Assessment of gamma oryzanol variability, an attractive rice bran bioactive compound

Gamma-oryzanol is a compound present on rice bran, which has been studied for its bioactive properties, including its cytotoxic activity. The gamma-oryzanol biosynthesis occurs on the lipidic membrane of the plant and can be influenced by edaphoclimatic grown conditions. Two Portuguese rice varieties (Ceres and Macarico) from 6 growing environments were analysed in order to explore the influence of the growing conditions on the gamma-oryzanol content, its constituents, and cytotoxic effect against 4 human tumour cell lines (NCI-H460, HeLa, HepG2, and MCF-7). The overall variability of gamma-oryzanol concentration was from 1.56 g/Kg to 3.19 g/Kg, Ceres reveals higher values than Macarico; those concentrations also varied with the growing environment. The environment was also determinant for the individual concentration of the 3 gamma-oryzanol compounds (cycloartenyl ferulate, 24-methylenecycloartanyl ferulate, and campesteryl ferulate). A cytotoxic effect was observed for all the tested tumour cell lines and also varied with the growing environment.This study was financially supported by FEDER (Fundo Europeu de Desenvolvimento Regional, Portugal) under the Program PT2020, Project POCI-01-0247- FEDER-017931 - ArrozBig - Development of rice products with low glycemic index; which also supported C. Pereira research grant. The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Program PT2020 for financial support to CIMO ID/AGR/00690/2019 and R. Calhelha contract and to FCT, Portugal for the PhD grant of A. Castanho (SFRH/BD/120929/2016).