Safety evaluation of proanthocyanidin-rich extract from grape seeds

Acute and subchronic oral toxicity of Galega officinalis in rats

Galega officinalis L. (Papilionaceae) is widely used in folk medicine as antidiabetic or for increasing lactation. There is a little information about its possible toxicity. In this study, acute and subchronic toxicity of aerial parts of Galega officinalis in Wistar rats have been evaluated. For the acute toxicity study, the animals received orally four different single dose of plant suspension and were kept under observation for 14 days. The results indicated that LD50 of Galega officinalis is higher than 5 g/kg. In the subchronic study, 48 rats were divided into four groups and were fed a diet containing 0%, 0.15%, 1.5% and 3% (w/w) of Galega officinalis. After 90 days blood and tissue samples were taken for hematological, biochemical and histopathological determinations. An increase in serum levels of cholesterol, creatine phosphokinase, lactate dehydrogenase and total and conjugated bilirubin was observed. Some parameters such as calcium, albumin, albumin/globulin ratio, hematocrit, WBC and platelet counts were decreased. In microscopic examination, sinusoidal congestion in liver and alveolar hemorrhage was observed. Other parameters showed non-significant difference between treatment and control groups. Present data suggest that liver and lung could serve as target organs in oral toxicity of this plant.

Proanthocyanidin promotes free radical-scavenging activity in muscle tissues and plasma

The present study was carried out to clarify the effect of oral administration of proanthocyanidin (PA) on radical-scavenging activity in muscle and plasma using electron spin resonance (ESR). Eight-week-old male Wistar rats were orally administered with 3 doses per day of 1 mL of 0.05% (PA0.05), 0.5% (PA0.5) or 5% (PA5) PA for 1 week. Control animals received the same volume of distilled water. We also examined the effect of a single dose of 0.5% PA. Blood and muscle were collected from rats 1 h after the final administration. Scavenging activity against superoxide anions in the plasma and m. soleus (Sol), m. plantaris (Pla), deep and surface areas of the m. gastrocnemius (GasD and GasS, respectively) and myocardium (Hrt) was determined using ESR with the spin trap, 5,5-dimethyl-1-pyrroline-N-oxide The scavenging activity in plasma for all groups given PA was 34%–44% higher than the control (p < 0.05). The scavenging activity in Hrt, Sol and GasD increased by up to 50% compared with the control and tended to increase depending on the dose of PA (p < 0.05). The impact of a single dose of PA was undetectable in all tissues. These results suggested that 1 week of oral PA improves the radical-scavenging activity in both plasma and muscle, especially in highly oxidative muscle. A single dose of PA was insufficient to improve the antioxidative capacity of muscle tissues.

Evaluation of the safety and toxicity of the oligomerized polyphenol Oligonol

Oligonol((R)) is an optimised phenolic product containing catechin-type monomers and lower oligomers of proanthocyanidin that emanate from a technology process which converts polyphenol polymers into oligomers. In a single dose toxicity study administration of Oligonol (2000mg/kg bw) by gavage for 4 weeks was found to be safe with no side effects (such as abnormal behavior and alopecia). Body weight gain and food consumption were within normal range. Oligonol had no observed toxicity at the dose (1/25 of LD(50)) administered for 6 months. This suggests that Oligonol is safe at repeated human intakes of Oligonol in doses lower than 200mg/day. The highest dose used in this study is equal to 12g daily for an adult man with 60kg body weight. The LD(50) was calculated to be 5.0g/kg body weight (95% confidence limit: 3.5-6.4g/kg). Studies conducted on 30 healthy volunteers consuming Oligonol at doses of 100mg/day and 200mg/day for 92 days showed good bioavailability. The biochemical parameters attesting to liver and kidney functions as well as the hematological parameters were within the normal ranges. The potential of Oligonol to induce gene mutation (a reverse mutation test) was tested using Salmonella typhimurium TA98, TA100, TA104, TA1535, TA153 and Escherichia coli WP2uvrA. Oligonol was not mutagenic to the tester strains. The lack of toxicity supports the potential use of Oligonol as a food or dietary supplement and for use as an additive in pharmaceutical and cosmetological applications.

Grape seed extract inhibits in vitro and in vivo growth of human colorectal carcinoma cells

PURPOSE

Accumulating evidences suggest the beneficial effects of fruit-and-vegetable consumption in lowering the risk of various cancers, including colorectal cancer. Herein, we investigated the in vitro and in vivo anticancer effects and associated mechanisms of grape seed extract (GSE), a rich source of proanthocyanidins, against colorectal cancer.

EXPERIMENTAL DESIGN

Effects of GSE were examined on human colorectal cancer HT29 and LoVo cells in culture for proliferation, cell cycle progression, and apoptosis. The in vivo effect of oral GSE was examined on HT29 tumor xenograft growth in athymic nude mice. Xenografts were analyzed by immunohistochemistry for proliferation and apoptosis. The molecular changes associated with the biological effects of GSE were analyzed by Western blot analysis.

