Low molecular weight phenolics of grape juice and winemaking byproducts: antioxidant activities and inhibition of oxidation of human low-density lipoprotein cholesterol and DNA strand breakage

Antidiabetic and Lipid-Lowering Effects of the Polyphenol Extracts from the Leaves of Clausena lansium (Lour.) Skeels on Streptozotocin-Induced Type 2 Diabetic Rats

Clausena lansium (Lour.) Skeels (Wampee) is widely grown in China and considered as a healthy fruit. Its leaves are also considered as traditional herbs. This study analyzed polyphenol compounds in polyphenol extracts of the leaves C. lansium (lour.) Skeels (PEL) and investigated the protective effect of PEL against hyperglycemia and hyperlipidemia in T2DM rats. The result showed that PEL is composed mainly of gallic acid, chlorogenic acid, coffee acid, ferulic acid, and rutin. PEL could obviously relieve some symptoms of T2DM rats, including emaciation, hyperhidrosis, polyphagia, diuresis, liver swelling, kidney, and pancreas hypertrophy, as well as reduce fasting blood glucose. Moreover, the supplementation of PEL significantly ameliorated lipids disorder and protected liver in T2DM rats, including fat accumulation, improvement of lipid distribution and hepatocyte protection. These results indicate that the Oral of PEL have potential effects of against hyperglycemia and hyperlipidemia in diabetic disorders.

PRACTICAL APPLICATION

The leaves Clausena lansium (lour.) Skeels is rich in polyphenol and other ingredients. In this research, the preliminary study shows that PEL can reduce fasting blood glucose and improve lipids disorder in rats, which will bring to diabetic patients a way to improve the disease and enhance the quality of life. The PEL therefore can be used for the production of pharmaceutical raw materials and the design of novel functional foods by simple conversion.

Dietary Polyphenols in the Prevention of Stroke

Polyphenols have an important protective role against a number of diseases, such as atherosclerosis, brain dysfunction, stroke, cardiovascular diseases, and cancer. Cardiovascular diseases are the number one cause of death worldwide: more people die annually from cardiovascular diseases than from any other cause. The most important behavioural risk factors of heart disease and stroke are unhealthy diet, physical inactivity, tobacco use, and excess alcohol intake. The dietary consumption of polyphenols has shown to be inversely associated with morbidity and mortality by cardio- and cerebrovascular diseases. It is well-known that the protective effects of polyphenols in vivo depend on the grade how they are extracted from food and on their intestinal absorption, metabolism, and biological action with target tissues. The aim of this review was to summarise the relation between polyphenols of different plant sources and stroke in human intervention studies, animal models, and in vitro studies.

Phenolics from Winemaking By-Products Better Decrease VLDL-Cholesterol and Triacylglycerol Levels than Those of Red Wine in Wistar Rats

Winemaking by-products account for more than 30% of the grape production, but this inexpensive feedstock has not yet been fully exploited. Accordingly, we evaluated the potential biological activity of winemaking by-products produced with Syrah grapes in comparison with those of the wine produced using the same grape cultivar. Winemaking by-products showed higher contents of total anthocyanins, flavonols, stilbenes, and flavanols than red wine as evaluated by HPLC-DAD-FD (on a dry weight basis). In contrast, red wine was a better source of phenolic acids. However, the contribution of phenolic acids was minor for both samples. Furthermore, equivalent concentration of winemaking by-products (100 mg/kg/d) showed greater biological activity by than that of red wine by decreasing the levels of VLDL-cholesterol and triacylglycerols in Wistar rats. Therefore, this study supports the use of winemaking by-products as an economical source of bioactive phenolics with potential use in the food and nutraceutical industries.

Phenolic profiles and antioxidant activity of defatted camelina and sophia seeds

Phenolic compounds in oilseeds occur in the free, esterified and insoluble-bound forms and serve as natural antioxidants by preventing food oxidation as well as oxidative stress and various disorders in the body. In this work, free, esterified and insoluble-bound phenolics were extracted from defatted camelina and sophia seeds. Samples were evaluated for their total contents of phenolics (TPC), flavonoids (TFC) and proanthocyanidins (PC) as well as the antioxidant activity of their various phenolic fractions. Several in vitro methods, namely Trolox equivalent antioxidant capacity (TEAC), reducing power (RP) and metal chelation activity were used for all fractions. High performance liquid chromatography-diode array detection- tandem mass spectrometry (HPLC-DAD-MS/MS) identified 29 phenolics belonging to phenolic acids and their derivatives, flavonoids and procyanidins in different fractions of camelina and sophia extracts. Esterified fraction was the predominant form of phenolics in both seeds. Thus, camelina and sophia seeds may serve as viable functional food ingredients with protective antioxidant potential.

