl-L-histidyl-L-leucine (HHL). The angiotensin-converting enzyme from rabbit lung acetone powder extract, when assayed by this method, is optimally active at pH 8.1 to 8.3 at a chloride ion concentration of 300 mM and an HHL concentration of 5–10 mM; the Km for HHL is 2–6 mM. The enzyme was inhibited by metal-chelating agents, heavy metal salts and certain peptides. The most effective inhibitors were EDTA; CdBr2; angiotensin II; bradykinin; and a pentapeptide, L-pyroglutamyl-L-lysyl-L-tryptophyl-L-alanyl-L-proline, a component of Bothrops jararaca venom. Enzyme inhibited by 0.1 mM EDTA was completely reactivated after removal of EDTA by dialysis but, after prolonged dialysis of the enzyme against 1 mM EDTA, reactivation could only be achieved by addition of metal ions: MnCI2 (40%), ZnCl2 (100%) or Co(NO3)2 (160%). The angiotensin-converting enzyme of rabbit lung is a stable, chloride ion-activated metalloenzyme, similar to both the angiotensin-converting enzyme and kininase II of plasma.
Article
Because considerable important information has been published since our previous review, this update concentrates on new findings with regard to cardiovascular and renal risk factors contributing to the striking morbidity and mortality of these coexisting diseases. For example, a large body of investigative data has recently emerged suggesting or delineating a pathogenic role for hyperglycemic-related glycosylation and oxidation of lipoproteins and vascular and renal tissues. Great strides have recently been made in the understanding of platelet, coagulation, lipoprotein, and endothelial abnormalities in the pathogenesis of cardiovascular and renal disease associated with diabetes mellitus and hypertension. Major progress has been made in clarifying the pathophysiology of glomerulosclerosis and other processes involved in the progression of diabetic nephropathy. Furthermore, accumulating data surveyed in this review address new and promising pharmacological interventions that specifically address these pathophysiological mechanisms.
Article
The recent explosion of interest in the bioactivity of the flavonoids of higher plants is due, at least in part, to the potential health benefits of these polyphenolic components of major dietary constituents. This review article discusses the biological properties of the flavonoids and focuses on the relationship between their antioxidant activity, as hydrogen donating free radical scavengers, and their chemical structures. This culminates in a proposed hierarchy of antioxidant activity in the aqueous phase. The cumulative findings concerning structure-antioxidant activity relationships in the lipophilic phase derive from studies on fatty acids, liposomes, and low-density lipoproteins; the factors underlying the influence of the different classes of polyphenols in enhancing their resistance to oxidation are discussed and support the contention that the partition coefficients of the flavonoids as well as their rates of reaction with the relevant radicals define the antioxidant activities in the lipophilic phase.
Article
Tea decoctions prepared from a number of black and green teas inhibited amylase in human saliva. Black teas gave higher levels of inhibition than green teas, and removal of tea tannins with gelatin led to the loss of inhibitory activity from all decoctions. Streptococcal amylase was similarly inhibited by tea decoctions. Fluoride was without effect on amylase. Since salivary amylase hydrolyzes food starch to low molecular weight fermentable carbohydrates, experiments were carried out to determine whether tea decoctions would interfere with the release of maltose in food particles that became entrapped on the dentition. Subjects consumed salted crackers and rinsed subsequently for 30 s with black or green tea decoctions, or water. Maltose release was reduced by up to about 70% after rinsing with the teas. Black tea decoction was significantly more effective than green tea, in agreement with the in vitro data. The observations supported the hypothesis that tea consumption can be effective in reducing the cariogenic potential of starch-containing foods such as crackers and cakes. Tea may reduce the tendency for these foods to serve as slow-release sources of fermentable carbohydrate.
