Optimization of the Extraction of Proanthocyanidins from Grape Seeds Using Ultrasonication-Assisted Aqueous Ethanol and Evaluation of Anti-Steatosis Activity In Vitro.

Conventional extraction methods of proanthocyanidins (PAC) are based on toxic organic solvents, which can raise concerns about the use of extracts in supplemented food and nutraceuticals. Thus, a PAC extraction method was developed for grape seeds (GS) and grape seed powder using food-grade ethanol by optimizing the extraction conditions to generate the maximum yield of PAC. Extraction parameters, % ethanol, solvent: solid (s:s) ratio, sonication time, and temperature were optimized by the central composite design of the response surface method. The yields of PAC under different extraction conditions were quantified by the methylcellulose precipitable tannin assay. The final optimum conditions were 47% ethanol, 10:1 s:s ratio (v:w), 53 min sonication time, and 60 °C extraction temperature. High-performance liquid chromatography analysis revealed the presence of catechin, procyanidin B2, oligomeric and polymeric PAC in the grape seed-proanthocyanidin extracts (GS-PAC). GS-PAC significantly reduced reactive oxygen species and lipid accumulation in the palmitic-acid-induced mouse hepatocytes (AML12) model of steatosis. About 50% of the PAC of the GS was found to be retained in the by-product of wine fermentation. Therefore, the developed ethanol-based extraction method is suitable to produce PAC-rich functional ingredients from grape by-products to be used in supplemented food and nutraceuticals.

AGSE: A Novel Grape Seed Extract Enriched for PP2A Activating Flavonoids That Combats Oxidative Stress and Promotes Skin Health.

Environmental stimuli attack the skin daily resulting in the generation of reactive oxygen species (ROS) and inflammation. One pathway that regulates oxidative stress in skin involves Protein Phosphatase 2A (PP2A), a phosphatase which has been previously linked to Alzheimer's Disease and aging. Oxidative stress decreases PP2A methylation in normal human dermal fibroblasts (NHDFs). Thus, we hypothesize agents that increase PP2A methylation and activity will promote skin health and combat aging. To discover novel inhibitors of PP2A demethylation activity, we screened a library of 32 natural botanical extracts. We discovered Grape Seed Extract (GSE), which has previously been reported to have several benefits for skin, to be the most potent PP2A demethylating extract. Via several fractionation and extraction steps we developed a novel grape seed extract called Activated Grape Seed Extract (AGSE), which is enriched for PP2A activating flavonoids that increase potency in preventing PP2A demethylation when compared to commercial GSE. We then determined that 1% AGSE and 1% commercial GSE exhibit distinct gene expression profiles when topically applied to a 3D human skin model. To begin to characterize AGSE's activity, we investigated its antioxidant potential and demonstrate it reduces ROS levels in NHDFs and cell-free assays equal to or better than Vitamin C and E. Moreover, AGSE shows anti-inflammatory properties, dose-dependently inhibiting UVA, UVB and chemical-induced inflammation. These results demonstrate AGSE is a novel, multi-functional extract that modulates methylation levels of PP2A and supports the hypothesis of PP2A as a master regulator for oxidative stress signaling and aging in skin.

Grape seed and skin extract protects kidney from doxorubicin-induced oxidative injury.

The study investigated the protective effect of grape seed and skin extract (GSSE) against doxorubicin-induced renal toxicity in healthy rats. Animals were treated with GSSE or not (control), for 8 days, administered with doxorubicin (20mg/kg) in the 4th day, and renal function as well as oxidative stress parameters were evaluated. Data showed that doxorubicin induced renal toxicity by affecting renal architecture and plasma creatinine. Doxorubicin also induced an oxidative stress characterized by an increase in malondialdehyde (MDA), calcium and H(2)O(2) and a decrease in catalase (CAT) and superoxide dismutase (SOD). Unexpectedly doxorubicin increased peroxidase (POD) and decreased carbonyl protein and plasma urea. Treatment with GSSE counteracted almost all adverse effects induced by doxorubicin. Data suggest that doxorubicin induced an oxidative stress into rat kidney and GSSE exerted antioxidant properties, which seem to be mediated by the modulation of intracellular calcium.

