Health and longevity benefits of plant polyphenols – focus grape seed extract

As the productivity of conventional drug discovery methods declines, there is a growing interest in the use of natural dietary substances for the prevention and treatment of multiple disease conditions.  In previous blog entries I have discussed a number of substances rich in plant polyphenols which offer health and longevity benefits including ginger, resveratrol(ref)(ref),curcumin (ref)(ref), folic acid, valproic acid, caffeic acid, rosmarinic acid, and some of the the phyto-ingredients in olive oil, walnuts, chocolate, hot peppers, and blueberries.  This blog post focuses on grapeseed extract (GSE), a seemingly mundane but actually quite interesting substance. Grape seed extract is rich in a class of flavanols known as Oligomeric proanthocyanidins.  A substantial number of publications relating to the health and longevity benefits of GSE were published in 2011 alone.  

Grapeseed extract and Alzheimer’s disease

Before getting to published 2011 results I site a few earlier publications.

The 2008 publication Grape-derived polyphenolics prevent Abeta oligomerization and attenuate cognitive deterioration in a mouse model of Alzheimer’s disease reported “Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by progressive impairments in memory and cognition. Extracellular accumulation of soluble high-molecular-weight (HMW) Abeta oligomers has been proposed to be largely responsible for AD dementia and memory deficits in the Tg2576 mice, a model of AD. In this study, we found that a naturally derived grape seed polyphenolic extract can significantly inhibit amyloid beta-protein aggregation into high-molecular-weight oligomers in vitro. When orally administered to Tg2576 mice, this polyphenolic preparation significantly attenuates AD-type cognitive deterioration coincidentally with reduced HMW soluble oligomeric Abeta in the brain. Our study suggests that grape seed-derived polyphenolics may be useful agents to prevent or treat AD.”

The 2009 publication Heterogeneity in red wine polyphenolic contents differentially influences Alzheimer’s disease-type neuropathology and cognitive deterioration reported “We recently found that moderate consumption of two unrelated red wines generate from different grape species, a Cabernet Sauvignon and a muscadine wine that are characterized by distinct component composition of polyphenolic compounds, significantly attenuated the development of Alzheimer’s disease (AD)-type brain pathology and memory deterioration in a transgenic AD mouse model. Interestingly, our evidence suggests that the two red wines attenuated AD phenotypes through independent mechanisms. In particular, we previously found that treatment with Cabernet Sauvignon reduced the generation of AD-type amyloid-beta (Abeta) peptides. In contrast, evidence from our present study suggests that muscadine treatment attenuates Abeta neuropathology and Abeta-related cognitive deterioration in Tg2576 mice by interfering with the oligomerization of Abeta molecules to soluble high-molecular-weight Abeta oligomer species that are responsible for initiating a cascade of cellular events resulting in cognitive decline. Collectively, our observations suggest that distinct polyphenolic compounds from red wines may be bioavailable at the organism level and beneficially modulate AD phenotypes through multiple Abeta-related mechanisms. Results from these studies suggest the possibility of developing a “combination” of dietary polyphenolic compounds for AD prevention and/or therapy by modulating multiple Abeta-related mechanisms.”

The 2009 publication Consumption of grape seed extract prevents amyloid-beta deposition and attenuates inflammation in brain of an Alzheimer’s disease mouse reports “Polyphenols extracted from grape seeds are able to inhibit amyloid-beta (Abeta) aggregation, reduce Abeta production and protect against Abeta neurotoxicity in vitro. We aimed to investigate the therapeutic effects of a polyphenol-rich grape seed extract (GSE) in Alzheimer’s disease (AD) mice. APP(Swe)/PS1dE9 transgenic mice were fed with normal AIN-93G diet (control diet), AIN-93G diet with 0.07% curcumin or diet with 2% GSE beginning at 3 months of age for 9 months. Total phenolic content of GSE was 592.5 mg/g dry weight, including gallic acid (49 mg/g), catechin (41 mg/g), epicatechin (66 mg/g) and proanthocyanidins (436.6 mg catechin equivalents/g). Long-term feeding of GSE diet was well tolerated without fatality, behavioural abnormality, changes in food consumption, body weight or liver function. The Abeta levels in the brain and serum of the mice fed with GSE were reduced by 33% and 44%, respectively, compared with the Alzheimer’s mice fed with the control diet. Amyloid plaques and microgliosis in the brain of Alzheimer’s mice fed with GSE were also reduced by 49% and 70%, respectively. Curcumin also significantly reduced brain Abeta burden and microglia activation. Conclusively, polyphenol-rich GSE prevents the Abeta deposition and attenuates the inflammation in the brain of a transgenic mouse model, and this thus is promising in delaying development of AD.”

A July 2011 publication Grape Seed Polyphenolic Extract Specifically Decreases Aβ*56 in the Brains of Tg2576 Mice reports “Amyloid-β (Aβ) oligomers, found in the brains of Alzheimer’s disease (AD) patients and transgenic mouse models of AD, cause synaptotoxicity and memory impairment. Grape seed polyphenolic extract (GSPE) inhibits Aβ oligomerization in vitro and attenuates cognitive impairment and AD-related neuropathology in the brains of transgenic mice. In the current study, GSPE was administered to Tg2576 mice for a period of five months. Treatment significantly decreased brain levels of Aβ*56, a 56-kDa Aβ oligomer previously shown to induce memory dysfunction in rodents, without changing the levels of transgenic amyloid-β protein precursor, monomeric Aβ, or other Aβ oligomers. These results thus provide the first demonstration that a safe and affordable intervention can lower the levels of a memory-impairing Aβ oligomer in vivo and strongly suggest that GSPE should be further tested as a potential prevention and/or therapy for AD.”  

