Daidzin suppresses melanogenesis through ERK and AKT signaling pathways mediated MITF proteasomal degradation

Daidzin, a prominent isoflavone found in soybeans, Pueraria lobata, and various legumes, has been extensively investigated for its diverse pharmacological activities, which include anticancer, antioxidant, anti-inflammatory, antiepileptic, and alcohol detoxification properties. Previous studies have shown that the dichloromethane fraction of Pueraria lobata stem (DCM-PLS) exhibits significant anti-melanogenic activity, with daidzin identified as the principal active compound. However, the precise role of daidzin in pigmentation remains incompletely understood. This study aimed to investigate the effects of daidzin on pigmentation and to elucidate the underlying mechanisms. Our findings revealed that daidzin not only inhibited basal melanin production but also reduced melanin synthesis induced by α-MSH, ACTH, and UV exposure. The effects of daidzin were primarily mediated through the activation of the extracellular signal-regulated protein kinase (ERK) and protein kinase B (AKT) pathways. Upon activation, these pathways facilitated the ubiquitination and degradation of Melanocytes Inducing Transcription Factor (MITF), resulting in decreased expression of tyrosinase, TRP-1, and TRP-2, ultimately inhibiting melanogenesis. Importantly, our research further demonstrated that daidzin reduced pigmentation in both zebrafish and human skin explants, highlighting its potential application as a therapeutic approach for disorders related to skin pigmentation.