Target action of antioxidants using iontophoresis.

Background: The use of antioxidants in applications for topical use seems promising, however, many studies must be performed to ensure processes and products that can effectively bring benefits to combat the action of free radicals in the skin. For topical antioxidants to be effective against free radicals from the skin, it is essential that the antioxidants compounds permeate the different skin layers, to reach deeper layers of the epidermis in active form and stay there for a sufficient time to cause the beneficial effects.

Aim: This work aimed to evaluate the antioxidant action of formulations with phenolic compounds as well as to comprehend the skin retention profile of these actives.

Methods: The antioxidant potential was recognized with isolated phenolic acids (gallic, caffeic, and ferulic acid) or in combinations, using different in vitro methods (DPPH ABTS , FRAP , β-carotene/linoleic acid system and ORAC). The skin retention study was performed through in vitro assay with Franz's diffusion cell associating, or not, the cathodic iontophoresis.

Results: 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. The present study demonstrated the importance of polymeric gelling agents for optimizing the antioxidant activity.

Conclusion: The cathodic iontophoresis represents a promising strategy to promote a target action of antioxidants in the skin.