A July 15, 2011 Science Daily article Natural Chemical Found in Grapes I May Protect Against Alzheimer’s Disease on this latest research reports “Previous studies suggest that increased consumption of grape-derived polyphenols, whose content, for example, is very high in red wine, may protect against cognitive decline in Alzheimer’s. This new finding, showing a selective decrease in the neurotoxin Aβ*56 following grape-derived polyphenols treatment, corroborates those theories. — “Since naturally occurring polyphenols are also generally commercially available as nutritional supplements and have negligible adverse events even after prolonged periods of treatment, this new finding holds significant promise as a preventive method or treatment, and is being tested in translational studies in Alzheimer’s disease patients,” said Dr. Pasinetti. — The study authors emphasize that in order for grape-derived polyphenols to be effective, scientists need to identify a biomarker of disease that would pinpoint who is at high risk to develop Alzheimer’s disease. —  “It will be critical to identify subjects who are at high risk of developing Alzheimer’s disease, so that we can initiate treatments very early and possibly even in asymptomatic patients,” said Dr. Pasinetti. “However, for Alzheimer’s disease patients who have already progressed into the initial stages of the disease, early intervention with this treatment might be beneficial as well. Our study implicating that these neurotoxins such as Aβ*56 in the brain are targeted by grape-derived polyphenols holds significant promise.”

I note that other plant polyphenmols may also be effective against Alzheimer’s Disease, caffeine and coffee being a prime example(ref)(ref)(ref)(ref).

Grapeseed extract and mitochondrial metabolism

The 2011 publication Acute administration of grape seed proanthocyanidin extract modulates energetic metabolism in skeletal muscle and BAT mitochondriareports “Proanthocyanidin consumption might reduce the risk of developing several pathologies, such as inflammation, oxidative stress and cardiovascular diseases. The beneficial effects of proanthocyanidins are attributed to their antioxidant properties, although they also can modulate gene expression at the transcriptional level. Little is known about the effect of proanthocyanidins on mitochondrial function and energy metabolism. In this context, the objective of this study was to determine the effect of an acute administration of grape seed proanthocyanidin extract (GSPE) on mitochondrial function and energy metabolism. To examine this effect, male Wistar rats fasted for fourteen hours, and then they were orally administered lard oil containing GSPE or were administered lard oil only. Liver, muscle and brown adipose tissue (BAT) were used to study enzymatic activity and gene expression of proteins related to energetic metabolism. Moreover, the gastrocnemius muscle and BAT mitochondria were used to perform high-resolution respirometry. The results showed that, after 5 h, the GSPE administration significantly lowers plasma triglycerides, free fatty acids, glycerol and urea concentrations. In skeletal muscle, GSPE lowers FATP1 mRNA levels and increases mitochondrial oxygen consumption, using pyruvate as the substrate, suggesting a promotion of glycosidic metabolism. Furthermore, GSPE increased the genetic expression of key genes in energy metabolism such as peroxisome proliferator-activated receptor gamma, coactivator 1 alpha (PGC1α), and modulated the enzyme activity of proteins, which are involved in the citric acid cycle and electron transport chain (ETC) in BAT. In conclusion, GSPE affects mainly the skeletal muscle and BAT mitochondria, increasing their oxidative capacity rapidly after acute supplementation.”  The importance of PGC1α in mitochondrial biogenesis, metabolism and aging is described blog entries PGC-1alpha and exercise, , SIRT3 research – tying together knowledge of aging and PQQ – activator of PGC-1alpha, SIRT3 and mitochondrial biogenesis.

Another relevant 2011 publication is Chronic dietary supplementation of proanthocyanidins corrects the mitochondrial dysfunction of brown adipose tissue caused by diet-induced obesity in Wistar rats.  “The present study aims to determine the effects of grape seed proanthocyanidin extract (GSPE) on brown adipose tissue (BAT) mitochondrial function in a state of obesity induced by diet. Wistar male rats were fed with a cafeteria diet (Cd) for 4 months; during the last 21 d, two groups were treated with doses of 25 and 50 mg GSPE/kg body weight. In the BAT, enzymatic activities of citrate synthase, cytochrome c oxidase (COX) and ATPase were determined and gene expression was analysed by real-time PCR. The mitochondrial function of BAT was determined in fresh mitochondria by high-resolution respirometry using both pyruvate and carnitine-palmitoyl-CoA as substrates. The results show that the Cd causes an important decrease in the gene expression of sirtuin 1, nuclear respiratory factor 1, isocitrate dehydrogenase 3γ and COX5α and, what is more telling, decreases the levels of mitochondrial respiration both with pyruvate and canitine-palmitoyl-CoA. Most of these parameters, which are indicative of mitochondrial dysfunction due to diet-induced obesity, are improved by chronic supplementation of GSPE. The beneficial effects caused by the administration of GSPE are exhibited as a protection against weight gain, in spite of the Cd the rats were fed. These data indicate that chronic consumption of a moderate dose of GSPE can correct an energy imbalance in a situation of diet-induced obesity, thereby improving the mitochondrial function and thermogenic capacity of the BAT.”  

