Melanin is the pigment that determines skin color. Melanin synthesis is catalysed by the enzyme tyrosinase and is controlled by TYR, TYRP1 and TYRP2 genes. The objective of this study was to evaluate the anti pigmentation property of palm tocotrienol rich fraction by determining melanin synthesis and expression of genes involved in its regulation in skin melanocytes. Palm tocotrienol rich fraction (TRF) which contains 75% a-tocotrienol and 25% tocopherol was used to inhibit melanin synthesis which was determined by determining melanin level and tyrosinase enzyme activity. Expression of TYR, TYRP1 and TYRP2 genes was determined by quantitative real time reverse transcriptase polymerase chain reaction (real time RT-PCR). Primary culture of skin melanocytes was divided into two groups; untreated control and cells that were treated with 500 µg/ml tocotrienol rich fraction for 24 h. Our results showed that there was a reduction in tyrosinase activity and melanin content in melanocytes treated with tocotrienol rich fraction compared to control (p < 0.05). Expression of TYRP2 gene in melanocytes treated with tocotrienol rich fraction was also decreased (p < 0.05) compared to control. In conclusion, palm tocotrienol rich fraction has an anti pigmentation property that inhibit melanin synthesis by inhibiting tyrosinase activity and down regulating TYRP2 gene expression.
Key words: Melanin synthesis, gene expression, tocotrienol rich fraction, skin melanocytes