Reduction of the active-site iron by potent inhibitors of lipoxygenases.

Lipoxygenases are non-heme iron dioxygenases that catalyze the oxygenation of polyunsaturated fatty acids. Using soybean lipoxygenase-1 as a model, we have shown that two classes of lipoxygenase inhibitors currently in development as potential antiinflammatory agents obtain a significant amount of their potency by reducing the lipoxygenase active-site iron from the active ferric state to the inactive ferrous state. It is not surprising that the members of the first of these classes, the 2-benzyl-1-naphthols, are reducing agents. The members of the second class, the N-alkyl-hydroxamic acids, were not anticipated to be sufficiently strong reducing agents to be oxidized by the lipoxygenase ferric center; that they are provides additional evidence for that iron having a high reduction potential. This brings to (at least) five the number of classes of lipoxygenase inhibitors that are capable of reducing the active-site ferric ion and suggests the generality of this approach in the rational design of lipoxygenase inhibitors.