Antipsoriatic anthrones with modulated redox properties. 1. Novel 10-substituted 1,8-dihydroxy-9(10H)-anthracenones as inhibitors of 5-lipoxygenase.

The syntheses, the biological evaluation, and the structure-activity relationships of a novel series of 1,8-dihydroxy-9(10H)-anthracenones bearing acyl-, alkyl-, or alkylidene-linked aromatic substituents in the 10-position are described. The phenylacyl and phenylalkylidene analogs were far more potent inhibitors of 5-lipoxygenase (5-LO) from bovine polymorphonuclear leukocytes (IC50 values in the 10(-7) M range) than the antipsoriatic drug anthralin, whereas phenylalkyl analogs were only weak inhibitors. Among the active compounds were both potent generators of hydroxyl radicals, as determined by deoxyribose degradation, and strong reducers of the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH).