Introduction: Tyrosinase is considered an important target of melanin biosynthesis inhibitors. Curcuma longa L. has been used in the Javanese traditional whitening cosmetics. This work aimed to explore the effect of C. longa extracts on mushroom tyrosinase activity and the cytotoxicity of the extract towards murine skin cancer B16F10 cells.
Methods: C. longa rhizomes were cold-extracted using ethanol 70% and yielded 15.3% w/w of extract (ECL). The presence of curcuminoids in ECL was determined by reversed-phase high-performance liquid chromatography (RP-HPLC). ECL was assessed for its inhibitory effects on mushroom tyrosinase activity using L-DOPA as substrate and kojic acid as the positive control drug. The cytotoxicity of ECL and curcumin was studied in B16F10 cells.
Results: Triplet peaks of RP-HPLC chromatogram revealed that curcuminoids were available in ECL. The level of bisdemethoxycurcumin was 6.3306% (tR = 12.646 minutes), demethoxycurcumin was 3.1414% (tR = 13.675 minutes), and curcumin was 8.3754% (tR = 14.802 minutes). ECL had a weak inhibitory activity towards mushroom tyrosinase with IC50 = 564.8 µg/mL, while the IC50 = of kojic acid was 55.70 µg/mL. Both ECL and kojic acid had moderate toxicity to B16F10 cells (IC50 survival growth rates were 98.06 µg/mL and 65.54 µg/ mL, respectively). Curcumin was highly toxic to B16F10 cells (IC50 = 14.42 µg/mL).
Conclusion: Taken together, ECL might be able to prevent melanogenesis via the inhibition of tyrosinase activity, and interestingly, it could inhibit the growth of murine skin cancer B16F10 cells. However, further studies are needed to verify its antimelanogenesis and anticancer properties.