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.
Pharmaceutical Screening Team, Korea Research Institute of Chemical Technology, P.O. Box 107, Yuseong, Daejeon 305-600, South Korea. hycho@krict.re.kr
Heeyeong
H
Cho
Cheol-Won
CW
Yun
Woo-Kyu
WK
Park
Jae-Yang
JY
Kong
Kyoung Soon
KS
Kim
Youmie
Y
Park
Sanghyun
S
Lee
Bak-Kwang
BK
Kim
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