1,4-NAPHTHOQUINONES .25. REACTION OF THE REDOX 5-LIPOXYGENASE INHIBITOR UTYL-4-HYDROXYPHENYL)-3-HYDROXY-1,4-NAPHTHOQUINONE WITH O-2(CENTER-DOT-) AND O-3(2)

The 5-lipoxygenase inhibitor utyl-4-hydroxyphenyl)-3-hydroxy-1,4-napht hoquinone (2), its deoxygenation product 1 as well as the oxygenated s pecies 3 are O-2(.-) quenchers with different power in aqueous solutio n. In alcoholic solution the antioxidative capacity of 1 does not chan ge, 2 indeed is still only a weak O-2(.-) quencher while 3 shows proox idative properties. This phenomenon was explored in the O-2(.-) genera ting oxygenation system (OS) DMSO-CO32--O-2 by preparative techniques. The following reaction sequence could be proven: 3 double right arrow 2 double right arrow 4 (2,6-di-tert-butyl-1,4-benzoquinone). While th e step 3 double right arrow 2 would be O-2(.-) dependent the transitio n 2 double right arrow 4 occurs on two levels: 1. retro Michael reacti on with release of 2,6-di-tert-butylphenol (5), 2. base catalysed oxyg enation of 5 double right arrow 4 by O-3(2). The diphenoquinone 6 occu rring as byproduct is split with the OS - in contrast to the reaction with 1 O-2 -in considerable yield to give 4.