Anti-Tyrosinase Properties Of Different Species of Turmeric And Isolation of Active Compounds From Curcuma Amada

Turmeric is traditionally used as a skin cosmetic in some religious and cultural occasions on the Indian subcontinent. In this study, we compared the tyrosinase inhibitory properties of four Curcuma spp., namely, C. xanthorrhiza, C. aromatica, C. amada, and C. zedoaria. Bioassay-guided isolation and purification of tyrosinase inhibitors using silica gel column and high-performance liquid chromatography. Structural identification of the compounds was conducted using 1H NMR, 13C NMR, and liquid chromatography-tandem mass spectrometry. C. amada showed the highest tyrosinase inhibitory activity, with an IC50 of 53.4 μg/mL. Therefore, it was chosen for the isolation and purification of tyrosinase inhibitors. The purified compounds were zederone (1), furanodienone (2), 1,5-epoxy-3-hydroxy-1-(3,4-dihydroxy-5-methoxyphenyl)-7-(4-hydroxyphenyl) heptanes (3), 3,5-dihydroxy-1-(3,4-dihydroxyphenyl)-7-(4-hydroxy-3-methoxyphenyl) heptanes (4) and 1,5-epoxy-3-hydroxy-1-(3,4-dihydroxy-5-methoxyphenyl)-7-(4-hydroxy-3-methoxyphenyl) heptanes (5). The IC50 values for the mushroom anti-tyrosinase activity of compounds 1, 2, 3, 4, and 5 were 108.2, 89.2, 92.3, 21.7, and 41.3 µM, respectively. These compounds also inhibited intracellular tyrosinase activity, thus reducing melanin synthesis in B16F10 melanoma cells. Compound 4 showed significantly stronger anti-tyrosinase activity than that of arbutin (a positive control drug). No significant difference was observed in the tyrosinase inhibitory effect between compound 5 and arbutin. Our findings strongly suggest that C. amada is a promising source of natural tyrosinase inhibitors to prevent melanogenesis and could be used as a whitening cosmetic.