Characterisation of Mediterranean grape pomace seed and skin extracts: polyphenolic content and antioxidant activity.

Grape pomace seeds and skins from different Mediterranean varieties (Grenache [GRE], Syrah [SYR], Carignan [CAR], Mourvèdre [MOU] and Alicante [ALI]) were extracted using water and water/ethanol 70% in order to develop edible extracts (an aqueous extract [EAQ] and a 70% hydro-alcoholic extract [EA70]) for potential use in nutraceutical or cosmetic formulations. In this study, global content (total polyphenols, total anthocyanins and total tannins), flavan-3-ols and anthocyanins were assessed using HPLC-UV-Fluo-MSn. In addition, extract potential was evaluated by four different assays: Oxygen Radical Absorbance Capacity (ORAC), Ferric Reducing Antioxidant Potential assay (FRAP), Trolox equivalent antioxidant capacity (TEAC) or ABTS assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. As expected, seed pomace extracts contained higher amounts of polyphenols then skin pomace extracts. Indeed, seeds from Syrah contained a particularly important amount of total polyphenols and tannins in both type of extract (up to 215.84 ± 1.47 mg of gallic acid equivalent [GAE]/g dry weight (DW) and 455.42 ± 1.84 mg/g DW, respectively). These extracts also expressed the highest antioxidant potential with every test. For skins, the maximum total phenolic was found in Alicante EAQ (196.71 ± 0.37 mg GAE/g DW) and in Syrah EA70 (224.92 ± 0.18 mg GAE/g DW). Results obtained in this article constitute a useful tool for the pre-selection of grape pomace seed and skin extracts for nutraceutical purposes.

Differences in the phenolic composition and antioxidant properties between Vitis coignetiae and Vitis vinifera seeds extracts.

Phenolic compounds were extracted from European and Japanese grapevine species (Vitis vinifera and V. coignetiae) seeds using 80% methanol or 80% acetone. The total content of phenolic compounds was determined utilizing Folin-Ciocalteu's phenol reagent, while the content of tannins was assayed by the vanillin and BSA precipitation methods. Additionally, the DPPH free radical and ABTS cation radical scavenging activities and the reduction power of the extracts were measured. The HPLC method was applied to determine the phenolic compounds, such as phenolic acids and catechins. The seeds contained large amounts of tannins and gallic acid and observable quantities of catechins, p-coumaric, ferulic and caffeic acids. The dominant form of phenolic acids in the extracts was the ester-bound form. The content of total phenolics was higher in the European grape V. vinifera seeds, which also contained more tannins, catechins and phenolic acids, except for caffeic acid. Extracts from V. vinifera seeds showed better radical scavenger properties and stronger reducing power. The total contents of phenolic compounds and tannins in acetone extracts were higher than in methanolic extracts. Acetone extracts also exhibited stronger antiradical properties as well as stronger reducing power.

The relationship between antiglycation activity and procyanidin and phenolic content in commercial grape seed products.

Eight commercial grape seed products (GSPs) were assessed for their inhibition of the formation of advanced glycation end-products in vitro. All 8 commercial GSPs included in this study were potent inhibitors of advanced glycation end-product formation with IC(50) values ranging from 2.93 to 20.0 µg/mL. Total procyanidin content ranged from 60% to 73%. HPLC-DAD-ELSD results indicate that (+)-catechin, (-)-epicatechin, procyanidin B1, and procyanidin B2 were predominant and ubiquitously present in all the products under study, while gallic acid and procyanidin B4 were present in relatively minor amounts. The IC(50) values correlated with total phenolic content, and multiple regression analysis indicated that IC(50) is a linear function of the concentration of gallic acid and procyanidins B1, B2, and B4. Based on this study, GSPs have the potential to complement conventional diabetes medication toward disease management and prevention.

Supercritical fluid extraction of phenolic compounds and antioxidants from grape (Vitis labrusca B.) seeds.

