Selective inhibition of the lipoxygenase metabolic pathway of arachidonic acid by the SRS-A antagonist, FPL 55712.

Arachidonic acid, metabolized by the enzyme contained in the cell-free homogenate of rat basophilic leukemia (RBL-1) cells, yields products of both the lipoxygenase and cyclooxygenase pathways. FPL 55712, the SRS-A antagonist, was found to inhibit the formation of lipoxygenase products, but not the cyclooxygenase products. Proxicromil was qualitatively similar, but markedly less potent. Disodium cromoglycate was inactive as an inhibitor of either metabolic pathway at concentrations up to 300 microM.