Inhibitory Effects of Caulerpa racemosa , Ulva intestinalis , and Lobophora challengeriae on Tyrosinase Activity and α-MSH-Induced Melanogenesis in B16F10 Melanoma Cells.

Melanogenesis involves a synthesis of melanin pigment and is regulated by tyrosinase. The addition of whitening agents with tyrosinase-inhibiting properties in cosmetics is becoming increasingly important. In this study, the ethanolic extracts from twelve seaweeds were assessed for tyrosinase-inhibiting activity using mushroom tyrosinase and melanin synthesis in B16F10 melanoma cells. The highest mushroom tyrosinase inhibition (IC 50 ) was observed with Lobophora challengeriae (0.15 ± 0.01 mg mL -1 ); treatment was more effective than kojic acid (IC 50 = 0.35 ± 0.05 mg mL -1 ), a well-known tyrosinase inhibitor. Three seaweeds, Caulerpa racemosa , Ulva intestinalis , and L. challengeriae , were further investigated for their ability to reduce melanogenesis in B16F10 cells. The ethanolic extracts of C. racemosa , U. intestinalis , and L. challengeriae showed inhibitory effects by reducing melanin and intracellular tyrosinase levels in B16F10 cells treated with α-melanocyte stimulating hormone in a dose-dependent manner. C. racemosa (33.71%) and L. challengeriae (36.14%) at 25 µg mL -1 reduced melanin production comparable to that of kojic acid (36.18%). L. challengeriae showed a stronger inhibition of intracellular tyrosinase (decreased from 165.23% to 46.30%) than kojic acid (to 72.50%). Thus, ethanolic extracts from C. racemosa , U. intestinalis , and L. challengeriae can be good sources of natural tyrosinase inhibitors and therapeutic or cosmetic agents in the future.