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Antioxidant activities and contents of polyphenol oxidase substrates from pericarp tissues of litchi fruit
Abstract
The experiments were performed to extract and purify substrates for polyphenol oxidase (PPO) from pericarp tissue of postharvest litchi fruit. Two purified PPO substrates were identified as (−)-epicatechin and procyanidin A2. The antioxidant properties of two PPO substrates were further evaluated in the present study. Variation in the content of the major substrate (−)-epicatechin of litchi fruit during storage at 25°C was analysed using the HPLC-UV method. The results showed that (−)-epicatechin exhibited stronger antioxidant capability than procyanidin A2, in terms of reducing power and scavenging activities of DPPH radical, hydroxyl radical and superoxide radical. Furthermore, (−)-epicatechin content in pericarp tissue tended to decrease with increasing skin browning index of litchi fruit during storage at 25°C. Thus, these two compounds can be used as potential antioxidants in litchi waste and the fresh pericarp tissue of litchi fruit exhibited a better utilisation value.
... The supernatant was the crude enzyme solution of PPO. [7] ...
... Experiments were repeated by three times. [7] Purification of PPO enzyme: Solid ammonium sulfate was added to the crude enzyme until the saturation reach to 30%, then removed the impurities. Keep on added the solid ammonium sulfate until the saturation reach to 50%, 60%, 70%, 80% and 90% respectively. ...
... Experiment must be repeated three times. [7] ...
... Among them, flavonoids were considered as the major constituents responsible for bioactive in lychee seed [10]. Previous chemical studies on lychee seeds reported the isolation and determination of the following flavonoids compounds: (+)-catechin, (-)-epicatechin, rutin, pinocembrin 7-O-neohesperidoside and a type of proanthocyanidins analogues [11][12], which exhibited better radical scavenging capacities and reducing power of DPPH and superoxide radicals than positive control (Vitamin C). [13] However, these flavonoids derivatives might not be the only contributors for the high antioxidant activity of lychee seeds. Further phytochemical investigation on lychee seed is required for better medicine utilization. ...
... The molecular formula was identified to be C 17 H 18 O 8 dependence on the 1 H NMR and 13 C NMR. Although the 1 H and 13 C NMR spectra of 15 were exactly similar to those of 14, differences in the chemical shifts of three of cycloparaffin signals were observed: in the 13 C NMR spectrum of 15, carbon signals at δ C 64.5, 75.7 and 65.5 were assigned to C-3, C-4 and C-5, respectively. In the HMBC spectrum (Fig. 2), the correlations of δ H 4.74 (H-4′) with δ C 64.5 (C-3′)/38.0 ...
... In the present study, the DPPH assay was applied to evaluate the antioxidant capacities of compounds 115. The results were summarized in Fig. 3, compounds 9 Previous pharmacological research demonstrated that lychee seed contains ample flavonoids derivatives which contribute to its excellent antioxidant abilities [13]. The antioxidant effects of compounds 1, 4, 7, 9 displayed that flavonoids derivatives might not be the only member responsible for the high antioxidant activity of lychee seeds, and further study on lychee seed is needed for discovering more multifunctional bioactivity ingredients from it. ...
... Phenylpropanoid metabolic processes represent the principal pathways of anthocyanin and flavonoid synthesis. The major polyphenols present in litchi fruit were flavonoids 26 . A large number of genes in the phenylpropanoid metabolic pathway linked with cytochrome P450 were up-regulated during fruit senescence but more so in the PCS fruit than in the AC fruit (Supplementary Excel S1), which might lead to enhanced polyphenol synthesis. ...
... However, which process plays the more important role needs to be examined in a future study. In the present study, polyphenol oxidase, an important enzyme in litchi pericarp browning 26 , was not detected in either AC or PCS fruit, possibly because the sequencing depth was less. ...
Litchi is a non-climacteric subtropical fruit of high commercial value. The shelf life of litchi fruit under ambient conditions (AC) is approximately 4–6 days. Post-harvest cold storage prolongs the life of litchi fruit for up to 30 days with few changes in pericarp browning and total soluble solids. However, the shelf life of litchi fruits at ambient temperatures after pre-cold storage (PCS) is only 1–2 days. To better understand the mechanisms involved in the rapid fruit senescence induced by pre-cold storage, a transcriptome of litchi pericarp was constructed to assemble the reference genes, followed by comparative transcriptomic and metabolomic analyses. Results suggested that the senescence of harvested litchi fruit was likely to be an oxidative process initiated by ABA, including oxidation of lipids, polyphenols and anthocyanins. After cold storage, PCS fruit exhibited energy deficiency, and respiratory burst was elicited through aerobic and anaerobic respiration, which was regulated specifically by an up-regulated calcium signal, G-protein-coupled receptor signalling pathway and small GTPase-mediated signal transduction. The respiratory burst was largely associated with increased production of reactive oxygen species, up-regulated peroxidase activity and initiation of the lipoxygenase pathway, which were closely related to the accelerated senescence of PCS fruit.
... Studies carried out by Gupta et al. [7] on fruit residues have verified the presence of saturated and unsaturated free fatty acids and minerals (mainly Ca, K, Mg, Na, and P) that can be important in food supplements. The presence of phenolic compounds and antioxidants on fruit residues has been reported by many researchers [8,9]. ...
... Appreciable amounts of anthocyanin were found in acerola extract (60.83 mg/100 g), which also has contributed to the high antioxidant property of this residue. High concentrations of antioxidants have been reported previously by several authors in residues of grape, passion fruit, banana, tangerine, and lychee [5,8,9,19,40], but acerola residue showed higher antioxidant capacity. ...
Seven residues from tropical fruit (acerola, cashew apple, guava, mango, papaya, pineapple, and sapota) processing were prospected for physicochemical parameters (pH, total soluble solids, water activity, reducing sugar, acidity, protein, moisture, ash, and lipids), functional compounds (total phenolic content, anthocyanins, ascorbic acid, and free radical scavenging activity—DPPH), fatty acid profile, and mineral content. Prospection of these industrial residues aimed its use as potential sources for food supplementation. Acerola residue was found to be a valuable source of anthocyanins, phenolics, and vitamin C; cashew apple residue could be a source of unsaturated fatty acids; pineapple and papaya residues could be used, respectively, as manganese and phosphorous source.
... Black raspberry seed extract significantly reduced the degradation of biologically important n-3-polyunsaturated fatty acids under accelerated oxidative conditions [50]. Polyphenols from pericarp tissue of postharvest litchi fruit, which were identified as (−)-epicatechin and procyanidin, tended to decrease with increasing skin browning index of litchi fruit during storage at 25 °C [51]. These studies suggested the potential for developing natural food preservatives from rich polyphenols plants to improving food stability, quality, safety, and consumer acceptance. ...
... Antioxidant Activity References phenolic-rich extract of grape reduced oxidative stress in serum [41] grape seed extract decreased the oxidated LDL in plasma [42] ethanol extracts of Chardonnay grape food preservatives for fish flesh and oil [50] (−)-epicatechin and procyanidin food preservatives for fruit [51] hydroxytyrosol and its derivatives decreased the oxidized-LDL in plasma and affected several biomarkers of oxidative damage [43] catechin, epicatechin and gallate induced a dose-response effect on plasma antioxidant activity [44] anthocyanins scavenged free radical [6] extracts of walnuts and almonds reduced plasma lipid peroxidation [45] ascarnosic acid, camosol, rosmadial, genkwanin, and rosmarinic acid protected the membranes against oxidative damage [46] ...
The oxidative stress imposed by reactive oxygen species (ROS) plays an important role in many chronic and degenerative diseases. As an important category of phytochemicals, phenolic compounds universally exist in plants, and have been considered to have high antioxidant ability and free radical scavenging capacity, with the mechanism of inhibiting the enzymes responsible for ROS production and reducing highly oxidized ROS. Therefore, phenolic compounds have attracted increasing attention as potential agents for preventing and treating many oxidative stress-related diseases, such as cardiovascular diseases, cancer, ageing, diabetes mellitus and neurodegenerative diseases. This review summarizes current knowledge of natural polyphenols, including resource, bioactivities, bioavailability and potential toxicity.
... Since superoxide anions could cause severe damage to cells, it is necessary to determine the O 2 − radical scavenging ability (Li et al., 2016). FRAP is generally regarded as "total antioxidant capacity" and commonly serves as a significant reflection of reducing power (Sun et al., 2010). As shown in Figure 2, all the antioxidant activity assays exhibited a dose-effect relationship with concentration. ...
In the present study, we investigated the protection of hemp seed polyphenols on human umbilical vein endothelial cells (HUVEC) from H2O2‐mediated oxidative stress injury. Fractions with different polarities were obtained by separating the hemp seed extract using HPD300 macroporous resin‐packed column. The fraction, desorbed by 50% ethanol, is rich in polyphenol (789.51 ± 21.92 mg GAE/g) and has the highest antioxidant activity in vitro. HPLC‐QTOF‐MS/MS identified the main polyphenol components in hemp seed shells: 4 hydroxycinnamic acid amides and 15 lignanamides. The protective effects of hemp seed polyphenol against oxidative‐stress injury in HUVEC cells were evaluated by cell viability, intracellular antioxidant parameters, and cell apoptosis assay. After HUVEC cells were precultured with 50 µg/ml hemp seed polyphenols, the cell viability increased significantly from 53.07 ± 2.46% (model group) to 80.65 ± 1.32% (p < 0.01). In addition, the pretreatment of HUVEC cells with polyphenol could substantially increase their intracellular superoxide dismutase activity and reduce their intracellular reactive oxygen species level, malondialdehyde content, and lactate dehydrogenase leakage index. These findings demonstrate the defensive potential of hemp seed polyphenol in reducing the incidence of cardiovascular disease.
Practical Application
Hemp seed shell waste is produced while producing hemp seed kernel and has abundant phenolic compounds. This research showed that hemp seed polyphenol has potent antioxidant activity in vitro and protects HUVEC cells against H2O2‐induced oxidative stress injury, suggesting that hemp seed polyphenol has the defensive potential to reduce the incidence of cardiovascular disease. These results indicated that polyphenol separated from hemp seed shells is valuable for further research and development, which will improve the utilization rate of hemp seed.
