Seven traditional Chinese herbal extracts fermented by Lactobacillus rhamnosus provide anti‐pigmentation effects by regulating the CREB/MITF/tyrosinase pathway

Skin pigmentation is resulted from several processes, such as melanin synthesis transportation and abnormal melanin accumulation in keratinocytes. Various studies have suggested that seven traditional Chinese herbal extracts from Atractylodes macrocephala, Paeonia lactiflora, Bletilla striata, Poria cocos, Dictamnus dasycarpus, Ampelopsis japonica and Tribulus terrestris (which we collectively named ChiBai), show several protective effects toward skin‐related diseases. Lactobacillus rhamnosus, a lactic acid bacterium, has been reported to treat skin inflammation and atopic dermatitis. In this study, the broth produced by the cofermentation of ChiBai with Lactobacillus rhamnosus was studied for its effects on skin pigmentation through in vitro and in vitro experiments. In the in vitro experiments, we found that the fermented broth of ChiBai (FB‐ChiBai) suppressed alpha‐melanocyte stimulating hormone (α‐MSH)‐induced melanogenesis in B16F0 murine melanoma cells without any cytotoxicity at a concentration of 0.5%. FB‐ChiBai significantly attenuated melanin production, tyrosinase activities and melanogenesis‐related signaling pathways. Treatment with FB‐ChiBai also reduced the nuclear translocation and promoter binding activities of MITF. In the in vivo experiments, FB‐ChiBai was topically applied to the dorsal skin of C57BL/6J nude mice and concurrently irradiated with UVB, three times a week for 8 weeks. The results indicated that FB‐ChiBai alleviated UVB‐induced hyperpigmentation by reducing epidermal hyperplasia and inhibiting the CREB/MITF/tyrosinase pathway. In conclusion, our data indicated that the anti‐melanogenic effects of FB‐ChiBai are mediated by the inhibition of CREB/MITF/tyrosinase signaling pathway. The findings suggest that FB‐ChiBai can protect against UV‐B irradiation and that it might be used as an agent in cosmetic products to protect against UVB‐induced hyperpigmentation.