Asian diets feature rice as a staple grain, contributing to nearly 90% of the world’s rice consumption. Brown rice, in particular, is known to have several health benefits. As a regular addition to the diet, it can help reduce body weight, lower cholesterol and suppress inflammation. Brown rice’s ability to neutralize reactive oxygen species and prevent cellular damage is vital to many of its health-promoting effects. Although previous studies have shown that the antioxidant compounds in brown rice can protect cells against oxidative stress, knowledge about which key compound contributes to these beneficial properties has remained a mystery.
In a recent study led by Professor Yoshimasa Nakamura of the Graduate School of Environmental and Life Sciences at Okayama University, researchers from Japan identified ferulated cycloartenyl (CAF) as the main “cytoprotective” or cell-protecting compound in rice. integral. CAF is a unique compound due to its hybrid structure. As Professor Nakamura explains, “CAF is a hybrid compound of polyphenol and phytosterol and is expected to be a potent bioactive substance with various pharmacological properties such as antioxidant effect and blood fat reducing effect”.
The study published on January 3, 2023 in volume 24, number 1 of the International Journal of Molecular Sciences, was co-authored by Hongyan Wu of Dalian Polytechnic University and Toshiyuki Nakamura of the Graduate School of Environmental and Life Science at the University of Okama. In it, the researchers provide evidence of the antioxidant properties of CAF, demonstrating that it can protect cells from the stress caused by hydrogen peroxide. Although hydrogen peroxide is a by-product of a cell’s metabolic processes, abnormal amounts of the compound can be toxic to cells and cause irreversible damage. Treatment of cells with CAF increased their resistance to toxic stress induced by hydrogen peroxide. Furthermore, CAF provided greater protection against hydrogen peroxide-induced stress compared to alpha-tocopherol and gamma-tocopherol, two other prominent antioxidant compounds that were previously speculated to be major contributors to brown rice’s antioxidant capacity.
According to the study’s estimates, the amount of CAF in the whole grain of brown rice is five times greater than that of other antioxidant compounds found in brown rice. Furthermore, CAF increases the concentration of heme oxygenase-1 or HO-1, an enzyme that facilitates the production of antioxidants. “We demonstrate here that CAF significantly increased the mRNA level of HO-1, the enzyme producing small molecular weight antioxidants, in concentrations similar to those required for cytoprotective effects in resistance to oxidative damage”, explains Professor Nakamura.
The researchers explored this mechanism of action further through experiments in which blocking HO-1 activity using inhibitors considerably reduced the antioxidant effect of CAF. The high abundance and unique mechanism of action are evidence that CAF is the main antioxidant contributing to brown rice.
Through this study, researchers not only unlocked the secret to the health benefits of brown rice, but also identified the component that is primarily responsible for these benefits. This will enable the use of CAF in the development of better new supplements and food products focused on consumer health. As an optimistic teacher Nakamura observes, “Our study may help in the development of new functional foods and supplements based on the functionality of CAFs, such as CAF-based nutraceuticals.“