Anti-Melanogenic and Anti-Inflammatory Activities of Triterpenoids from Jatropha macrantha

Three pentacyclic triterpenes, the oleanolic acid, azarolic acid, and 3-oxo euscaphic acid, were isolated from the hexane extract of Jatropha macrantha Mull.Arg., Euphorbiaceae. The structures of these compounds were elucidated by spectroscopic means. The cytotoxicity of the compounds was evaluated against the THP-1, HEK001, NIH-3T3, and B16-F10 cell lines by the XTT assay. All analyzed compounds were less cytotoxic than the positive control (actinomycin D, CC50 0.00797 μM). The anti-inflammatory activity was evaluated by means of inhibition of NF-κB production and activation of Nrf2 of these compounds against THP-1, HEK001, NIH-3T3, and B16-F10 cell lines. The three compounds had anti-inflammatory activity; however, azarolic acid had a statistically significant higher inhibitory activity of NF-κB production (IC50 1.87–1.98 μM) than the positive control (celastrol, IC50 7.41–7.49 μM). In addition, it had an activation potential of Nrf2 (EC50 2.29–2.85 nM) similar to the positive control (CDDO-Me, EC50 0.11–0.12 nM). The anti-melanogenic activity was evaluated by means of melanin and tyrosinase inhibition of these compounds against the B16-F10 cell line. The three compounds had anti-melanogenic activity; however, azarolic acid was the most active for the inhibition of tyrosinase (IC50 0.95 μM) and inhibition of melanin (IC50 5.21 μM) while the positive control, the kojic acid, had an IC50 of 13.94 μM.