The practical implication again is very significant: GSD supplementation may be useful for averting diet-induced obesity. Subsequent citations also deal with aspects of this topic.

Yet-another relevant 2011 publication is Improvement of  Mitochondrial Function in Muscle of Genetically Obese Rats after Chronic Supplementation with Proanthocyanidins. “The aim of this study was to determine the effect of chronic dietary supplementation of a grape seed proanthocyanidin extract (GSPE) at a dose of 35 mg/kg body weight on energy metabolism and mitochondrial function in the skeletal muscle of Zucker obese rats. Three groups of 10 animals each were used: lean Fa/fa lean group (LG) rats, a control fa/fa obese group (OG) of rats, and an obese supplemented fa/fa proanthocyanidins obese group (POG) of rats, which were supplemented with a dose of 35 mg GSPE/kg of body weight/day during the 68 days of experimentation. Skeletal muscle energy metabolism was evaluated by determining enzyme activities, key metabolic gene expression, and immunoblotting of oxidative phosphorylation complexes. Mitochondrial function was analyzed by high-resolution respirometry using both a glycosidic and a lipid substrate. In muscle, chronic GSPE administration decreased citrate synthase activity, the amount of oxidative phosphorylation complexes I and II, and Nrf1 gene expression, without any effects on the mitochondrial oxidative capacity. This situation was associated with lower reactive oxygen species (ROS) generation. Additionally, GSPE administration enhanced the ability to oxidize pyruvate, and it also increased the activity of enzymes involved in oxidative phosphorylation including cytochrome c oxidase. There is strong evidence to suggest that GSPE administration stimulates mitochondrial function in skeletal muscle specifically by increasing the capacity to oxidize pyruvate and contributes to reduced muscle ROS generation in obese Zucker rats.”

Grapeseed extract and insulin resistance

Insulin resistance can come about through epigenetic changes due to a high glycemic-index diet. The 2010 publication Preventive effect of grape seed extract against high-fructose diet-induced insulin resistance and oxidative stress in rats reports “The purpose of the present study was to investigate the preventive effect of grapeseed extract (GSE) on insulin resistance and oxidative stress in rats fed a high-fructose diet. After 8 weeks of the experiment, the fasting plasma glucose, insulin concentrations, and the homeostasis model assessment of basal insulin resistance (HOMA-IR) of rats fed a high-fructose diet supplemented with 1% GSE were significantly lower than that of a high-fructose diet group. In the oral glucose tolerance test, rats fed a high-fructose diet supplemented with 1% GSE had a significantly reduced plasma glucose and insulin concentrations after 15 min of glucose loading, indicating that GSE improved glucose intolerance. In addition, fed rats fed a high-fructose diet supplemented with 1% GSE markedly increased activity of hepatic superoxide dismutase, catalase, and suppressed lipid peroxidation when compared to rats fed a high-fructose diet. However, rats fed a high-fructose diet supplemented with GSE were not found to have a significant change in the activity of hepatic glutathione peroxidase. In conclusion, intake of GSE may be a feasible therapeutic strategy for prevention of a high-fructose diet-induced insulin resistance and oxidative stress.” Again, this finding points to an extremely simple and low-cost potentialapproach for averting both Type 2 diabetes and obesity.

A more-recent to 2011 publication dealing with the same issue is Grape seed extract supplementation prevents high-fructose diet-induced insulin resistance in rats by improving insulin and adiponectin signalling pathways.  “Recent evidence strongly supports the contention that grapeseed extract (GSE) improves hyperglycaemia and hyperinsulinaemia in high-fructose-fed rats. To explore the underlying molecular mechanisms of action, we examined the effects of GSE on the expression of muscle proteins related to the insulin signalling pathway and of mRNA for genes involved in the adiponectin signalling pathway. Compared with rats fed on a normal diet, high-fructose-fed rats developed pathological changes, including insulin resistance, hyperinsulinaemia, hypertriacylglycerolaemia, a low level of plasma adiponectin and a high level of plasma fructosamine. These disorders were effectively attenuated in high-fructose-fed rats supplemented with GSE. A high-fructose diet causes insulin resistance by significantly reducing the protein expression of insulin receptor, insulin receptor substrate-1, Akt and GLUT4, and the mRNA expression of adiponectin, adiponectin receptor R1 (AdipoR1) and AMP-activated protein kinase (AMPK)-α in the skeletal muscle. Supplementation of GSE enhanced the expression of insulin signalling pathway-related proteins, including Akt and GLUT4. GSE also increased the mRNA expression of adiponectin, AdipoR1 and AMPK-α. In addition, GSE increased the mRNA levels of glycogen synthase and suppressed the mRNA expression of glycogen synthase kinase-3-α, causing an increase in glycogen accumulation in the skeletal muscle. These results suggest that GSE ameliorates the defective insulin and adiponectin signalling pathways in the skeletal muscle, resulting in improved insulin resistance in fructose-fed rats.”

