ConclusionAA and its derivates showed an in vitro antiox-idant activity but AA had the best antioxidanteffect. In in vivo efficacy studies on human skin,all studied formulations enhanced stratum cor-neum moisture content when compared with thebaseline values. Only the formulation containingAA led to provoked alterations in TEWL valuesand the formulation containing MAP causedalterations in the viscoelastic-to-elastic ratio.This way, vitamin C derivatives did not show the same effects of AA on human skin; however,MAP showed other significant effects in improving skin hydration, which is very important for normal cutaneous metabolism and also to prevent skin alterations and early ageing.