Polyphenols

Green tea polyphenols have been included in a growing number of skin care products for their antioxidant and anti-inflammatory effects [32]. These polyphenolic compounds are called epicatechins, and the most powerful member of this group is called epigallocatechin-3-gallate (EGCG). Studies have demonstrated the ability of EGCG pretreated skin to inhibit erythema, myeloperoxidase activity, and inflammation following UVB irradiation [33, 34]. Studies have also demonstrated UV-radiated skin pretreated with green tea polyphenols shows a histologic decrease in sunburn cells [35, 36]. In addition, pretreated skin had less DNA damage as evidenced by fewer UV-induced DNA pyrimidine dimers formed than in untreated skin.

Another polyphenol that differs from those found in green tea are the procyanidins. Procyanidins are powerful free radical scavengers whose richest source is from the seeds of red grapes. Grapeseed extract is rich in polyphenols, and studies have reported it to have higher antioxidant activity than both vitamins C and E [37, 38]. In fact, in mice, grapeseed polyphenols have demonstrated greater inhibition of lipid peroxidation than green tea polyphenols [39]. The role of polyphenols, whether from green tea or grapeseed extract, has a great deal of potential as part of a growing natural anti-aging skin care market.With all natural ingredients, however, it is important to standardize extraction methods as well as assays for their activity.