Relationship between sulfhydryl reactivity and toxicity of vinyl sulfone molluscicidal agents

Abstract

Vinyl sulfone was tested to determine (a) sulfhydryl reactivity, ascertained by monitoring the color-forming reaction between 5,5′-dithiobis(2-nitrobenzoic acid) and cysteine, (b) inhibition of malic dehydrogenase, (c) inhibition of in vitro endogenous respiration in the snail Australorbis glabratus, (d) the in vitro effect on endogenous respiration and pyruvate metabolism of liver and brain of albino rats, and (e) pyruvate metabolism in liver, kidney, and brain homogenates of male rats treated in vivo with vinyl sulfone. The effects of sublethal doses of vinyl sulfone on albino rats were also investigated. A series of vinyl sulfone molluscicidal agents was shown to exhibit a positive correlation between sulfhydryl reactivity and molluscicidal potency. High concentrations (>2 m m) of vinyl sulfone were required to inhibit the activity of malic dehydrogenase. No effect on endogenous respiration was observed in snails. Similarly, no effects on endogenous respiration or pyruvate metabolism was observed in rats. An ip LD50 of 3 mg/kg vinyl sulfone was found in female rats. A sublethal dose of vinyl sulfone increased blood urea nitrogen and decreased urinary output while producing no effect on SGOT and SGPT activity or on hematocrit values in rats. These data indicate that the toxicity of vinyl sulfone is not related to the inhibition of endogenous respiration in either snails or rats. The toxicity of sublethal doses of vinyl sulfone was postulated to be caused by impairment of normal renal function.