Supercritical fluid extraction (SFE) technique was applied and optimized for temperature, CO2 pressure and ethanol (modifier) concentration using orthogonal array design and response surface methodology for the extract yield, total phenols and antioxidants from grape (Vitis labrusca B.) seeds. Effects of extraction temperature and pressure were found to be significant for all these response variables in SFE process. Optimum SFE conditions (44 ~ 46 °C temperature and 153 ~ 161 bar CO2 pressure) along with ethanol (<7 %) as modifier, for the maximum predicted values of extract yield (12.09 %), total phenols (2.41 mg GAE/ml) and antioxidants (7.08 mg AAE/ml), were used to obtain extracts from grape seeds. The predicted values matched well with the experimental values (12.32 % extract yield, 2.45 mg GAE/ml total phenols and 7.08 mg AAE/ml antioxidants) obtained at optimum SFE conditions. The antiradical assay showed that SFE extracts of grape seeds can scavenge more than 85 % of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radicals. The grape seeds extracts were also analyzed for hydroxybenzoic acids which included gallic acid (1.21 ~ 3.84 µg/ml), protocatechuic acid (3.57 ~ 11.78 µg/ml) and p-hydroxybenzoic acid (206.72 ~ 688.18 µg/ml).

Novel oligomeric proanthocyanidin derivatives interact with membrane androgen sites and induce regression of hormone-independent prostate cancer.

Prostate cancer is the most common malignancy among men in Western societies, and current therapeutic approaches are evolving to manage growth, recurrence, and mortality neoplasia. Membrane androgen receptors (mARs) have been characterized in human prostate cancer, being preferentially expressed in tumor rather than benign gland areas. Furthermore, mAR agonists (protein-conjugated testosterone) decrease in vitro prostate cancer cell growth and induce apoptosis, whereas in vivo they regress growth of tumor xenografts alone or in combination with taxane drugs. In this respect, targeting mARs might be a novel therapeutic approach in prostate cancer. In our search for new small-molecule ligands of mAR, we report that flavanol dimers B1-B4 (oligomeric procyanidins) decrease in vitro growth of the androgen-sensitive (LnCaP) and androgen-resistant (DU145) human prostate cancer cell lines in the following order: B3 = B4 > B2 ≫ B1 (LnCaP) and B2 ≫ B3 = B4 ≫ B1 (DU145). Some of these analogs were previously shown to trigger signaling cascades similar to testosterone-bovine serum albumin (BSA) conjugate. Galloylation does not confer an additional advantage; however, oleylation increases the dimers' antiproliferative potency by a factor of 100. In addition, we report that B2, oleylated or not, displaces testosterone from mARs with an IC(50) value at the nanomolar range and induces DU145 tumor xenograft regression by 50% (testosterone-BSA 40%). In this respect, oleylated B2 is a potent small-molecule agonist of mAR and could be a novel therapeutic agent for advanced prostate cancer, especially when taking into account the absence of androgenic actions and (liver) toxicity.

[Effects of oligomeric grape seed proanthocyanidins on isoproterenol-induced cardiac remodeling in rats].

The purpose of this study is to evaluate the effect of oligomeric grape seed proanthocyanidins (GSP) on isoproterenol (ISO)-induced cardiac remodeling in rats. ISO was given subcutaneously (5 mg x kg(-1), sc, 7 days) to induce cardiac remodeling in rats. Therapeutic groups were given GSP (50, 100, and 150 mg x kg(-1)) after ISO treatment. After 2 weeks intervention, heart rate (HR), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), rate of rise of left ventricular pressure (+/- dp/dt(max)) were examined. The myocardial hypertrophy index was expressed as heart weight/body weight (HW/BW) and left ventricle weight/body weight (LVW/BW), the histological changes were investigated by HE and Van Gieson stain. SOD activity and MDA content in serum, contents of hydroxyproline (Hyp) in the left ventricular tissue were assayed by xanthinoxidase method, thiobarbituric acid (TBA) method and alkaline hydrolysis method, respectively. After the onset of ISO-treatment, GSP therapy potently improved cardiac function, inhibited myocardial hypertrophy, improved cardiac pathology change, decreased the myocardial cross-section area (CSA), collagen volume fraction (CVF) and perivascular circumferential collagen area (PVCA), reduced the content of Hyp in the left ventricular tissue, inhibited the decrease of SOD activity and increase of MDA content in serum. GSP possess protective effect against ISO induced cardiac remodeling in rats, this may be related to reducing the oxidative stress and improving antioxidant capacity.

