S-(O-ethyl phenylphosphonothionyl) glutathione; evidence for its formation in the in vitro metabolism of EPN in houseflies.

Double labelling experiments using [phenyl-14C], [2,6-p-nitro-phenyl-14C]- or, nonradioactive EPN with [35S]-, [glycine-3H]- or nonradioactive glutathione in the presence of the 100,000g supernatant fraction from the Rutgers strain of houseflies resulted in the formation of a radiolabelled conjugate. Hydrolysis of the [phenyl-14C] conjugate formed the phenyl-[14C]-phosphonothioic acid. The proposed structure of the conjugate is S-(O-ethyl phenylphosphonothionyl) glutathione. The conjugate is formed with racemic, (+), or (-) EPN. Structure activity studies indicate the following: a decrease in the electron withdrawing properties of the substituents on the O-p-nitrophenyl moiety results in a decrease in the formation of the conjugates; substituting the phenylphosphonothioic moiety with the ethyl-phosphonothioate, inhibits the formation of the corresponding conjugate' substituting the O-ethyl group with other alkyl groups did not effect the formation of the corresponding conjugate.