... The polyphenols, namely, anthocyanins and flavonoids, and other phenolic components are the main constituents that influence the antioxidant activity in litchi (3,30). In the treated litchi fruits, the decline of anthocyanins, flavonoids, and total phenols was markedly inhibited (Figure 3); and the DPPH radical scavenging capacity and reducing power were maintained (Figure 5), when compared with that in control. ...
Litchi fruit contains abundant polyphenols and is susceptible to browning after harvest. Herein the combined treatments of malic acid (MA) and lycopene (LYC) to delay the development of browning in litchi fruit stored at room temperature (25°C) and low temperature (4°C) was investigated. The results showed that the pericarp browning could be alleviated, and the increase of malondialdehyde (MDA) content and relative leakage rate was retarded by the combined MA and LYC during storage. As compared to control, the content of pericarp anthocyanins, flavonoids, and the total phenols maintained higher levels; and the decrease of antioxidant activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity and reducing power were slowed down in treated fruit. The enzyme activity of polyphenol oxidase (PPO) and peroxidase (POD) related to oxidation of polyphenols were depressed by the combined treatments. Furthermore, correlation analysis revealed that the content of phenols in the pericarp negatively affected the changes in the browning index, and was positively related to the DPPH radical scavenging capacity. Taken together, the combined treatments of MA and LYC exhibited potential effects in delaying the pericarp browning of litchi fruit by maintaining the content of polyphenols, antioxidant activity, and membrane integrity.
... Preservatives for fruit, radical scavenging DPPH assay, hydroxyl radical scavenging capacity method, superoxide anion radical method [46,47] Extracts of blueberries Regulate enzyme activity, chelate trace metals, regulate miRNA FRAP assay, DPPH assay, ABTS assay [48,49] Extracts of pine Radical scavenging, the skin against oxygen reactive species DPPH assay, superoxide anion radical method, hydroxyl radical scavenging capacity method [50,51] Extracts of tea Increase antioxidant enzyme activity, inhibit lipid peroxidation, radical scavenging DPPH assay, FRAP assay, TEAC assay [52,53] ...
Polyphenols are micronutrients that are widely present in human daily diets. Numerous studies have demonstrated their potential as antioxidants and anti-inflammatory agents, and for cancer prevention, heart protection and the treatment of neurodegenerative diseases. However, due to their vulnerability to environmental conditions and low bioavailability, their application in the food and medical fields is greatly limited. Nanoformulations, as excellent drug delivery systems, can overcome these limitations and maximize the pharmacological effects of polyphenols. In this review, we summarize the biological activities of polyphenols, together with systems for their delivery, including phospholipid complexes, lipid-based nanoparticles, protein-based nanoparticles, niosomes, polymers, micelles, emulsions and metal nanoparticles. The application of polyphenol nanoparticles in food and medicine is also discussed. Although loading into nanoparticles solves the main limitation to application of polyphenolic compounds, there are some concerns about their toxicological safety after entry into the human body. It is therefore necessary to conduct toxicity studies and residue analysis on the carrier.
... The antioxidant activity has been usually attributed to the phenolic and bioactive organic compound as indicated by Sun et al. (2010) who identified the presence of two compounds in the epicarp of litchi namely epicatechin and procyanidin A2 which exhibited antioxidant capability. In addition Singh et al. (2013) reported that 1% of Litchi seeds powder solution have more antioxidant property than 1% ascorbic acid solution. ...
The aims of this study were to evaluate ethanolic and acetonic extracts of both Litchi chinensis pulp and waste (including seeds and pericarp) of fruit for antibacterial, antioxidant activity, total flavonoid and total phenolic contents. Extracts were tested for antibacterial activity against six strains of pathogenic bacteria using agar diffusion method. Ethanolic extract of waste showed the highest inhibition over other extracts. It inhibited the growth of Escherichia coli, Neisseria gonorrhoeae, Psuedomonas aeruginosa, Staphylococcus aureus, Staphylococcus faecalis, Bacillussubtilis, with inhibition percentages equal to 52, 60, 58, 79, 55 and 71%; respectively. The results of the antibacterial test were found to be coincident with the results of total phenolics (12466 GAE g/100gm), total flavonoids (10530 mg QE/100gm) and total antioxidants (174.35 mg AAE/gm) of waste ethanolic extract which showed the highest values compared to other extracts. Positive correlation was reported between TAA and TPC, R 2 = 0.9 suggesting the contribution of phenolic compounds of the extract by 90% to its total antioxidant activity. Also correlation between TPC and TFC, R 2 =0.805, indicating contribution of flavonoids in the extracts by 80% to its total phenolic content. Therefore, Litchi waste and pulp extracts can be proposed as new potential sources of natural additives for food quality and preservation and/or pharmaceutical applications.
... 37 In the pericarp of litchi fruit, the phenolic compounds (−)-epicatechin and procyanidin A2 have been identified as substrates of PPO, which oxidizes them into quinines that are further polymerized to insoluble brown pigments. 38,39 Anthocyanidin produced via anthocyanasecatalyzed hydrolysis of anthocyanins in litchi fruit may serve as an oxidation substrate for POD in the presence of H 2 O 2 . 40 Effective inhibition of POD and PPO by suitable postharvest techniques has been viewed as promising means of delaying litchi browning. ...
... X-ray diffractograms of all the BCs are presented in Fig. 4 and all them exhibit three characteristic 2θ angles, 14.05°-16.77° and 22.68° [83,84] which correspond to 101, 101̅ and 002 planes of Cellulose I crystal structure. The largest 2θ angles of 14.05°-16.77° ...
Cellulose is the most common polymer in the world, formed by β-1,4 linked glucopyranose units. In this study, citrus peels (lemon, mandarin, orange and grapefruit) were used for the production of bacterial cellulose (BC). The peels were hydrolyzed with dilute acid and hydrolysates were used for BC production. The production of BC was carried out at 28–32 °C for 21 days under static conditions with Komagataeibacter hansenii GA2016. BC yields were found to be between 2.06 and 3.92%. It was found that the FTIR spectra of the BCs produced in citrus peel hydrolysates were similar to BC produced in the commercially available nutrients. The result of this study showed that all the BCs produced from citrus peels were characterized to have high water holding capacity, thin fiber diameter, high the thermal stability and high crystallinity.
... Thus, reducing power may serve as a good reflection of the antioxidant activity for potential antioxidants. Higher reducing power means better antioxidant activity (Sun et al., 2010). ...
h i g h l i g h t s " Antioxidants were solvent-extracted from steam exploded sugarcane bagasse (SESB). " Solid, phenolic and total sugar yields of different extractions were different. " The extracts showed potent antioxidant activities. " Enzymatic convertibility of solid fraction after extraction was enhanced. a b s t r a c t Solvent extraction of steam exploded lignocellulosic biomass may be a potential way to obtain antioxi-dative extracts and to enhance the enzymatic convertibility of the solid residue. Boiling solvent extraction (BSE) showed higher solid and phenolic yields than room temperature extraction. Solubilities of pheno-lics and sugars were higher in anhydrous ethanol (AE) and deionized water (DW) than in ethyl acetate under each individual extraction condition. The antioxidant activities of the AE and DW extract obtained under BSE were better than those of 10 mM vitamin C. Conversion of the solid fractions into reducing sugar using Celluclast 1.5 L and Novozym 188 after AE and DW extraction was 95.13% and 92.97%, respectively , higher than that obtained with SESB (88.95%).
... Yeni teknolojilerin geliflmesi ile birlikte bu art›klar›n geri dönüflümü daha mümkün hale gelmifltir (11,12). Bu art›klar›n yap›s›nda tafl›d›klar› bileflenlerden ötürü antibakteriyel, antiviral, antioksidan, antiinflamatuar ve antikansorejen özellikler tafl›d›¤› rapor edilmektedir (13)(14)(15)(16) (17). Meyve-sebze suyu iflleme sektörünün verileri dikkate al›narak yap›lan hesaplamaya göre siyah havuçtan % 70 düzeyinde verim sa¤lanabilmektedir. ...
... A PPO activity scanning in piñuela juices over time (Figure 1), clearly shows that the maximal enzyme activity is reached after 60 min in the ripe fruit, undergoing dramatic changes in enzyme activity before and after that time (more in ripe than in unripe fruit). Later, the activity decreases in both states, perhaps due to exhaustion of the substrate as other authors have found [28,29]. Meanwhile, it can be seen in Figure 2 that changes between pH 5 and 8 on ripe fruit are not significant; however, for unripe state there is a steady increase as the pH rises to a maximum activity peak at pH 8. ...
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Functional and Rheological Properties of Piñuela (Bromelia karatas) in Two Ripening Stages.
María N Osorio, Diego F Moyano, Walter Murillo, Elizabeth Murillo, Albert Ibarz, José F Solanilla
International Journal of Food Engineering 13 (1), 2017
The physicochemical characteristics and the activity of the polyphenol oxidase from piñuela fruit juices were determined at two ripening stages. The antioxidant capacity was evaluated by the superoxide anion yield. The ripening stage showed greater ability to inhibit (, 35.3 %). The inhibition of superoxide dismutase was higher for both ripe (88.29 %) and unripe (95.94 %) states. The rheological behaviour of the juice was satisfactorily described using Herschel-Bulkley model (R2 > 0.99). The concentration effect on the rheological parameters was described by the potential law model, and the temperature effect on the viscosity was described based on the Arrhenius equation, finding activation energy values from 11.94 and 17.80 kJ/mol. These results make Bromelia karatas L. a promissory fruit due to their content of secondary metabolites and its antioxidant activity, which could be associated to the presence of phenolic compounds, specifically flavonoids. Variations in these metabolites could also account for structural changes, physicochemical properties, the integrity protection of the fruit against adverse and an alternative to food products.
... A PPO activity scanning in piñuela juices over time (Figure 1), clearly shows that the maximal enzyme activity is reached after 60min in the ripe fruit, undergoing dramatic changes in enzyme activity before and after that time (more in ripe than in unripe fruit). Later, the activity decreases in both states, perhaps due to exhaustion of the substrate as other authors have found [28,29]. Meanwhile, it can be seen in Figure 2 that changes between pH 5 and 8 on ripe fruit are not significant; however, for unripe state there is a steady increase as the pH rises to a maximum activity peak at pH 8. ...
