Anti-tumor-promoting activity of a polyphenolic fraction isolated from grape seeds in the mouse skin two-stage initiation–promotion protocol and identification of procyanidin B5-3′-gallate as the most effective antioxidant constituent

Abstract

Procyanidins present in grape seeds are known to exert anti-inflammatory, anti-arthritic and anti-allergic activities, prevent skin aging, scavenge oxygen free radicals and inhibit UV radiation-induced peroxidation activity. Since most of these events are associated with the tumor promotion stage of carcinogenesis, these studies suggest that grape seed polyphenols and the procyanidins present therein could be anticarcinogenic and/or anti-tumor-promoting agents. Therefore, we assessed the anti-tumor-promoting effect of a polyphenolic fraction isolated from grape seeds (GSP) employing the 7,12-dimethylbenz[a]anthracene (DMBA)-initiated and 12-O-tetradecanoylphorbol 13-acetate (TPA)-promoted SENCAR mouse skin two-stage carcinogenesis protocol as a model system. Following tumor initiation with DMBA, topical application of GSP at doses of 0.5 and 1.5 mg/mouse/application to the dorsal initiated mouse skin resulted in a highly significant inhibition of TPA tumor promotion. The observed anti-tumor-promoting effects of GSP were dose dependent and were evident in terms of a reduction in tumor incidence (35 and 60% inhibition), tumor multiplicity (61 and 83% inhibition) and tumor volume (67 and 87% inhibition) at both 0.5 and 1.5 mg GSP, respectively. Based on these results, we directed our efforts to separate and identify the individual polyphenols present in GSP and assess their antioxidant activity in terms of inhibition of epidermal lipid peroxidation. Employing HPLC followed by comparison with authentic standards for retention times in HPLC profiles, physiochemical properties and spectral analysis, nine individual polyphenols were identified as catechin, epicatechin, procyanidins B1-B5 and C1 and procyanidin B5-3'-gallate. Five of these individual polyphenols with evident structural differences, namely catechin, procyanidin B2, procyanidin B5, procyanidin C1 and procyanidin B5-3'-gallate, were assessed for antioxidant activity. All of them significantly inhibited epidermal lipid peroxidation, albeit to different levels. A structure-activity relationship study showed that with an increase in the degree of polymerization in polyphenol structure, the inhibitory potential towards lipid peroxidation increased. In addition, the position of linkage between inter-flavan units also influences lipid peroxidation activity; procyanidin isomers with a 4-6 linkage showed stronger inhibitory activity than isomers with a 4-8 linkage. A sharp increase in the inhibition of epidermal lipid peroxidation was also evident when a gallate group was linked at the 3'-hydroxy position of a procyanidin dimer. Procyanidin B5-3'-gallate showed the most potent antioxidant activity with an IC(50) of 20 microM in an epidermal lipid peroxidation assay. Taken together, for the first time these results show that grape seed polyphenols possess high anti-tumor-promoting activity due to the strong antioxidant effect of procyanidins present therein. In summary, grape seed polyphenols in general, and procyanidin B5-3'-gallate in particular, should be studied...

Effect of Ankaferd blood stopper® on tendon healing: an experimental study in a rat model of Achilles tendon injury

“…[23] Thymus vulgaris has anti-oxidative effects, [24] and Vitis vinifera has anti-tumor and anti-atherosclerotic effects. [25,26] The action mechanism of ABS maintains the formation of an encapsulated protein network, [19] and this ABS-induced protein network formation involves the erythrocytes in particular. [19] Hemostatic efficacy of ABS was reported in multiple studies.…”

Grape extracts suppress the formation of preneoplastic foci and activity of fatty acid synthase in rat liver

“…In recent years, grape, grape extracts, and wine have been public interest for chemopreventive effect on human health, such as cancer prevention (Bomser et al, 1999;Carbo et al, 1999;Zhao et al, 1999), the induction of vasorelaxation (Flesch et al, 1998), and the modulation of plasma lipid profiles (Yamakoshi et al, 1999). The most of evidences have been reported on the polyphenolic compounds in some parts of grapes.…”

“…Recently, some researchers reported the physiological modification by polyphenolic compounds from grape, which include the cancer prevention (Bomser et al, 1999;Carbo et al, 1999;Zhao et al, 1999), the suppression of inflammation, the induction of vasorelaxation (Flesch et al, 1998), the decrease of blood pressure (de Moura et al, 2002), and so on. Resveratrol, the natural compound rich in red grapes, has the possibility of the phytoestrogenic action with the preventive or therapeutic effect for the hormonerelated diseases, because its similar structure to estrogen (Jang et al, 1997;Gehm et al, 1999;Lu and Serrero, 1999).…”

Aqueous Extract of Peanut Skin and Its Main Constituent Procyanidin A1 Suppress Serum IgE and IgG1 Levels in Mice-Immunized with Ovalbumin

“…ELISA for OVA-specific IgE was measured according to the manufacturer's recommendations using the rat anti-mouse OVA-specific IgE ELISA assay kit (Dainippon Sumitomo, Tokyo, Japan). 21) Toxicological Study To investigate the toxicities of PSE, GP, AP and PA by oral administration, body weight of mice in these regimens was checked every day and the activity of hepatic marker enzyme, alanine aminotransferase (ALT, EC 2.6.1.2), in plasma collected on day 21 was also measured using a commercial diagnostic assay kit (Transaminase C-II test Wako, Wako Pure Chem., Tokyo, Japan).…”