RESULTS

GSE (25-100 microg/mL) causes a significant dose- and time-dependent inhibition of cell growth with concomitant increase in cell death. GSE induced G1 phase cell cycle arrest along with a marked increase in Cip1/p21 protein level and a decrease in G1 phase-associated cyclins and cyclin-dependent kinases. GSE-induced cell death was apoptotic and accompanied by caspase-3 activation. GSE feeding to mice at 200 mg/kg dose showed time-dependent inhibition of tumor growth without any toxicity and accounted for 44% decrease in tumor volume per mouse after 8 weeks of treatment. GSE inhibited cell proliferation but increased apoptotic cell death in tumors. GSE-treated tumors also showed enhanced Cip1/p21 protein levels and poly(ADP-ribose) polymerase cleavage.

CONCLUSIONS

GSE may be an effective chemopreventive agent against colorectal cancer, and that growth inhibitory and apoptotic effects of GSE against colorectal cancer could be mediated via an up-regulation of Cip1/p21.

Ingestion of IH636 grape seed proanthocyanidin extract to prevent selenite-induced oxidative stress in experimental cataract

PURPOSE

To investigate whether dietary supplementation with IH636 grape seed proanthocyanidin extract (GSPE) prevents selenite-induced cataract.

SETTING

Department of Ophthalmology, Gulhane Military Medical Academy, Ankara, Turkey.

METHODS

Thirty Spraque-Dawley rat litters were put randomly into 3 groups. In group 1 (n = 10), sodium selenite (30 nmol/g body weight) was injected subcutaneously on postpartum day 10. In group 2 (n = 10), sodium selenite (30 nmol/g body weight) was injected on postpartum day 10 and oral GSPE (100 mg/kg body weight) was given for 1 week after sodium selenite injection. Only subcutaneous saline was injected in group 3 (control, n = 10). The development of cataract was assessed for 3 weeks, and its density was graded and photographed with a slitlamp. Removed rat lenses were analyzed for glutathione (GSH) and malondialdehyde (MDA).

RESULTS

All of the rats in group 1 had cataract between stage 6 and stage 3. In group 2, only 5 of 10 eyes had cataract between stage 3 and stage 2 and no cataract occurred in the remaining 5 rats. The difference between mean cataract stages in group 1 and group 2 was significant (P<.05). The mean GSH level in group 1 was significantly lower than in group 2 and controls (P<.05). The mean MDA level in group 1 was significantly higher than in group 2 and controls (P<.05).

CONCLUSIONS

IH636 grape seed proanthocyanidin extract effectively suppressed cataract formation in rats. Routine consumption of grape seed proanthocyanidin extract in the form of food or dietary supplement may offer a prophylactic measure against onset and progression of cataract.

Polyphenol contents in grape-seed extracts correlate with antipica effects in cisplatin-treated rats

BACKGROUND

Grape-seed (Vitis spp.) extract (GSE) is a widely used antioxidant dietary supplement. Chemotherapeutic agents such as cisplatin induce oxidative damage in the gastrointestinal tract and cause nausea and vomiting.

MATERIALS AND METHODS

A rat model of simulated emesis was used to observe that cisplatin significantly increased kaolin consumption (or pica). Three GSEs from different sources were used in this study.

RESULTS

High-performance liquid chromatographic analysis of five major constituents (gallic acid, catechin, epicatechi, procyanidin B2, and epicatechin gallate) revealed that each constituent had different levels in the three GSEs. Extract #1, prepared in the laboratory of the investigators, had the lowest total polyphenol content (27.27 mg/g); Extract #2, obtained from a dietary supplement company in the United States, had a somewhat higher level (35.84 mg/g); and Extract #3, obtained from China, had the highest level (194.21 mg/g). Subsequently these GSEs were intraperitoneally administered in rats to evaluate their ability to decreasing cisplatin induced pica. At 10 mg/kg all three GSEs, with varying degrees of effect, decreased cisplatin-induced pica. The areas under the curves of kaolin intake from time 0 to 72 hours, compared to those in the cisplantin-only group, were reduced 45% for Extract #1 (p < 0.01), 54% for Extract #2 (p < 0.01), and 66% Extract #3 (p < 0.001).

CONCLUSIONS

The study data showed variable polyphenol contents and proportions in the three GSEs correlated to variable pharmacologic effects, indicating the importance of standardization of herbal product preparations. However further increasing of the GSE doses reversed the antipica effects of GSEs, probably because of their pro-oxidant effects. Results from this study suggest that an appropriate dose of GSE has therapeutic value in treating cisplatin-induced emesis.