The physicochemical characteristics and the activity of the polyphenol oxidase from piñuela fruit juices were determined at two ripening stages. The antioxidant capacity was evaluated by the superoxide anion yield. The ripening stage showed greater ability to inhibit (O2.−, 35.3 %). The inhibition of superoxide dismutase was higher for both ripe (88.29 %) and unripe (95.94 %) states. The rheological behaviour of the juice was satisfactorily described using Herschel-Bulkley model (R² > 0.99). The concentration effect on the rheological parameters was described by the potential law model, and the temperature effect on the viscosity was described based on the Arrhenius equation, finding activation energy values from 11.94 and 17.80 kJ/mol. These results make Bromelia karatas L. a promissory fruit due to their content of secondary metabolites and its antioxidant activity, which could be associated to the presence of phenolic compounds, specifically flavonoids. Variations in these metabolites could also account for structural changes, physicochemical properties, the integrity protection of the fruit against adverse and an alternative to food products.
... Open air drying is a lengthy process at an ambient temperature which favors the enzyme catalyzing the oxidation of procyanidin monomers and anthocyanins, leading to the formation of brown polymeric pigments [19]. Sun et al. [20] reported procyanidin A2 and (´)-epicatechin as the substrate to PPO enzyme-catalyzed oxidation, leading to their degradation during dehydration. Khanal et al. [21] investigated effects of heating on procyanidin and anthocyanin stability in grape and blueberry pomace. ...
The effects of different treatment methods on the stability and antioxidant capacity of the bioactive phenolic compounds of litchi pericarps were investigated. Fresh litchi pericarps were open air-dried, steam-blanched for 3 min in combination with hot air oven drying at 60 and 80 °C, and unblanched pericarps were dried in a hot air oven at 40, 60, 70 and 80 °C until equilibrium weight was reached. The total phenolic compounds, flavonoids, anthocyanins, proanthocyanidins and individual procyanidins, and antioxidant activity were analyzed. The combination of blanching and drying at 60 °C significantly (p < 0.05) improved the release of phenolic compounds, individual procyanidins, and the extracts' antioxidant capacity compared with the unblanched hot air oven-dried and open air-dried pericarps. Drying of fresh unblanched litchi pericarps in either open air or a hot air oven caused significant losses (p < 0.05) in phenolic compounds and individual procyanidins, leading to a reduction in the antioxidant activity. A similar increase, retention or reduction was reflected in flavonoids, proanthocyanidins and anthocyanins because they are sub-groups of phenolic compounds. Ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picryldydrazyl (DPPH) radical-scavenging capacity of the treated pericarps were significantly correlated (r ≥ 0.927, p < 0.01) with the total phenolic compounds. Thus, the combination of steam blanching and drying treatments of fresh litchi pericarps could produce a stable and dry litchi pericarp that maintains phenolic compounds and antioxidant capacity as a raw material for further recovery of the phytochemicals.
... The antioxidant activity of volatile components involved phenolic and non phenolic compounds (Hayes et al. 2011), hydrophilic and hydrophobic HAYATI J Biosci compounds (Manian et al. 2008), and many antioxidant mechanisms, such as iron chelating and reducing activities, donating hydrogen atoms, and peroxidative decomposition (Zhu et al. 2010). Sun et al. (2010) reported that strong antioxidant activity was supported by ferric reducing power. Bloknina et al. (2003) stated that lipid peroxidation inhibition activity, one of antioxidant mechanism, is free radical scavenging activity. ...
This research was conducted to identify volatile compounds of pluchea and basil essential oils and their antioxidant capacity to scavenge a DPPH (1,1-diphenyl-2-picrylhidrazyl) free radical and inhibit lipid peroxidation. Essential oil of pluchea and basil leaves was prepared by hydrodistillation method and then their volatile compounds were identified by GC-MS. The volatile compounds in the essential oil of pluchea leaves consist of 66 components with (10S,11S)-Himachala-3-(12)-4-diene (17.13%) made up the highest proportion of volatile compounds. Basil leaves had 70 volatile components in which the major components were (E)-3,7-dimethyl-2,6-octadienal (23.98%) and (Z)- 3,7-dimethyl-2,6-octadienal (17.35%). Total phenol levels in pluchea and basil essential oils were 275 and 209 ppm, respectively. DPPH scavenging activity of the essential oil of pluchea leaves was lower than that of basil leaves, conversely inhibition activity of lipid peroxidation in palm oil of pluchea essential oil was higher than that of basil leaves.
... PPO enzymes have often been found to localize to the chloroplasts, where they are associated with the internal thylakoid membranes; cytoplasm and in vesicles (Obukowicz and Kennedy, 1981), this was correlated with the rapid browning after degreening. So far, there have been reports that potential of browning was directly related to the enzymatic activity of the PPO, POD (Nguyen, 2003;Sun et al., 2010); and increases in activities of PPO, POD followed by chemical, physical or biological treatments are involved in inducing resistance such as anti-browning and limiting the deterioration of fruit (Zheng et al., 2007(Zheng et al., , 2011. With the ripening of fruit, especially when the skin color began to change into yellow and the chloroplast activity also declined, the banana fruit skin was rapidly browning. ...
This study aims to investigate the impacts of the peach gum (PG) edible coating film on pericarp browning of ‘Guiwei’ litchi stored at ambient temperature. Factor analysis was applied to comprehensively evaluate the effect of different concentrations (0, 1%, 2%, 4%) of PG treatments. Compared to the control, 4% PG treatment could effectively suppress the rising of relative electric conductivity, delay the degradation of anthocyanin, maintain the a* and c*value and higher TSS content, and inhibit the browning index. Moreover, 4% PG treatment reduced the accumulation of total phenols and flavonoids, including gallic catechin (GC), epigallocatechin (EGC), epigallocatechin gallate (EGCG), epicatechin (EC), epicatechin gallate (ECG), and catechin gallate (CG), restrain the peroxidase activity. 4% PG treatment also contributes to higher organic acid content (oxalic acid, ascorbic acid, malic acid, and succinic acid), maintaining good litchi flavor. In conclusion, the 4% PG treatment provides good performance, and these findings will provide a promising approach for litchi preservation.
Litchi (Litchi chinensis Sonn.) is a tropical fruit with various health benefits. The objective of this study is to present a thorough analysis of the cancer preventive and anticancer therapeutic properties of litchi constituents and phytocompounds. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis criteria were followed in this work. Various litchi extracts and constituents were studied for their anticancer effects. In vitro studies showed that litchi-derived components reduced cell proliferation, induced cytotoxicity, and promoted autophagy via increased cell cycle arrest and apoptosis. Based on in vivo studies, litchi flavonoids and other extracted constituents significantly reduced tumor size, number, volume, and metastasis. Major signaling pathways impacted by litchi constituents were shown to stimulate proapoptotic, antiproliferative, and antimetastatic activities. Despite promising antineoplastic activities, additional research, especially in vivo and clinical studies, is necessary before litchi-derived products and phytochemicals can be used for human cancer prevention and intervention.
Litchi (Litchi chinensis Sonn.) fruit, with its bright red color and sweet and juicy aril, is an important fruit crop in Asia, Africa, Australia, and South America. A major cause of the postharvest loss of litchi fruit is browning and decay. Chlorophyll breakdown and flavonoid synthesis occur simultaneously during the maturation of this nonclimacteric fruit. However, once litchi fruit is harvested, pericarp desiccation and membrane breakdown occur, which leads to browning with the rate of browning and later microcracking paralleling water loss rate. In addition, chilling injury can contribute to and increase pericarp browning and membrane leakage. Polyphenol oxidase and peroxidase are possibly key enzymes in the early stages of browning. An increase in the leakage of the pericarp membrane also occurs that correlates with browning. Many chemical treatments have been evaluated to retard pericarp browning, such as melatonin, hot water, acidified calcium sulfate (ACS), adenosine triphosphate, and tea seed oil. During long distance transportation, chemical treatments that involve sulfur are used, including SO2 fumigation, acid dip after SO2 fumigation, SO2 fumigation and sulfur sheet package, or SO2 fumigation followed by controlled atmosphere (CA), if approved by the importing country. Other treatments that avoid the use of SO2 include melatonin, ACS, and hot water brushing combined with an acid dip, CA, and modified atmosphere packaging. Anthracnose is a common disease that accelerates browning and decay. Penicillium species as a saprophyte is also common with fruit infection occurring in the field, during harvest, in the packhouse, cold rooms, and shipping containers. Sulfur sheet or CA is used to reduce fruit rot after SO2 fumigation and Sportak (prochloraz) for the control of penicillium. However, a replacement for postharvest SO2 use is still urgently needed.
A‐type proanthocyanidins (PAs) are a subgroup of PAs that differ from B‐type PAs by the presence of an ether bond between two consecutive constitutive units. This additional C–O–C bond gives them a more stable and hydrophobic character. They are of increasing interest due to their potential multiple nutritional effects with low toxicity in food processing and supplement development. They have been identified in several plants. However, the role of A‐type PAs, especially their complex polymeric form (degree of polymerization and linkage), has not been specifically discussed and explored. Therefore, recent advances in the physicochemical and structural changes of A‐type PAs and their functional properties during extraction, processing, and storing are evaluated. In addition, discussions on the sources, structures, bioactivities, potential applications in the food industry, and future research trends of their derivatives are highlighted. Litchis, cranberries, avocados, and persimmons are all favorable plant sources. Α‐type PAs contribute directly or indirectly to human nutrition via the regulation of different degrees of polymerization and bonding types. Thermal processing could have a negative impact on the amount and structure of A‐type PAs in the food matrix. More attention should be focused on nonthermal technologies that could better preserve their architecture and structure. The diversity and complexity of these compounds, as well as the difficulty in isolating and purifying natural A‐type PAs, remain obstacles to their further applications. A‐type PAs have received widespread acceptance and attention in the food industry but have not yet achieved their maximum potential for the future of food. Further research and development are therefore needed.
