Grape Seed Proanthocyanidins Research Articles

Sex Differences in the Absorption, Disposition, Metabolism, and Excretion of Grape Seed Proanthocyanidins in Prepubescent Rats.

The absorption, disposition, metabolism, and excretion (ADME) of phenolic compounds are key factors in determining their bioactivity. The group demonstrates that the ADME of a Grape Seed Proanthocyanidin Extract (GSPE) depends on sex in adult rats and specifically, methylated metabolites are only quantified in brain male adult rats. The aim of this study is to determine whether these differences exist before puberty. Prepubescent 4-week-old male and female Wistar rats are administered GSPE at a dose of 1000mgkg-1. Plasma, liver, mesenteric white adipose tissue (MWAT), brain, and kidneys are extracted excised 2h after GSPE administration, and the PAs metabolite profile is studied by HPLC-ESI-MS/MS. Moreover, plasma estradiol and brain and liver catechol-O-methyltransferase (COMT) protein levels are also studied. Results showed that there are no differences in plasma and brain among sexes and only differences are observed in liver, MWAT, and kidney with individual metabolites. This agrees with the lack of differences in estradiol and COMT levels among sexes. However, the ADME of PAs metabolites is higher in male rats. The results demonstrate lack of sex-dependence in metabolite profile in prepubescent rats, suggesting that sex differences in the metabolism of GSPE occur due to puberty.

Exploring separation patterns and mechanisms of proanthocyanidins in grape seeds and pomace with diverse molecular weights, compositions, and structures

The function of proanthocyanidins (PAs) relies on their structure and requires high-purity PAs. Though Sephadex LH-20 gel permeation chromatography (GPC) is expected to separate PAs based on structure, its usage rules and mechanisms remain unclear. This study delves into the PAs separation patterns on Sephadex LH-20, first confirming the purification mechanisms of PAs with various mean degrees of polymerization (DP) using the adsorption kinetic model. The study found that an increase in the molecular weight or mean DP of PAs results in decreased polarity, reduced hydrogen bonding actions, and intensified hydrophobic effect, causing delayed extraction of PAs on Sephadex LH-20, with galloylated PA as an exception, which was extracted first despite its high DP. Additionally, the principles for separating specific composition, such as monomers, dimers, etc., were evaluated. The study sheds light on enhancing the purification efficiency of PAs, thus advancing the precise separation technology of diverse proanthocyanidins.

Grape seed proanthocyanidin improves intestinal inflammation in canine through regulating gut microbiota and bile acid compositions.

Although certain progress has been made in treating canine inflammatory bowel disease (IBD), a large proportion of dogs have a poor prognosis and may develop resistance and side effects. Therefore, it is of great significance to prevent or alleviate canine IBD through nutritional intervention. Plant polyphenol can interact with intestinal bacteria and has important prospects in the intestinal health improvement. This study evaluated the effect of grape seed proanthocyanidin (GSP), a plant-derived natural polyphenol, on Labrador Retrievers with mild IBD. In Experiment 1 of this study, GSP alleviated persistent intestinal inflammation in canines by improving inflammatory indexes and reducing intestinal permeability. Moreover, GSP treatment increased the abundance of bacteria with potential anti-inflammatory properties and engaging bile acid metabolism, including Ruminococcaceae, Faecalibacterium, Ruminococcus_torques_group, and Lachnospiraceae_NK4A136_group. Notably, targeted metabolomic analysis identified elevated productions of fecal chenodeoxycholic acid and its microbial transformation product lithocholic acid, which might contribute to relieving canine intestinal inflammation. Further, in Experiment 2, fecal microbiota transplantation was used to determine whether gut microbiota is a potential mechanism for GSP efficacy. Dogs with mild IBD received the fecal microbiota from the group administered GSP and mirrored the improvement effects of GSP, which results verified that gut microbial alteration could be an underlying mechanism for GSP efficiency on canine IBD. Our findings highlight that the mechanism of the GSP function on canine IBD is mediated by altering gut microbial composition and improving bile acid metabolism. This study proposes a natural polyphenol-based dietary strategy for improving canine intestinal health.

