Oligomeric proanthocyanidins

From: http://en.wikipedia.org/wiki/Proanthocyanidin

In 1948 Jack Masquelier discovered oligomeric proanthocyanidins (OPCs) in the skin of a peanut by accident. Oligomeric proanthocyanidins are a class of flavonoid complexes. OPCs are found in most plants and thus are a part of the human diet. Especially the skin, seeds and seed coverings of plants contain large amounts of oligomeric proanthocyanidins. They can be found in large quantities in grape seed extract and skin, in red grapes, in the red skins of peanuts, in coconuts, apples (dimeric procyanidin B2), in cocoa, and in the bark of Pinus pinaster (formerly known as Pinus maritima). It can also be found in sea buckthorn oil.[27]
Oligomeric proanthocyanidins can be obtained by the mean of Vaccinium pahalae in vitro cell culture.[28]
[edit] Biological signifiance
In nature, it is possible that OPCs serve as a plant defense against herbivory.
[edit] Health benefits
Proanthocyanidins have strong anti-oxidant properties. Foods rich in proanthocyanidins have high oxygen radical absorbance capacity which has been linked to numerous health benefits such as weight management, cell health, and cardiovascular health.[29] Scientists continue to research the relevance of proanthocyanidins' strong anti-oxidant properties in vivo for such applications as cancer prevention and cardiovascular health.[30] USDA does maintain a database of proanthocyanidin content and structure for many foods, but dietary supplements proanthocyanidin content has not been well-documented.[31]
In the human body, they might act as antioxidants (free radical scavengers).[citation needed] OPCs may help protect against the effects of internal and environmental stresses such as cigarette smoking and pollution, as well as supporting normal body metabolic processes. The effects may include depressing blood fat, emolliating blood vessels, lowering blood pressure, preventing blood vessel scleroses, dropping blood viscidity and preventing thrombus formation.[32]
Additionally, studies have shown that OPCs may prevent cardiovascular diseases by counteracting the negative effects of high cholesterol on the heart and blood vessels.
A French maritime pine bark extract of OPCs, Pycnogenol, has been shown to improve microcirculation, retinal edema and visual acuity in the early stages of diabetic retinopathy.[33] Further study has shown that Pycnogenol maintains antioxidant and anti-inflammatory properties, selectively binds to collagen and elastin in the body, and aids in the production of endothelial[34] nitric oxide. Pycnogenol has also been shown to help normalize blood glucose (sugar) levels,[35] and delay sugar absorption.[36]
OPCs are available from fresh grapes, grape juice, and red wine. Although in milligrams per ounce red wine may contain more OPCs than red grape juice, red grape juice contains more OPCs per average serving size. An 8 ounce serving of grape juice averages 124 milligrams OPCs, while a 5 ounce serving of red wine averages 91 milligrams.[37][38] Many other foods and beverages also contain high amounts of OPCs, but very few come close to the levels found in red grape seeds and skins (which readily disperse into grape juice when crushed).[37]
[edit] Grape seed oil controversy
A number of grape seed oil vendors have claimed that grape seed oil is high in OPCs. However independent studies have indicated that grape seed oil is actually the grape product with the lowest concentration of OPCs. This is because OPCs are polar molecules which have very low solubility in nonpolar solvents such as oils.