Grapeseed extract and coronary heart disease

The 2011 publication Botanical flavonoids on coronary heart disease reports “Ischemic heart disease (IHD) is one of the leading causes of death in Western countries. Prevention rather than treatment of heart disease can significantly improve patients’ quality of life and reduce health care costs. Flavonoids are widely distributed in vegetables, fruits and herbal medicines. Regularly consuming botanicals, especially those containing flavonoids, has been associated with a reduction in cardiovascualar disease; thus, it is important to investigate how flavonoids improve cardiac resistance to heart disease and their related mechanisms of action. It has been shown that cardiomyocyte injury and death can result from ischemia-reperfusion, which is pathognomonic of ischemic heart disease. Massive reactive oxygen species (ROS) release at the onset of reperfusion produces cell injury and death. “Programming” the heart to either generate less ROS or to increase strategic ROS removal could reduce reperfusion response. Additionally, profuse nitric oxide (NO) release at reperfusion could be protective in “preconditioning” models. Botanical flavonoids induce preconditioning of the heart, thereby protecting against ischemia-reperfusion injury. In this article, we will discuss two herbs containing potent flavonoids, Scutellaria baicalensis and grape seed proanthocyanidin, which can potentially offer cardiac protection against ischemic heart disease.”

Grapeseed extract and cancer chemoprevention or therapy

The 2009 review publication Anticancer and cancer chemopreventive potential of grape seed extract and other grape-based products reports “With emerging trends in the incidence of cancer of various organ sites, additional approaches are needed to control human malignancies. Intervention or prevention of cancer by dietary constituents, a strategy defined as chemoprevention, holds great promise in our conquest to control cancer, because it can be implemented on a broader population base with less economic burden. Consistent with this, several epidemiological studies have shown that populations that consume diets rich in fruits and vegetables have an overall lower cancer incidence. Based on these encouraging observations, research efforts from across the globe have focused on identifying, characterizing, and providing scientific basis to the efficacy of various phytonutrients in an effort to develop effective strategy to control various human malignancies. Cancer induction, growth, and progression are multi-step events and numerous studies have demonstrated that various dietary agents interfere with these stages of cancer, thus blocking malignancy. Fruits and vegetables represent untapped reservoir of various nutritive and nonnutritive phytochemicals with potential cancer chemopreventive activity. Grapes and grape-based products are one such class of dietary products that have shown cancer chemopreventive potential and are also known to improve overall human health. This review focuses on recent advancements in cancer chemopreventive and anticancer efficacy of grapeseed extract and other grape-based products. Overall, completed studies from various scientific groups conclude that both grapes and grape-based products are excellent sources of various anticancer agents and their regular consumption should thus be beneficial to the general population.”

Grape seed extract and skin cancer

The 2008 publication Grape seed proanthocyanidines and skin cancer prevention: Inhibition of oxidative stress and protection of immune system reported “Overexposure of the skin to ultraviolet (UV) radiation has a variety of adverse effects on human health, including the development of skin cancers. There is a need to develop nutrition-based efficient chemopreventive strategies. The proanthocyanidins present in grape seeds (Vitis vinifera) have been shown to have some biological effects, including prevention of photocarcinogenesis. The present communication discusses the in vitro and in vivo studies of the possible protective effect of grape seed proanthocyanidins (GSPs) and the molecular mechanism for these effects. In SKH-1 hairless mice, dietary supplementation with GSPs is associated with a decrease of UVB-induced skin tumor development in terms of tumor incidence, tumor multiplicity, and a decrease in the malignant transformation of papillomas to carcinomas. It is suggested that the chemopreventive effects of dietary GSPs are mediated through the attenuation of UV-induced: (a) oxidative stress; (b) activation of mitogen-activated protein kinases and nuclear factor-κB signaling pathways; and (c) immunosuppression through alterations in immunoregulatory cytokines. Collectively, these studies indicate protective potential of GSPs against experimental photocarcinogenesis in SKH-1 hairless mice, and the possible mechanisms of action of GSPs, and suggest that dietary GSPs could be useful in the attenuation of the adverse UV-induced health effects in human skin.”

The 2009 publication Dietary grape seed proanthocyanidins inhibit 12-O-tetradecanoyl phorbol-13-acetate-caused skin tumor promotion in 7,12-dimethylbenz[a]anthracene-initiated mouse skin, which is associated with the inhibition of inflammatory responses reports that the protectivity of GS E against skin cancers are is associated with the inhibition of inflammatory responses caused by tumor promoters. “Grape seed proanthocyanidins (GSPs) possess anticarcinogenic activities. Here, we assessed the effects of dietary GSPs on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced skin tumor promotion in 7,12-dimethylbenz[a]anthracene (DMBA)-initiated mouse skin. Administration of dietary GSPs (0.2 and 0.5%, wt/wt) supplemented with control AIN76A diet resulted in significant inhibition of TPA-induced skin tumor promotion in C3H/HeN mice. The mice treated with GSPs developed a significantly lower tumor burden in terms of the percentage of mice with tumors (P < 0.05), total number of tumors per group (P < 0.01, n = 20) and total tumor volume per tumor-bearing mouse (P < 0.01-0.001) as compared with the mice that received the control diet. GSPs also delayed the malignant progression of papillomas into carcinomas. As TPA-induced inflammatory responses are used routinely as markers of skin tumor promotion, we assessed the effect of GSPs on biomarkers of TPA-induced inflammation. Immunohistochemical analysis and western blotting revealed that GSPs significantly inhibited expression of cyclooxygenase-2 (COX-2), prostaglandin E(2) (PGE(2)) and markers of proliferation (proliferating cell nuclear antigen and cyclin D1) in both the DMBA-initiated/TPA-promoted mouse skin and skin tumors. In short-term experiments in which the mouse skin was treated with acute or multiple TPA applications, we found that dietary GSPs inhibited TPA-induced edema, hyperplasia, leukocytes infiltration, myeloperoxidase, COX-2 expression and PGE(2) production in the mouse skin. The inhibitory effect of GSPs was also observed against other structurally different skin tumor promoter-induced inflammation in the skin. Together, our results show that dietary GSPs inhibit chemical carcinogenesis in mouse skin and that the inhibition of skin tumorigenesis by GSPs is associated with the inhibition of inflammatory responses caused by tumor promoters.”