Grape seed proanthocyanidins regulate mitophagy of endothelial cells and promote wound healing in mice through p-JNK/FOXO3a/ROS signal pathway

Skin wound healing is a dynamic and complex process that involves multiple physiological and cellular events. Grape seed proanthocyanidins (GSP) have strong anti-oxidation and elimination of oxygen free radicals, and have been shown to significantly promote wound healing, but the underlying mechanism remains unclear. Studies have indicated that reactive oxygen species (ROS) acts as an upstream signal to induce mitophagy, suggesting that GSP can regulate mitophagy through the signal pathway. This study aimed to investigate whether GSP regulates mitophagy by down-regulating oxidative stress to promote wound healing. In vivo, GSP treatment accelerated wound healing, granulation tissue formation, collagen deposition, and angiogenesis in mice. Moreover, GSP down-regulated ROS levels and promoted the expression of antioxidant proteins by up-regulating the expression of p-JNK/FOXO3a protein, thereby regulating the expression of mitophagy-related proteins. In vitro, 4 μg/mL GSP showed no apparent toxic effects on cells and effectively reduce the oxidative stress damage of cells induced by H2O2. Western blot and superoxide anion fluorescence probe further confirmed that GSP effectively reduced Dihydroethidium content and up-regulated the expression of antioxidant proteins by activation of p-JNK/FOXO3a protein expression, thereby regulating mitophagy. Taken together, the findings from in vitro and in vivo experiments provide new insights into the promotion of wound healing by GSP.

Grape Seed Proanthocyanidins Improve the Quality of Fresh and Cryopreserved Semen in Bulls.

Oxidative stress leads to a decrease in semen quality during semen cryopreservation and fresh semen production. Grape seed proanthocyanidins (GSPs) are endowed with well-recognized antioxidant, anti-inflammatory, anti-cancer, and anti-aging activities. Therefore, the objective of this experiment was to explore the effects of GSPs on the quality of fresh and cryopreserved semen to provide a basis for GSPs as a new dietary additive and semen diluent additive for males' reproduction. Fresh semen from three healthy bulls aged 3 to 5 years old were gathered and mixed with semen diluents dissolved with 0 µg/mL, 30 µg/mL, 40 µg/mL, 50 µg/mL, and 60 µg/mL GSPs respectively. The motility, physiological structures (acrosome integrity, membrane integrity, mitochondrial activity), and antioxidant capacity of frozen-thawed sperm were measured after storage in liquid nitrogen for 7 days (d). Bulls were fed with 20 mg/kg body weight (BW) GSPs in their diet for 60 days; the weight of the bull is about 600 kg. Then, the reproductive performance and antioxidant indexes of bulls were measured before and after feeding. The results demonstrated that GSPs supplementation significantly increased sperm motility, physiological structures, GSH-Px, and CAT enzyme activities and significantly decreased MDA content in sperm during semen cryopreservation. The optimal concentration of GSPs was 40 µg/mL (p < 0.05). After 20 mg/kg (body weight) GSP supplementation, sperm motility was significantly heightened (p < 0.05), the sperm deformity rate was significantly reduced (p < 0.05), and antioxidant enzyme activities (such as SOD, CAT, and GSH-Px) were significantly enhanced (p < 0.05), and the production of MDA was significantly suppressed (p < 0.05) in serum compared with that before feeding. In conclusion, these results reveal that a certain concentration of GSPs has a good protective effect on sperm damage caused by semen cryopreservation and the reproductive performance reduction caused by stress in bulls, which may be attributed to the antioxidant function of GSPs. In summary, GSPs are a useful cryoprotective adjuvant and dietary additive for bull sperm quality.

