Tyrosinase Inhibitory Activity of Combined Camellia sinensis (L.) Kuntze and Oryza sativa (L.) Extract Incorporated Serum

Abstract

Aims: The efficacy of combined Camellia sinensis (L.) Kuntze (green tea) and Oryza sativa (rice bran) extract in inhibiting the activity of tyrosinase was evaluated. Methodology: Phytochemical analysis of the extracts was performed to detect various contituents using standard techniques, including LC-MS and GC-MS. Water- and oil-based serum were formulated with an optimum amount of combined Camellia sinensis and Oryza sativa extract. Tyrosinase assay of both formulas was determined with the presence of DOPA as oxidase activity. Results: Anthocyanins and fatty acids were found in rice bran, whereas the green tea sample contained mainly catechins including GC, EGC, EC, EGCG, and ECG. The combination of the two extracts of equal amount (w_w) at 100 ppm achieved the optimum percentage of tyrosinase inhibitory activity (56.76% ± 0.15). Tyrosinase inhibitory activity of two serum products (water- and oil-based) containing 1% of combined Camellia sinensis and Oryza sativa extract (ratio of 5:5) were 18.7% ± 0.38 and 22.5% ± 0.41, respectively. Conclusion: The combination of Camellia sinensis and Oryza sativa extract with the ratio of 5:5 (w_w) achieved the highest percentage of tyrosinase inhibitory activity. The catechins in green tea extract protecting against lipid oxidation of fatty acids of rice bran oil might play a key role in enhancing tyrosinase inhibitory activity.