Pineapple as an important tropical fruit in the world is prone to internal browning (IB) caused by the oxidation of phenolic substances. To address the occurrence of IB, endogenous polyphenol oxidase (PPO) substrates were extracted, separated, and purified from pineapple fruit, and then four compounds were obtained and identified as catechin, epicatechin, chlorogenic acid and pyrocatechol. The contents of these substrates increased, reached the maximum value in the middle storage period, decreased gradually, and then maintained a relatively stable level by the end of storage. Meanwhile, pineapple PPO substrates were unstable in structure and susceptible to be degraded under the condition of light, high temperature (>40 °C), alkalinity (pH > 9) or metal ion (Ca2+, Cu2+, Fe2+, Pb2+ and Zn2+). Additionally, the presences of O2 and H2O2 increased the enzymatic oxidation of the pineapple PPO substrates, whereas CO2, N2, Vc (Vitamin C), l-cysteine, Na2SO3 and Na2S2O5 inhibited this oxidation.
Browning is a crucial factor affecting the quality of fresh-cut apples. A safe, simple, and effective method to inhibit browning is urgently needed in fresh-cut apple production. We carried out this study to explore the effect mechanism of exogenous selenium (Se) fertilizer on fresh-cut apple browning. During the development of apples, 0.75 kg/plant Se fertilizer was exerted on the 'Fuji' apple tree at the critical stage of the young fruit stage (late May), early fruit expansion stage (late June), and fruit expansion stage (late July), an equal amount of Se-free organic fertilizer was used as control. Polyphenol oxidase (PPO), peroxidase (POD), and phenylalanine ammonia-lyase (PAL) activities, phenolic and malondialdehyde (MDA) content, antioxidant enzymes activity, and DPPH free radical scavenging rate of the apple at different development stages were investigated. The highest Se accumulation efficiency was observed in apple fruit one month after applying Se fertilizer, which was 41.1%. Se-rich apples exhibited a more remarkable ability to resist browning than control after fresh-cut. The anti-browning effect of the fertilization group (M7) was the best, the PPO activity decreased to 0.5 × 103 U kg-1, and the browning index was 28.6. The total Se content (TSC) of 331.4 μg kg-1 DW and organic Se content (OSC) of 292.0 μg kg-1 DW were the highest in the apple samples, reached the classification standard of Se content in Se-rich food. The correlation analysis found that fresh-cut apple browning was closely related to antioxidant capacity and PPO activity. The stronger the antioxidant capacity of fresh-cut apples treated with Se fertilizer, the lower their browning degree. Therefore, exogenous Se can alleviate fresh-cut apples browning by improving antioxidant capacity and reducing PPO activity. Se-rich apples could increase the Se content of the human essential trace element and inhibit the browning of fresh-cut apples, which would become a new, safe and effective way to solve the fresh-cut apples browning.
Rapid pericarp browning is the leading factor for quality deterioration and marketing decline of litchi fruit. In the present study, litchi fruit was treated with phenolic compounds, proanthocyanidin, p-coumalic acid, chlorogenic acid, apple polyphenol, and tea polyphenol, before being stored at 20°C for 10 d. Phenolic compound treatment delayed pericarp browning and weight loss, reduced respiration rate, and maintained high total acid levels and vitamin C content in litchi fruit. Subsequently, the key antioxidant characteristics were determined to evaluate the effects of phenolic compounds on the antioxidant system during pericarp browning. The phenolic compound-treated fruit exhibited higher levels of antioxidant enzymes, anthocyanins, total phenols, flavonoids, and antioxidant capacity, as well as a lower superoxide radical production rate and polyphenol oxidase and peroxide activities during whole-fruit storage than the control. Of the five treatments, proanthocyanidin application produced the most significant effects; therefore, this may be the best method for inducing antioxidant system-related factors, enhancing antioxidant capacity, and delaying pericarp browning in litchi.
Since ancient times, litchi has been well recognized as a functional food for the management of various ailments. Many bioactives, including flavanoids, anthocyanins, phenolics, sesquiterpenes, triterpenes, and lignans, have been identified from litchi with a myriad of biological properties both in vitro and in vivo. In spite of the extensive research progress, systemic reviews regarding the bioactives of litchi are rather scarce. Therefore, it is crucial to comprehensively analyze the pharmacological activities and the structure-activity relationships of the abundant bioactives of litchi. Besides, more and more studies have focused on litchi preservation and development of its by-products, which is significant for enhancing the economic value of litchi. Based on the analysis of published articles and patents, this review aims to reveal the development trends of litchi in the healthcare field by providing a systematic summary of the pharmacological activities of its extracts, its phytochemical composition, and the nutritional and potential health benefits of litchi seed, pulp and pericarp with structure-activity relationship analysis. In addition, its by-products also exhibited promising development potential in the field of material science and environmental protection. Furthermore, this study also provides an overview of the strategies of the postharvest storage and processing of litchi.
The potent role of endogenous melatonin (MEL) in affecting chilling injury (CI) and related chilling tolerance regulatory mechanisms in harvested litchi fruit during refrigeration at 4 °C were investigated in this study. In the first experiment, exogenous MEL exposure exerted an inhibitory impact on the development of CI severity in refrigerated litchi fruit, as indicated by the lower CI index and delayed red color loss of pericarp, whereas treatment with p-chlorophenylalanine (p-CPA), an inhibitor of MEL biosynthesis, aggravated the degree of CI. The suppression of CI afforded by exogenous MEL was abated under the combined application of exogenous MEL and p-CPA. In the second experiment, the effects of p-CPA alone treatment on changes in biochemical parameters during refrigeration were analyzed. The results showed that p-CPA down-regulated the expressions of MEL biosynthesis genes, including LcTDC, LcT5H and LcSNAT, contributing to reduced generation of endogenous serotonin and MEL. p-CPA treatment accelerated oxidative stress-triggered membrane deterioration, as reflected by increases in relative leakage rate (RLR), reactive oxygen species (ROS) production, lipoxygenase (LOX) activity and malondialdehyde (MDA) accumulation. The membrane damage caused by p-CPA further resulted in loss of subcellular compartmentalization and enzymatic oxidation, as demonstrated by increased activities of polyphenol oxidase (PPO) and peroxidase (POD) in parallel with reduced contents of total phenolics and anthocyanin. Compared with control fruit, lower activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR), were observed in fruit receiving p-CPA. Additionally, p-CPA suppressed the expression levels of genes encoding oxidized protein repair-related enzymes, including LcMsrA1, LcMsrA2, LcMsrB1 and LcMsB2. These results suggest that endogenous MEL might confer a protective role against chilling stress by modulating cellular redox status in harvested litchi fruit during refrigeration.
Pericarp browning is one of the most important factors limiting the shelf life of litchi fruit. The storage behavior of three cultivars of litchi with different shelf life were studied to comprehensively address the importance of phenolic content and energy status in delaying the development of browning in litchi fruit after harvest. Results revealed that slower changes of browning indices; higher content of EGC, EC, ECG, GCG, PA2, total phenols and anthocyanins; lower activities of ANT, LAC, PPO, POD and PAL were detected in ‘Jingganghongnuo’, as compared to that in ‘Guiwei’ and ‘Nuomici’. The transcript abundant of oxidation-enzyme corresponding genes LcANT, LcLAC, LcPPO, LcPOD and LcPAL exhibited similar trends as changes of phenolics and enzyme activities in three cultivars. The energy status and the relative expression intensity of ATP metabolic-related genes LcATPb, LcSnRK2, LcAAC1, and LcAOX1 differed among the three cultivars and maintained higher levels in ‘Jingganghongnuo’. Accordingly, the development of pericarp browning was significantly related to the content of phenolics, especially ECG and EC, and to the changes in ATP of litchi fruit after harvest. The comparative study on variety of litchi cultivars evident that the phenolics, energy status as well as the transcript abundant of their corresponding genes are potential indicators to mark the browning change in litchi fruit.
Considerable pharmacological studies have demonstrated that the extracts and ingredients from different parts (seeds, peels, pulps, and flowers) of Litchi exhibited anticancer effects by affecting the proliferation, apoptosis, autophagy, metastasis, chemotherapy and radiotherapy sensitivity, stemness, metabolism, angiogenesis, and immunity via multiple targeting. However, there is no systematical analysis on the interaction network of “multiple ingredients-multiple targets-multiple pathways” anticancer effects of Litchi. In this study, we summarized the confirmed anticancer ingredients and molecular targets of Litchi based on published articles and applied network pharmacology approach to explore the complex mechanisms underlying these effects from a perspective of system biology. The top ingredients, top targets, and top pathways of each anticancer function were identified using network pharmacology approach. Further intersecting analyses showed that Epigallocatechin gallate (EGCG), Gallic acid, Kaempferol, Luteolin, and Betulinic acid were the top ingredients which might be the key ingredients exerting anticancer function of Litchi, while BAX, BCL2, CASP3, and AKT1 were the top targets which might be the main targets underling the anticancer mechanisms of these top ingredients. These results provided references for further understanding and exploration of Litchi as therapeutics in cancer as well as the application of “Component Formula” based on Litchi’s effective ingredients.
We examined the protective effects of procyanidin A2 (PA2) against oxidative stress in a human fetal hepatocyte line (L-02), and its mechanism with respect to regulating nuclear factor erythroid 2-related factor 2 (Nrf2), a key factor in the cellular antioxidant response. PA2 protected L-02 cells from oxidative damage that was induced by tert-butyl hydroperoxide, as evidenced by the increase in cell viability and the reduction in lactate dehydrogenase release and intracellular reactive oxygen species production. PA2 promoted the nuclear translocation of Nrf2 and upregulated heme oxygenase-1 and NAD(P)H quinone oxidoreductase 1. In addition, the c-Jun N-terminal kinase and p38 MAP kinase signaling pathways were activated by PA2. PA2 penetrated L-02 cells in dimeric form, with the cytosolic concentration peaking at 24 h, later than the flavan-3-ol monomers. PA2 can be absorbed into plasma and distributed to the liver after oral administration in mice.