Grape Seed Proanthocyanidin Ameliorates LPS-induced Acute Lung Injury By Modulating M2a Macrophage Polarization Via the TREM2/PI3K/Akt Pathway

Acute lung injury (ALI) is an acute and progressive pulmonary inflammatory disease that is difficult to cure and has a poor prognosis. Macrophages, which have various phenotypes and diverse functions, play an essential role in the pathogenesis of ALI. Grape seed proanthocyanidin (GSP) has received much attention over several decades, and many biological activities such as anti-apoptotic, antioxidant, and anti-inflammatory have been identified. This study aimed to determine the effect of GSP on lipopolysaccharide (LPS)-induced ALI. In this study, we established an ALI mouse model by tracheal instillation of LPS, and by pre-injection of GSP into mice to examine the effect of GSP on the ALI mouse model. Using H&E staining, flow cytometry, and ELISA, we found that GSP attenuated LPS-induced lung pathological changes and decreased inflammatory cytokine expression in ALI mice. In addition, GSP reduced the recruitment of monocyte-derived macrophages to the lung and significantly promoted the polarization of primary mouse lung macrophages from M1 to M2a induced by LPS. In vitro, GSP also decreased the expression levels of inflammatory cytokines such as TNF-α, IL-6, IL-1β, and M1 macrophage marker iNOS induced by LPS in MH-S cells, while increasing the expression levels of M2a macrophage marker CD206. Bioinformatics analysis identified TREM2 and the PI3K/Akt pathway as candidate targets and signaling pathways that regulate M1/M2a macrophage polarization in ALI, respectively. Furthermore, GSP activated PI3K/Akt and increased TREM2 expression in vivo and in vitro. Meanwhile, GSP's impact on M2a polarization and inflammation suppression was attenuated by the PI3K inhibitor LY294002 or siRNA knockdown TREM2. In addition, GSP-enhanced PI3K/Akt activity was prevented by TREM2 siRNA. In conclusion, this study demonstrated that GSP could ameliorate LPS-induced ALI by modulating macrophage polarization from M1 to M2a via the TREM2/PI3K/Akt pathway.

Photoperiod-Dependent Effects of Grape-Seed Proanthocyanidins on Adipose Tissue Metabolic Markers in Healthy Rats.

Variations in photoperiod patterns drive metabolic adaptations in mammals, involving important changes in body weight and adiposity. Moreover, (poly)phenols can help heterotrophs adopt metabolic adaptations to face the upcoming environmental conditions. Particularly, proanthocyanidins from grape-seeds show photoperiod-dependent effects on different metabolic parameters. The present study aims to explore whether grape-seed proanthocyanidin extract (GSPE) consumption differently affects the expression of metabolic markers in WAT (subcutaneous and visceral depots) and BAT in a photoperiod-dependent manner. GSPE (25mgkg-1 day-1 ) is orally administrated for 4 weeks to healthy rats exposed to three photoperiods (L6, L12, and L18). In WAT, GSPE consumption significantly upregulates the expression of lipolytic genes in all photoperiods, being accompanied by increased serum concentrations of glycerol and corticosterone only under the L6 photoperiod. Moreover, adiponectin mRNA levels are significantly upregulated in response to GSPE regardless of the photoperiod, whereas Tnfα and Il6 expression are only downregulated in L6 and L18 photoperiods but not in L12. In BAT, GSPE upregulates Pgc1α expression in all groups, whereas the expression of Pparα is only increased in L18. The results indicate that GSPE modulates the expression of important metabolic markers of WAT and BAT in a photoperiod-dependent manner.

Malic acid enhances proanthocyanidin stability and their combined effects on dough rheological properties and bread quality

Proanthocyanidins, as one of the most common phenolic compounds in cereals, have various beneficial functionalities. However, baking can lead to proanthocyanidin degradation, which limits its application in baked products. This study aimed to use malic acid (MA) for the first time to stabilize grape seed proanthocyanidins (GSPs) in bread formulations and investigate the effects of the concentration ratios of two additives on dough properties and bread quality. Proanthocyanidin stability showed that MA can effectively enhance the retention of GSP in the dough up to 96.9%. Confocal laser scanning microscopy showed that the increase in MA concentration can effectively enhance the compact gluten structure of GSP dough. The dough rheological and textural properties indicated that when GSP was compounded with MA, the hardness of bread can be significantly reduced, and the color and specific volume can be improved.

Boosting the Antioxidant Potential of Polymeric Proanthocyanidins in Litchi (Litchi chinensis Sonn.) Pericarp via Biotransformation of Utilizing Lactobacillus Plantarum.

