Effects of Cocoa Extracts on Endothelium-Dependent Relaxation

Abstract

The aim of this study was to examine the effects of procyanidins derived from cocoa on vascular smooth muscle. Two hypotheses were tested: 1) extracts of cocoa, which are rich in procyanidins, cause endothelium-dependent relaxation (EDR), and 2) extracts of cocoa activate endothelial nitric oxide synthase (NOS). The experiments were carried out on aortic rings obtained from New Zealand White rabbits. The polymeric procyanidins (tetramer through decamer of catechin) caused an EDR. In addition, the Ca(2+)-dependent NOS activity, measured by the L-arginine to L-citrulline conversion assay, was significantly increased in aortic endothelial cells exposed to polymeric procyanidins, whereas monomeric compounds had no such effect. These findings demonstrate that polymeric procyanidins cause an EDR that is mediated by activation of NOS.

(–)-Epicatechin mediates beneficial effects of flavanol-rich cocoa on vascular function in humans

“…Experiments were carried out by using isolated rabbit (New Zealand Whites) aortic rings as detailed in ref. 39. We controlled for artifacts that might be caused by hydrogen peroxide, a product of flavanol decomposition in buffers and media (40), by adding catalase (400 units͞ml) into the tissue bath.…”

Acute cocoa flavanol supplementation improves muscle macro- and microvascular but not anabolic responses to amino acids in older men

“…These beneficial effects have been linked to flavanols, a sub-group of flavonoids -the polyphenolic family of antioxidant chemicals, which are found in abundance in various foods (Heiss et al 2005), including, but not limited to red wine, black tea, apples, onions and cocoa (Campia & Panza 2008). The benefits of flavanol consumption are purported to be due to increased nitric oxide (NO) synthase activity and therefore an increased supply of bio-active NO (Fisher et al 2003;Karim et al 2000), with numerous studies showing that both acute (Duffy et al 2001;Engler et al 2004;Heiss et al 2003;Leikert et al 2002) and chronic flavanol supplementation can improve endothelium dependent vasodilation (Fisher et al 2003;Karim et al 2000). Interest in flavanols spread when initial beliefs that the acidic environment of the stomach degraded flavanol oligomers were disproven (Kwik-Uribe & Bektash 2008;Rios et al 2002).…”

Oligomeric Cocoa Procyanidins Possess Enhanced Bioactivity Compared to Monomeric and Polymeric Cocoa Procyanidins for Preventing the Development of Obesity, Insulin Resistance, and Impaired Glucose Tolerance during High-Fat Feeding

“…EC and CPCs have been shown to possess antiobesity and anti-diabetic properties [24][25][26] . Emerging data suggest that these bioactivities may be highly correlated to flavanol DP [27][28][29] . Recently, Yamashita et al 30 demonstrated that a tetrameric cocoa flavanol significantly improved insulin secretion in mice compared to monomeric, dimeric, and trimeric flavanols (EC, PC B 2 , and PC C 1 , respectively) 30 .…”