Dans la présente étude, nous avons étudié les effets des infusions de feuilles de caroube et de cladodes OFI riches en polyphénols sur l'inflammation associée à l'obésité et la colite ulcéreuse induite par le dextran de sulfate de sodium (DSS) chez les souris suisse.Des études in vitro ont révélé que les extraits aqueux de feuilles de caroube et de cladodes OFI présentaient des propriétés anti-inflammatoires marquées par l'inhibition de la production d'IL-6, de TNF-α et d'oxyde nitrique (NO) dans les cellules RAW 264.7 stimulées par des lipopolysaccharides (LPS). Inhibition de la translocation du noyau NF-κβ.Pour des investigations in vivo, des souris mâles suisses ont été soumises à un régime contrôle (ND) ou à un régime riche en graisses (HFD). A la 4ème semaine après le début de l'étude, les animaux ont reçu ou non 1% d'infusion de feuilles de caroube ou d'OFI-cladode pendant 6 semaines et ont été soumis à une administration de DSS à 2% dans l'eau potable au cours des 7 derniers jours. Après sacrifice, les niveaux de cytokines pro-inflammatoires dans le plasma et l'expression de leur ARNm dans différents organes ont été déterminés. Les résultats ont montré que les infusions de feuille de caroube et de OFI-cladode réduisaient la sévérité de l'inflammation associée à l'obésité induite par HFD et la colite aiguë induite par le DSS indiquée par une diminution de l'expression des cytokines pro-inflammatoires (comme TNF-α, IL1b et IL-6) tissu adipeux et rate. En outre, les taux plasmatiques d'IL-6 et de TNF-α ont également été réduits en réponse au traitement par les infusions. Ainsi, les infusions de feuilles de caroube et d'OFI-cladode ont empêché la perméabilité intestinale grâce à la restauration des protéines de jonctions serrées (Zo1, occludines) et à l'homéostasie immunitaire. Ainsi, l'effet anti-inflammatoire des feuilles de caroube et des cladodes OFI pourrait être attribué à leurs polyphénols qui pourraient atténuer la gravité de l'inflammation associée à l'obésité et à la colite.
Rapid and accurate measurement of polyphenol oxidase (PPO) activity is important in the food industry as PPOs play a vital role in catalyzing enzymatic reactions. In this study, the possibility of using surface-enhanced Raman scattering (SERS) approach based on the reduction in SERS intensity of catechol in reaction medium for accurate determination of PPO activity in fruit and vegetables was investigated. Within a certain catechol concentration, when a purified PPO solution was analyzed, the reduction in SERS intensity (ΔI) was linear to PPO activity (Ec) in a wide range of 500-50000 U/L, and a linear regression equation of logΔI/Δt = 0.6223 logEc + 0.8072, with a correlation coefficient of 0.9689 and a limit of detection of 224.65 U/L was obtained. The method was used for detecting PPO activity in real apple and potato samples, and the results were compared with those obtained from colorimetric assay, demonstrating that the proposed method could be successfully used for detecting PPO activity in food samples.
The main objective of this chapter was to describe the physicochemical and biological characteristics of selected lichenized ascomycetes and the influence of their physiologically active compounds on human health, through scientifically proven information. The chapter presents the biologically active metabolites derived from lichen species (polyphenols, volatile compounds, lipids, phospholipids, fatty acids, and organic acids). Lichens and their metabolites have been demonstrated to possess numerous biological activities, including antiviral, antibacterial, antitumor, and enzyme inhibitory activity. The influence of environmental factors on the lipid and fatty acid composition of some lichen species has also been reported. Lichens are easily exposed to halogens, which are present in polluted air. We present chlorinated metabolites, which are isolated from various species of lichens. Chlorine is one of the main pollutants in nature. The structures of about 50 chlorinated metabolites of phenolic nature generated by lichenized ascomycetes are considered. Some active lichen substances are used in the pharmaceutical industry.
Litchi (Litchi chinensis Sonn.) is a famous fruit in south China, and it is also effective for chest tightness or chest pain, irritability, flatulence, epigastric pain and neuralgic pain, hernia pain and testicular swelling, cough, etc. It is valued because a great amount of polyphenol was found in litchi pericarp. In this paper, we got litchi pericarp pure extract by a simple purification method, then evaluated its activity to clear oxygen free radicals in vitro, and evaluated its myocardial protection effect in vivo through acute myocardial ischemia rat model. The results showed that the pure extract had protective effect on myocardial ischemia injury in a certain dose-effect relationship, which reflected in the electrocardiogram, myocardial pathological morphology and other indicators such as cardiac function enzymes, serum and myocardial antioxidant capacity, and eNOS, Bcl-2 and Bax gene expression. Furthermore, we analyzed the components of pure extract by UPLC-MS, ESI-MS and NMR. The main components of PLPE were procyanidin which were identified as procyanidin B2(1), (-)-epicatechin(2), epicatechin-(4β → 8,2β → O → 7)-epicatechin-(4β → 8)-epicatechin(3), A-type procyanidin trimer(4), B-type procyanidin dimer(5) and procyanidin A2(6).This study proved that litchi pericarp extract may have antioxidant activity and cardioprotection effect. It suggested that litchi pericarp may be good for cardiovascular disease. Copyright © 2017 John Wiley & Sons, Ltd.
Litchi (Litchi chinensis Sonn.) is a medium sized evergreen tree indigenous to China, Vietnam, Indonesia and Philippines. Litchi and its different parts viz., leaves, flowers, fruits, seeds, and pericarp contain significantly high amounts of phenolics and flavonoids compounds which are potential sources of natural antioxidants. Many previously published reports have demonstrated plenty of bioactivities, such as anti-oxidant, antimicrobial, hepato-protective, anti-cancer, cytotoxic, anti-inflammatory, analgesic, and immunomodulatory of litchi and its different parts. Litchi fruit is a good source of food nutrition and highly rich in natural anti-oxidants. It very much liked by consumers because of its delicious taste and beneficial health effects. Consumption of litchi and its products owing to their beneficial health promoting effects is rapidly increasing in humans. Litchi as an important plant of traditional medicine and its promising bioactivities has drawn much attention from researchers all over the world. In this chapter phytochemical composition and important bioactive properties of the litchi and different parts have been discussed with given emphasis to the mechanism of action of bioactive principle.
Litchi chinensis Sonn. has been widely used as anti-cancer, antiseptic, hypoglycemic, antihyperlipidemic, antiplatelet, antitussive, analgesic, anti-pyretic, diuretic, anti-viral, and hemostatic activities. Several bioactive compounds have been isolated and reported by the scientist using the modern techniques. Several new compounds are being reported. The litchi has now gained a status like other important medicinal plants because of its compound constituent as well as the activities like therapeutic drugs. The ethnomedical use of L. chinensis has been recorded in China, India, Vietnam, Indonesia, and Philippines. Phytochemical exploration has established that the key chemical constituents of litchi are flavonoids, sterols, triterpenes, phenolics, and other bioactive compounds. Crude extracts and pure compounds isolated from L. chinensis exhibited noteworthy anti-oxidant, anti-cancer, anti-inflammatory, antimicrobial, anti-viral, anti-diabetic, anti-obesity, hepato-protective, and immunomodulatory activities. The civilized cultures are using this since ancient time for the treatment of several diseases such as diabetes, stomach ulcers, cough, flatulence, obesity, testicular swelling, epigastric, and neuralgic pains. However, litchi extracts and fruit juices have been established to be secure at a dosage from the toxicological point of view.
Litchi (Litchi chinensis Sonn.) is an evergreen subtropical fruit, which is well acclaimed for its delicious, juicy aril and refreshing taste. Litchi fruit cultivation became an integral part of many Southeast Asian country’s economy with a significant demand in domestic and export market. Insufficient genetic data about the native cultivar, availability of the superior cultivars, lack of pest management control, production and post- harvest storage are the major constraints in litchi production and development all over the world. Biotechnological interventions have been successfully introduced in the field of litchi production for the massive micro propagation, in vitro regeneration and to improve the quality of the available cultivars to produce superior cultivars with high yield. Biotechnological tools may help in widening of the genetic base of native cultivars using various molecular markers, introduction of genetic engineering to produce promising hybrids with large fruit, resistance to pericarp browning and long life span is highly recommended in this field. In the present review, we have attempted to highlight research and development for the improvement of fruit quality and post-harvest storage using various conventional as well as biotechnological tools.
Pumpkin pomace obtained from cultivar (Cucurbita moschata Duch) was analyzed for their chemical composition and functional properties. Pumpkin pomace powder contained more than 50 mass % of total dietary fibre and showed high hydration properties such as water holding capacity (5.70 g · g−1) and swelling capacity (10.26 cm3 · g−1). The effect of pumpkin pomace incorporation to wheat dough by replacement of wheat flour with pumpkin pomace (5 or 7.5 %) on physical properties (volume, volume index, width, thickness, spread ratio) and sensory parameters (appearance, hardness, taste, odor, overall acceptability) of cracker were evaluated. The results indicated that the addition of higher amount (7.5 % mass) of pumpkin pomace powder negatively affected the volume, volume index, spread ratio and reduced their overall acceptance. Pumpkin pomace is a good source of ash and dietary fibres and may be incorporated into baked goods as a functional ingredient.
In this study, litchi juice was fermented at 30°C by probiotics of Lactobacillus casei, Lactobacillus bulgaricus and Leuconstoc mesenteroides, and the changes of microbial count and quality of fermented litchi juice during storage at 4°C were also investigated. Results showed that the three lactic acid bacteria grew rapidly in litchi juice, and received the highest number (above 9.0 log) after fermented 12 h. The three lactic acid bacteria showed obvious difference in utilizing sugar and organic acid of litchi juice, where Lactobacillus casei and Lactobacillus bulgaricus produced as much as 37.5 g/L exopolysaccharides. Moreover, after 12 h fermentation, the polyphenol and Vc contents appeared no significant change (p≤0.05). But L* values were significantly decrease (p<0.05), and the color became more pale in all fermented litchi juice. During storage of 28 d at 4°C, no further fermentation was found in all fermented litchi juice, but the number of Leuconostoc mesenteroides dropped to less than 7 log, whereas Lactobacillus casei and Lactobacillus bulgaricus only decreased 0.5 log.
