Padina boryana, a brown alga from the Maldives: inhibition of α-MSH-stimulated melanogenesis via the activation of ERK in B16F10 cells

The present study investigates the potent skin whitening ability of ethanol extract from the brown alga, Padina boryana (PBE) which was collected in the shores of Fulhadhoo Island, the Maldives, and its specific pathways of action. The effect of PBE which contains a rich amount of polyphenols was evaluated using B16F10 murine melanoma cells and provides insight to the underlying mechanisms with reference to the inhibition of melanin formation. Melanin synthesis and cellular tyrosinase inhibition were assessed in the α-MSH-stimulated melanocytes. Melanogenic pathway-related protein expressions were investigated via Western blotting. ERK 42/44 was particularly examined considering its involvement in the melanogenic pathway. Further, RT-qPCR techniques were involved in gene expression analysis. PBE dose-dependently inhibited the cellular melanin synthesis and tyrosinase levels. Western blotting revealed the potential of PBE to downregulate microphthalmia-associated transcription factor (MITF), tyrosinase, and tyrosinase-related protein-1 and protein-2 (TRP-1 and TRP-2). Moreover, results explained the phosphorylation of ERK was sustained via PBE and hence declined the ultimate melanin synthesis. Gene expression analysis reinforced the results obtained. The study provides substantial evidence to express the potential of PBE to inhibit B16F10 melanoma cell melanin synthesis. Concisely, results suggest the ability of PBE to be involved in medicinal and cosmeceutical applications.