Extraction solvent concentration affecting the anthocyanins and other phytochemicals profile and antioxidant properties of bran extracts of pigmented rice cultivars

Different concentrations (100%, 90%, and 80%) of extracting solvent methanol were used to determine antioxidant capacities of seven pigmented rice cultivars bran on the basis of phytochemicals and other antioxidants. TPCs of red-colored bran (Zag, Kaw quder, and Shel kaw) were the highest in 100% methanol, and those of black pigmented bran (Samarkand), lightly blackish (Kaw kareed) and brown (Gull zag, Teli zag), were the highest in 80% and 90% methanol. The higher avonoid contents in non-pigmented Gull zag and Teli zag resulted from luteolin-7-O-glucoside, quercetinhexoside, apigenin-7-Oglucoside, quercetin-3-O-galactoside, apigenin and (epi)catechin rather than anthocyanins in pigmented rice. Higher anthocyanin contents of extracts in lower methanol concentration resulted from higher percentage of Cyanidin-3-O-rutinoside, Pelargonidin-3-O-diglucoside, and cyanidin-3-O-galactoside. The antioxidant activity showed a similar trend in which the pigmented cultivars showed higher antioxidant activity in 100% methanol, except redcolored Shel kew with higher value in 90% methanol, while, among the light colored brown rice brans, Kaw kareed showed higher activities in 80% methanol and Teli zag in 90% methanol.