Inhibitory effects of a rice hull constituent on tumor necrosis factor alpha, prostaglandin E2, and cyclooxygenase-2 production in lipopolysaccharide-activated mouse macrophages.
Isovitexin, isolated from rice hull of Oryza sativa, has been characterized as a potent antioxidant. Its antioxidant activity, determined on the basis of inhibition of lipid peroxidation by the Fenton reaction, was comparable with that of alpha-tocopherol, a well-established antioxidant. Isovitexin was able to reduce the amount of hydrogen peroxide production induced by lipopolysaccharide (LPS) in mouse macrophage RAW264.7 cells. In this study, we assessed its effects on the production of tumor necrosis factor alpha (TNF-alpha), prostaglandin E2 (PGE2), and the expression of cyclooxygenase-2 (COX-2) in LPS-activated RAW 264.7 macrophages. Isovitexin inhibited the release of TNF-alpha, a proinflammatory cytokine, upon LPS activation with a 50% inhibitory concentration (IC50) of 78.6 microM. Isovitexin markedly reduced LPS-stimulated PGE2 production in a concentration-dependent manner, with an IC50 of 80.0 microM. The expression of COX-2 was also inhibited by isovitexin treatment. Our results suggest that suppression of ROS-mediated COX-2 expression by isovitexin is beneficial in reducing inflammation and carcinogenesis.
Huang
Sheng-Tung
ST
College of Medicine, Taipei Medical University, Wu-Hsing Street, Taipei 110, Taiwan.
Chen
Chien-Tsu
CT
Chieng
Kur-Ta
KT
Huang
Shih-Hao
SH
Chiang
Been-Huang
BH
Wang
Leng-Fang
LF
Kuo
Hsien-Saw
HS
Lin
Chun-Mao
CM
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D047310:Apigenin / Q000494:pharmacology; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000096:biosynthesis*; D015232:Dinoprostone / Q000096:biosynthesis*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism*; D051379:Mice; D012275:Oryza / Q000737:chemistry*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
D000975:Antioxidants; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D047310:Apigenin; D051546:Cyclooxygenase 2; D015232:Dinoprostone; C049772:isovitexin