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Vitamin P, Flavonoids, Polyphenols: from Grape Seed and Grape Skin

Vitamin P, Flavonoids, Polyphenols: from Grape Seed and Grape Skin

Article by Don Goldberg

Vitamin P? — Grape Seed & Grape Skin Flavonoids

In the thirties, Hungarian investigators discovered that flavonoids, commonly present in the human diet, had relevant properties in respect to the cardiovascular system.1 Flavonoids and other polyphenols were described as exerting a vitamin-like action, which the investigators named vitamin P activity, primarily associated with the capacity to improve capillary resistance and to normalize an altered capillary permeability. In the following years, a controversial debate took place in the scientific community about the validity of the term vitamin P, and finally this denomination was rejected since the role of polyphenols was recognized to be not comparable to that of vitamins. Nevertheless what remained well demonstrated by a number of pharmacological tests, pharmacokinetic evidences and clinical trials was the tropism of some polyphenols for the cardiovascular system. Within this huge family of natural products, some specific compounds, such as grape procyanidins, demonstrated an elevated specificity in targeting the cardiovascular system. This constituted the basis for the development (in some European countries) of prescription drugs containing standardized extracts from grape seeds (a part of the plant particularly rich in procyanidins) and devoted to the relief of disturbances of microcirculation. Recently, another interesting finding originating from epidemiology, suggested that red wine (very rich in polyphenols) could exert a preventive action in respect of the development of chronic diseases of the cardiovascular system, such as atherosclerosis.2 This evidence was revealed mostly from the evaluation that the low incidence of cardiovascular diseases in France is paralleled by a very high dietary intake of lipids, but concomitantly by an elevated consumption of red wine. Scientists agree that this last event well explains the apparent "French Paradox" and they suggest that the "antioxidant properties" of red wine polyphenols could be good candidates for the preventive effect.3,4

Currently, a number of papers are available dealing with the biological properties of natural polyphenols, most of the studies having been conducted in vitro and focused on monomeric products. In this respect, the studies on grape procyanidins constitute an unique example, since they deal with oligomeric polyphenols and include both in vitro and in vivo investigations. Most of the studies performed on grape procyanidins were made possible by the availability of standardized extracts which could guarantee the constancy of composition of such a complex chemical mixture. One such extract is LEUCOSELECT™, manufactured by Indena.
The composition of LEUCOSELECT™ is as follows:
(+)-catechin, (-)-epicatechin and gallic acid (15%)
(-)-epicatechin gallate, dimers, trimers, tetramers and their gallates (80%)
pentamers, hexamers, heptamers and their gallates (5%).
LEUCOSELECT™ demonstrated in vitro the following properties 6,8
DPPH scavenging activity
Hydroxyl radical entrapping capacity