Polyphenols from Wine Lees as a Novel Functional Bioactive Compound in the Protection Against Oxidative Stress and Hyperlipidaemia

The study examines the potential of wine industry by-product, the lees, as a rich mixture of natural polyphenols, and its physiological potential to reduce postprandial metabolic and oxidative stress caused by a cholesterol-rich diet in in vivo model. Chemical analysis of wine lees showed that their total solid content was 94.2%. Wine lees contained total phenols, total nonflavonoids and total flavonoids expressed in mg of gallic acid equivalents per 100 g of dry mass: 2316.6±37.9, 1332.5±51.1 and 984.1±28.2, respectively. The content of total anthocyanins expressed in mg of cyanidin-3-glucoside equivalents per 100 g of dry mass was 383.1±21.6. Antioxidant capacity of wine lees determined by the DPPH and FRAP methods and expressed in mM of Trolox equivalents per 100 g was 259.8±1.8 and 45.7±1.05, respectively. The experiment lasted 60 days using C57BL/6 mice divided in four groups: group 1 was fed normal diet and used as control, group 2 was fed normal diet with added wine lees, group 3 was fed high-cholesterol diet (HCD), i.e. normal diet with the addition of sunflower oil, and group 4 was fed HCD with wine lees. HCD increased serum total cholesterol (TC) by 2.3-fold, triacylglycerol (TAG) by 1.5-fold, low-density lipoprotein (LDL) by 3.5-fold and liver malondialdehyde (MDA) by 50%, and reduced liver superoxide dismutase (SOD) by 50%, catalase (CAT) by 30% and glutathione (GSH) by 17.5% compared to control. Conversely, treatment with HCD and wine lees reduced TC and LDL up to 1.4 times more than with HCD only, with depletion of lipid peroxidation (MDA) and restoration of SOD and CAT activities in liver, approximating values of the control. HDL levels were unaffected in any group. Serum transaminase activity showed no hepatotoxic properties in the treatment with lees alone. In the proposed model, wine lees as a rich polyphenol source could be a basis for functional food products without alcohol.

Protective effects of rambutan (Nephelium lappaceum) peel phenolics on H2O2-induced oxidative damages in HepG2 cells and d-galactose-induced aging mice

Rambutan peel phenolic (RPP) extracts were prepared via dynamic separation with macroporous resin. The total phenolic content and individual phenolics in RPP were determined. Results showed that the total phenolic content of RPP was 877.11 mg gallic acid equivalents (GAE)/g extract. The content of geranin (122.18 mg/g extract) was the highest among those of the 39 identified phenolic compounds. RPP protected against oxidative stress in H₂O₂-induced HepG2 cells in a dose-response manner. The inhibitory effects of RPP on cell apoptosis might be related to its inhibitory effects on the generation of intracellular reactive oxygen species and increased effects on superoxide dismutase activity. The in vivo anti-aging activity of RPP was evaluated using an aging mice model that was induced by d-galactose (d-gal). The results showed that RPP enhanced the antioxidative status of experimental mice. Moreover, histological analysis indicated that RPP effectively reduced d-gal-induced liver and kidney tissue damage in a dose-dependent manner. Therefore, RPP can be used as a natural antioxidant and anti-aging agent in the pharmaceutical and food industries.

Tocopherols and Tocotrienols in Common and Emerging Dietary Sources: Occurrence, Applications, and Health Benefits

Edible oils are the major natural dietary sources of tocopherols and tocotrienols, collectively known as tocols. Plant foods with low lipid content usually have negligible quantities of tocols. However, seeds and other plant food processing by-products may serve as alternative sources of edible oils with considerable contents of tocopherols and tocotrienols. Tocopherols are among the most important lipid-soluble antioxidants in food as well as in human and animal tissues. Tocopherols are found in lipid-rich regions of cells (e.g., mitochondrial membranes), fat depots, and lipoproteins such as low-density lipoprotein cholesterol. Their health benefits may also be explained by regulation of gene expression, signal transduction, and modulation of cell functions. Potential health benefits of tocols include prevention of certain types of cancer, heart disease, and other chronic ailments. Although deficiencies of tocopherol are uncommon, a continuous intake from common and novel dietary sources of tocopherols and tocotrienols is advantageous. Thus, this contribution will focus on the relevant literature on common and emerging edible oils as a source of tocols. Potential application and health effects as well as the impact of new cultivars as sources of edible oils and their processing discards are presented. Future trends and drawbacks are also briefly covered.