Design and Characterization of Chitosan-Graphene Oxide Nanocomposites for the Delivery of Proanthocyanidins.

INTRODUCTION: In the last years, the utilization of phytomedicines has increased given their good therapeutic activity and fewer side effects compared to allopathic medicines. However, concerns associated with the biocompatibility and toxicity of natural compounds, limit the phytochemical therapeutic action, opening the opportunity to develop new systems that will be able to effectively deliver these substances. This study has developed a nanocomposite of chitosan (CS) functionalized with graphene oxide (GO) for the delivery of proanthocyanidins (PAs), obtained from a grape seed extract (Ext.). METHODS: The GO-CS nanocomposite was covalently bonded and was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM) and by dynamic light scattering (DLS). The loading and release of Ext. from the GO-CS nanocomposite were performed in simulated physiological, and the cytotoxicity of the raw materials (GO and Ext.) and nanocomposites (GO-CS and GO-CS-Ext.) was determined using a human kidney cell line (HEK 293). RESULTS: The chemical characterization indicated that the covalent union was successfully achieved between the GO and CS, with 44 wt. % CS in the nanocomposite. The GO-CS nanocomposite was thermostable and presented an average diameter of 480 nm (by DLS). The Ext. loading capacity was approximately 20 wt. %, and under simulated physiological conditions, 28.4 wt.% Ext. (g) was released per g of the nanocomposite. GO-CS-Ext. was noncytotoxic, presenting a 97% survival rate compared with 11% for the raw extract and 48% for the GO-CS nanocomposite at a concentration of 500 µg mL-1 after 24 hrs. CONCLUSION: Due to π-π stacking and hydrophilic interactions, GO-CS was reasonably efficient in binding Ext., with high loading capacity and Ext. release from the nanocomposite. The GO-CS nanocomposite also increased the biocompatibility of PAs-rich Ext., representing a new platform for the sustained release of phytodrugs.

Novel Catechin-Tiopronin Conjugates Derived from Grape Seed Proanthocyanidin Degradation: Process Optimization, High-Speed Counter-Current Chromatography Preparation, as Well as Antibacterial Activity.

Tiopronin, as a novel thiol-containing nucleophile, was introduced for depolymerizing polymeric proanthocyanidins from grape seed into catechins and three new proanthocyanidin-tiopronin degradation products: (+)-catechin-4ß-S-tiopronin methyl ester (CT), (-)-epicatechin-4ß-S-tiopronin methyl ester (ECT), and (-)-epicatechin gallate-4ß-S-tiopronin methyl ester (ECGT). A Box-Behnken design was employed to optimize degradation conditions based on single-factor experiments to obtain target products. Each of the new degradation compounds was isolated by the high-speed counter-current chromatography combined with semipreparative high performance liquid chromatography in large amounts, and then, their structures were identified by 1H NMR, 13C NMR, 2D-NMR, as well as mass spectrometry analysis. The absolute configurations were further confirmed by comparison between the calculated electronic circular dichroism and experimental spectra. Further evaluation of antibacterial activities of these compounds showed that CT and ECT possessed more inhibiting capacity against Staphylococcus aureus and Escherichia coli than parent compound catechin and epicatechin. However, ECGT has no bacteriostatic capacity against these two bacteria.

The properties of chitosan and gelatin films incorporated with ethanolic red grape seed extract and Ziziphora clinopodioides essential oil as biodegradable materials for active food packaging.

