Abstract
Rice is a staple food consumed globally and its processing results in millions of tons of rice bran (RB) each year. RB is typically wasted or sold as feed, but recently considered a novel food product with human health benefits because it contains bioactive compounds and essential nutrients. RB has a higher lipid content than other cereal brans, and this unique composition merits attention across a global suite of varieties using non-targeted lipidomics. Methanolic extracts of 17 RB varieties were analyzed by UPLC-MS/MS and GC-MS. Phytoprostanes and phytofurans from 12 RB were performed by microLC-QTRAP-MS/MS conducted in MRM. Calrose-USA RB variety was used for dietary supplementation at 15 g/day for 28 days to hypercholesteremic children (NCT01911390). The plasma extract was analyzed by UPLC-MS/MS. Metabolite profiles of RB and plasma extracts were obtained and peak-identified by Metabolon. Lipid’s identifications were confirmed by an internal library of standards or recurrent unknown entities maintained by Metabolon. Data acquisition and processing of phytoprostanes and phytofurans were performed using MultiQuant3.0. Globally, 163 lipids were identified in RB (118 were present in all varieties). The RB lipidome includes 13 subgroups of chemical classifications. Phospholipids (34%) were the most diversified class. Other important classes based on potential bioactivity were glycolipids, oxylipins and sphingolipids. Oleic and linoleic acids were the most abundant lipids. Target analysis showed the presence of phytoprotanes(7) and phytofurans(3). Multivariate analysis showed discriminant RB lipids and biomarkers of RB consumption in plasma. Lipidomics were essential to characterize the RB lipid composition and revealed a core set of bioactive lipids that does not significantly differ by variety or growing conditions. Some lipids/classes could be dependent on processing conditions due to the distribution between the grain tissues. Novel lipid biomarkers of RB consumption will help to enhance our knowledge of human health benefits of dietary RB intake.