Identification of phenolic antioxidants and bioactives of pomegranate seeds following juice extraction using HPLC-DAD-ESI-MSn

Phenolics from free and hydrolyzed fractions of pomegranate juice (PJ) and seeds (PS) were evaluated. In general, total phenolic contents and scavenging of ABTS⁺, DPPH and hydroxyl radicals, as well as metal chelation of the soluble fraction from PS, were higher than those for PJ. Insoluble-bound phenolics from PS accounted for up to 27% of total scavenging capacity (free+esterified+insoluble-bound). Phenolic acids (13), monomeric flavonoids (8), hydrolysable tannins (12), proanthocyanidin (1) and anthocyanins (12) were tentatively characterized using HPLC-DAD-ESI-MSⁿ. Several compounds were identified for the first time in PJ or PS. The inhibition of DNA damage (induced by hydroxyl and peroxyl radicals), copper-induced LDL-cholesterol peroxidation, as well as alpha-glucosidase and lipase activities were demonstrated, therefore supporting the potential exploitation of PJ and PS as sources of bioactive compounds.

α-Glucosidase inhibiting activity and bioactive compounds of six red wine grape pomace extracts

Grape pomace contains considerable amounts of polyphenols and it has been reported to exhibit specific inhibitory activity against mammalian intestinal α-glucosidases. This study aims to investigate the anti-diabetes potential of Chambourcin, Merlot, Norton, Petit Verdot, Syrah and Tinta Cão red wine grape pomaces by assessing their rat intestinal α-glucosidase inhibitory activity in relation to their total phenolic content and individual identified phenolic compounds by HPLC. Among the selected pomaces, Tinta Cão, Syrah and Merlot extracts showed higher potency in inhibiting α-glucosidase, and appeared to have higher respective total phenolic contents. Fifteen phenolic compounds were identified in the pomace samples, however, none of them showed significant inhibition of intestinal α-glucosidases. Red grape pomace, namely Tinta Cão, appears to be a promising functional food for the potential future development of a food-derived α-glucosidase inhibitor for preventing and treating diabetes.

Phenolic Compounds of Pomegranate Byproducts (Outer Skin, Mesocarp, Divider Membrane) and Their Antioxidant Activities

Pomegranate peel was separated into outer leathery skin (PS), mesocarp (PM), and divider membrane (PD), and its phenolic compounds were extracted as free (F), esterified (E), and insoluble-bound (B) forms for the first time. The total phenolic content followed the order PD > PM > PS. ABTS(•+), DPPH, and hydroxyl radical scavenging activities and metal chelation were evaluated. In addition, pomegranate peel extracts showed inhibitory effects against α-glucosidase activity, lipase activity, and cupric ion-induced LDL-cholesterol oxidation as well as peroxyl and hydroxyl radical-induced DNA scission. Seventy-nine phenolic compounds were identified using HPLC-DAD-ESI-MS(n) mainly in the form of insoluble-bound. Thirty compounds were identified for the first time. Gallic acid was the major phenolic compound in pomegranate peel, whereas kaempferol 3-O-glucoside was the major flavonoid. Moreover, ellagic acid and monogalloyl-hexoside were the major hydrolyzable tannins, whereas the dominant proanthocyanidin was procyanidin dimers. Proanthocyanidins were detected for the first time.

Antioxidative and prooxidative effects in food lipids and synergism with α-tocopherol of açaí seed extracts and grape rachis extracts

Extracts of açaí seed and of grape rachis alone or in combination with α-tocopherol were evaluated as antioxidants in (i) bulk soybean oil, (ii) soybean oil liposomes and (iii) soybean-oil/water emulsions. The extracts made with 57% aqueous ethanol showed an antioxidant activity not dependent on concentration for grape rachis extracts and a concentration-dependent prooxidative activity for açaí seed extracts in bulk soybean oil. Both the extracts, however, protected liposome suspensions and oil/water emulsions against lipid oxidation. Synergism was demonstrated when extracts were combined with α-tocopherol, effects explained by the solubility of extract components in the water-phase and of α-tocopherol in the lipid-phase. Phenolic profiling of the extracts by U-HPLC-ESI-LTQ-MS was used to identify active antioxidants. Açaí seed and grape rachis extracts served as good sources of procyanidins and flavan-3-ols, imparted high antioxidant activity especially when combined with α-tocopherol and are suggested for protection of food oil/water emulsions.

Enzyme-assisted extraction of phenolics from winemaking by-products: Antioxidant potential and inhibition of alpha-glucosidase and lipase activities

Phenolics in food and agricultural processing by-products exist in the soluble and insoluble-bound forms. The ability of selected enzymes in improving the extraction of insoluble-bound phenolics from the starting material (experiment I) or the residues containing insoluble-bound phenolics (experiment II) were evaluated. Pronase and Viscozyme improved the extraction of insoluble-bound phenolics as evaluated by total phenolic content, antioxidant potential as determined by ABTS and DPPH assays, and hydroxyl radical scavenging capacity, reducing power as well as evaluation of inhibition of alpha-glucosidase and lipase activities. Viscozyme released higher amounts of gallic acid, catechin, and prodelphinidin dimer A compared to Pronase treatment. Furthermore, p-coumaric and caffeic acids, as well as procyanidin dimer B, were extracted with Viscozyme but not with Pronase treatment. Solubility plays an important role in the bioavailability of phenolic compounds, hence this study may assist in better exploitation of phenolics from winemaking by-products as functional food ingredients and/or supplements.

