Anti-melanin deposition activity and active constituents of Jatropha multifida stems

Jatropha multifida is a medicinal plant that belongs to the Euphorbiaceae family. Our investigation revealed that the chloroform extract of J. multifida stems showed anti-melanin deposition activity against α-melanocyte stimulating hormone (α-MSH)- and 3-isobutyl-1-methylxanthine (IBMX)-induced melanogenesis in the mouse melanoma cell line (B16-F10). Further fractionation and purification of the major constituents led to the isolation of two coumarins (1 and 2) and seven known lignoids (3-9). All isolated compounds exhibited anti-melanin deposition activities against the mouse melanoma cell line (B16-F10) with IC₅₀ values ranging from 37.5 to 560.1 µM, without any cytotoxicity even at high concentrations, except for 8. Further mechanistic studies suggested that 9 downregulated tyrosinase mRNA expression, while the anti-melanin deposition activities of 4 and 8 appeared to be unrelated to tyrosinase inhibition and the downregulated expression of the key melanogenesis-associated mRNAs. These results suggested that J. multifida could possess potent skin whitening ingredients.