Resveratrol is a naturally occurring polyphenolic compound which has received much attention in the prevention of and therapy for cardiovascular diseases and cancers ( Fig. 1).1) Red grapes and wines contain considerable amounts of resveratrol. Resveratrol has many benefits for the skin. Topically applied resveratrol has been shown to possess strong antiproliferative and chemopreventive properties against skin carcinogenesis.2-4) Resveratrol affords substantial protection against skin damage from ultraviolet B (UVB) exposure. 5,6) Resveratrol shows antimicrobial activity against dermatophytes and herpes simplex virus. 7,8) Resveratrol can also be used in the dermocosmetic field because of its role as a phytoestrogen based on its ability to activate estrogen receptors.
9)The oral bioavailability of resveratrol is poor, leading to an irrelevant in vivo effect with oral administration compared to its powerful in vitro efficacy. 10) Resveratrol also has a short initial half-life (8-14 min) and is extensively metabolized in the body.11) Several phase I clinical trials are currently underway for oral resveratrol in humans at doses of as high as 7.5 g per day. This would require 2.7 kg of resveratrol a year at a current cost of ca. US$6800. Therefore it is becoming increasingly important to find ways to improve the bioavailability of and block the metabolism of resveratrol. Delivery of resveratrol via the skin is an attractive alternative to oral dosing for both topical and transdermal applications.No evidence currently exists in the literature to support the notion that a sufficient amount of resveratrol can be delivered to produce therapeutic benefits via a skin route. Designs of optimal formulations for resveratrol permeation via the skin are also lacking. The purposes of this study were to establish basic profiles of resveratrol permeability into and across the skin. The optimal pH and co-solvent of the vehicles for resveratrol were investigated for better permeation. The present study utilized Franz cells to explore the in vitro skin permeation of resveratrol. The drug amount retained within the skin reservoir was determined by in vitro and in vivo methods. Various skin membranes, including nude mouse skin, stratum corneum (SC)-stripped skin, delipidized skin, and cellulose membranes, were used as permeation barriers to elucidate the mechanisms and pathways. One particular problem common to drug delivery systems designed for use on the skin is the poor retention at the site of application. This problem can be resolved by incorporating bioadhesive hydrogels within the system. Hence, the ability of a series of hydrogel formulations to deliver topically applied resveratrol was examined. The permeability of piceatannol (Fig. 1), a resveratrol analogue with considerably higher activity, was also evaluated in this study. Resveratrol, the main active polyphenol in red wine, has been demonstrated to show benefits against skin disorders. The bioavailability of orally administered resveratrol is insufficient to permit high...