Relationship of radical scavenging activities and anthocyanin contents in the 12 colored rice varieties in Korea

Total polyphenolic, protein, lipid, and anthocyanin contents in grains of 12 Korean colored rice varieties were evaluated for their 2,2-di(4-tert-octylphenyl)-1-picrylhydrazyl) (DPPH) and 2,2- Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium (ABTS) radical- scavenging activities. Three anthocyanins, cyanidin-3-O-glucoside (Cy-3-G), petunidin-3-O-glucoside (Pt-3-G), and peonidin-3-O-glucoside (Pn-3-G), were also characterized by ultra performance liquid chromatography. Among the rice varieties, ‘Heugjinju’, ‘Heugseol’, and ‘Sintoheugmi’ contained high total phenolic contents compared to other varieties. Anthocyanin content was highest in ‘Heugjinju’; no anthocyanins were detected in ‘Hongjinju’ and ‘Jeogjinju’. Highest antioxidant activity was observed in ‘Heugjinju’ and ‘Jeogjinju’ exhibited the lowest activity. To determine the correlation of total polyphenolic and anthocyanin contents to antioxidant activity, linear regression analysis was carried out. The results showed total polyphenolic content was strongly correlated with antioxidant activity, suggesting total phenolic content as key factor in antioxidant activity of colored rice. ‘Heugjinju’, ‘Heugseol’, and ‘Sintoheugmi’ could have important nutritional value.