Grape seed extract induces anoikis and caspase-mediated apoptosis in human prostate carcinoma LNCaP cells: possible role of ataxia telangiectasia mutated–p53 activation

Prostate cancer is the second leading cancer diagnosed in elderly males in the Western world. Epidemiologic studies suggest that dietary modifications could be an effective approach in reducing various cancers, including prostate cancer, and accordingly cancer-preventive efficacy of dietary nutrients has gained increased attention in recent years. We have recently shown that grape seed extract (GSE) inhibits growth and induces apoptotic death of advanced human prostate cancer DU145 cells in culture and xenograft. Because prostate cancer is initially an androgen-dependent malignancy, here we used LNCaP human prostate cancer cells as a model to assess GSE efficacy and associated mechanisms. GSE treatment of cells led to their detachment within 12 hours, as occurs in anoikis, and caused a significant decrease in live cells mostly due to their apoptotic death. GSE-induced anoikis and apoptosis were accompanied by a strong decrease in focal adhesion kinase levels, but an increase in caspase-3, caspase-9, and poly(ADP-ribose) polymerase cleavage; however, GSE caused both caspase-dependent and caspase-independent apoptosis as evidenced by cytochrome c and apoptosis-inducing factor release into cytosol. Additional studies revealed that GSE causes DNA damage-induced activation of ataxia telangiectasia mutated kinase and Chk2, as well as p53 Ser(15) phosphorylation and its translocation to mitochondria, suggesting this to be an additional mechanism for apoptosis induction. GSE-induced apoptosis, cell growth inhibition, and cell death were attenuated by pretreatment with N-acetylcysteine and involved reactive oxygen species generation. Together, these results show GSE effects in LNCaP cells and suggest additional in vivo efficacy studies in prostate cancer animal models.

Flavonoids inhibit the amidolytic activity of human thrombin

The effect of a group of natural flavonoids on human thrombin amidolytic activity was investigated using a spectrophotometric inhibition assay while information on the kinetics and thermodynamics was obtained using optical biosensor techniques. All the flavonoids tested acted as reversible inhibitors, and the quercetin-thrombin complex was found to be most stable at pH=7.5. Docking analysis indicated that quercetin's inhibitory behavior could be related to its planar structure and low steric hindrance, and to its ability to form a critical H-bond with thrombin His57.

Polymeric grape-seed procyanidins, but not monomeric catechins and oligomeric procyanidins, impair degranulation and membrane ruffling in RBL-2H3 cells

Grape-seed proanthocyanidins (GSPs) are catechin polymers that are predicted to form helices in their global minimum-energy conformation and to have a mean degree of polymerization of seven (mDP = 7). The highly polymerized GSP-H fraction (mDP = 10) was found to impair degranulation in RBL-2H3 cells after stimulation with an antigen (Ag) and treatment with the Ca-ATPase inhibitor thapsigargin (Tg). In addition, GSP-H affected actin cytoskeleton and inhibited membrane ruffling in these cells, resulting in the suppression of exocytosis. By contrast, monomeric epicatechin, the dimeric procyanidins PA-1, PA-2, and PB-2, and the oligomerized GSP-L (mDP = 3) had no effect on membrane ruffling and degranulation. These findings indicate that the molecular size and length of GSP-H are needed for the inhibition of membrane ruffling and degranulation in RBL-2H3 mast-cell lines.

Antihypertensive and cognitive effects of grape polyphenols in estrogen-depleted, female, spontaneously hypertensive rats

Both endogenous and dietary estrogens reduce hypertension and enhance cognitive abilities in estrogen-depleted female spontaneously hypertensive rats (SHR). Many of the beneficial effects of estrogens/phytoestrogens also appear to be provided by other polyphenols (e.g., proanthocyanidins) in grape seed, which lack appreciable estrogenic receptor binding. The present study tested the hypothesis that similar to phytoestrogens, proanthrocyanidins in grape seed polyphenols reduce salt-sensitive hypertension in young, estrogen-depleted SHR. SHR were ovariectomized at 4 wk of age and placed on phytoestrogen-free diets with or without 0.5% grape seed extract added and with high (8.0%) or basal (0.6%) NaCl. After 10 wk on the diets, grape proanthrocyanidin supplementation significantly reduced arterial pressure in the rats fed the basal (10 mmHg) and high (26 mmHg)-NaCl diet, compared with the nonsupplemented controls. In vitro superoxide production was significantly reduced (23%) by the grape seed polyphenols. Spatial learning (8-arm-radial maze) in the SHR on the basal NaCl diets was improved by dietary grape seed polyphenols. These results indicate that grape seed polyphenols decrease arterial pressure in SHR, probably via an antioxidant mechanism.

