Anti-tyrosinase activity of purple glutinous rice Thailand local genotypes

ABSTRACT

Purple glutinous rice (Oryza sativa L.) is widely cultivated in the north and northeast of Thailand. Its purplish black pericarp layers is rich in anthocyanin. Purple glutinous rice is a good source of fiber, minerals, and several important amino acids; furthermore, the high content of γ-oryzanol and the anthocyanin which were identified as cyanidin 3-glucoside and peonidin 3-glucoside. The aim of this study was to examine anti-tyrosinase compoundin difference local genotypes of purple glutinous rice. Among 36 genotypes of purple glutinous rice were collected, K-Entry 9 showed the highest anti-tyrosinase activity (IC50 = 369.5 μg/ml). By means of column chromatography and high performance liquid chromatography, the ethyl acetate extract yielded purified compound which inhibited tyrosinase enzyme activity with IC50 = 64.2 ± 1.04 μg/ml. The structure was elucidated by spectroscopic method as protocatechuic acid. This valuable data would be useful for standardization of purple glutinous rice products used in anti-aging and whitening cosmetics. Also, this was an alternative process for value added to purple glutinous rice Thailand local genotypes