38 Emir. J. Food Agric ● Vol 32 ● Issue 1 ● 2020 Assessment of gamma oryzanol variability, an attractive rice bran bioactive compound M. Manuela Lageiro a , Ana Castanho a , Cristiana Pereira a , Ricardo C. Calhelha b , Isabel C.F.R. Ferreira b , Carla Brites a,c * a Instituto Nacional de Investigação Agrária e Veterinária, I.P., Unidade de Tecnologia e Inovação (INIAV/UTI), Av. da República, Quinta do Marquês, 2784-505 Oeiras, Portugal, b Centro de Investigação de Montanha (CIMO), Instituto Politécnico de Bragança, Campus de Santa Apolónia, 5300-253 Bragança, Portugal, c GREEN-IT, ITQB NOVA, Av. da República, 2780-157 Oeiras, Portugal INTRODUCTION Rice bran is a by-product of the rice milling process and comprises the outer layer of rice kernel which mainly includes the pericarp, aleurone, sub aleurone layer and germ, accounting for approximately 10 % of the total rice weight. Despite the claimed health benefts (Agarwal et al., 2016), rice bran is under-utilised as human food and commonly used as animal feed. In recent years, both academy and industry have shown a growing interest in gamma-oryzanol (GO), which is a mixture of bioactive compounds existing in the unsaponifable part of rice bran (Bhatnagar et al., 2014). GO have been studied for its health properties for decades, showing positive results for its cholesterol lowering effect in hyperlipidemic subjects (Bumrungpert et al., 2018). The cytotoxic properties of GO have also been explored in tumour-bearing mice (Kim et al., 2012), showing positive effects. In a recent study, Castanho et al. (2019) tested rice bran lipid extracts from different origins and pericarp colours against four human tumour cell lines (NCI-H460, HeLa, HepG2, and MCF -7); the results showed the effectiveness of the extracts and also a signifcant negative correlation between GO concentration and GI 50 values for HeLa, HepG2 and MCF7. The high availability of GO and its bioactive potential led to several applications in the cosmetic industry, nutrition and medicines (Peanparkdee and Iwamoto, 2019). GO applications in medicines are almost 50 % of the total market application, followed by nutrition and cosmetics uses (Market Reports World, 2018). The GO market demand was 11520 tons in 2014 and is expected to reach 18598 tons by 2022. Japan is the biggest producer, with about 68 % of the total production followed by China with almost 22 %. The GO is commercialised by several companies being the major ones Oryza Oil & Fat Chemical, TSUNO and Henry Lamotte OILS (Market Reports World, 2018). Chemically, GO is a mixture of ferulic esters of fatty acid or triterpene alcohols. However 95 % of GO is composed 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 infuenced by edaphoclimatic grown conditions. Two Portuguese rice varieties (Ceres and Maçarico) from 6 growing environments were analysed in order to explore the infuence 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 Maçarico; 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. Keywords: Cytotoxicity; Gamma-oryzanol; HPLC; Rice bran ABSTRACT Emirates Journal of Food and Agriculture. 2020. 32(1): 38-46 doi: 10.9755/ejfa.2020.v32.i1.2056 http://www.ejfa.me/ RESEARCH ARTICLE *Corresponding author: Carla Brites, Instituto Nacional de Investigação Agrária e Veterinária, I.P., Unidade de Tecnologia e Inovação (INIAV/UTI), Av. da República, Quinta do Marquês, 2784-505 Oeiras, Portugal, GREEN-IT, ITQB NOVA, Av. da República, 2780-157 Oeiras, Portugal. E-mail: carla.brites@iniav.pt Received: 24 September 2019; Accepted: 21 January 2020