Article
A method for the screening of antioxidant activity is reported as a decolorization assay applicable to both lipophilic and hydrophilic antioxidants, including flavonoids, hydroxycinnamates, carotenoids, and plasma antioxidants. The pre-formed radical monocation of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS*+) is generated by oxidation of ABTS with potassium persulfate and is reduced in the presence of such hydrogen-donating antioxidants. The influences of both the concentration of antioxidant and duration of reaction on the inhibition of the radical cation absorption are taken into account when determining the antioxidant activity. This assay clearly improves the original TEAC assay (the ferryl myoglobin/ABTS assay) for the determination of antioxidant activity in a number of ways. First, the chemistry involves the direct generation of the ABTS radical monocation with no involvement of an intermediary radical. Second, it is a decolorization assay; thus the radical cation is pre-formed prior to addition of antioxidant test systems, rather than the generation of the radical taking place continually in the presence of the antioxidant. Hence the results obtained with the improved system may not always be directly comparable with those obtained using the original TEAC assay. Third, it is applicable to both aqueous and lipophilic systems.
Article
Most nonenzymatic antioxidant activity (scavenging of free radicals, inhibition of lipid peroxidation, etc.) is mediated by redox reactions. The antioxidant (AO) activity of polyphenols (PPs), as ferric-reducing power, was determined for the first time using a modified FRAP (ferric reducing/antioxidant power) assay. Reaction was followed for 30 min, and both Fe(II) standards and samples were dissolved in the same solvent to allow comparison. Selected representative PPs included flavonoids (quercetin, rutin, and catechin), resveratrol, tannic acid, and phenolic acids (gallic, caffeic, and ferulic). Carotenoids (beta-carotene and zeaxanthine), ascorbic acid, Trolox, and BHA were included for comparison. Equivalent concentration 1 (EC(1)), as the concentration of AO with a reducing effect equivalent to 1 mmol/L Fe(II), was used to compare AO efficiency. PPs had lower EC(1) values, and therefore higher reducing power, than ascorbic acid and Trolox. Tannic acid and quercetin had the highest AO capacity followed by gallic and caffeic acids. Resveratrol showed the lowest reducing effect. Carotenoids had no ferric reducing ability. Polyphenol's AO efficiency seemed to depend on the extent of hydroxylation and conjugation.
Article
Over 11 million Americans have both diabetes and hypertension-comorbid diseases that strongly predispose people to both renal as well as cardiovascular (CV) injury. Hypertension substantially contributes to CV morbidity and mortality in people with diabetes. Diabetes is the most common cause of end-stage renal disease in the United States. Furthermore, hypertension and diabetes are particularly prevalent in certain populations, such as African-Americans and Native Americans. Since the 1994 Working Group Report on Hypertension and Diabetes, a large body of clinical trial data has affirmed the original blood pressure goal of less than 130/85 mmHg recommended to preserve renal function and reduce CV events in people with hypertension and diabetes. Data that are more recent have emerged, however, to support an even lower diastolic blood pressure goal, ie, 80 mmHg, in order to optimally preserve renal function and reduce CV events in people with diabetic nephropathy. A review of clinical trials indicates that more than 65% of people with diabetes and hypertension will require two or more different antihypertensive medications to achieve the new suggested target blood pressure of 130/80 mmHg. The purpose of this report is to update the previous recommendations with a focus on level of blood pressure control, proteinuria reduction, and therapeutic approaches to achieve these goals. We provide an evidence-based approach, integrating data from the major clinical trials that were designed as randomized prospective, long-term studies that had as a primary endpoint either progression of diabetic nephropathy or reduction in CV events. This report also addresses socioeconomic and cultural barriers that hinder achievement of blood pressure goals. Lastly, the report discusses approaches to resolve cultural barriers, both physician- and patient-derived, that interfere with achievement of lower blood pressure goals.
Article
CAM represents medical and health care practices that are not an integral part of conventional (Western) medicine. At least 42% of the general population and a similar proportion of liver disease patients use some form of CAM on a regular basis. Herbal preparations are used by 20% of liver disease patients, typically without the advice or even knowledge of their physician, the most common herb used being milk thistle or silymarin. Other candidate herbals for liver disease are glycyrrhizin, HM861, TJ-9, and Phyllanthus amarus. Many of these have been shown to protect against experimental liver injury in vivo, and most possess one or a combination of anti-oxidant, antifibrogenic, immune modulatory, or antiviral activities. None, however, have been shown to be effective in ameliorating the course of chronic liver disease in properly conducted RCTs. Current impediments to progress in developing reliable information on the safety and efficacy of botanicals are the incomplete understanding of their modes of action, the lack of standardization in their manufacture, and the complexity of the chemical ingredients in the average herbal extract.