Proanthocyanidin from grape seeds enhances doxorubicin-induced antitumor effect and reverses drug resistance in doxorubicin-resistant K562/DOX cells

With the aim of enhancing the efficacy of chemotherapeutic agents, we investigated the antitumor actions and reversal effect on drug resistance of proanthocyanidin plus doxorubicin. The results showed that proanthocyanidin 12.5-200 mg/L significantly inhibited proliferation of K562, K562/DOX, SPC-A-1, and Lewis cells in vitro in a time- and concentration-dependent manner, as determined by microculture tetrazolium assay. A combination of proanthocyani din 12.5, or 25 mg/L and doxorubicin treatment synergistically inhibited cell proliferation with decreased IC50 values. Proanthocyanidin reverses drug resistance in doxorubicin-resistant K562/DOX cells, and IC50 values were decreased by 9.19 (3.64-23.19), 2.56 (1.48-.44), and 0.94 (0.81-1.09) mg/L, respectively, after 24 h treatment with doxorubicin 0.1-9.0 mg/L alone or in combination with proanthocyanidin 12.5 or 25 mg/L; the proanthocyanidin reversal fold was 3.6 and 9.8, respectively. Under confocal laser scanning microscope, the combination of proanthocyanidin 25 or 50 mg/L with doxorubicin 3 mg/L significantly increased the accumulation of intracellular doxorubicin, Ca2+, and Mg2+, and reduced the pH value and mitochondrial membrane potential in K562/DOX cells as compared with doxorubicin alone (p < 0.01). Additionally, the apoptosis rate was increased by 11.3% +/- 3.3%, 14.2% +/- 5.4%, and 23.8% +/- 2.8%, respectively, for doxorubicin 3 mg/L alone or with proanthocyanidin 12.5 or 25 mg/L, as compared with controls (3.0% +/- 1.4%), as demonstrated by flow cytometry. In vivo experiments demonstrated that i.p. administration of proanthocyanidin 10 mg/kg with doxorubicin 2 mg/kg had an inhibitory effect on the growth of transplantation tumor sarcoma 180 and hepatoma 22 in mice as compared with doxorubicin alone (p < 0.05). These results suggest that proanthocyanidin enhances doxorubicin-induced antitumor effect and reverses drug resistance, and its mechanism is attributed partially to the promotion of doxorubicin-induced apoptosis through an elevation of intracellular doxorubicin, and Ca2+, Mg2+ concentration, and a reduction of pH value and mitochondrial membrane potential.

Rejuvenation of antioxidant system in central nervous system of aged rats by grape seed extract

Oxidative stress is considered as a major risk factor that contributes to age-related increase in lipid peroxidation and declined antioxidants in the central nervous system during aging. Grape seed extract, one of the bioflavonoid, is widely used for its medicinal properties. In the present study, we evaluated the role of grape seed extract on lipid peroxidation and antioxidant status in discrete regions of the central nervous system of young and aged rats. Male albino rats of Wistar strain were divided into four groups: Group I-control young rats, Group II-young rats treated with grape seed extract (100 mg/kg body weight) for 30 days, Group III-aged control rats and Group IV-aged rats supplemented with grape seed extract (100 mg/kg body weight) for 30 days. Age-associated increase in lipid peroxidation was observed in the spinal cord, cerebral cortex, striatum and the hippocampus regions of aged rats (Group III). Activities of antioxidant enzymes like superoxide dismutase, catalase, glutathione peroxidase and levels of non-enzymic antioxidants like reduced glutathione, Vitamin C and Vitamin E were found to be significantly decreased in all the brain regions studied in aged rats when compared to young rats. However, normalized lipid peroxidation and antioxidant defenses were reported in the grape seed extract-supplemented aged rats. These findings demonstrated that grape seed extract enhanced the antioxidant status and decreased the incidence of free radical-induced lipid peroxidation in the central nervous system of aged rats.

Age‐related oxidative protein damages in central nervous system of rats: modulatory role of grape seed extract

Oxidative stress has been shown to play a major role in aging and in neurodegenerative disorders. Protein modification is one of the important consequences of oxidative stress. In the present study, we evaluated the role of grape seed extract on memory, reactive oxygen species production, protein carbonyls (PCO), and thiol status in discrete regions of central nervous system of young and aged rats. Male albino rats of Wistar strain were divided into four groups: Group I--control young rats, Group II--young rats treated with grape seed extract (100 mg/kg BW) for 30 days, Group III--aged control rats and Group IV-aged rats supplemented with grape seed extract (100 mg/kg BW) for 30 days. Memory loss was observed in the aged rats. Age associated increase in reactive oxygen species production and protein oxidation was observed in the spinal cord; cerebral cortex, striatum and the hippocampus regions of aged rats (Group III). The levels of total thiol, non-protein thiol, protein thiols were found to be significantly decreased in spinal cord and all the brain regions studied in aged rats when compared to young rats. Supplementation of aged rats with grape seed extract showed increased memory performance and declined reactive oxygen species production, decreased protein carbonyl levels and improved thiol levels. These findings demonstrated that grape seed extract enhanced the antioxidant status and decreased the incidence of free radical induced protein oxidation in aged rats thereby protecting the central nervous system from the reactive oxygen species.