In order to enhance the efficient utilization of polymeric proanthocyanidins from litchi pericarp, a process for transforming litchis' polymeric proanthocyanidins (LPPCs) by using Lactobacilli has been established for products with highly antioxidative properties. Lactobacillus plantarum was selected to enhance the transformation effect. The transformation rate of LPPCs reached 78.36%. The content of litchis' oligomeric proanthocyanidins (LOPCs) in the products achieved 302.84 μg grape seed proanthocyanidins (GPS)/mg DW, while that of total phenols was 1077.93 gallic acid equivalents (GAE) μg/mg DW. Seven kinds of substances have been identified in the products by using the HPLC-QTOF-MS/MS method, among which 4-hydroxycinnamic acid, 3,4-dihydroxy-cinnamic acid, and proanthocyanidin A2 were major components. The in vitro antioxidative activity of the products after transformation was significantly (p < 0.05) higher than those of LOPCs and LPPCs. The scavenging activity of the transformed products for DPPH free radicals was 1.71 times that of LOPCs. The rate of inhibiting conjugated diene hydroperoxides (CD-POV) was 2.0 times that of LPPCs. The scavenging activity of the products for ABTS free radicals was 11.5 times that of LPPCs. The ORAC value of the products was 4.13 times that of LPPCs. In general, this study realizes the transformation of polymeric proanthocyanidins into high-activity small-molecule substances.

The Action Potential of Antioxidant Grape Seed Proanthocyanidin as a Rumen Modifier to Mitigate Rumen Methanogenesis In Vitro

Grape seed proanthocyanidin (GSP) contains polyphenolic bioflavonoids ubiquitously found in the lignified portions of grape seeds from the winery and distillery industries, as an antioxidant. To explore its potential as a rumen modifier in methanogenesis inhibition, a 2 × 5 factorial experiment was conducted to determine the effect of GSP at 0, 15, 30, 60 and 120 mg/g of substrate on the rumen fermentation and methanogenesis of two representative total mixed rations (HY, a diet for high-yield (&gt;2 kg/d) lactating cows, and LY, a diet for low-yield (&lt;25 kg/d) lactating cows). By using the MIXED procedure, after a 48 h in vitro rumen incubation, increasing the GSP addition linearly decreased the in vitro dry matter digestion (IVDMD) and slowed down the rates of ration fermentation (RmaxS, g/h) and kinetic gas production (RmaxG, mL/h), with the decreases being more pronounced in the LY than HY group (p &lt; 0.05). The GSP addition decreased hydrogen recovery (2Hrec) and altered the fermentation gas composition. The molar CH4 proportion was significantly reduced with both 60 and 120 mg GSP addition (p &lt; 0.01). The total volatile fatty acid production was linearly decreased with the increasing GSP addition (p &lt; 0.01). In addition, the GSP addition significantly decreased the ratio of methanogens to total bacteria (p &lt; 0.05), and the reduction was notably greater in the HY than in the LY substrate (45.3% vs. 15.2% decrease), although the diversity of rumen methanogenic archaea was not affected in either the HY or the LY group. Bioinformatic analysis illustrated that the rumen archaeal community was predominated by a Methanobrevibacter genus (&gt;72.5%), followed by Methanomassiliicoccus (&gt;20.9%) and Methanosphaera (&gt;1.0%). Methanobrevibacter could play an important role in methanogenesis in the presence of GSP, though it is usually considered to be the main hydrogenotrophic methanogen. In brief, the GSP addition presented high potential as a rumen modifier to mitigate methanogenesis by decreasing the ratio of methanogens to total bacteria. Methanobrevibacter could play an important role in methanogenesis in the presence of GSP. However, a relatively low administration level of GSP should be taken into consideration in order to obtain its inhibitory effect on CH4 emission, with a minimal negative effect on rumen digestion and fermentation.

Effect of Grape Seed Proanthocyanidins on Fat Metabolism and Adipocytokines in Obese Rats.