Grapeseed extract and small-cell lung cancer

the 2009 publication Inhibition of non-small cell lung cancer cell migration by grape seed proanthocyanidins is mediated through the inhibition of nitric oxide, guanylate cyclase, and ERK1/2 reports “Tumor cell migration is considered as a major event in the metastatic cascade. Here we examined the effect of grape seed proanthocyanidins (GSPs) on migration capacity and signaling mechanisms using nonsmall cell human lung cancer cells. Using in vitro migration assay, we found that treatment of A549 and H1299 cells with GSPs resulted in concentration-dependent inhibition of migration of these cells. The migration capacity of cells was reduced in presence of N(G)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase. GSPs suppressed the elevated levels of endogenous NO/NOS in A549 and H1299 cells and blocked the migration promoting capacity of L-arginine. Treatment with guanylate cyclase (GC) inhibitor 1-H-[1,2,4]oxadiaxolo[4,3-a]quinolalin-1-one (ODQ) reduced the migration of A549 cells whereas additional presence of 8-bromoguanosine 3’5′-cyclic monophosphate (8-Br-cGMP, cGMP analogue) restored the migration of these cells, suggesting a role for GC in migration of A549 cells. GSPs reduced the elevated levels of cGMP in cancer cells and also blocked the migration restoring activity of 8-Br-cGMP. The mitogen-activated protein kinase kinase (MAPKK) inhibitor, UO126, inhibited the migration of A549 cells, indicating a role for MAPKK in the migration. Additionally, UO126 and ODQ inhibited the migration restoring effects of L-arginine in L-NAME-treated cells, suggesting the involvement of cGMP and MAPK pathways in NO-mediated migration. GSPs inhibited L-arginine and 8-Br-cGMP-induced activation of ERK1/2 in A549 cells. Together, these results indicate sequential inhibition of NO/NOS, GC, and MAPK pathways by GSPs in mediating the inhibitory signals for cell migration, an essential step in invasion and metastasis.”

An interesting 2009 publication relates how GSE can inhibit proliferation of melanoma in part by blocking expression of COX-2, in part by blocking a transition to melanoma stem cells. The publication is Grape Seed Proanthocyanidins Inhibit Melanoma Cell Invasiveness by Reduction of PGE(2) Synthesis and Reversal of Epithelial-to-Mesenchymal Transition. “Melanoma is the leading cause of death from skin disease due, in large part, to its propensity to metastasize. We have examined the effect of grape seed proanthocyanidins (GSPs) on melanoma cancer cell migration and the molecular mechanisms underlying these effects using highly metastasis-specific human melanoma cell lines, A375 and Hs294t. Using in vitro cell invasion assays, we observed that treatment of A375 and Hs294t cells with GSPs resulted in a concentration-dependent inhibition of invasion or cell migration of these cells, which was associated with a reduction in the levels of cyclooxygenase (COX)-2 expression and prostaglandin (PG) E(2) production. Treatment of cells with celecoxib, a COX-2 inhibitor, or transient transfection of melanoma cells with COX-2 small interfering RNA, also inhibited melanoma cell migration. Treatment of cells with 12-O-tetradecanoylphorbol-13-acetate, an inducer of COX-2, enhanced the phosphorylation of ERK1/2, a protein of mitogen-activated protein kinase family, and subsequently cell migration whereas both GSPs and celecoxib significantly inhibited 12-O-tetradecanoylphorbol-13-acetate -promoted cell migration as well as phosphorylation of ERK1/2. Treatment of cells with UO126, an inhibitor of MEK, also inhibited the migration of melanoma cells. Further, GSPs inhibited the activation of NF-κB/p65, an upstream regulator of COX-2, in melanoma cells, and treatment of cells with caffeic acid phenethyl ester, an inhibitor of NF-κB, also inhibited cell migration. Additionally, inhibition of melanoma cell migration by GSPs was associated with reversal of epithelial-mesenchymal transition process, which resulted in an increase in the levels of epithelial biomarkers (E-cadherin and cytokeratins) while loss of mesenchymal biomarkers (vimentin, fibronectin and N-cadherin) in melanoma cells. Together, these results indicate that GSPs have the ability to inhibit melanoma cell invasion/migration by targeting the endogenous expression of COX-2 and reversing the process of epithelial-to-mesenchymal transition.”  Given the deadliness of melanoma this study could be important even though it is only an in-vitro study.

