Inhibition of housefly oxidative detoxication by phthaleins, fluoresceins and related compounds

Abstract

1. Phenolphthalein, halogenated fluoresceins, and other triphenylmethane and diphen-ylmethane derivatives inhibited biphenyl hydroxylation, aldrin epoxidation and several O-dealkylations in insect abdomen homogenates. Phenolphthalein and eosin (50μM) were 2ù3 times more effective than SKF 525-A and piperonyl butoxide (50μM) as inhibitors of biphenyl hydroxylation in vitro.

2. The phthaleins, Aurin and Aluminon, inhibited both epoxidation and hydroxylation to similar extents, but fluoresceins, Rhodamine B, Malachite Green, and basic diphenyl-methane derivatives preferentially inhibited hydroxylation.

3. Tetrabromophenolphthalein ethyl ester and bis-(N-dimethyl-4-aminophenyl-methane inhibited biphenyl hydroxylation in vivo. Bis-(N-dimethyl-4-aminophenyl) methane synergized the toxic effects of 1-naphthyl N-methylcarbamate in live houseflies.