Although this is the first time these
apigenin derivatives have been detected in black–purple rice seeds,
they are known to occur in red rice grains (Hirawan et al., 2011).
Moreover, Chi, Lee, Kim, Kim, and Chung (2007) reported free
(poly)phenolic compounds, such as catechin, chlorogenic acid
and p-coumaric acid in one red and two white varieties of grain
rice. Gunarate, Wu, Li, Bentota, Corke & Cai (2013) identified caffeic,
p-coumaric, ferulic and sinapinic acids in eight traditional
red-grained and three light brown-grained rice varieties. However,
these (poly)phenolic compounds were not present in the Japanese
black–purple rice seeds used in the present study.