Tocopherols, Tocotrienols, and γ‐Oryzanol Contents in Japonica and Indica Subspecies of Rice (Oryza sativa L.) Cultivated in Brazil

Abstract

Whole rice contains several fat‐soluble phytochemicals such as tocopherols, tocotrienols, and γ‐oryzanol which have been reported to possess beneficial health properties. This study was conducted to determine whether brown rice belonging to indica and japonica subspecies were distinguishable from each other regarding the concentration of these compounds by analyzing 32 genotypes. The fat‐soluble compounds were analyzed by normal‐phase HPLC in a single run. The variability of the compounds analyzed was high, but the mean content of γ‐oryzanol across all samples was significantly higher (P < 0.01) in japonica (246.3 mg/kg) than in indica rice (190.1 mg/kg). Similar differences were found for total vitamin E contents which were 24.2 mg/kg in japonica and 17.1 mg/kg in indica rice, respectively. In japonica rice, α‐tocopherol, α‐tocotrienol, and γ‐tocotrienol were the most abundant homologs, while in indica rice the most abundant were γ‐tocotrienol, α‐tocopherol, and α‐tocotrienol. A significant Pearson coefficient (0.80, P < 0.001) between α‐tocopherol and α‐tocotrienol levels was found, independent of the subspecies. Both compounds were positively correlated to total tocols and γ‐oryzanol contents. Although more studies are needed to evaluate the interference of growing rice in different environments and multiple years, the present study provided information on natural variations of the vitamin E isomers and the γ‐oryzanol contents in different rice genotypes.

Bioactive compounds in rice during grain development

“…The contents of tocol homologues and coryzanols are listed in Table 3. The total content of tocols in KFSW and TK16 ranged from 23.7 to 45.7 lg/g dry meal and 30.4 to 59.3 lg/g dry meal, respectively, in agreement with the literature reported by Heinemann et al (2008) that the average content of vitamin E in japonica rice was significantly higher than in indica rice. In the immature grains, the total tocols content was about 2-fold higher than that in the mature seeds.…”

Changes in lipid substances in rice during grain development

“…In a previous study, the bioactive lipid components of rice seed at different degrees of milling were investigated and shown to decrease markedly as milling progressed (Ha et al, 2006). There are also several studies on other factors that affect lipid composition, such as processing, cultivation condition, and genotypes (Asaoka et al, 1984;Bergman and Xu, 2003;Dolde et al, 1999;Ha et al, 2006;Heinemann et al, 2008;Lerma-García et al, 2009;Miller and Engel, 2006;Wang et al, 2013;Yoon et al, 2014). Shin et al (1997) reported that rice bran stabilization and oil extraction lead to decreases in the levels of vitamin E (17-24) and c-oryzanol (9)(10)(11)(12).…”

Comparative study of phenolic compounds in different Brazilian rice (Oryza sativa L.) genotypes

“…The several bran layers that cover the endosperm and protect the grain from the environment contain a complex mixture of biologically active unique phytochemicals such as g-oryzanol, tocopherols, tocotrienols, which together with other vitamins and minerals are believed to exert important roles in protection against various degenerative diseases (Goffman and Bergman, 2004). Therefore, increasing the habitual intake of whole rice would be an attractive way to take advantage of the assigned health benefits from these phytochemicals (Heinemann et al, 2008). Gamma-oryzanol that has not been found in significant amounts in fruit and vegetables has received attention for its ability to reduce serum cholesterol and for its potent antioxidant properties (Wilson et al, 2002).…”