Pycnogenol

Proanthocyanidins found in French maritime pine bark and grape seed extract work directly to help strengthen all the blood vessels and improve the delivery of oxygen to the cells. Proanthocyanidins also have an affinity for cell membranes, providing nutritional support to reduce capillary permeability and fragility. Although flavonoids are widespread in nature, the powerful proanthocyanidin compound is most abundant and available from the bark of the maritime pine and in grape seeds, or pips. In addition, the particular proanthocyanidins found in the proprietary extract of maritime pine bark called Pycnogenol have been shown to optimize the production of nitric oxide in the artery walls so as to relax them and allow greater blood flow and reduced pressure. Additionally, this same preparation, Pycnogenol, has been found to normalize platelet adhesion (aggregation) so as to facilitate normal blood flow.
http://en.wikipedia.org/wiki/Proanthocyanidin