Antioxidant Activity of Tocopherols, Tocotrienols, and γ-Oryzanol Components from Rice Bran against Cholesterol Oxidation Accelerated by 2,2‘-Azobis(2-methylpropionamidine) Dihydrochloride

Abstract

The antioxidant activities of vitamin E (alpha-tocopherol, alpha-tocotrienol, gamma-tocopherol, and gamma-tocotrienol) and gamma-oryzanol components (cycloartenyl ferulate, 24-methylenecycloartanyl ferulate, and campesteryl ferulate) purified from rice bran were investigated in a cholesterol oxidation system accelerated by 2,2'-azobis(2-methylpropionamidine) dihydrochloride. All components exhibited significant antioxidant activity in the inhibition of cholesterol oxidation. The highest antioxidant activity was found for 24-methylenecycloartanyl ferulate, and all three gamma-oryzanol components had activities higher than that of any of the four vitamin E components. Because the quantity of gamma-oryzanol is up to 10 times higher than that of vitamin E in rice bran, gamma-oryzanol may be a more important antioxidant of rice bran in the reduction of cholesterol oxidation than vitamin E, which has been considered to be the major antioxidant in rice bran. The antioxidant function of these components against cholesterol oxidation may contribute to the potential hypocholesterolemic property of rice bran.

Comparative efficaciesin vitroof antibacterial, fungicidal, antioxidant, and herbicidal activities of momilatones A and B

“…Wu et al (1994) reported that wild rice kernels contain 2.1Á2.4% of phytic acid, a strong metal chelating agent, and therefore possess antioxidant activity, and noted the beneficial effects of using wild rice as an antioxidant. Especially after particle size reduction and cooking, some compounds, such as g-oryzanol were found as antioxidants in rice bran (Xu et al 2001) and cyaniding-3-glucoside has been reported to be one of major antioxidant compounds in black-hulled rice (Osawa 1999) For herbicidal activity, this study reconfirms that both M A and M B are plant growth inhibitors, and M B shows greater strength to inhibit noxious paddy weeds. This observation concurs with several previous reports.…”

The efficacy of vitamin C supplementation on reducing total serum cholesterol in human subjects: a review and analysis of 51 experimental trials

“…However a study on gamma-oryzanol, extracted from rice bran, found this compound able to significantly reduce cholesterol oxidation and the authors suggested that this may contribute to the potential hypocholesterolemic property of rice bran. 84 Although the underlying mechanisms are not yet fully understood, it is reasonable to assume that the hypocholesterolemic properties of vitamin C are most profound when total serum cholesterol is greater than 240mg/dl. However these effects may be limited to a subset of the population who possess an underlying vitamin C deficiency and therefore only certain groups of hypercholesterolemic subjects could potentially benefit from vitamin C supplementation.…”

Evaluation and comparison of in vitro antioxidant activities of unsaponifiable fraction of 11 kinds of edible vegetable oils

“…β‐carotenoid was found to inhibit the oxidation of rapeseed oil and could work with tocopherols to achieve higher antioxidative activities (Xu, Li, & Zhang, 1999). Xu, Hua, and Godber (2001) investigated the antioxidant activities of tocopherols, tocotrienols, and gamma‐oryzanol in a cholesterol oxidation system and found that all these compounds exhibited notable antioxidant activities.…”