ABSTRACT
Genetic diversity and growing environment cause differentiation of chemical constituents in purpleglutinous rice (Oryza Sativa L.) The colors of pericarp layers are characterized by anthocyanins profile. Theanthocyanins are cyanidin dihexoside, cyanidin 3-glucoside, cyanidin hexoside and peonidin 3-glucoside. They belong to parent class of flavonoids, which have antioxidant activity. In this study was to investigate for antioxidant activity and chemical constituents in purple glutinous rice Thailand local genotypes. The 36 local genotypes of purple glutinous rice were collected from the north and northeast of Thailand. K-Entry 12 Niewdam gave the highest antioxidant activity both DPPH radical scavenging assay (IC50 = 26.64 ± 1.14 μg/ml) and lipid peroxidation assay (IC50 = 50.22 ± 5.51 μg/ml). Furthermore, the highest content of total phenolics compound and cyanidin 3-glucoside were 1.73 ± 0.04 mg GAE/g (grain) and 536.57 ± 4.05 μg/g (grain), respectively. K-Entry 17 Niewdamtubmhoo gave high antioxidant activity by lipid peroxidation assay (IC50 = 70.24 ± 2.20 μg/ml) and high cyaniding 3-glucoside content [488.22 ± 3.45 μg/g (grain)]. This data demonstrated to cultivated K-Entry 12 Niewdam promotion. This genotype could be useful raw material for nutraceutical product.
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