The alkaline hydrolysis of rice bran was performed according to
the method described by Adom and Liu (2002) with minor modifications.
Briefly, rice bran (1.2 kg) was grinded and homogenized in
a Polytron homogenizer before being extracted three times with
12 L 80% acetone (1:10, w/v) at ambient temperature for 24 h.
The supernatant was discarded after each extraction. The residues
were then digested with 2 M 10 L sodium hydroxide at ambient
temperature for 2 h with shaking under nitrogen gas. The mixture
was neutralized with an appropriate amount of hydrochloric acid
and extracted with hexane to remove lipids. The final solution
was extracted five times with EtOAc, and the combined EtOAc
extracts were concentrated under vacuum at 40 C to give the
crude extract (8.2 g).