The aim of this study was to improve different characteristics including antibacterial, antioxidant, physical and mechanical properties of chitosan (Ch) and gelatin (Ge) films by incorporating Ziziphora clinopodioides essential oil (ZEO; 0 and 1% v/w) and ethanolic grape seed extract (GSE; 0 and 1% v/w). The main compounds of the ZEO were carvacrol (65.22%) and thymol (19.51%). According to our findings, addition of aforementioned materials could improve total phenolic content, antibacterial and antioxidant activities, thickness and also water vapor barrier property. ZEO and GSE reduces swelling index, tensile strength, puncture force and puncture deformation of Ch and Ge films. Pure Ch and Ge films had slightly yellow and white appearances, respectively, while films incorporated with GSE in combination with ZEO had grey appearances. This study indicated the some benefits of addition of ZEO and GSE into Ch and Ge films and their potentials for application as biodegradable active packaging.

Grape seed procyanidin B2 inhibits adipogenesis of 3T3-L1 cells by targeting peroxisome proliferator-activated receptor γ with miR-483-5p involved mechanism.

Procyanidins have lipolysis effect on adipose metabolism, but the underlying mechanism is not fully understood. The aim of present study was to examine the effect of grape seed procyanidin B2 (GSP) on the adipogenic differentiation of 3T3-L1 preadipocyte cell line and investigate the underlying mechanism. The results showed that GSP treatment significantly reduced the intracellular lipid accumulation in induced 3T3-L1 cells by targeting miR-483-5p as well as peroxisome proliferator-activated receptor γ (PPARγ). In addition, our results revealed that overexpression of miR-483-5p increased adipogenic differentiation, while inhibition of miR-483-5p reduced the lipid accumulation by suppressing the adipogenic differentiation. Moreover, overexpression of miR-483-5p could reverse GSP's inhibition of adipocyte differentiation as well as increase the level of PPARγ. These results demonstrate that GSP inhibits adipogenesis by targeting PPARγ and suggest this effect might be mediated by miR-483-5p.

Synthetic and natural antioxidants attenuate cisplatin-induced vomiting.

BACKGROUND: Synthetic and natural antioxidants including Bacopa monnieri (L.) Pennell (Scrophulariaceae) which also possess anti-dopaminergic properties, have been proposed to be useful for emetogenic chemotherapy. In this study, synthetic [N-(2-mercaptopropionyl) glycine (MPG), vitamin C (Vit-C)] and natural [grape seed proanthocyanidin (GP), B. monnieri n-butanolic fraction (BM-ButFr)] antioxidants and their combinations were evaluated against cisplatin-induced emesis in pigeons during a 24 h observation period. METHODS: Emesis was induced using cisplatin (7.0 mg/kg, i.v). MPG (10, 20, 30 mg/kg), Vit-C (100, 200, 300 mg/kg), GP (50, 100, 150 mg/kg) and BM-ButFr (5, 10, 20 mg/kg) and their combinations were administered i.m., 15 min before cisplatin administration. The number of vomiting bouts, retching, emetic latency and % weight loss were recorded to assess antiemetic potential. Antioxidant activity was evaluated by the DPPH free radical scavenging assay (FRSA). RESULTS: Significant attenuation of vomiting bouts, retching, % weight loss along with an increase in latency was produced by all the antioxidants and their combinations compared to cisplatin alone and this is the first report of this activity of GP in pigeons. Low EC50 values in the FRSA for MPG (67.66 µg/mL), Vit-C (69.42 µg/mL), GP (6.498 µg/mL) and BM-ButFr (55.61 µg/mL) compared to BHT standard (98.17 µg/mL) demonstrated their radical scavenging capacity. Correlation between the antioxidant activity and antiemetic efficacy disclosed a high degree of correlation for the tested antioxidants. CONCLUSION: The selected synthetic and natural antioxidants and their combinations were able to attenuate cisplatin-induced vomiting, which correlated with their potent in vitro antioxidant activity.

Thioredoxin is implicated in the anti­apoptotic effects of grape seed proanthocyanidin extract during hyperglycemia.

