Antiaging and antioxidant effects of topical autophagy activator: A randomized, placebo-controlled, double-blinded study.

BACKGROUND: Recently, potential roles of autophagy in skin homeostasis received many interests. But, little has been reported for the potential antiaging effects of autophagy activator. OBJECTIVE: With the newly synthesized autophagy activator, heptasodium hexacarboxymethyl dipeptide-12 (Aquatide™) in vitro and clinical efficacy of the topical autophagy activator as an antiaging cosmeceutical ingredient was evaluated. METHODS: Antioxidant effect of Aquatide™ was evaluated by radical scavenging assay. In vitro effect was assessed by measuring the cytotoxicity of hydrogen peroxide in cultured normal human epidermal keratinocytes. Clinical evaluation was performed by a randomized, placebo-controlled, double-blinded study. Antioxidant efficacy was observed by measuring the carbonylated proteins in stratum corneum (SC) by fluorescein-5-thiosemicarbazide (FTZ) staining. RESULTS: Radical scavenging effects of Aquatide were observed with the ABTS assay, and significant reduction in hydrogen peroxide-induced cytotoxicity was observed in Aquatide™-treated cells. Autophagy inhibitor treatment abrogated cytoprotective effects of Aquatide™. In a clinical study, statistically significant increase in skin elasticity was observed after 4 and 8 weeks. Quantitative analysis of carbonylated proteins in SC also showed significant reduction in Aquatide™-treated group, which is consistent with the in vitro data. CONCLUSION: These results suggest that autophagy plays important roles in antioxidant system and aging process in skin, and topical autophagy activators can be potential cosmeceutical ingredients for skin antiaging.