This study aimed to investigate the effect of Grape Seed Proanthocyanidin (GSP) on fat metabolism and adipocytokines in obese rats. Fifty 5-week-old rats were randomly assigned to five groups (n = 10 per group) and given either a basal diet, a high-fat diet, or a high-fat diet supplemented with GSP (25, 50, and 100 mg/d) per group. The experiment lasted for five weeks, including a one-week adaptation period and a four-week treatment period. At the end of the experimental period, serum and adipose tissue samples were collected and analyzed. Additionally, we co-cultured 3T3-L1 preadipocytes with varying concentrations of GSP to explore its effect on adipocyte metabolism. The results demonstrated that GSP supplementation reduced weight, daily gain, and abdominal fat weight coefficient (p < 0.05). It also decreased levels of glucose, cholesterol (TC) (p < 0.05), triglycerides (TG) (p < 0.05), low-density lipoprotein (LDL), cyclooxygenase-2 (COX-2), and interleukin-6 (IL-6) in adipose tissue. Furthermore, GSP addition caused adipocyte crumpling in vitro and reduced the mRNA expression of COX-2, LEP, and TNF-α in adipocytes in vitro. These findings provide compelling evidence for exploring the role of GSP in the prevention and treatment of obesity and related diseases.

Grape-Seed Proanthocyanidins Modulate Adipose Tissue Adaptations to Obesity in a Photoperiod-Dependent Manner in Fischer 344 Rats

Seasonal rhythms drive metabolic adaptations that influence body weight and adiposity. Adipose tissue is a key regulator of energy homeostasis in the organism, and its healthiness is needed to prevent the major consequences of overweight and obesity. In this context, supplementation with proanthocyanidins has been postulated as a potential strategy to prevent the alterations caused by obesity. Moreover, the effects of these (poly)phenols on metabolism are photoperiod dependent. In order to describe the impact of grape-seed proanthocyanidins extract (GSPE) on important markers of adipose tissue functionality under an obesogenic environment, we exposed Fischer 344 rats to three different photoperiods and fed them a cafeteria diet for five weeks. Afterwards, we supplemented them with 25 mg GSPE/kg/day for four weeks. Our results revealed that GSPE supplementation prevented excessive body weight gain under a long photoperiod, which could be explained by increased lipolysis in the adipose tissue. Moreover, cholesterol and non-esterified fatty acids (NEFAs) serum concentrations were restored by GSPE under standard photoperiod. GSPE consumption slightly helped combat the obesity-induced hypertrophy in adipocytes, and adiponectin mRNA levels were upregulated under all photoperiods. Overall, the administration of GSPE helped reduce the impact of obesity in the adipose tissue, depending on the photoperiod at which GSPE was consumed and on the type of adipose depots.

Effect of grape seed proanthocyanidin on the structural and physicochemical properties of bread during bread fermentation stage

Bread was prepared using wheat flour with grape seed proanthocyanidin (GSP) (0.4%). GSP improved the textural properties of bread including hardness, cohesiviness, gumminess and chewiness. At the last stage of fermentation, GSP reinforced the gluten microstructure with increased the disulfide bonds and hydrophobic interaction and α-helix in the secondary structures. Moreover, GSP addition could increase the total phenolics and antioxidative acitivity of the bread significantly. In addition, the degree of fermentation had a strong influence on the dough forces, and the reasonable control of bread fermentation time was beneficial to improve the bread quality, which provided a reference for the bread processing industry.

Proanthocyanidins prevent tau protein aggregation and disintegrate tau filaments

Occurrence of neurofibrillary tangles of the tau protein is a hallmark of tau-related neurodegenerative diseases, i.e. Alzheimer's disease (AD) and frontotemporal dementia. The pathological mechanism underlying AD remains poorly understood, and effective treatments are still unavailable to mitigate the disease. Inhibiting of tau aggregation and disrupting the existing fibrils are key targets in drug discovery towards preventing or curing AD. In this study, grape seed proanthocyanidins (GSPs) was found to effectively inhibit the repeat domain of tau (tau-RD) aggregation and disaggregate tau-RD fibrils in a concentration-dependent manner by inhibiting β-sheet formation of tau-RD. In cells, GSPs relieved cytotoxicity induced by tau-RD aggregates. Molecular dynamics simulations indicated that strong hydrogen bonding, hydrophobic interaction and π-π stacking between GSPs and tau-RD protein were major reasons why GSPs had high inhibitory activity on tau-RD fibrillogenesis. These results provide preliminary data to develop GSPs into medicines, foodstuffs or nutritional supplements for AD patients, suggesting that GSPs could be a candidate molecule in the drug design for AD therapeutics.