Diabetic retinopathy has long been recognized as a microvascular disease, however, recent research has indicated that diabetic retinopathy may also be considered a neurodegenerative disease. The elucidation of the molecular mechanisms underlying the development of diabetic retinopathy is imperative for the development of preventive and treatment strategies for patients with diabetes. In the present study, grape seed proanthocyanidin extract (GSPE) was used to upregulate the expression of thioredoxin (Trx), in order to evaluate its potential as a novel agent for the prevention and treatment of neurodegenerative diseases, including diabetic retinopathy. Hematoxylin and eosin staining was performed to observe the morphology of retinal neurons, whereas flow cytometry and terminal deoxynucleotidyl transferase 2'­deoxyuridine, 5'­triphosphate nick­end labeling were employed to investigate cellular apoptosis. Reverse transcription­quantitative polymerase chain reaction and western blot analysis were performed to assess the mRNA and protein expression of target proteins in order to investigate the underlying molecular mechanisms. In vivo, it was found that the photoreceptor cell was damaged in diabetic mice but following GSPE treatment, the process could be inhibited. In vitro, the results of the current study demonstrated that, under hyperglycemic culture conditions, the expression of 78 kDa glucose­regulated protein, which is an endoplasmic reticulum stress marker, was upregulated. In addition, the expression of Trx was downregulated and cell apoptosis was enhanced. Notably, treatment with GSPE was revealed to inhibit the neurodegenerative process induced by hyperglycemia. However, treatment with the Trx inhibitor PX12 in combination with GSPE was demonstrated to potentiate apoptosis compared with GSPE treatment alone under hyperglycemic conditions. Furthermore, the protein expression of apoptosis signal­regulating kinase (ASK) 1 and Trx­interacting protein (Txnip) was also upregulated by hyperglycemia, whereas GSPE was revealed to counteract this upregulation. In conclusion, the results of the present study indicate that Trx may be implicated in the mechanisms underlying the protective effects of GSPE against hyperglycemia­induced cell degeneration and apoptosis. The molecular mechanisms may also involve inhibition of the activation of the Trx/ASK1/Txnip signaling pathway.

Grape seed and skin extract reduces pancreas lipotoxicity, oxidative stress and inflammation in high fat diet fed rats.

Obesity is related to an elevated risk of diabetes and the mechanisms whereby fat adversely affects the pancreas are poorly understood. We studied the effect of a high fat diet (HFD) on pancreas steatosis, oxidative stress and inflammation as well as the putative protection afforded by grape seed and skin extract (GSSE). HFD induced body weight gain, without affecting insulinemia, nor glycemia and dropped adiponectemia. HFD also provoked the ectopic deposition of cholesterol and triglyceride, and an oxidative stress characterized by increased lipoperoxidation and carbonylation, inhibition of antioxidant enzyme activities such as CAT, GPx and SOD, depletion of zinc and a concomitant increase in calcium and H2O2. HFD induced pro-inflammatory chemokines mRNA as RANTES and MCP1 as well as cytokines expression as TNFα, IL6 and IL1ß. Importantly GSSE counteracted all the deleterious effects of HFD on pancreas in vivo i-e lipotoxicity, oxidative stress and inflammation. In conclusion, GSSE could find potential applications in fat-induced pancreas lipotoxicity and dysfunction.

Proanthocyanidins from grape seeds inhibit UV-radiation-induced immune suppression in mice: detection and analysis of molecular and cellular targets.

Ultraviolet (UV)-radiation-induced immunosuppression has been linked with the risk of skin carcinogenesis. Approximately, 2 million new cases of skin cancers, including melanoma and nonmelanoma, diagnosed each year in the USA and therefore have a tremendous bad impact on public health. Dietary phytochemicals are promising options for the development of effective strategy for the prevention of photodamaging effects of UV radiation including the risk of skin cancer. Grape seed proanthocyanidins (GSPs) are such phytochemicals. Dietary administration of GSPs with AIN76A control diet significantly inhibits UV-induced skin tumor development as well as suppression of immune system. UV-induced suppression of immune system is commonly determined using contact hypersensitivity (CHS) model which is a prototype of T-cell-mediated immune response. We present evidence that inhibition of UV-induced suppression of immune system by GSPs is mediated through: (i) the alterations in immunoregulatory cytokines, interleukin (IL)-10 and IL-12, (ii) DNA repair, (iii) stimulation of effector T cells and (iv) DNA repair-dependent functional activation of dendritic cells in mouse model. These information have important implications for the use of GSPs as a dietary supplement in chemoprevention of UV-induced immunosuppression as well as photocarcinogenesis.