Bioactive compounds of juices from two Brazilian grape cultivars

BACKGROUND

Grape juice consumption may prevent several chronic diseases owing to the presence of phenolic compounds, which have an important role in the reduction of oxidative stress. This study investigated the polyphenol content and antioxidant activities of grape juices from two cultivars: BRS-Cora and Isabella. Total polyphenol content (TPC), anthocyanins, antioxidant capacity (oxygen radical absorbance capacity, ferric reducing antioxidant power and 1,1-diphenyl-2-picrylhydrazyl), and phenolic profile (high-performance liquid chromatography with diode array and fluorescence detection--HPLC-DAD-FLD) were determined.

RESULTS

BRS-Cora grape juice showed higher concentrations of total polyphenols and anthocyanins, as well as higher antioxidant potential, than those of Isabella grape juice. A significant positive correlation was found in TPC or anthocyanin contents when correlated with the remaining antioxidant assays. In addition, HPLC-DAD-FLD showed a higher total phenolic content in BRS-Cora grape juice compared to Isabella.

CONCLUSION

The present results show BRS-Cora as a promising cultivar for grape juice production with an improved functional potential.

Bioactivity-guided isolation and purification of α-glucosidase inhibitor, 6-O-D-glycosides, from Tinta Cão grape pomace

Bioactivity-guided fractionation methods were used to identify and purify active components in Tinta Cão grape pomace extract (GPE) that inhibit intestinal α-glucosidases. One active α-glucosidase inhibitor and one new natural product determined as 6-O-(p-coumaroyl)-D-glucopyranoside and methyl 6-O-(p-coumaroyl)-β-D-galactopyranoside, respectively, were isolated from GPE that were previously shown to potently inhibit α-glucosidase. Analysis of the relationship between structures and activity suggested that C₁-OH of saccharide moiety in phenolic glycosides is necessary for this potent inhibition of intestinal α-glucosidases for the potential development of a novel anti-hyperglycaemic dietary supplement.

HRMS Profile of a Hazelnut Skin Proanthocyanidin-rich Fraction with Antioxidant and Anti-Candida albicans Activities

Roasted hazelnut skins (RHS) represent a byproduct of kernel industrial processing. In this research, a RHS extract (RHS-M) and its fraction RHS-M-F3 enriched in proanthocyanidins (PAs), with antioxidant activity, were characterized in terms of total phenolic compound and PA contents. RHS-M and RHS-M-F3 showed antifungal properties against Candida albicans SC5314 (MIC2 = 3.00 and 0.10 μg/mL and MIC0 = 5.00 and 0.50 μg/mL, respectively), determined by the microbroth dilution method and Candida albicans morphological analysis. No cytotoxic effect on HEKa and HDFa cell lines was exhibited by RHS-M and RHS-M-F3. The metabolite profiling of RHS-M and RHS-M-F3 was performed by thiolysis followed by HPLC-UV-HRMS analysis and a combination of HRMS-FIA and HPLC-HRMS(n). Extract and fraction contain oligomeric PAs (mDP of 7.3 and 6.0, respectively, and DP up to 10) mainly constituted by B-type oligomers of (epi)-catechin. Also, (epi)-gallocatechin and gallate derivatives were identified as monomer units, and A-type PAs were detected as minor compounds.

Adsorption of ochratoxin A from grape juice by yeast cells immobilised in calcium alginate beads

Grape juice can be easily contaminated with ochratoxin A (OTA), one of the known mycotoxins with the greatest public health significance. Among the different approaches to decontaminate juice from this mycotoxin, microbiological methods proved efficient, inexpensive and safe, particularly the use of yeast or yeast products. To ascertain whether immobilisation of the yeast biomass would lead to successful decontamination, alginate beads encapsulating Candida intermedia yeast cells were used in our experiments to evaluate their OTA-biosorption efficacy. Magnetic calcium alginate beads were also prepared by adding magnetite in the formulation to allow fast removal from the aqueous solution with a magnet. Calcium alginate beads were added to commercial grape juice spiked with 20 μg/kg OTA and after 48 h of incubation a significant reduction (>80%), of the total OTA content was achieved, while in the subsequent phases (72-120 h) OTA was slowly released into the grape juice by alginate beads. Biosorption properties of alginate-yeast beads were tested in a prototype bioreactor consisting in a glass chromatography column packed with beads, where juice amended with OTA was slowly flowed downstream. The adoption of an interconnected scaled-up bioreactor as an efficient and safe tool to remove traces of OTA from liquid matrices is discussed.