I'm not an expert in this area. Therefore, only very general comments. The main pathway of antioxidant degradation is the oxidation by dioxygen. By definition, the antioxidants are very easily oxidized. Therefore, you can stabilize antioxidants working under inert atmosphere. Ascorbic acid is one of the most powerful antioxidant. You can add it to protect, e.g. polyphenols.

Yurii V Geletii Thanks for the sharing. We are also thinking about ascorbic acid but we're unsure if it can modify the skin integrity during our experiment.