Skin‐Lightening Efficacy of Leatherleaf Fern Extract and a Leatherleaf Fern‐Based Facial Serum In Vitro and Clinical Trial

BACKGROUND: Hyperpigmentation, caused by excessive melanin accumulation, is a significant cosmetic concern in dermatology. Natural compounds are receiving attention as safe and effective skin-lightening agents due to their antioxidant properties and ability to inhibit melanin synthesis. AIMS: To investigate the antioxidant and melanin biosynthesis inhibitory effects of leatherleaf fern water extract (LFWE) and the skin-lightening efficacy of a facial serum containing LFWE through in vitro and clinical trials: MATERIALS AND METHODS: The antioxidant and tyrosinase inhibitory activities of LFWE were confirmed in vitro, along with its inhibitory effects on factors involved in melanin biosynthesis. Its skin-lightening effects were then validated through clinical trials. RESULTS: LFWE demonstrated excellent 1,1-diphenyl-2-picrylhydrazyl and ABTS cation radical scavenging activity and inhibited mushroom tyrosinase activity in a concentration-dependent manner. LFWE also suppressed melanin biosynthesis in B16-F10 melanoma cells without toxicity up to 500 μg/mL and significantly inhibited the protein expression levels of tyrosinase, TRP-1, and TRP-2, which promote melanin production. Clinical trials of a serum containing LFWE showed that it reduced the melanin index after 4 and 8 weeks, thereby confirming its skin-lightening effects. CONCLUSION: LFWE exerts excellent antioxidant effects and inhibits the expression of factors involved in melanin biosynthesis, thereby demonstrating skin-lightening effects. Moreover, LFWE-containing serum significantly reduced melanin indices in clinical trials.