Although the white-spotted flower chafers beetle, Protaetia brevitarsis, receive attention to explore useful active ingredient for the preventive effect of liver-related diseases, little is known about cosmetic effect. Here we report that the larva extract of the white-spotted flower chafers has functional cosmetic effect using the B16F10 melanoma cell and HaCaT keratinocyte cell. The ethanol extract of hot-air dried P. brevitarsis larvae showed the inhibitory activity of tyrosinase (an enzyme that regulates the melanin production) and remarkably inhibit melanin biosynthesis in the B16F10 melanoma cell. Further, the ethanol extract induced the expression of hyaluronic acid synthetase (HAS2/HAS3), which produce hyaluronan related to epidermal structure, and indeed increased hyalurona in HaCaT keratinocyte cell. Consequently, P. brevitarsis could be new functional cosmetic material for whitening and moisturizing effect.

Conventional chemical ecology approach for identification of semiochemicals from natural sources is based on isolation of active ingredients after fraction and bioassay. Instead, we identify potential semiochemicals using reverse chemical ecology approach. In this way, we discovered an odorant receptor (CquiOR136) for DEET, which was not know how and why it work. Additionally, we identified a link between this synthetic repellent and methyl jasmonate, thus suggesting that DEET might work by mimicking defensive methyl jasmoante from plant. Moreover, we serendipitously found that a receptor, CquiOR36, responded to an old sample of nonanal in ethanol. Careful investigation led us to identify the active ligand as acetaldehyde (derived from ethanol) from “contaminants” in the old nonanal sample. We explored that acetaldehyde in a wide range of dose both attracts gravid mosquito and stimulate them to lay eggs in oviposition trays.