We investigated the effects of citric acid and chitosan coating on the fruit ripening attributes of cherimoya (Annona cherimola Mill.) stored at 15 ± 1. °C for 10 days. Compared to the controls, a combined treatment of citric acid and chitosan coating delayed the browning, splitting, and decay, maintained firmness, and inhibited the increase in respiration rate of the cherimoya fruits. The inhibition of softening and splitting was associated with decreases in the activities of pectin methylesterase and polygalacturonase and solubilization/degradation of pectin ensued. The citric acid and chitosan coating treatment delayed the softening and splitting of the harvested cherimoya fruits by regulating the CMCase activity and starch-sugar conversion. Throughout the storage period, the citric acid and chitosan coating treated cherimoya fruits also exhibited a lower polyphenol oxidase activity and higher superoxide dismutase, peroxidase, and catalase activities compared with the controls. Moreover, the production of superoxide free radicals and content of malondialdehyde were significantly declined in the treated fruits. Furthermore, the expression patterns of several cell wall-related genes in cherimoya were analyzed by quantitative real time PCR. The data showed that all these genes, including three AcXETs, three AcEXPs and one AcPE, exhibited highly diversified expression patterns during the fruit softening. AcXET1 and AcXET2 showed highest expression levels on the time points 6-d and 8-d, while the accumulation of AcEXP3 notably increased on the time point 6-d. The citric acid and chitosan coating treatment delayed the accumulation of AcXEP1, AcEXP1, AcEXP1 and AcPE by reducing their mRNA levels. Our findings suggest that treatment with 20.0. mM citric acid combined with 1.00% chitosan can provide an effective approach to maintain postharvest quality and extend the shelf life of cherimoya.
The macroporous resin adsorption method was used to purify the pigment from Hibiscus syriacus L. petals. Through the comparison of the adsorption and desorption rates of six types of macroporous resins including AB-8, S-8, NKA-9, DM-130, D101 and 860021 to the pigment, 860021 resin was selected as the most appropriate resin to purify the pigment. The antioxidant capacities of the pigment extract (PE) were evaluated through in vitro experiments using hydroxyl radical scavenging assay, 1,1- diphenyl-2-picrylhydrazyl (DPPH) scavenging assay and lipid peroxidantion (LPO) inhibition capacity assay induced by Fe 2+-H 2O 2. Total flavonoid content (TFC) of PE was determined using the colorimetric methodology and total phenolic content (TPC) using Folin-Ciocalteu reagent. PE produced significant antioxidant activity. In addition, PE demonstrated higher TFC and TPC of 63.4±1.8 mg rutin equivalents/g and 172.6±2.4 mg gallic acid equivalents/g, respectively. This study suggests that H. syriacus L. petal can be used potentially as a source of natural antioxidants.
Litchi chinensis Sonn. (Sapindaceae) has been widely used in many cultures for the treatment of cough, flatulence, stomach ulcers, diabetes, obesity, testicular swelling, hernia-like conditions, and epigastric and neuralgic pains. The ethnopharmacologial history of L. chinensis indicated that it possesses hypoglycemic, anticancer, antibacterial, anti-hyperlipidemic, anti-platelet, anti-tussive, analgesic, antipyretic, haemostatic, diuretic, and antiviral activities.
The aim of this review is to provide up-to-date information on the botanical characterization, distribution, traditional uses, and chemical constituents, as well as the pharmacological activities and toxicity of L. chinensis. Moreover, the focus of this review is the possible exploitation of this plant to treat different diseases and to suggest future investigations.
To provide an overview of the ethnopharmacology, chemical constituents, and pharmacological activities of litchi, and to reveal their therapeutic potentials and being an evidence base for further research works, information on litchi was gathered from scientific journals, books, and worldwide accepted scientific databases via a library and electronic search (PubMed, Elsevier, Google Scholar, Springer, Scopus, Web of Science, Wiley online library, and pubs.acs.org/journal/jacsat). All abstracts and full-text articles were examined. The most relevant articles were selected for screening and inclusion in this review.
A comprehensive analysis of the literature obtained through the above-mentioned sources confirmed that ethno-medical uses of L. chinensis have been recorded in China, India, Vietnam, Indonesia, and Philippines. Phytochemical investigation revealed that the major chemical constituents of litchi are flavonoids, sterols, triterpenens, phenolics, and other bioactive compounds. Crude extracts and pure compounds isolated from L. chinensis exhibited significant antioxidant, anti-cancer, anti-inflammatory, anti-microbial, anti-viral, anti-diabetic, anti-obesity, hepato-protective, and immunomodulatory activities. From the toxicological perspective, litchi fruit juice and extracts have been proven to be safe at a dose 1 g/kg.
Phytochemical investigations indicated that phenolics were the major bioactive components of L. chinensis with potential pharmacological activities. The ethnopharmacological relevance of L. chinensis is fully justified by the most recent findings indicating it is a useful medicinal and nutritional agent for treating a wide range of human disorders and aliments. Further investigations are needed to fully understand the mode of action of the active constituents and to fully exploit its preventive and therapeutic potentials.
Copyright © 2015. Published by Elsevier Ireland Ltd.
Recent research has indicated that consumption of fruits and vegetables protects us not only from constipation but also from a host of age-related diseases. Because of their unique flavor characteristics, tropical fruits and their products are gaining popularity all over the world. Topics related to three of the tropical fruits (guava, lychee, and papaya), such as their physiology and ripening characteristics, chemical composition, nutritive value, postharvest handling, storage and marketing, processing into value-added products, fresh-cut fruits, by-products of processing industry, are discussed in this chapter.
In this study, polyphenols from lotus seed epicarp (PLSE) at three different ripening stages were purified by column chromatography and identified by RP-HPLC and HPLC-ESI-MS(2). The antioxidant activities of PLSE were also investigated. We found that the contents of PLSE at the green ripening stage, half ripening stage and full ripening stage are 13.08%, 10.95% and 6.73% respectively. The levels of catechin, epicatechin, hyperoside, and isoquercitrin in PLSE at the three different ripening stages were different. Moreover, the amounts of catechin and epicatechin decreased, while the contents of hyperoside and isoquercitrin increased as the seed ripened. We found that PLSE at three different ripening stages had good scavenging abilities on DPPH and ABTS(+) radicals. However, the scavenging ability decreased with maturation. Our results may be valuable with regard to the utilization of lotus seed epicarp as a functional food material.
Copyright © 2015 Elsevier Ltd. All rights reserved.
Whey is an important surplus product of food industry. Based on the point of view, huge quantities of whey produced worldwide can represent an environmental problem with its disposal, or, due to the fact that whey is rich in fermentable nutrients, it can be considered as an attractive substrate for biotechnological production of various industrially interesting products. Therefore, this chapter is intended to summarize possible up-stream processing methods, general principles and fermentation strategies for the microbial productions using whey as a substrate. Further, among huge amount of potential products, this chapter focuses on the production of high value substances and materials which find applications especially in the fields of health care, medicine and pharmacy. At first, many biologically active substances such as vitamins, carotenoids, antibiotics etc. can be produced from whey employing various microorganisms and cultivation strategies. Moreover, also number of biopolymers which can be used in the form of drug carriers, scaffolds, sutures, adhesives etc. can be produced by using whey as a cheap complex substrate. Apart from poly (lactic acid), these materials include polyhydroxyalkanoates - bacterial polyesters and also several polysaccharides such as xanthan, alginate, hyaluronic acid, gellan, pullulan, dextran or chitosan. In addition, the aim of this review is also to provide basic economical consideration of fermentation processes. In conclusion, utilization of whey as a substrate for microbial productions of high value products could result in a very promising process meeting both economic and ecological requirements.
Litchi (Litchi chinensis Sonn.) fruit, cv. Huaizhi, was treated with 2 and 4mM oxalic acid and stored at room temperature to investigate the effect of oxalic acid on pericarp browning. The results showed that the pericarp browning indices of the fruit, treated with both oxalic acid concentrations, were significantly lower than that of the control, due to increase of membrane integrity, inhibition of anthocyanin degradation, decline of oxidation, and maintanance of relatively low peroxidase activity in the fruit during storage. It appears that application of oxalic acid can effectively control the pericarp browning of litchi fruit during postharvest storage.
Oxidative stress is induced by a wide range of environmental factors including UV stress, pathogen invasion (hypersensitive reaction), herbicide action and oxygen shortage. Oxygen deprivation stress in plant cells is distinguished by three physiologically different states: transient hypoxia, anoxia and reoxygenation. Generation of reactive oxygen species (ROS) is characteristic for hypoxia and especially for reoxygenation. Of the ROS, hydrogen peroxide (H(2)O(2)) and superoxide (O(2)(.-)) are both produced in a number of cellular reactions, including the iron-catalysed Fenton reaction, and by various enzymes such as lipoxygenases, peroxidases, NADPH oxidase and xanthine oxidase. The main cellular components susceptible to damage by free radicals are lipids (peroxidation of unsaturated fatty acids in membranes), proteins (denaturation), carbohydrates and nucleic acids. Consequences of hypoxia-induced oxidative stress depend on tissue and/or species (i.e. their tolerance to anoxia), on membrane properties, on endogenous antioxidant content and on the ability to induce the response in the antioxidant system. Effective utilization of energy resources (starch, sugars) and the switch to anaerobic metabolism and the preservation of the redox status of the cell are vital for survival. The formation of ROS is prevented by an antioxidant system: low molecular mass antioxidants (ascorbic acid, glutathione, tocopherols), enzymes regenerating the reduced forms of antioxidants, and ROS-interacting enzymes such as SOD, peroxidases and catalases. In plant tissues many phenolic compounds (in addition to tocopherols) are potential antioxidants: flavonoids, tannins and lignin precursors may work as ROS-scavenging compounds. Antioxidants act as a cooperative network, employing a series of redox reactions. Interactions between ascorbic acid and glutathione, and ascorbic acid and phenolic compounds are well known. Under oxygen deprivation stress some contradictory results on the antioxidant status have been obtained. Experiments on overexpression of antioxidant production do not always result in the enhancement of the antioxidative defence, and hence increased antioxidative capacity does not always correlate positively with the degree of protection. Here we present a consideration of factors which possibly affect the effectiveness of antioxidant protection under oxygen deprivation as well as under other environmental stresses. Such aspects as compartmentalization of ROS formation and antioxidant localization, synthesis and transport of antioxidants, the ability to induce the antioxidant defense and cooperation (and/or compensation) between different antioxidant systems are the determinants of the competence of the antioxidant system.
