Purple rice bran was separated and collected at two different milling periods, resulting in two bran
(outer and inner layer) fractions. The distribution of lipophilic and hydrophilic antioxidants and their
antioxidant activities in the two fractions were studied. The bran fractions were extracted with hexane
followed by methanol to obtain lipophilic and hydrophilic extracts, respectively. The total phenolic
content and free radical scavenging activity of the extracts were determined and compared. The
lipophilic extract from the outer bran fraction (OBF) exhibited a lower level of total tocols and γ-tocols,
compared with the inner bran fraction (IBF), while the levels of γ-oryzanol in both fractions were not
different. However, the lipophilic phenolic content and free radial scavenging activity of the OBF were
6.0 µg catechin equivalent (CE)/g and 5.6 µmol trolox equivalent (TE)/g and higher than those of the
IBF, respectively. For the hydrophilic extracts, the level of anthocyanins in the IBF (29.0 mg/g) was
8 times higher than that in the OBF. Also, the hydrophilic phenolic content and free radical scavenging
activity of the IBF were 489.1 µg CE/g and 433.6 µmol TE/g, respectively, while they were 113.9 µg
CE/g and 78.2 µmol TE/g in the OBF. Both hydrophilic extracts showed significantly higher phenolic
content and free radical scavenging activity than any lipophilic extract. The results of this study
indicated that the activity of purple rice bran hydrophilic antioxidants was much greater than that of
its lipophilic antioxidants and anthocyanins and γ-tocols largely located in the inner portion of purple
rice bran.