Effects of lactic acid bacteria-fermented soy milk on melanogenesis in B16F0 melanocytes

In our previous studies, soy milk fermented with lactic acid bacteria (LAB) was found to improve the nutritional and bioactivity values of consumed foods. In this study, we used soy milk fermented with LAB strains to evaluate the effects of LAB-fermented soy milk on melanogenesis. It was found that β-glucosidase-producing LAB strains exhibited a higher degree of β-glucosidase activity and significantly higher aglycone isoflavone content (p < 0.05). The extracts from Lactobacillus plantarum TWK10 (TWK10)-fermented soy milk inhibited mushroom tyrosinase activity and melanin production in B16F0 melanocytes more strongly compared to non-fermented and other LAB strains-fermented soy milk. TWK10-fermented soy milk also suppressed the activity and expression of tyrosinase, microphthalmia-associated transcription factor (MITF), and p38 mitogen-activated protein kinase (MAPK). Extracellular regulated kinase activation and MITF degradation were not affected by this pathway. Thus, TWK10-fermented soy milk inhibits melanogenesis by suppressing tyrosinase activity and expression through the positive regulator, MITF, and p38 MAPK inactivation. These results may be used to develop health foods and cosmetics, and to increase the range of applications of traditional agricultural products.