Abstract
Pseudomonas methanica KY4634 was found to produce 5-lipoxygenase inhibitor designated KF8940, MY12-62a and MY12-62c. The inhibitors were purified by solvent extraction, silica gel column chromatography, reversed-phase low pressure liquid chromatography and crystallization. The chemical structures of KF8940, MY12-62a and MY12-62c were determined to be 2-n-heptyl-4-hydroxyquinoline-N-oxide, 2-n-heptyl-4-hydroxyquinoline and 3-n-heptyl-3-hydroxy-1, 2, 3, 4-tetrahydroquinoline-2, 4-diore, respectively, on the basis of their physico-chemical properties. Among them, KF8940 was the most potent inhibitor. The compound inhibited 5-lipoxygenase of rat basophilic leukemia cells in a dose-dependent manner and the half maximal inhibitory concentration (IC50) was 1.5 × 10-7 M. At this concentration, KF8940 did not inhibit bovine platelet 12-lipoxygenase and cyclooxygenase, and the IC50 values for these enzyme were 3.5 × 10-5 M and 1.7 × 10-4 M, respectively. The results indicated that KF8940 is a potent and selective inhibitor of 5-lipoxygenase. The IC50 value of MY12-62c for 5-lipoxygenase was 1.9 × 10-5 M and that of MY12-62a was 1.9 × 10-5 M.
