Vol.:(0123456789) 1 3 Toxicology and Environmental Health Sciences https://doi.org/10.1007/s13530-020-00063-5 ORIGINAL ARTICLE Anti‑melanogenic efect of the aqueous ethanol extract of Ginkgo biloba leaf in B16F10 cells Bonhee Ku 1  · Dongsoo Kim 2  · Eun‑Mi Choi 1,2 Accepted: 14 July 2020 © Korean Society of Environmental Risk Assessment and Health Science 2020 Abstract Objective Ginkgo biloba leaf extract (GLE) shows diverse biological efects, and it is used as an ingredient in some skincare products. GLE and a few purifed compounds are known to inhibit melanogenesis. However, there are very few reports on the molecular mechanisms underlying the regulation of melanogenesis by GLE. We investigated the anti-melanogenic efect of a GLE, an aqueous ethanol extract of Ginkgo biloba leaves, and the molecular mechanisms involved. Methods B16F10 murine melanoma cells were treated with various concentrations of GLE (0–100 μg/mL), together with 0.1 nM α-melanocyte stimulating hormone (α-MSH), which was used to induce melanogenesis. Cell proliferation, total melanin content, cellular reactive oxygen species (ROS) content, and cellular tyrosinase activity were measured. The cellular levels of microphthalmia-associated transcription factor (MITF), tyrosinase, and tyrosinase-related protein 1 (TYRP1), and the phosphorylation levels of Akt, glycogen synthase kinase 3β (GSK3β), and β-catenin were analyzed. Results GLE inhibited α-MSH-induced melanogenesis and ROS generation, without causing cytotoxicity. GLE decreased cellular tyrosinase activity and the levels of MITF, tyrosinase, and TYRP1. GLE decreased the phosphorylation of Akt (Ser473) and GSK3β (Ser9) and increased the phosphorylation of β-catenin (Ser33/37/Thr41). Conclusions Our results suggest that GLE can inhibit α-MSH-induced melanogenesis in B16F10 cells by downregulating the expression of melanogenic proteins, i.e., MITF, tyrosinase, and TYRP1. The downregulation of melanogenic protein expression appears to result from stimulating β-catenin degradation, which is induced by phosphorylation by GSK3β that is activated via inhibition of Akt. GLE’s antioxidant activity can also play a role in its anti-melanogenic efect. Keywords Ginkgo biloba leaf · Melanogenesis · MITF · β-catenin · GSK3β · Reactive oxygen species Introduction Melanin is a pigment produced in melanosomes in melano- cytes present in the epidermal basal layer. The mature mela- nosomes are transferred to the neighboring keratinocytes in the outer layers of the epidermis. The epidermal melanin determines the skin color, and it protects the skin against the damage caused by an excessive UV exposure by absorbing and dissipating the UV energy [1]. Melanin is synthesized from L-tyrosine through a process of complex reaction steps, which are catalyzed by enzymes such as tyrosinase, tyrosinase-related protein 1 (TYRP1), and TYRP2. Tyrosinase is the rate-limiting enzyme in mel- anin synthesis, which catalyzes the initial two reactions, i.e., hydroxylation of tyrosine to 3,4-dihydroxyphenylala- nin (DOPA) and oxidation of DOPA to dopaquinone [2]. Melanogenesis process can be regulated by many factors, including genetic, endocrine, and environmental factors such as UV. The microphthalmia-associated transcription factor (MITF), a basic helix-loop-helix/leucine zipper (bHLH- Zip) transcription factor, is a crucial transcription factor that regulates the expression of proteins that are impor- tant for the melanogenesis, diferentiation, and survival of melanocytes [3]. MITF is regulated at both transcriptional and posttranslational levels. Cyclic AMP response ele- ment-binding protein (CREB), which is activated through phosphorylation (Ser133) by protein kinase A (PKA), in response to the increase in cyclic AMP (cAMP), stimulates * Eun-Mi Choi eunmi@inu.ac.kr 1 Department of Cosmetic Science and Management, Graduate School, Incheon National University, Incheon 22012, Korea 2 Department of Chemistry, Incheon National University, Incheon 22012, Korea