Correlating 13C Isotope in Oligomeric Proanthocyanidins with their Anticancer Properties

Upon considering the anticancer effects of larger oligomeric proanthocyanidins and observing various papers reporting the high resolution mass spectroscopy of the oligomeric proanthocyanidins, it is determined that the unusual 13C enrichment in some plant oligomeric proanthocyanidins may be responsible for the anticancer activities of these food products. Such correlation of the 13C in the oligomeric proanthocyanidins also correlate with their scavenging of free-radicals, anti-virial and anti-bacterial properties. Proanthocyanidins in grape seeds are observed to have high enrichment in heavy isotopes of 2H, 13C, 15N and/or 17O. Mass analysis of DNA from human cancer cells are compared to normal human cells and cancer cells show bond specific enrichment of heavy isotopes in nucleotides G, A, T and C. On such basis, this study suggests possible stronger interactions of proanthocyanidins with DNA in cancer verses DNA in normal cells due to heavy isotope bond specific enrichments in both proanthocyanidins and the cancer DNA. Such 13C interactions from oligomeric proanthocyanidins with nucleic acids and proteins involved in replications, transcriptions and translations in cancer cells for interacting and chemically altering anabolism and cell division of the cancer cells are consistent with the author’s mechanism for normal cell to cancer cell transformations via possible replacements of primordial 1H, 12C, 14N, 16O, and 24Mg isotopes by nonprimordial 2H, 13C, 15N, and 17O and 25Mg isotopes in the proteins and nucleic acids. Such is also consistent with the proposed treatment for cancer by the author by use of foods containing proteins, nucleic acids, carbohydrates and/or drug molecules enriched with the nonprimordial isotopes of 2H, 13C, 15N, and 17O and 25Mg.

Proanthocyanidins in grape seeds and their role in gut microbiota-white adipose tissue axis

Several factors can impact the gut microbiota, affecting host metabolism and immunity. It implies intestinal barrier disruption and translocation of gut microbiota metabolites to the bloodstream, such as lipopolysaccharides (LPS). LPS is an endotoxin from gram-negative gut bacteria that trigger the activation of the Toll-like receptor-4 (TLR-4) inflammatory pathway and can modulate white adipose tissue (WAT) metabolism. Dietary components, including diets rich in fiber and polyphenols, contribute to intestinal environment homeostasis. Grape seed proanthocyanidins extract (GSPE) may improve intestinal permeability and microbial diversity and increase short-chain fatty acids production. Furthermore, GSPE has been involved in LPS reduction, down-regulating the TLR-4 pathway, decreasing the WAT metainflammatory profile, and preventing adipocyte hypertrophy. Studies have pointed out strategies to promote health and control obesity by modulating the gut microbiota environment. Therefore, this review aims to summarize the potential effects of GSPE on the gut microbiota-white adipose tissue axis against obesity.

Grape Seed Proanthocyanidins Exert a Neuroprotective Effect by Regulating Microglial M1/M2 Polarisation in Rats with Spinal Cord Injury.

Spinal cord injury (SCI) is a highly disabling disorder for which few effective treatments are available. Grape seed proanthocyanidins (GSPs) are polyphenolic compounds with various biological activities. In our preliminary experiment, GSP promoted functional recovery in rats with SCI, but the mechanism remains unclear. Therefore, we explored the protective effects of GSP on SCI and its possible underlying mechanisms. We found that GSP promoted locomotor recovery, reduced neuronal apoptosis, increased neuronal preservation, and regulated microglial polarisation in vivo. We also performed in vitro studies to verify the effects of GSP on neuronal protection and microglial polarisation and their potential mechanisms. We found that GSP regulated microglial polarisation and inhibited apoptosis in PC12 cells induced by M1-BV2 cells through the Toll-like receptor 4- (TLR4-) mediated nuclear factor kappa B (NF-κB) and phosphatidylinositol 3-kinase/serine threonine kinase (PI3K/AKT) signaling pathways. This suggests that GSP regulates microglial polarisation and prevents neuronal apoptosis, possibly by the TLR4-mediated NF-κB and PI3K/AKT signaling pathways.

