Modulation of the activity of pro-inflammatory enzymes, COX-2 and iNOS, by chrysin derivatives.
Chrysin, a natural flavone compound found in plants, has anti-inflammatory activity that has been previously explained in part by the suppression of promoter activities of pro-inflammatory enzymes, cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). Here we present evidence that several chrysin derivatives modulate the activities, as well as the expression, of COX-2 and iNOS enzymes. Nitrate production triggered by lipopolysaccharide (LPS) was suppressed by treatment of cultured Raw264.7 cells (mice macrophage/monocyte) with chrysin, 5-hydroxy-7-methoxyflavone (Ch-2), and 5,7-diacetylflavone (Ch-4). Interestingly, COX-2 enzyme was strongly inhibited by Ch-4 (IC(50)=2.7 microM) but not by other derivatives. Furthermore, the inhibition of COX enzyme by Ch-4 was selective for COX-2 over COX-1. Three-dimensional modeling showed that Ch-4 fits well into the binding pocket of COX-2. The modeling suggested that a hydrogen bond exists between the oxygen of the ketone group at the 7-position of Ch-4 and the hydroxyl group of Tyr355. Docking Ch-4 into the V523I mutant of COX-2 indicated that Ile523 of COX-1 might contribute to the selectivity of COX-2 over COX-1. Ch-4 showed no effect on iNOS activity. Chrysin and Ch-2 weakly inhibited iNOS enzyme activity in the hemoglobin assay, but the underlying mechanisms of inhibition of iNOS by chrysin are not understood.
Cho
Heeyeong
H
Pharmaceutical Screening Team, Korea Research Institute of Chemical Technology, P.O. Box 107, Yuseong, Daejeon 305-600, South Korea. hycho@krict.re.kr
Yun
Cheol-Won
CW
Park
Woo-Kyu
WK
Kong
Jae-Yang
JY
Kim
Kyoung Soon
KS
Park
Youmie
Y
Lee
Sanghyun
S
Kim
Bak-Kwang
BK
D000818:Animals; D002460:Cell Line; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction / Q000187:drug effects; D005419:Flavonoids / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D015870:Gene Expression; D007213:Indomethacin / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors* / Q000096:biosynthesis* / Q000187:drug effects; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects; D008565:Membrane Proteins; D051379:Mice; D008958:Models, Molecular; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000096:biosynthesis* / Q000187:drug effects; D052247:Nitric Oxide Synthase Type II; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis* / Q000187:drug effects; D013329:Structure-Activity Relationship; D013379:Substrate Specificity / Q000502:physiology
C495277:5,7-diacetylflavone; D005419:Flavonoids; D007527:Isoenzymes; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D009569:Nitric Oxide; C043561:chrysin; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496512:Ptgs1 protein, mouse; D007213:Indomethacin