Grapeseed extract and prostate cancer 

A number of, in-vitro studies over the years strongly uggest that GSE may be useful for either preventing or slowing the progress of prostate cancer. For example the 2000 report Anticarcinogenic effect of a polyphenolic fraction isolated from grape seeds in human prostate carcinoma DU145 cells: modulation of mitogenic signaling and cell-cycle regulators and induction of G1 arrest and apoptosis, the 2003 report Inhibition of NF-kappaB pathway in grape seed extract-induced apoptotic death of human prostate carcinoma DU145 cells, the 2003 study Grape seed extract inhibits EGF-induced and constitutively active mitogenic signaling but activates JNK in human prostate carcinoma DU145 cells: possible role in antiproliferation and apoptosis, and the 2006 study Fractionation of grape seed extract and identification of gallic acid as one of the major active constituents causing growth inhibition and apoptotic death of DU145 human prostate carcinoma cells.

The 2006 report Grape seed extract induces anoikis and caspase-mediated apoptosis in human prostate carcinoma LNCaP cells: possible role of ataxia telangiectasia mutated-p53 activation relates  “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

A 2010 study is particularly interesting and unique among the other studies mentioned here because it describes the epigenetic mechanism through which GSE acts against prostate cancer.  The report is entitled Grape Seed Extract Regulates Androgen Receptor-Mediated Transcription in Prostate Cancer Cells Through Potent Anti–Histone Acetyltransferase Activity. “Histone acetylation, which is regulated by histone acetyltransferases (HATs) and deacetylases, is an epigenetic mechanism that influences eukaryotic transcription. Significant changes in histone acetylation are associated with cancer; therefore, manipulating the acetylation status of key gene targets is likely crucial for effective cancer therapy. Grape seed extract (GSE) has a known protective effect against prostate cancer. Here, we showed that GSE significantly inhibited HAT activity by 30–80% in vitro (P<.05). Furthermore, we demonstrated significant repression of androgen receptor (AR)-  mediated transcription by GSE in prostate cancer cells by measuring luciferase activity using a pGL3-PSA construct bearing the AR element in the human prostate cancer cell line LNCaP (P<.05). GSE treatment also decreased the mRNA level of the AR-regulated genes PSA and NKX 3.1. Finally, GSE inhibited growth of LNCaP cells. These results indicate that GSE potently inhibits HAT, leading to decreased AR-mediated transcription and cancer cell growth, and implicate GSE as a novel candidate for therapeutic activity against prostate cancer.  — The present study aimed to investigate the inhibitory effect of HAT activity from GSE on AR-mediated transcriptional regulation in prostate cancer cells. We demonstrate that GSE exhibits the strongest HAT inhibitory activity in a concentration-dependent manner and also suppresses the androgen-dependent transcriptional activity of the AR. Furthermore, we suggest the possible mechanisms of GSE to develop effective therapeutics in prostate cancer therapy.”

Grapeseed extract and neuroblastoma

“Neuroblastoma is the most common extracranial solid cancer in childhood and the most common cancer in infancy, with an annual incidence of about 650 new cases per year in the US. (ref)^[1]”     The 2011 report Effects of Grape Seed Proanthocyanidin on 5-Hydroxytryptamine(3) Receptors in NCB-20 Neuroblastoma Cells relates: “We investigated the actions of proanthocyanidin from grape seeds on 5-hydroxytryptamine (5-HT)(3) receptors in NCB-20 neuroblastoma cells using a whole-cell voltage clamp technique. Co-treatment of proanthocyanidin (0.3-100 µg/ml) and 3 µM 5-HT (near EC(50)) produced a slight inhibition of 5-HT-induced inward peak current (I(5-HT)) in NCB-20 cells, but pretreatment with proanthocyanidin for 30 s before application of 5-HT induced a much larger inhibition of I(5-HT) in an irreversible, concentration- and time-dependent manner (IC(50)=6.5±0.4 µg/ml, Hill coefficient=2.5±0.1). Proanthocyanidin also produced a concentration-dependent inhibition of currents induced by 30 µM 5-HT, near-maximal concentration (IC(50)=22.1±0.4 µg/ml, Hill coefficient=2.4±0.1). High concentrations (≧30 µg/ml) of proanthocyanidin caused a concentration-dependent inhibition of the activation and desensitization of currents induced by 30 µM 5-HT. Further studies showed that pretreatment of 20 µg/ml proanthocyanidin caused not only a rightward shift of the dose-response curve for 5-HT (EC(50) shift from 2.7±0.4 to 6.2±0.5 µM), but also a decreased E(max) (inhibition by 37.5±1.3%). The proanthocyanidin-induced inhibition of 5-HT(3) receptors did not show a significant difference within the testing holding potential ranges (-50-+30 mV). These results suggest that proanthocyanidin inhibits 5-HT(3) receptor function in NCB-20 cells in a noncompetitive mode, and that this inhibitory effect of proanthocyanidin probably contributes to the pharmacological actions of proanthocyanidin.”