Toxicology and safety of anti-oxidant of bamboo leaves. Part 1: Acute and subchronic toxicity studies on anti-oxidant of bamboo leaves

The anti-oxidant of bamboo leaves (AOB) has recently been certificated as a novel kind of natural anti-oxidant by the Ministry of Health of the People's Republic of China, and has been used in various food systems. Here, AOB was subjected to a series of acute and subchronic toxicological tests to evaluate its safety. It was examined to evaluate acute oral toxicity by using Kun-Ming mice and Sprague-Dawley rats, and its mutagenic potential assessed by reverse mutation test using Salmonella typhimurium, bone marrow cell micronucleus test using Kun-Ming mice, and sperm abnormality test using Kun-Ming mice. In addition, a 90-day oral toxicity study using Sprague-Dawley rats was conducted to evaluate subchronic toxicology. The results showed that the maximum tolerated dose (MTD) of AOB was >10 g/kg body weight in both rats and in mice, which can be regarded as virtually non-toxic. No mutagenicity evidence was detected in any of the three mutagenic tests. Administration at levels of 1.43, 2.87 and 4.30 g/kg per day to the rats for 90 days did not induce significant hematological, clinic, chemical and histopathological changes, and suggested a no-observed-adverse-effect level (NOAEL) of 4.30 g/kg per day. These results indicate that AOB can be generally regarded as safe for use as a food additive.

Grape seed extract prevents H(2)O(2)-induced chromosomal damage in human lymphoblastoid cells

We examined the effects of grape seed extract (GSE) on chromosomal damage in two ways; induction on its own and prevention against treatment of reactive oxygen species (ROS). Chromosomal damage was evaluated by cytokinesis-block micronucleus assay (CBMN) in a human lymphoblastoid cell line, WIL2-NS cells. The GSE was composed of 89% proanthocyanidin with a degree of polymerization ranging from 2 to 15. GSE did not induce chromosomal damage in WIL2-NS cells at GSE concentrations up to 5 mg/l. In contrast, pretreatment with GSE dose-dependently prevented H(2)O(2)-induced chromosomal damage at an effective dose of 0.3 to 1 mg/l. A similar preventive effect of GSE was not detected in tert-butyl hydroperoxide-induced damage even at 5 mg/l. In a cell free system, GSE (<5 mg/l) directly scavenged H(2)O(2), but produced slight amounts of H(2)O(2) at higher concentrations (>50 mg/l). These results suggest that GSE is not genotoxic, but rather has an antigenotoxic effect against H(2)O(2) via direct scavenging action of H(2)O(2).

Grape seed procyanidins improve atherosclerotic risk index and induce liver CYP7A1 and SHP expression in healthy rats

Moderate consumption of red wine reduces risk of death from cardiovascular disease. The polyphenols in red wine are ultimately responsible for this effect, exerting antiatherogenic actions through their antioxidant capacities and modulating intracellular signaling pathways and transcriptional activities. Lipoprotein metabolism is crucial in atherogenesis, and liver is the principal organ controlling lipoprotein homeostasis. This study was intended to identify the primary effects of procyanidins, the most abundant polyphenols in red wine, on both plasma lipoprotein profile and the expression of genes controlling lipoprotein homeostasis in the liver. We show that procyanidins lowered plasma triglyceride, free fatty acids, apolipoprotein B (apoB), LDL-cholesterol and nonHDL:nonLDL-cholesterol levels and slightly increased HDL-cholesterol. Liver mRNA levels of small heterodimer partner (SHP), cholesterol 7alpha-hydroxylase (CYP7A1), and cholesterol biosynthetic enzymes increased, whereas those of apoAII, apoCI, and apoCIII decreased. Lipoprotein lipase (LPL) mRNA levels increased in muscle and decreased in adipose tissue. In conclusion, procyanidins improve the atherosclerotic risk index in the postprandial state, inducing in the liver the overexpression of CYP7A1 (suggesting an increase of cholesterol elimination via bile acids) and SHP, a nuclear receptor emerging as a key regulator of lipid homeostasis at the transcriptional level. These results could explain, at least in part, the beneficial long-term effects associated with moderate red wine consumption.

Proteomics analysis of rat brain protein modulations by grape seed extract

Dietary supplements such as grape seed extract (GSE) enriched in proanthocyanidins (PA) (oligomeric polyphenols) have been suggested to have multiple health benefits, due to antioxidant and other beneficial activities of the PA. However, a systematic analysis of the molecular basis of these benefits has not been demonstrated. Because the brain is vulnerable to age-related oxidative damage and other insults including inflammation, it was hypothesized that rats ingesting GSE would experience changes in expression or modifications of specific brain proteins that might protect against pathologic events. Normal adult female rats were fed diets supplemented with 5% GSE for 6 weeks. Proteomics analysis (2D electrophoresis and mass spectrometry) of brain homogenates from these animals identified 13 proteins that were altered in amount and/or charge. Because many of these changes were quantitatively in the opposite direction from previous findings for the same proteins in either Alzheimer disease or mouse models of neurodegeneration, the data suggest that these identified proteins may mediate the neuroprotective actions of GSE. This is the first identification and quantitation of specific proteins in mammalian tissues modulated by a dietary supplement, as well as the first to demonstrate links of such proteins with any disease.

