Biological Abilities of Rice Bran-Derived Antioxidant Phytochemicals for Medical Therapy

Md.      Shafiqul Islam; Reiko      Nagasaka; Kazuyuki      Ohara; Takamitsu      Hosoya; Hiroshi      Ozaki; Hideki      Ushio; Masatoshi      Hori

Abstract

Rice bran contains important bioactive phytochemicals. Among these phytochemicals, steryl ferulates including γ-oryzanol and its major components such as cycloartenyl ferulate (CAF), 24-methylenecycloartanyl ferulate (24- mCAF), β-sitosteryl ferulate (β-SF), and campesteryl ferulate have been intensively studied due to their crucial roles in pathological processes. On the basis of experimental studies published during the last decade in relation to antioxidant, anti-inflammatory, anti-ulcerogenic, hypolipidemic, anti-neoplastic, anti-diabetic, and anti-allergic phenomena, these bioactive phytochemicals are reviewed in this paper. Particularly, in vivo and in vitro studies have clarified that rice bran phytosteryl ferulates mediate anti-inflammatory effects by down-regulating the inflammatory transcription factor, nuclear factor κB (NF-κB), which in turn reduces expression of inflammatory enzymes such as COX-2 and iNOS, and proinflammatory cytokines such as IL-1β, IL-6 and TNF-α. Moreover, rice bran phytosteryl ferulates up-regulate blood adiponectin levels via indirect activation of peroxisomal proliferator-activated receptor γ (PPARγ) through NF-κB inhibition. In this review, we discuss potential pharmacological aspects of rice bran phytosteryl ferulates in the clinical setting.

Keywords: Rice bran, Nuclear factor-κB (NF-κB), γ-oryzanol, Steryl ferulates, Adiponectin, Inflammation, Allergy, Antioxidant, cycloartenyl ferulate, rice milling process, HPLC