Isolation and Characterization of Endothelium-Dependent Vasorelaxing Compounds from Grape Seeds

Abstract

Previous work has shown that red wines, grape juices, and other grape products cause endothelium-dependent relaxation (EDR) of blood vessels in vitro by increasing nitric oxide production. In this paper we describe the isolation and characterization of some of the compounds responsible for EDR activity. Concord grape seeds were extracted with methanol and the compounds were separated by Toyopearl TSK HW-40S chromatography. Resulting fractions (primarily phenolic acids, catechins, and proanthocyanidins) were further separated semipreparatively by reversed-phase HPLC, and peaks were collected and bioassayed for EDR activity using the rat aorta preparation. EDR-active compounds were subsequently characterized by HPLC retention times and electrospray-ion-trap mass spectrometry. The compounds exhibiting the most EDR activity were proanthocyanidin trimers, tetramers, pentamers, and polymers and their gallates, as well as a dimer gallate (EC50 values in the range of 0.6-2.5 microg catechin equivalents/mL). These compounds should be useful for in vitro and in vivo studies, particularly as they relate to improvement of cardiovascular function.

A randomised trial to investigate the effects of acute consumption of a blackcurrant juice drink on markers of vascular reactivity and bioavailability of anthocyanins in human subjects

“…The urinary yield of anthocyanins was reported as 0.036± 0.043% of the ingested dose after consumption of a blackcurrant juice similar to that consumed in this study (Hollands et al, 2008). Vasodilatory effects of cyanidin-3-glucoside, and delphinidin glycoside-rich and cyanidin glycoside-rich juices have been reported but only at higher levels of intake (Stein et al, 1999;Fitzpatrick et al, 2000;Xu et al, 2004;George et al, 2009).…”

Resveratrol Inhibits Nicotinic Stimulation-Evoked Catecholamine Release from the Adrenal Medulla

“…The present findings that resveratrol inhibited the CA secretory responses evoked by both nicotinic receptor stimulation as well as by membrane depolarization from the rat adrenal medulla also seem to support the fact that, in in vivo studies, PCRW lowers blood pressure in normotensive and hypertensive rats (Mizutani et al, 1999;Diebolt et al, 2001). It has been reported that red wines and grapes exhibit endothelium-dependent relaxation of blood vessels via enhanced generation and/or increased biological activity of NO, leading to the elevation of cGMP levels (Fitzpatrick et al, 1993;Fitzpatrick et al, 1995;Fitzpatrick et al, 2000;Zenebe et al, 2003). Therefore, these experimental results indicate that resveratrol-induced inhibitory activity of CA secretory response evoked by stimulation of nicotinic receptors may contribute at least partly to its hypotensive mechanism.…”

Plant derived therapeutics for the treatment of Metabolic Syndrome

“…Interestingly, through bioassay-guided fractionation of crude GSE using the rat aortic vasorelaxation model, increasing EDR activity was demonstrated to correlate with increased concentrations of procyanidin oligomerization [56,57]. This finding suggests that highly polymerized polyphenols (Figure 1f), although not studied extensively in other botanicals, may play a significant role in the hypotensive activities of GSEs [56,57].…”

“…Several in vitro studies have demonstrated endothelium-dependent relaxation (EDR) as the primary mechanism of action for GSE [55][56][57]. Interestingly, through bioassay-guided fractionation of crude GSE using the rat aortic vasorelaxation model, increasing EDR activity was demonstrated to correlate with increased concentrations of procyanidin oligomerization [56,57].…”