Inhibition of human neutrophil arachidonate 5-lipoxygenase by 6,9-deepoxy-6,9-(phenylimino)-delta 6,8-prostaglandin I1 (U-60257).
6,9-Deepoxy-6,9-(phenylimino)-delta 6,8-prostaglandin I1 (U-60257) and its methyl ester (U-56467) are selective inhibitors of leukotriene C and D biosynthesis both in vitro and in vivo. In this study, we demonstrated that the principal site of inhibition may be arachidonate 5-lipoxygenase, the initial enzyme of leukotriene biosynthesis. U-60257 and its methyl ester block LTB4 synthesis in human peripheral neutrophils with an ID50 of 1.8 and 0.42 microM respectively. This inhibitory action of U-60257 on neutrophil 5-lipoxygenase can be reduced or reversed by a high concentration of exogenous arachidonic acid. U-60257 at 100 microM has no apparent effect on the following enzymes. 1) cyclooxygenase of sheep vesicular gland or human platelets; 2) 12-lipoxygenase of human platelets and 3) soybean 15-lipoxygenase. Thus, we conclude that U-60257 and its methyl ester are potent and selective inhibitors of arachidonate 5-lipoxygenase.
D001091:Arachidonate Lipoxygenases; D000001:Calcimycin / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D011464:Epoprostenol / Q000494:pharmacology* / Q000031:analogs & derivatives; D006801:Humans; D016859:Lipoxygenase Inhibitors; D009504:Neutrophils / Q000201:enzymology*; D013189:SRS-A / Q000037:antagonists & inhibitors*
D016859:Lipoxygenase Inhibitors; D013189:SRS-A; D000001:Calcimycin; D011464:Epoprostenol; D001091:Arachidonate Lipoxygenases; C035296:piriprost