Free radical scavenging and metal ion chelating properties of differently pigmented rice varieties

Abstract

Pigmented rice (Oryza sativa L.) becomes interestingly important in agroindustry because it contains high phytochemical compounds that can be antioxidants and metal ion chelating. This study attempted to relate the content of phenols, flavonoids, anthocyanin, and bioactive phytochemicals activity from differently pigmented rice (red and black) varieties. The bioactive phytochemical activities were evaluated by measuring free radical scavenging, hydroxyl scavenging, and metal ion chelating activity. The result showed that the highest phenolic, flavonoids, and anthocyanin content found in black rice, followed by red rice and non-pigmented rice. The anthocyanin in black rice was significantly higher (p  0.05) than in red and non-pigmented rice. The chlorophyll and carotenoids contents in all samples varied from 0.03 to 1.42 µg g-1 and 0.26 to 0.53 µg g-1, respectively. The antioxidant and metal ion chelating activities in black and red rice were significantly higher than non-pigmented rice. The correlation analysis showed that the phenols, flavonoids, and phytochemical pigments have a positive correlation (p  0.05) with antioxidant and metal chelating activity. In this study, black and red rice varieties showed the potential natural resources for the important effect of nutraceutical food products and pharmaceuticals.