Rice bran, a resource that has not been utilized much in the past, actually contains many functional components, each of which is now being utilized not only in foods and cosmetics, but also in pharmaceuticals. This paper focuses on γ-oryzanol, a characteristic component of rice, and introduces its wide range of functional properties, including its usefulness for the skin, mind and body, and women, as well as its effects on health maintenance, including adult diseases.

γ-Oryzanol is abundantly contained in rice bran and rice bran oil, which is extracted and refined from rice bran, and is well known as a physiologically active ingredient with many beneficial functions. Since γ-oryzanol is a mixture of ferulic acid esters of either triterpene alcohols or phytosterols, it has been studied as a mixture and few studies have focused on individual γ-oryzanol molecular species. Recent studies have revealed that each γ-oryzanol exhibits unique functionalities, and it is important to develop analytical methods for individual γ-oryzanol molecular species and to clarify the relationship between their chemical structures and biological activities. In recent years, as interest in functional foods increases against the backdrop of regulations such as Foods for Specified Health Uses (FOSHU) and Foods with Functional Claims, research focusing on these γ-oryzanol molecular species is expected to make progress. In this review, we will focus on the latest analytical techniques for γ-oryzanol molecular species in foods. Some examples of their applications (evaluation of absorption and metabolism of individual γ-oryzanol molecular species) will also be introduced.

Rice serves as an excellent source of antioxidants such as vitamin Es, ferulic acid, and γ-oryzanols as well as starch. Since these antioxidants are abundant in the rice bran layer and germ parts, it has been considered that brown rice is more physiologically active than white rice. However, it remains unclear how much the chemical or biological antioxidant activity of brown rice differs from that of white rice in terms of quality and quantity. Our research group has shown that, at the level of extracts, white rice exhibits chemical or biological antioxidant activity comparable to that of brown rice. In addition, the contribution of cycloartenyl ferulate (CAF), a major molecular species of γ-oryzanols, to the biological antioxidant activity of rice was found to be much greater than that of vitamin Es. Based on these results, this review highlights the potential of CAF for health functions based on their antioxidant properties.