The toxicology and safety of apple polyphenol extract

Apple polyphenol extract has strong antioxidant activity and various physiological functions, and is used in Japan as a food additive and nutritional supplements. Here, we tested the consumption safety of Applephenon, which is a polyphenol extract produced from unripe apples. The Ames test without S9 mixture revealed that Applephenon, had slight mutagenicity at a high concentration of 2500 microg/plate; however, both chromosomal aberration test and the micronucleus test found no significant mutagenicity. Furthermore, an acute oral-toxicity test, and a 90-day subchronic-toxicity test showed no significant hematological, clinical, chemical, histopathological, or urinary effects at a dose of 2000 mg/kg. These results confirm that Applephenon is safe and no toxic at average dietary level.

Efficient one pot extraction and depolymerization of grape (Vitis vinifera) pomace procyanidins for the preparation of antioxidant thio-conjugates

Antioxidant thio-conjugates were obtained from white grape pomace by a clean and efficient one pot extraction and depolymerization method using water and cysteamine hydrochloride. To evaluate the potential of grape pomaces of different origins as sources of proanthocyanidins and conjugates, we conducted varietal comparative studies of polyphenol content, antioxidant power, and procyanidin composition. Xarel.lo proved to be the richest source of polyphenols. The total conversion into the conjugates was as high as 8 g/kg of Xarel.lo grape pomace, with a 50-fold excess of cysteamine, and 3 g/kg, with a 5-fold excess of cysteamine. After purification by preparative cation exchange and reversed phase high-performance liquid chromatography, 17 g of 63% pure 4beta-(2-aminoethylthio)epicatechin (acetate salt) was obtained from 35 kg of moist pomace. The procedure described here will make the antioxidant thio-derivatives efficiently available directly from raw plant byproducts such as grape pomace.

Lightening Effect on Ultraviolet-Induced Pigmentation of Guinea Pig Skin by Oral Administration of a Proanthocyanidin-Rich Extract from Grape Seeds

Antioxidants such as vitamins C and E have been reported to inhibit the progression of ultraviolet (UV) radiation-induced pigmentation in the skin of hairless mice. However, little is known of the lightening effect of proanthocyanidin, a powerful polyphenolic antioxidant, on UV-induced pigmentation of the skin. We investigated the lightening effect of oral administration of a proanthocyanidin-rich grape seed extract (GSE) using guinea pigs with UV-induced pigmentation. These pigmented guinea pigs were fed diets containing 1% GSE or 1% vitamin C (w/w) for 8 weeks. GSE-feeding had an apparent lightening effect on the guinea pigs' pigmented skin. Histologic evaluation demonstrated a decrease in the number of 3,4-dihydroxyphenylalanine (DOPA)-positive melanocytes as well as 8-hydroxy-2'-deoxyguanosine (8-OHdG)-positive, Ki-67-positive, proliferating cell nuclear antigen (PCNA)-positive melanin-containing cells in the basal epidermal layer of the UV-irradiated skin in GSE-fed guinea pigs. In contrast, these parameters did not change in the skin of vitamin C-fed or control guinea pigs. GSE inhibited the activity of mushroom tyrosinase and also inhibited melanogenesis without inhibiting the growth of cultured B16 mouse melanoma cells. In conclusion, we demonstrated that oral administration of GSE is effective in lightening the UV-induced pigmentation of guinea pig skin. This effect may be related to the inhibition of melanin synthesis by tyrosinase in melanocytes and the reactive oxygen species (ROS)-related proliferation of melanocytes.

Metabolism of grape seed polyphenol in the rat

The metabolism of grape seed polyphenol (GSP) has been investigated in rats by high-performance liquid chromatography analysis of the serum and urinary concentrations of the GSP metabolites (+)-catechin (CT), (-)-epicatechin (EC), 3'-O-methyl-(+)-catechin, and 3'-O-methyl-(-)-epicatechin. The serum concentration of these four metabolites reached a maximum 3 h after the oral administration of GSP. The urinary excretion of these GSP metabolites accounted for 0.254% (w/w) of the administered dose of GSP (1.0 g/kg), and the majority of these metabolites were excreted within 25 h of oral administration. The serum concentration and urinary excretion of these metabolites were also compared after the oral administration of different GSP monomers (gallic acid, CT, and EC), normal GSP, and the high molecular weight components of GSP (GSPH). No metabolites were detected in the serum of rats given GSPH. The urinary percentage excretion of the GSP metabolites derived from the respective monomers (CT or EC) did not vary with the administration of different substances (CT or EC, GSP, or GSPH). Taken together, these results suggest that only the monomers of GSP are absorbed and metabolized.

