Alternative Medicine Review 2000 (Apr); 5 (2): 144–151 ~ FULL TEXT
Anne Marie Fine, CPA, ND Candidate 2000
In 1534, a French explorer, Jacques Cartier, led a winter expedition up the St. Lawrence River in New York. The group soon found themselves trapped by ice and forced to survive on salted meat and hard biscuits. The crew began to show signs and symptoms of scurvy, long before anyone knew what caused it. Due to a chance meeting with a Native American, who showed them how to make a tea from the bark and needles of pine trees, the men survived. 
Professor Jacques Masquelier, of the University of Bordeaux, France, read the book eventually written by Cartier, became intrigued with the story and postulated that the pine bark must contain vitamin C as well as flavonoids having ascorbate-like effects. Thus began an exhaustive study of these compounds which Masquelier named pycnogenols, a term no longer used in the scientific community today except as a trademark for OPCs derived from French maritime pine bark. Today they are known as oligomeric proanthocyanidin complexes (OPCs) or procyanidolic oligomers (PCOs). Professor Masquelier confirmed the structure, effects, and lack of toxicity of these proanthocyanidins. 
Masquelier went on to patent the method of extracting OPCs from pine bark in 1951, and from grape seeds in 1970 (which research has supported as the preferential source). 
The biological properties of flavonoids, including proanthocyanidins, have been extensively reviewed. [2, 7-9] In addition to their free radical scavenging and antioxidant activity, [1, 8, 10, 11] proanthocyanidins have been reported to have antibacterial, antiviral, anticarcinogenic, anti-inflammatory, anti-allergic, and vasodilatory actions. [2, 12] Proanthocyanidins have also been shown to inhibit lipid peroxidation, platelet aggregation, capillary permeability and fragility, and to affect enzyme systems including phospholipase A2, cyclooxygenase, and lipoxygenase. [1, 2, 12, 13]
The free radical scavenging abilities of proanthocyanidins have been well documented and command the most attention. [1, 2, 12, 14] In vivo studies have shown grape seed proanthocyanidin extract is a better free radical scavenger and inhibitor of oxidative tissue damage than vitamin C, vitamin E succinate, vitamin C and vitamin E succinate combined, and beta carotene.  Moreover, in vitro experimental results have demonstrated proanthocyanidins have specificity for the hydroxyl radical [1, 2] in addition to having the ability to non-competitively inhibit the activity of xanthine oxidase, a major generator of free radicals, [1, 9, 14] elastase, collagenase, hyaluronidase, and beta-glucuronidase. 
OPCs have also demonstrated preferential binding to areas characterized by a high content of glycosaminoglycans (epidermis, capillary wall, gastrointestinal mucosa, etc.). This feature makes them useful for decreasing vascular permeability and enhancing capillary strength, vascular function, and peripheral circulation.