Carbamate Insecticides, Hydride-Transferring Ability of Methylenedioxybenzenes as a Basis of Synergistic Activity

Abstract

An explanation of the inhibition of the metabolism of carbamates and other pesticides by methylenedioxybenzenes is proposed. Oxidative metabolism of the methylenedioxybenzene with transfer of hydride from the methylenedioxy group is postulated. If the resulting electrophilic benzodioxolium ion were to react with a nucleophilic group in a com-

Inhibition of Cytochrome P-450 Enzymes

“….. carbocation 71 and carbanion 63 intermediates have been suggested, but the results are most consistent with formation of the carbene from the 2-hydroxylated metabolite or from a radical precursor of it ( Fig. 7).…”

Mode of Action of Carbamate Synergists

“…Evidently, the methylenedioxy group itself provides some rather specific inhibitory property to the molecule. The twofold lower activity of 2,2-dideutero-l,3-benzodioxole compared with benzodioxole and the much lower activity of the alkylsubstituted methylenedioxy compounds indicate that the hydrogen atoms are involved in the inhibition process (21).…”

Molecular orbital study of hydride-transferring ability of benzodiheterolines as a basis of synergistic activity

“…The four oxygen-containing cations have positive LEMO orbital energies. As noted previously (Hennessy, 1965), NAD+ or NADP+ could ultimately act as the hydride acceptor in the biological oxidationreduction process. these are ready electron acceptors.…”

“…This follows because the electronegativities vary in the reverse order, and the parameters reflect electronegativities (Streitwieser, 1961). Thus, from the aspect of charge densities on the cation, electron or hydride acceptor activity at C-2 in cations where Y is 0 is expected to be greater than when Y is N or S (Hennessy, 1965). With the exception of C=C, the heteroatoms contribute lone pair electrons to the Ksystem.…”