Target-action of Antioxidants using Iontophoresis.

Antioxidants obtained from plant resources can be delivered topically for dermatological and pharmaceutical applications. The present study evaluated plant-derived phenolic acids (gallic, caffeic, and ferulic acid) alone or in combination, as well as gel-based topical formulations (hydroxyethylcellulose, HEC, 1.5%; or ammonium acryloyldimethyltaurate, ACR, 1.5%) containing these compounds, using five in vitro measures of antioxidant activity: 2,2-diphenyl-1-picryl-hydrazyl (DPPH method), 2,2 azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS method), oxygen radical absorption using fluorescein (ORAC-FI), ferric reducing antioxidant power (FRAP method), and β-carotene/linoleic acid assays. The concentrations applied in the formulations were 0.6% (w/w) for the isolated compounds and 0.6% (w/w) for each phenolic acid when considering the application of the mixture. Phenolic acid levels were also quantified using a validated high-performance liquid chromatography method. Gallic acid showed the greatest antioxidant activity and was selected for a study of skin permeation following gel application to porcine skin, with or without cathodic iontophoresis. Gallic acid retention in deeper skin layers was promoted by iontophoresis, and increased skin antioxidant activity was detected after only 20 min of iontophoresis. Furthermore, the present study demonstrated the importance of polymeric gelling agents for optimizing the antioxidant activity of these topical antioxidant preparations.