The potential of antioxidants to reduce the cellular damage induced by ionizing radiation has been studied in animal models for more than 50 years. The application of antioxidant radioprotectors to various human exposure situations has not been extensive although it is generally accepted that endogenous antioxidants, such as cellular non-protein thiols and antioxidant enzymes, provide some degree of protection. This review focuses on the radioprotective efficacy of naturally occurring antioxidants, specifically antioxidant nutrients and phytochemicals, and how they might influence various endpoints of radiation damage. Results from animal experiments indicate that antioxidant nutrients, such as vitamin E and selenium compounds, are protective against lethality and other radiation effects but to a lesser degree than most synthetic protectors. Some antioxidant nutrients and phytochemicals have the advantage of low toxicity although they are generally protective when administered at pharmacological doses. Naturally occurring antioxidants also may provide an extended window of protection against low-dose, low-dose-rate irradiation, including therapeutic potential when administered after irradiation. A number of phytochemicals, including caffeine, genistein, and melatonin, have multiple physiological effects, as well as antioxidant activity, which result in radioprotection in vivo. Many antioxidant nutrients and phytochemicals have antimutagenic properties, and their modulation of long-term radiation effects, such as cancer, needs further examination. In addition, further studies are required to determine the potential value of specific antioxidant nutrients and phytochemicals during radiotherapy for cancer.
Oxygen free radicals (OFRs) have been implicated in the pathogenesis of an increasing number of diseases and inflammatory states. They may cause cell and tissue damage by their chemical modification of proteins, carbohydrates, nucleotides, and lipids. Under physiological conditions OFRs are part of normal regulatory circuits and are neutralized by antioxidants. Infections are one cause of increased OFR production. The aims of our study were to assess whether the increased oxidative stress in experimental otitis media with effusion (OME) is reflected in erythrocytes by lipid peroxidation and to survey the alterations in oxidant and antioxidant enzyme activities in experimental OME in guinea pigs. Erythrocyte total (enzymatic plus non-enzymatic) superoxide scavenger activity (TSSA), non-enzymatic superoxide scavenger activity (NSSA), superoxide dismutase (SOD), catalase (CAT), and xanthine oxidase (XO) activities, and malondialdehyde (MDA) level were measured in 6 guinea pigs with OME and in 6 controls. The TSSA, SOD, XO activities, and MDA level in experimental OME were significantly higher than in controls. No significant differences were found in erythrocyte NSSA and CAT activities. In experimental OME induced by histamine injection, increased OFR production was observed, suggesting that OFRs may play an important role in cell and tissue damage due to OME.
Phenolics were extracted from litchi fruit pericarp (LFP) tissues, purified and their antioxidant properties analyzed. LFP phenolics strongly inhibited linoleic acid oxidation and exhibited a dose-dependent free-radical scavenging activity against alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH*) and hydroxyl radicals and superoxide anions. The degradation of deoxyribose by hydroxyl radicals was inhibited by phenolics acting mainly as iron ion chelators, rather than by directly scavenging the radicals. Phenolics from litchi fruit pericarp were found to display similar reducing power activity as ascorbic acid. The effect of phenolic compound treatment on pericarp browning and electrolyte leakage of litchi fruit was also evaluated and it was observed that application of exogenous litchi phenolics to harvested litchi fruit significantly prevented pericarp browning and delayed increases in electrolyte leakage. These results suggest that litchi pericarp tissue phenolics could be beneficial in scavenging free radicals, maintaining membrane integrity and, thereby inhibiting pericarp browning of litchi fruit.
Products of browning reaction of glucosamine were prepared from glucosamine-HCl by incubating it at 37°C for 0-30 days, and the antioxidative activity, reducing power, degree of browning, aminosugar contents, pH, moisture and total nitrogen contents of the products were measured. In addition, the brown products prepared from glucosamine by incubation at 37°C for 0, 15 and 30 days were fractionated by gel filtration using Sephadex G-15, and the antioxidative activity, reducing power, degree of browning and pH of each fraction were also measured.
The results obtained were as follows:
1) When white powder of free glucosamine was allowed to stand for 3 days at 37°C, it transformed to a brown paste.
2) The strongest antioxidative activity was observed in the product obtained after incubation between 20 and 30 days.
3) The increase in antioxidative activity of the products of browning reaction was accompanied by the increase in the degree of browning.
4) The brown products prepared from glucosamine by long incubation were fractionated into fractions according to their molecular weights.
Antioxidative activity was detected in the fractions corresponding to intermediate molecular weight.
Phenolic compounds occur in all fruits as a diverse group of secondary metabolites. Hence, they are a component of the human diet although data for dietary intakes and metabolic fate are limited. Their role in oxidation processes, as either antioxidants or substrates in browning reactions, is examined. They are characterised by high chemical reactivity and this complicates their analysis.
A tannin extract was isolated from freeze-dried litchi pericarp (Litchi chinensis). HPLC analysis, after thioacidolysis reaction, revealed that this tannin fraction consisted of epicatechin units linked by both A- and B-type interflavonoid bonds. The calculated average degree of polymerization, considering the presence of A-type linkages, was 6.4. Characterization of oligomeric and polymeric procyanidins was performed using electrospray ionization mass spectrometry. Numerous oligomers containing one or more A-type interflavanoid linkages were detected. A regular repartition of the number of A-type linkages for each polymer length (e.g. from 2 to 7 for DP17 with mostly 4 A-type linkages) was observed. The average number of A-type linkages also increased with the DP, the predominant species containing one A-type linkage (denoted 1A) from DP2 to 5, 2A from DP6 to 10, 3A from DP11 to 15 and 4A from DP16 to 20. The highest DP was estimated at 22, with predominantly 5–6 A-type interflavanoid linkages.
There is a growing interest in natural antioxidants found in plants because of the world-wide trend toward the use of natural additives in food and cosmetics. Herbs and spices are one of the most important targets to search for natural antioxidants from the point of view of safety. This review presents the results on stabilization of lipids and lipid-containing foods with different herbs and spices (ground materials or extracts) and reports the structure of the main antioxidatively acting compounds isolated from them. The review presents information about the antioxidative effects of rosemary, sage, oregano, thyme, ginger, summer savory, black pepper, red pepper, clove, marjoram, basil, peppermint, spearmint, common balm, fennel, parsley, cinnamon, cumin, nutmeg, garlic, coriander, etc. Among the herbs of the Labiatae family, rosemary has been more extensively studied and its extracts are the first marketed natural antioxidants. Sage and oregano, which belong to the same family, have gained the interest of many research groups as potential antioxidants.
Postharvest browning of litchi fruit results in a short life and a reduced commercial value. The experiments were conducted to separate, purify and identify the polyphenol oxidase (PPO) substrates that cause litchi fruit to brown. PPO and its substrates were, respectively, extracted from fruit pericarp tissues. The substrates for litchi PPO were separated and purified using polyamide column chromatography, silica gel column chromatography and preparative thin layer chromatography. The substrate was further identified by 0.5% FeCl3 solution and enzymatic reaction with litchi PPO. On the basis of UV, 1H NMR, 13C NMR, and ESI-MS data, the direct substrate for the PPO from litchi fruit pericarp tissues was identified to be (−)-epicatechin.
The main oligomeric procyanidins from litchi pericarp (Litchi chinensis) were isolated and identified. Complete assignment of epicatechin-(4β→8, 2β→O→7)-epicatechin-(4β→8)-epicatechin structure was obtained using CD, NMR and ESI-MS techniques. The known (−)-epicatechin and procyanidin A2 were also isolated from litchi pericarp. The effects of oligomeric procyanidins, A2 and epicatechin-(4β→8, 2β→O→7)-epicatechin-(4β→8)-epicatechin from litchi pericarp on free radical-scavenging were determined by using a chemiluminescent method. The results showed that all of them had a strong scavenging effect on OH, and the IC50 values were 2.60 μg/ml, 1.75 μg/ml and 1.65 μg/ml for oligomeric procyanidins, A2 and the trimeric procyanidins, respectively. The antioxidant activities of A-type dimeric and trimeric procyanidins seemed to be related to the number of hydroxyls in their molecular structures.
Postharvest browning of litchi fruit results in short shelf life and reduced commercial value. Experiments were conducted to separate, purify and identify polyphenol oxidase (PPO ) substrates that cause litchi fruit to brown. PPO and its substrate were extracted from the pericarp tissues of litchi fruit. The litchi PPO substrate was purified using polyamide column, silica gel column and Sephadex LH-20 column chromatography. The browning substrate was selected by a 0.5% FeCl3 solution and then identified using a partially purified litchi PPO. Analyses of ultraviolet spectrometry, nuclear magnetic resonance and electrospray ionization mass spectrometry indicated that the PPO substrate was procyanidin A2. The substrate can be oxidized to ο-quinones by litchi PPO and then form brown-colored by-products, resulting in pericarp browning of harvested litchi fruit.
Litchi fruit can be stored at −18 °C without obvious adverse effects on the aril, but the pericarp darkens and browns when they are frozen or thawed. Experiments were conducted to test effects of hydrochloric acid on browning inhibition of litchi fruit pericarp for displacement of sulphur application. Litchi fruit were soaked in 0.5%, 1% and 2% HCl for 2–10 min. Fruit appearance and membrane leakage were assessed after 1 day of storage under ambient conditions of 25 °C and 80–90% relative humidity. In terms of browning control of and fruit pericarp damage, treatment with 1% HCl for 6 min gave the best red colour and minimal damage. 1% HCl treatment markedly inhibited polyphenol oxidase activity and maintained high anthocyanin content in litchi fruit pericarp tissue. Fruit treated with 1% HCl and stored at −18 °C for 12 months had a shelf life of 12 h at ambient temperature, with a uniform red colour and acceptable quality. Use of 1% HCl could be considered for commercial application in extending shelf life and maintaining quality of frozen litchi fruit following storage and during marketing.
We investigated reactive oxygen species (ROS) involvement in polymorphonuclear neutrophilic leukocyte (neutrophil) apoptosis triggering. Neutrophils were incubated with xanthine oxidase (XO), which produces superoxide anion (O2•−) and hydrogen peroxide (H2O2) or glucose oxidase (GO), which produces only H2O2. Both XO and GO accelerated apoptosis when compared to spontaneously aged neutrophils. Catalase inhibited both spontaneous apoptosis and XO- or GO-accelerated apoptosis, but superoxide dismutase did not. Hydrogen peroxide can enter the cell, thus generating intracellular oxidation, which was observed by flow cytometry. Furthermore, the intracellular reduced glutathione content fell in the presence of XO or GO; however, apoptosis was not accelerated in the presence of buthionine sulfoximine (BSO), suggesting that the fall in glutathione in the presence of XO or GO is a consequence of oxidative stress but not a trigger of apoptosis. Hydrogen peroxide can react with iron to form hydroxyl radicals (HO•); we observed that two iron chelators, deferoxamine and hydroxybenzyl ethylenediamine (HBED), both inhibited spontaneous and accelerated apoptosis, suggesting that HO• may mediate neutrophil apoptosis.