Bio-inspired green synthesis of sunlight driven AuNPs/RGO nanocomposites with enhanced photocatalytic activity and their promising electrochemical performance

The present study demonstrates the bio-inspired synthesis of AuNPs/RGO nanocomposites using grape seed proanthocyanidin (GSP) towards photocatalysis and supercapacitor applications. The obtained nanocomposites were characterized using various analytical studies, which confirms the AuNPs are successfully decorated on the graphene nanosheets. The photocatalytic performance of AuNPs/RGO nanocomposites exhibit higher photocatalytic activity (97% and 88% for MB and MO) in comparison with GO and RGO after 60 min of irradiation. Furthermore, the electrochemical supercapactive performances of the AuNPs/RGO nanocomposites were studied by electrochemical techniques, which disclosed that the AuNPs/RGO nanocomposites possess a better specific capacitance (370 F g-1) compared with RGO nanosheets (67 F g-1) at a potential scan rate of 10 mV s−1. These improved performances are associated with a higher specific surface area and hindrance of photo − generated charge carrier recombination in AuNPs/RGO nanosheets.These synergistic performance may further evinced that the biogenic nanocomposites is a promising candidate for photocatalysis and supercapacitor applications.

Time-of-day dependent effect of proanthocyanidins on adipose tissue metabolism in rats with diet-induced obesity.

Grape-seed proanthocyanidin extract (GSPE) improve white adipose tissue (WAT) expansion during diet-induced obesity. However, because adipose metabolism is synchronized by circadian rhythms, it is plausible to speculate that the bioactivity of dietary proanthocyanidins could be influenced by the time-of-day in which they are consumed. Therefore, the aim of the present study was to determine the interaction between zeitgeber time (ZT) and GSPE consumption on the functionality of WAT in rats with diet-induced obesity. Male Wistar rats were fed a cafeteria diet for 9 weeks. After 5 weeks, the animals were supplemented with 25 mg GSPE/kg for 4 weeks at the beginning of the light/rest phase (ZT0) or of the dark/active phase (ZT12). Body fat content was determined by nuclear magnetic resonance and histological analyses were performed in the epididymal (EWAT) and inguinal (IWAT) fat depots to determine adipocyte size and number. In addition, the expression of genes related to adipose metabolism and circadian clock function were analyzed by qPCR. GSPE consumption at ZT0 was associated with a potential antidiabetic effect without affecting adiposity and energy intake and downregulating the gene expression of inflammatory markers in EWAT. In contrast, GSPE consumption at ZT12 improved adipose tissue expansion decreasing adipocyte size in IWAT. In accordance with this adipogenic activity, the expression of genes involved in fatty acid metabolism were downregulated at ZT12 in IWAT. In turn, GSPE consumption at ZT12, but not at ZT0, repressed the expression of the clock gene Cry1 in IWAT. The interaction between ZT and GSPE consumption influenced the metabolic response of WAT in a tissue-specific manner. Understanding the impact of circadian clock on adipose metabolism and how this is regulated by polyphenols will provide new insights for the management of obesity.

A novel thiolysis-high-performance liquid chromatography method for the determination of proanthocyanidins in grape seeds.

A novel thiolysis-high-performance liquid chromatography method for the quantitative determination of total proanthocyanidins and the mean degree of polymerization in grape seeds has been developed. Following thiolysis with formic acid and benzyl mercaptan, reaction products were separated and purified. Three proanthocyanidin monomers and three derivatives were obtained and their structures were identified by liquid chromatography-mass spectrometry, FTIR spectroscopy, and NMR spectroscopy. A decomposition model of the thiolysis products and a correction formula for proanthocyanidins concentration were established. This thiolysis-high-performance liquid chromatography method displayed good calibration linearity (R2 >0.999 over the concentration range 0.01 to 10mg/mL), excellent accuracy (recoveries of 97.9-99.6%), and precision (repeatability relative standard deviations of 0.45-0.75%). This method is suitable for the quantitative analysis of proanthocyanidins in grape seed products.