Leukotriene A. Isolation from human polymorphonuclear leukocytes.

Leukotriene A, an unstable intermediate in the conversion of arachidonic acid to stable leukotrienes, was isolated from human polymorphonuclear leukocytes. The allylic epoxide intermediate is rapidly hydrolyzed under acidic conditions. A method was therefore developed for esterification and extraction of the intermediate as the methyl ester from an alkaline aqueous phase, into an aprotic solvent. This was achieved by addition of methanol and an excess of diazomethane in ether to the incubatio mixture, followed by addition of water, and phase separation. The identity of the isolated compound with the previously synthesized methyl ester of 5 (S)-trans-5,6-oxido-7,9-trans-11,14-cis-eicostatetraenoic acid (leukotriene A), was established by comparing chromatographic and chemical properties of the isolated compound and synthetic leukotriene A.