Temperature-dependent kinetics of grape seed phenolic compounds extraction: experiment and model.

The kinetics of a batch solid-liquid extraction of total phenolic compounds (PC) from milled grape seed (Vitis vinifera L. cv. "Frankovka") using 50% ethanol at different extraction temperatures (25-80°C) was studied. The maximum yield of PC was 0.13 kg(GAE)/kg(db) after 200 min of extraction in agitated vessel at 80°C. A new model based on the assumptions of a first order kinetics mechanism for the solid-liquid extraction and a linear equilibrium at the solid-liquid interface was developed. The model involves the concept of broken and intact cells in order to describe two successive extraction periods: a very fast surface washing process followed by slow diffusion of phenolic compounds from grape seeds to the solvent. The proposed model is suited to fit experimental data and to simulate the extraction of phenolic compounds, which was confirmed by the correlation coefficient (r≥0.965), the root mean square error (RMSE≤0.003 kg(GAE)/kg(db)) and the mean relative deviation modulus (E≤2.149%). The temperature influenced both equilibrium partition coefficients of phenolic compounds and transport properties, which is manifested by a relatively high value of activation energy (23-24) kJ/mol and by values of effective diffusivity in seed particles.

Identification of oligomer proanthocyanidins (F2) isolated from grape seeds as a formyl peptide receptor 1 partial agonist.

Formyl peptide receptor 1 (FPR1) plays an important role in the rapid progression of glioblastoma and has been considered as a molecular target for the treatment. Previously, we have shown that oligomer proanthocyanidins (F2, degree of polymerization 2-15), isolated from grape seeds, inhibited FPR1-mediated chemotaxis of U-87 glioblastoma cells. In the present study, we investigated the capacity of F2 to interact with FPR1. The cross attenuation of chemotaxis revealed that F2 shared FPR1 with formyl-methionyl-leucyl-phenylalanine (fMLF), which is a prototype agonist of FPR1. F2 was chemotactic for U-87 cells, and the chemotactic response was abolished when FPR1 gene was silenced or FPR1 was competitively occupied. We further show that F2 specifically blocked the binding of fluorescent agonist to FPR1. Interestingly, F2 exhibited the characteristic of a partial agonist for FPR1, as shown by its capacity to activate FPR1-mediated PI3K-PKC-MAPK pathways. Meanwhile, F2 also attenuated fMLF-triggered MAPK activation, suggesting that F2 could antagonize the effect of an agonist. Furthermore, F2 abolished the invasion of U-87 cells induced by fMLF. Thus, we have identified F2 as a novel, partial agonist for FPR1, which may be useful for glioblastoma therapy.

Grape seed procyanidin extract modulates proliferation and apoptosis of pancreatic beta-cells.

Grape seed procyanidin extract (GSPE) modulates glucose homeostasis and insulinemia in several animal models. Under pathological conditions, insulin levels are dependent on pancreatic beta-cell functionality, as well as on the beta-cell mass expansion or apoptosis in the pancreas. In this study, we analysed the effects of GSPE on modulating apoptosis and proliferation in beta-cells. We tested the effects of GSPE in the INS-1E pancreatic beta-cell line, either under basal or altered conditions with high glucose, insulin or palmitate levels. GSPE enhanced the pro-apoptotic effect of high glucose and showed clear antiproliferative effects under high glucose, insulin and palmitate conditions. These antiproliferative effects are likely due to high molecular weight compounds contained in the extract. GSPE also modulated pro- and anti-apoptotic markers in the pancreas of rats fed a cafeteria diet, with the effect depending on the dose of GSPE and duration of treatment. Thus, GSPE is able to modulate apoptosis and proliferation of beta-cells under altered, but not basal, conditions.