Anthocyanins were extracted and purified from litchi fruit pericarp and their antioxidant properties were investigated. Effects of exogenous anthocyanin treatments on pericarp browning and membrane permeability of harvested litchi fruit were also evaluated. Anthocyanins from litchi fruit pericarp strongly inhibited linoleic acid oxidation and exhibited a dose-dependent free-radical-scavenging activity against DPPH radical, superoxide anions and hydroxyl radical. The degradation of deoxyribose by hydroxyl radicals was shown to be inhibited by anthocyanins acting mainly as chelators of iron ions rather than directly scavenging hydroxyl radicals. Anthocyanins were also found to have excellent reducing power. The reducing power of anthocyanins, ascorbic acid and butylated hydroxytoluene all at 100 μg/ml were 3.70, 0.427 and 0.148, respectively, indicating that anthocyanins from litchi pericarp had a strong electron-donating capacity. Furthermore, application of anthocyanins to harvested litchi fruit significantly prevented pericarp browning and delayed the increase in membrane permeability. It was therefore suggested that anthocyanins could be beneficial in scavenging free radicals and reducing lipid peroxidation of litchi fruit pericarp.
An important field of research today is the control of ‘redox’ status with the properties of food and food components. Natural antioxidants present in the diet increase the resistance toward oxidative damages and they may have a substantial impact on human health.Dietary antioxidants such as ascorbates, tocopherols and carotenoids are well known and there is a surplus of publications related to their role in health. Plant phenols have not been completely studied because of the complexity of their chemical nature and the extended occurrence in plant materials.Extensively studied sources of natural antioxidants are fruits and vegetables, seeds, cereals, berries, wine, tea, onion bulbs, olive oil and aromatic plants. Attempts are also made to identify and evaluate antioxidants in agricultural by-products, ethnic and traditional products, herbal teas, cold pressed seed oils, exudates resins, hydrolysis products, not evaluated fruits and edible leaves and other raw materials rich in antioxidant phenols that have nutritional importance and/or the potential for applications in the promotion of health and prevention against damages caused by radicals.
Phenolic compounds, ubiquitous in plants are an essential part of the human diet, and are of considerable interest due to their antioxidant properties. These compounds posses an aromatic ring bearing one or more hydroxyl groups and their structures may range from that of a simple phenolic molecule to that of a complex high-molecular weight polymer. Flavonoids, which bear the C6–C3–C6 structure, account for more than half of the over eight thousand different phenolic compounds. The antioxidant activity of phenolic compounds depends on the structure, in particular the number and positions of the hydroxyl groups and the nature of substitutions on the aromatic rings. Fruits, vegetables and beverages are the major sources of phenolic compounds in the human diet. The food and agricultural products processing industries generate substantial quantities of phenolics-rich by-products, which could be valuable natural sources of antioxidants. Some of these by-products have been the subject of investigations and have proven to be effective sources of phenolic antioxidants. When tested in edible oils, and in fish, meat and poultry products, phenolic-rich extracts have shown antioxidant activities comparable to that of synthetic antioxidants. Practical aspects of extraction and production of sufficient amounts of natural antioxidants from most of these sources remain to be elucidated.
In this paper, are presented the results of physical and chemical investigations of differently treated samples of oak acorn. The aim of this investigation is to estimate the influence of thermal treatment on physical and nutritive characteristics of investigated samples. Oak acorn, Quercus robur, (belonging to Fagaceae family) was investigated in native and thermally treated forms. By subsequent extraction of dry toasted oak acorn (Quercus semen tostum) the aqueous extract was obtained which is then dried in a spout-fluid bed. The content of total polyphenols, then polyphenols unadsorbed on hide powder and tannins was determined by spectrophotometric methods with phosphor-wolfram acid according to Ph. Yug. V. Galic acid was determined by HPLC. The total antioxidant activity (TAA) of the aqueous extract compared to the control samples of pigs fat and synthetic antioxidant butylated hydroxyanisole BHA was estimated by Schall–Oven test at 60 ± 1 °C in dark, and oxidative changes were determined by measuring the Peroxide value (PV). For determination of macro- and microelements the method of AAS was used.By detecting the changes of PV it is established that aqueous extract was influencing the stability of pigs fat, that is, showing the antioxidant activity. The activity was increasing with increasing concentration in tested samples. The obtained results regarding the total polyphenols content, the content of galic acid, nitrogen compounds, macro and microelements show that acorn, after treatment, was retaining and in some cases improving its functional properties.
Litchi (Litchi chinensis Sonn.) is a subtropical to tropical fruit of high commercial value in international trade. However, harvested litchi fruit rapidly lose their bright red skin colour. Peel browning of harvested litchi fruit has largely been attributed to rapid degradation of red anthocyanin pigments. This process is associated with enzymatic oxidation of phenolics by polyphenol oxidase (PPO) and/or peroxidase (POD). PRO and POD from litchi pericarp cannot directly oxidize anthocyanins. Moreover, PPO substrates in the pericarp are not well characterised. Consequently, the roles of PPO and POD in litchi browning require further investigation. Recently, an anthocyanase catalysing the hydrolysis of sugar moieties from anthocyanin to anthocyanidin has been identified in litchi peel for the first time. Thus, litchi enzymatic browning may involve an anthocyanase-anthocyanin-phenolic-PPO reaction. Current research focus is on characterising the properties of the anthocyanase involved in anthocyanin degradation. Associated emphasis is on maintenance of membrane functions in relation to loss of compartmentation between litchi peel oxidase enzymes and their substrates. (C) 2004 Elsevier Ltd. All rights reserved.
An ethanol extract of the stem of Opuntia ficus-indica var. saboten (OFS) was assessed to determine the mechanism(s) of its antioxidant activity. The ethanol extract exhibited a concentration-dependent inhibition of linoleic acid oxidation in a thiocyanate assay system. In addition, the OFS extract showed dose-dependent free-radical scavenging activity, including DPPH radicals, superoxide anions (O(2)(*-)), and hydroxyl radicals (*OH), using different assay systems. The OFS ethanol extract was also found to be effective in protecting plasmid DNA against the strand breakage induced by hydroxyl radicals in a Fenton's reaction mixture. Furthermore, the extract showed significant (p < 0.01) dose-dependent protection of mouse splenocytes against glucose oxidase-mediated cytotoxicity. Finally, the OFS extract was characterized as containing a high amount of phenolics (180.3 mg/g), which might be the active compounds responsible for the antioxidant properties of the OFS extract.
Flavonoids are a class of secondary plant phenolics with significant antioxidant and chelating properties. In the human diet, they are most concentrated in fruits, vegetables, wines, teas and cocoa. Their cardioprotective effects stem from the ability to inhibit lipid peroxidation, chelate redox-active metals, and attenuate other processes involving reactive oxygen species. Flavonoids occur in foods primarily as glycosides and polymers that are degraded to variable extents in the digestive tract. Although metabolism of these compounds remains elusive, enteric absorption occurs sufficiently to reduce plasma indices of oxidant status. The propensity of a flavonoid to inhibit free-radical mediated events is governed by its chemical structure. Since these compounds are based on the flavan nucleus, the number, positions, and types of substitutions influence radical scavenging and chelating activity. The diversity and multiple mechanisms of flavonoid action, together with the numerous methods of initiation, detection and measurement of oxidative processes in vitro and in vivo offer plausible explanations for existing discrepancies in structure-activity relationships. Despite some inconsistent lines of evidence, several structure-activity relationships are well established in vitro. Multiple hydroxyl groups confer upon the molecule substantial antioxidant, chelating and prooxidant activity. Methoxy groups introduce unfavorable steric effects and increase lipophilicity and membrane partitioning. A double bond and carbonyl function in the heterocycle or polymerization of the nuclear structure increases activity by affording a more stable flavonoid radical through conjugation and electron delocalization. Further investigation of the metabolism of these phytochemicals is justified to extend structure-activity relationships (SAR) to preventive and therapeutic nutritional strategies.
According to the free radical theory, aging can be considered as a progressive, inevitable process partially related to the accumulation of oxidative damage into biomolecules -- nucleic acids, lipids, proteins or carbohydrates -- due to an imbalance between prooxidants and antioxidants in favor of the former. More recently also the pathogenesis of several diseases has been linked to a condition of oxidative stress. In this review we focus our attention on the evidence of oxidative stress in aging brain, some of the most important neurodegenerative diseases -- Alzheimer's disease (AD), mild cognitive impairment (MCI), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS) and Huntington's disease (HD) -- and in two common and highly disabling vascular pathologies--stroke and cardiac failure. Particular attention will be given to the current knowledge about the biomarkers of oxidative stress that can be possibly used to monitor their severity and outcome.
The thrust of this presentation takes a more programmatic approach and gives an overview of the programs at the NIH and the NCI that have a broad nutritional and basic science undercurrent and outline. Also discussed briefly are some areas of general concern that are under investigation in the nutrition group and are included in the group's outreach efforts among professional and academic organizations. The overarching focus of these efforts is to stress the importance of nutrition as a potential modulator of health/disease risks associated with genetic predisposition and environmentally induced disease from diet, lifestyle and exposure to pollutants.
Polyphenol oxidase (PPO) from litchi (Litchi chinensis Sonn.) pericarp was characterized using (-)-epicatechin, which was the major endogenous polyphenol in litchi pericarp as a substrate. The optimum pH for PPO activity with (-)-epicatechin was 7.5, and the enzyme was unstable below pH 4.5 and stable in the pH range of 6.0-8.0. Residual activities of PPO were 86.25, 86.31, and 80.17% after 67 days of incubation at 4 degrees C at pH 6.0, 7.5, and 8.0, respectively. From thermostability studies, the Ki value increased with temperature and the results suggested that the enzyme was unstable above 45 degrees C. Moreover, the results also provided strong evidence that the denaturalization temperature of PPO was near 70 degrees C. The inhibition studies indicated that l-cysteine and glutathione were strong inhibitors even at low concentrations while NaF inhibited moderately. In addition, the results also indicated that the inhibition mechanisms of thiol groups were different from those of halide salts.