Procyanidins from grape seeds protect endothelial cells from peroxynitrite damage and enhance endothelium-dependent relaxation in human artery: new evidences for cardio-protection

The peroxynitrite scavenging ability of Procyanidins from Vitis vinifera L. seeds was studied in homogeneous solution and in human umbilical endothelial cells (EA.hy926 cell line) using 3-morpholinosydnonimine (SIN-1) as peroxynitrite generator. In homogeneous phase procyanidins dose-dependently inhibited 2',7'-dichloro-dihydrofluorescein (DCFH) oxidation induced by SIN-1 with an IC50 value of 0.28 microM. When endothelial cells (EC) were exposed to 5 mM SIN-1, marked morphological alterations indicating a necrotic cell death (cell viability reduced to 16 +/- 2.5%) were observed. Cell damage was suppressed by procyanidins, with a minimal effective concentration of 1 microM (cell morphology and integrity completely recovered at 20 microM). Cellular localization of procyanidins in EC was confirmed using a new staining procedure and site-specific peroxyl radical inducers: AAPH and cumene hydroperoxide (CuOOH). Endothelial cells (EC) pre-incubated with procyanidins (20 microM) and exposed to FeCl3/K3Fe(CN)6 showed a characteristic blue staining, index of a site-specific binding of procyanidins to EC. Procyanidins dose-dependently inhibit the AAPH induced lipid oxidation and reverse the consequent loss of cell viability, but were ineffective when oxidation was driven at intracellular level (CuOOH). This demonstrates that the protective effect is due to their specific binding to the outer surface of EC thus to quench exogenous harmful radicals. Procyanidins dose-dependently relaxed human internal mammary aortic (IMA) rings (with intact endothelium) pre-contracted with norepinephrine (NE), showing a maximal vasorelaxant effect (85 +/- 9%) at 50 microM (catechin: 18 +/- 2% relaxation at 50 microM). This effect was completely abolished when IMA-rings were de-endothelized and when IMA-rings with intact endothelium were pretreated with L-NMMA or with the soluble guanylate cyclase inhibitor, ODQ. Pre-incubation with indomethacin reduces (by almost 50%) the vasodilating effect of procyanidins, indicating the involvement also of a COX-dependent mechanism. This was confirmed in another set of experiments, where procyanidins dose-dependently stimulate the prostacyclin (PGI2) release, reaching a plateau between 25 and 50 microM. Finally, pre-incubation of IMA-rings with procyanidins (from 6.25 to 25 microM) resulted in a dose-dependent prevention of the endothelin-1 (ET-1) vasoconstriction. The ability of procyanidins to prevent peroxynitrite attack to vascular cells, by layering on the surface of coronary EC, and to enhance endothelial NO-synthase-mediated relaxation in IMA rings provide further insight into the molecular mechanisms through which they exert cardioprotective activity in ischemia/reperfusion injury in vivo.

Inhibitory effects of grape seed extract on lipases

OBJECTIVE

The aim of the present study was to assess the effects of grape seed extract (GSE) on the fat-metabolizing enzymes pancreatic lipase, lipoprotein lipase, and hormone-sensitive lipase in vitro and evaluate its potential application as a treatment for obesity.

METHODS

Crushed grape seeds were extracted in ethanol, and the extract was assayed for the measurement of inhibitory effects on pancreatic lipase and lipoprotein lipase activities and on lipolysis of 3T3-L1 adipocytes.

RESULTS

The GSE rich in bioactive phytochemicals showed inhibitory activity on the fat-metabolizing enzymes pancreatic lipase and lipoprotein lipase, thus suggesting that GSE might be useful as a treatment to limit dietary fat absorption and the accumulation of fat in adipose tissue. The observed reduction in intracellular lipolytic activity of cultured 3T3-L1 adipocytes may reduce the levels of circulating free fatty acids that have been linked to insulin resistance in obese patients.

CONCLUSION

The GSE rich in compounds that inhibit lipases may provide a safe, natural, and cost-effective weight control treatment.

