(418cg) The Role of Alpha-Mangostin on Cellular and Intracellular Level of Melanin Bio-Synthesis and Tyrosinase Activity of B16F1 Melanoma Cells

In the present study an inhibitory effect of melanin synthesis and tyrosinase activity of α-mangostin from mangosteen (Garcinia mangostana) pericarp extract has been investigated and verify on B16F1 melanoma cell line. Mangosteen pericarp contains mangostins of which a major constituent is α-mangostin. Alpha-mangostin has been known to possess antibacterial causing acne. Our investigation focused upon identification of anti-melanogenic efficacy of alpha-mangostin since it has been known to possess strong anti-oxidant activities. Determination of alpha-mangostin was carried out by using UV-spectrophotometric method and NMR analysis. Anti-melanogenic effect of alpha-mangostin was analyzed using cultured B16F1 melanoma cells. Cytotoxicity of that compound was measured using 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay; the highest concentration of the extract that did not affect cell viability was 5 µg/mL. Formation of melanin from cultured B16F1 melanoma was estimated using spectrophotometry. α-MSH-induced melanin synthesis was significantly inhibited with dose-dependent manner by treatment of alpha-mangostin, which was more powerful than kojic acid and arbutin. α-mangostin also directly inhibited intracellular melanin formation as well as intracellular tyrosinase activity of B16F1. The inhibition of intracellular tyrosinase activity was found to be exerted at the protein expression level when analyzed by immunoblot and tyrosinase zymography. The expression level of microphthalmia-associated transcription factor (MITF) was also reduced by treatment of alpha-mangostin. Down-regulation of intracellular tyrosinase expression seemed to correlate with decrease in MITF (microphtalmia-associated transcription factor) protein level since MITF is the key factor for the genes involved in melanogenesis. The overall results suggest that α-mangostin has strong and potent anti-melanogenic activity that is exerted by direct inhibition of tyrosinase enzyme activity and by down-regulation of the genes expression involved in the melanogenesis pathways. These finding will lead to the development of a safe pharmacological or cosmetic agent based on α-mangostin.