We have shown in previous work that extracts of grape seeds (GSE) and skins, grape juice, and many red wines exhibit endothelium-dependent relaxing (EDR) activity in vitro. This EDR activity involves endothelial nitric oxide (NO) release and subsequent increase in cyclic GMP levels in the vascular smooth muscle cells. The NO/cyclic GMP pathway is known to be involved in many cardiovascular-protective roles. The current study focuses on the isolation and identification of EDR-active compounds (procyanidins) from GSE. Crushed Concord grape seeds were extracted with methanol and the extract was separated into seven fractions (A-G) on a Toyopearl TSK-HW-40 column. EDR-active fractions (D-G) were further separated into 25 individual compound peaks by HPLC, 16 of which were EDR active (threshold for relaxation ranged between less than 0.5 microg/mL and greater than 4 microg/mL). Procyanidin identification was accomplished by electrospray-ion trap mass spectrometry (ES-ITMS), MS/MS, and by tannase treatment and acid thiolysis, followed by HPLC and ES-ITMS of the products. Activity of isolated procyanidins tended to increase with degree of polymerization, epicatechin content, and with galloylation. These EDR-active compounds (many of which also possess antioxidant activity), individually or in the form of wines, juices, or nutritional supplements, may be useful in preventing or treating cardiovascular diseases.
Fitzpatrick DF, Bing B, Maggi DA, Fleming RC, O'Malley RM. Vasodilating procyanidins derived from grape seeds. Ann N Y Acad Sci. 2002 May Department of Pharmacology, College of Medicine, University of South Florida, Tampa, Florida 33612-4799, USA.