Curcuma longa extract inhibits the activity of mushroom tyrosinase and the growth of murine skin cancer B۱۶F۱۰ cells

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 B۱۶F۱۰ cells. Methods: C. longa rhizomes were cold-extracted using ethanol ۷۰% and yielded ۱۵.۳% 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 B۱۶F۱۰ cells. Results: Triplet peaks of RP-HPLC chromatogram revealed that curcuminoids were available in ECL. The level of bisdemethoxycurcumin was ۶.۳۳۰۶% (tR = ۱۲.۶۴۶ minutes), demethoxycurcumin was ۳.۱۴۱۴% (tR = ۱۳.۶۷۵ minutes), and curcumin was ۸.۳۷۵۴% (tR = ۱۴.۸۰۲ minutes). ECL had a weak inhibitory activity towards mushroom tyrosinase with IC۵۰ = ۵۶۴.۸ μg/mL, while the IC۵۰ = of kojic acid was ۵۵.۷۰ μg/mL. Both ECL and kojic acid had moderate toxicity to B۱۶F۱۰ cells (IC۵۰ survival growth rates were ۹۸.۰۶ μg/mL and ۶۵.۵۴ μg/mL, respectively). Curcumin was highly toxic to B۱۶F۱۰ cells (IC۵۰ = ۱۴.۴۲ 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 B۱۶F۱۰ cells. However, further studies are needed to verify its antimelanogenesis and anticancer properties.