Grapeseed extract and liver protection

GSE appears to be effective in reducing liver stress which in some cases is unavoidable.. The 2008 publication Role of grape seed extract on methotrexate induced oxidative stress in rat liver reports “The efficacy of methotrexate (MTX), a widely used cytotoxic chemotherapeutic agent, is often limited by its severe hepatotoxicity. Regarding the mechanisms of these adverse effects, several hypotheses have been put forward, among which oxidative stress is noticeable. The present study was undertaken to determine whether grape seed extract (GSE), a new natural free radical scavenger, could ameliorate the MTX-induced oxidative injury in the rat liver. The animals were divided into 3 groups. Each group consisted of 12 animals. MTX-GSE group: rats were given GSE (100mg/kg body weight) orally for 15 days, and a single dose of MTX (20 mg/kg, intraperitoneally) was added on the 10th day. MTX group: these received placebo distilled water (orally) instead of GSE for 15 days and the same MTX protocol applied to this group on the 10th day. Control group: rats were given distilled water (orally) through 15 days and physiological saline (intraperitoneally) instead of MTX was administered on the 10th day in a similar manner. On the 16th day, liver tissue samples were obtained under deep anaesthesia. The level of malondialdehyde (MDA), an end product of lipid peroxidation, and the activities of süperoxide dismutase (SOD) and catalase (CAT), two important endogenous antioxidants, were evaluated in the tissue homogenates. MTX administration increased the MDA level and decreased the SOD and CAT activities in the liver homogenates (p < 0.001), while these alterations were significantly reversed by GSE treatment (p < 0.001). MTX led to significantly reduced whole blood count parameters (p < 0.05). When GSE was supplemented, no significant changes in blood count parameters were noted. It appears that GSE protects the rat liver and inhibits methotrexate-induced oxidative stress. These data indicate that GSE may be of therapeutic benefit when used with MTX.”

Radiation exposure can be another cause of oxidative stress on the liver. The 2008 publication The effect of grape seed extract on radiation-induced oxidative stress in the rat liver reports: “The tolerance of the liver is considerably low when an effective radiation (RTx) dose needs to be delivered in patients in whom either their liver or whole body area has to be irradiated. The aim of this study was to evaluate the possible protective effect of grape seed extract on liver toxicity induced by RTx in the rat liver. — We used four groups, each consisting of 12 healthy male Wistar rats. RTx-grape seed extract group: rats were given grape seed extract (100 mg/kg) orally for seven days, following 8 Gy whole body irradiation, and grape seed extract was maintained for four days. RTx group: the same protocol was applied in this group; however, they received distilled water instead of grape seed extract. Grape seed extract group: only grape seed extract solution was administered for 11 consecutive days in the same fashion. Control group: only distilled water (orally) was administered in a similar manner. The level of malondialdehyde, an end product of lipid peroxidation, and the activities of superoxide dismutase and catalase, two important endogenous antioxidants, were evaluated in tissue homogenates. — Grape seed extract was seen to protect the cellular membrane from oxidative damage and consequently from protein and lipid oxidation. In the RTx group, malondialdehyde levels were extremely higher than those of the grape seed extract-RTx group (p<0.001). Grape seed extract administration moderately reserved the malondialdehyde levels. RTx therapy decreased superoxide dismutase and catalase activities in the liver homogenates (p<0.001), and these alterations were significantly reversed by grape seed extract treatment (p<0.001). There were no differences between the grape seed extract- RTx, grape seed extract and control groups with regard to antioxidant activity (p>0.05). — The levels of antioxidant parameters on RTx-induced liver toxicity were restored to control values with grape seed extract therapy. Grape seed extract may be promising as a therapeutic option in RTx-induced oxidative stress in the rat liver.”

Another study related to liver protection by grape seed extract is described in the 2011 report Hepatoprotective and antioxidant activities of grapeseeds against ethanol-induced oxidative stress in rats.  “The present study was carried out to evaluate the hepatoprotective effect and antioxidant role of grape (Vitis vinifera L.) seeds (GS) against ethanol-induced oxidative stress. The hepatoprotective and antioxidant roles of the GS supplementation feed against ethanol-induced oxidative stress were evaluated by measuring liver damage serum marker enzymes, aspartate aminotransferase, alanine aminotransferase, γ-glutamyl transpeptidase and lactate dehydrogenase, antioxidant defence system such as GSH, glutathione reductase, superoxide dismutase, glutathione S-transferase and glutathione peroxidase and malondialdehyde (MDA) content in various tissues of rats. Rats were divided into four experimental groups: I (control), II (20 % ethanol), III (15 % GS) and IV (20 % ethanol+15 % GS). According to the results, the level of serum marker enzymes was significantly increased in group II as compared to that of group I, but decreased in group IV as compared to that of group II. Also, administration of GS-supplemented food restored the ethanol-induced MDA, which was increased near the control level. The results indicated that GS could be as important as diet-derived antioxidants in preventing oxidative damage in the tissues by reducing the lipid oxidation or inhibiting the production of ethanol-induced free radicals in rats.”

Grapeseed extract and wound healing

The wound healing properties of GSE have been known for some time.  The 2002 publication Dermal wound healing properties of redox-active grape seed proanthocyanidins reports “Angiogenesis plays a central role in wound healing. Among many known growth factors, vascular endothelial growth factor (VEGF) is believed to be the most prevalent, efficacious, and long-term signal that is known to stimulate angiogenesis in wounds. — Oxidants are known to promote both VEGF as well as tenascin expression. In summary, our current study provides firm evidence to support that topical application of GSPE represents a feasible and productive approach to support dermal wound healing.”