Dietary feeding of proanthocyanidins from grape seeds prevents photocarcinogenesis in SKH-1 hairless mice: relationship to decreased fat and lipid peroxidation

The use of dietary botanicals is receiving considerable interest in the protection of skin from the adverse biological effects of solar ultraviolet (UV) radiation. Dietary feeding of proanthocyanidins extracted from grape seeds (GSP) (0.2 and 0.5%, w/w) in AIN76 control diet to SKH-1 hairless mice resulted in prevention of photocarcinogenesis in terms of tumor incidence (20-95%), tumor multiplicity (46-95%) and tumor size (29-94%) against UVB-induced complete (both initiation + promotion), initiation and promotion stages of photocarcinogenesis. Feeding of GSP (0.5%, w/w) also resulted in prevention of malignant transformation of UVB-induced papillomas to carcinomas in terms of carcinoma incidence (45%), carcinoma multiplicity (61%) and carcinoma size (75%) compared with non-GSP treated mice following UVB-induced complete carcinogenesis protocol at the end of 30 weeks. Biochemical analysis revealed that treatment of GSP in vivo and in vitro systems significantly inhibited UVB- or Fe3+-induced lipid peroxidation by 57-66% (P<0.01) and 41-77% (P< 0.05-0.001), respectively, thus suggesting the antioxidant mechanism of photoprotection by GSP. Long-term feeding of GSP did not show apparent signs of toxicity in mice when determined in terms of body weight, diet consumption and physical characteristics of internal body organs like spleen, liver and kidney. Feeding of GSP also did not show apparent signs of toxicity when determined in terms of total body mass (mass of lean + fat), total bone mineral density and total bone mineral content by employing dual-energy X-ray absorptiometry (DXA). DXA analysis also revealed that feeding of GSP significantly decreased tissue fat level (24-27%, P<0.05) without changing the total body mass of the animals compared with non-GSP-fed animals. This can be attributed to increased lipolysis or decreased synthesis of fat due to administration of GSP. Together, it can be suggested that inhibition of photocarcinogenesis by GSP treatment may be associated with the reduction in UVB-induced oxidative damage and tissue fat content.

Repeated oral administration of high doses of the pomegranate ellagitannin punicalagin to rats for 37 days is not toxic

The water-soluble ellagitanin punicalagin has been reported to be toxic to cattle. Taking into account that this antioxidant polyphenol is very abundant in pomegranate juice (> or =2 g/L), the present study evaluated the possible toxic effect of punicalagin in Sprague-Dawley rats upon repeated oral administration of a 6% punicalagin-containing diet for 37 days. Punicalagin and related metabolites were identified by HPLC-DAD-MS-MS in plasma, liver, and kidney. Five punicalagin-related metabolites were detected in liver and kidney, that is, two ellagic acid derivatives, gallagic acid, 3,8-dihydroxy-6H-dibenzo[b,d]pyran-6-one glucuronide, and 3,8,10-trihydroxy-6H-dibenzo[b,d]pyran-6-one. Feedstuff intake, food utility index, and growth rate were lower in treated rats during the first 15 days without significant adverse effects, which could be due to the lower nutritional value of the punicalagin-enriched diet together with a decrease in its palatability (lower food intake). No significant differences were found in treated rats in any blood parameter analyzed (including the antioxidant enzymes gluthatione peroxidase and superoxide dismutase) with the exception of urea and triglycerides, which remained at low values throughout the experiment. Although the reason for the decrease is unclear, it could be due to the lower nutritional value of the punicalagin-enriched diet with respect to the standard rat food. Histopathological analysis of liver and kidney corroborated the absence of toxicity. In principle, the results reported here, together with the large safety margin considered, indicate the lack of toxic effect of punicalagin in rats during the 37 day period investigated. However, taking into account the high punicalagin content of pomegranate-derived foodstuffs, safety evaluation should be also carried out in humans with a lower dose and during a longer period of intake.

Procyanidin-rich extract from grape seeds prevents cataract formation in hereditary cataractous (ICR/f) rats

Antioxidants such as vitamin C, vitamin E, and carotenoids have been reported to prevent the progression of experimentally induced cataracts. However, little is known of the effect of procyanidins, a powerful antioxidant, on cataract formation. This paper investigates the anticataract activity of grape seed extract (GSE, which contains 38.5% procyanidins) in hereditary cataractous rats (ICR/f rats). The ICR/f rats were fed a standard diet containing 0 or 0.213% GSE [0.082% procyanidins in the diet (w/w)] for 27 days. The GSE significantly prevented and postponed development of cataract formation by evaluation of slit lamp observations of the rats' eyes. Lens weight and malondialdehyde concentration in the lens and plasma cholesteryl ester hydroperoxide (ChE-OOH) level induced by CuSO4 were significantly lower in the GSE group compared with the control group. The rats were also fed for 14 days either the diet containing 0.085% procyanidin dimer to tetramer fraction (0.085% as the procyanidins), the diet containing 0.090% procyanidin pentamer to heptamer fraction (0.085% as the procyanidins), or the diet containing 0.093% procyanidin oligomers more than decamer fraction (0.085% as the procyanidins). The ChE-OOH levels in the procyanidin pentamer to heptamer and procyanidin oligomers more than decamer groups were significantly lower than in the procyanidin dimer to tetramer group. These results suggested that procyanidins and their antioxidative metabolites prevented the progression of cataract formation by their antioxidative action. The larger molecular procyanidins in the GSE might contribute this anticataract activity.