Various whitening cosmetics are available in the market, usually containing active whitening ingredients. However, most of the reported active ingredients have low dermal penetration due to their lipophilic structure. Therefore, it is necessary to develop effective whitening agents and novel formulations to address this. In previous studies, natural compounds such as chalcones have shown inhibitory effects on tyrosinase. However, most chalcone compounds have the disadvantage of poor water solubility, which restricts their dermal absorption. Flavokawain C (FKC) is a natural chalcone obtained from the root of the kava tree (Piper methysticum) and can also be obtained through organic synthesis. Since FKC is a chalcone, it is also water-insoluble, showing poor dermal absorption. In this study, electrospinning technology was used to develop FKC nanofibers (FKCNFs) to improve FKC's physicochemical properties. The results showed that FKCNFs significantly improved water solubility and percutaneous absorption. Based on the results of in vitro experiments with B16F10 melanoma cells, 10 µM FKCNFs repressed the expressions of melanogenesis-related proteins MITF and TRP2. Furthermore, cosmetic safety assessment revealed that FKCNFs displayed a good margin of safety. This study suggests that FKCNFs have great potential as an effective active ingredient for whitening cosmetics.
Keywords: cosmetic safety assessment; flavokawain C; nanofibers; skin whitening.