Clinical trials of GSE

A search of the clinicaltrials.gov database reveals 15 clinical trials of GSE:

1.    Enrolling by invitation: The Effect of Grape Seed Extract on Estrogen Levels of Postmenopausal Women

2.     Recruiting: The Effect of Grape Seed Extract on Blood Pressure in People With Pre-Hypertension

3.     Completed: The Efficacy of Red Grape Seed Extract on Lipid Profile and Oxidized Low-Density Lipoprotein (OX-LDL)

4.     Recruiting: Physiological Effects of Grape Seed Extract in Diastolic Heart Failure

5.     Unknown: Comparison of Ascorbic Acid and Grape Seed Extract in Oxidative Stress Induced by on Pump Heart Surgery

6.     Completed: Effect of Grape Seed Extract on Blood Pressure

7.     Completed: Effect of Grape Seed Extract Plus Ascorbic Acid on Endothelial Function

8.     Recruiting: Grape Seed Extract and Postprandial Oxidation and Inflammation

9.     Completed: Study of Growing Biofilm by an Antiplaque Mouthrinse

10.    Recruiting: IH636 Grape Seed Extract in Preventing Breast Cancer in Postmenopausal Women at Risk of Developing Breast Cancer

11.     Unknown: IH636 Grape Seed Extract in Treating Hardening of Breast Tissue in Women Who Have Undergone Radiation Therapy for Early Breast Cancer

12.      Recruiting: Beans, Inflammation and Satiety

13.       Recruiting: Efficacy of Provex CV Supplement to Reduce Markers of Inflammatory Cytokines and Blood Pressure in Subjects With Metabolic Syndrome

14.        Completed: Determination of the Efficacy and Safety of Psirelax in the Relief of the Disease in Psoriasis

15.         Completed: Study to Assess the Efficacy of Cognitex

Some comments

• Although many of the studies mentioned here are based on in-vitro or small-animal experiments, they indicate that GSE may serve as a powerful disease preventative and the life extending agent in humans.   Specifically, the studies suggest that GSE might act as An effective weapon against Alzheimers Disease, several deadly cancers, insulin resistance, diabetes, coronary heart disease, obesity, and liver failure.  The studies originate from multiple sources, appear to be done with integrity, and deserve to be taken seriously.
• Yet, GSE continues to be seen by most otherwise-informed people as yet-another unregulated dietary supplement which is probably “good for you.”  Despite claims by supplement sellers, its specific potential health and longevity values remain largely invisible to and ignored by both the general public and the medical establishment. 
• There appeared to be no published large-population studies related to the longitudinal impacts of taking GSE.  My impression is that completed clinical trials to date have mostly involved limited testing with proprietary GSE formulations and have so far resulted in few publications.  Until there are such published results, it cannot be expected that the medical establishment will begin to take GSE seriously. The same applies to a large number of other phyto-substances.
• Several of the disease conditions that may be amenable to GSE prevention/treatment according to the above publications like Alzheimer’s Disease, diabetes and prostate cancer remain as serious problems after decades of research focus on them.  Taking Alzheimer’s Disease as an example, it is amazing that in 2011 after some 40-50 years of research into sophisticated drug approaches to treatment costing tens of billions of dollars , that research has produced very few practical results basically leaving AD as an untreatable disease.  Only now is some focus shifting to what have could been obvious in the first place, aggressive investigation of plant polyphenols including GSE and coffee. The fact that these substances have largely remained in the mouse model testing phase is a comment on the economic structure of the pharmaceutical industry which cannot make large profits from natural substances.  The same kind of comment can be made about neuroblastoma, prostate cancer and coronary heart disease, and  cancers which might be amenable to GSE chemoprevention.
• Only one of the above-cited studies describes the health-creating actions of GSE in epigenetics terms, a situation I expect to change soon given that research focus is rapidly shifting to the epigenetic.  See the blog entry Aging as a genomic-epigenomic dance. Much more is known about the epigenetic impacts of certain other plant polyphenols like resveratrol and curcumin.  Following this blog entry I plan shortly to generate another on the epigenetics of plant polyphenols.

MEDICAL DISCLAIMER

FROM TIME TO TIME, THIS BLOG DISCUSSES DISEASE PROCESSES. THE INTENTION OF THOSE DISCUSSIONS IS TO CONVEY CURRENT RESEARCH FINDINGS AND OPINIONS, NOT TO GIVE MEDICAL ADVICE. THE INFORMATION IN POSTS IN THIS BLOG IS NOT A SUBSTITUTE FOR A LICENSED PHYSICIAN’S MEDICAL ADVICE. IF ANY ADVICE, OPINIONS, OR INSTRUCTIONS HEREIN CONFLICT WITH THAT OF A TREATING LICENSED PHYSICIAN, DEFER TO THE OPINION OF THE PHYSICIAN. THIS INFORMATION IS INTENDED FOR PEOPLE IN GOOD HEALTH. IT IS THE READER’S RESPONSIBILITY TO KNOW HIS OR HER MEDICAL HISTORY AND ENSURE THAT ACTIONS OR SUPPLEMENTS HE OR SHE TAKES DO NOT CREATE AN ADVERSE REACTION