Structure-toxicity relationships of selected nitrogenous heterocyclic compounds II. Dinitrogen molecules.

Abstract

Thirteen dinitrogen-containing cyclic compounds were examined to determine the relationship between selected structural and physicochemical parameters and impairment to population growth of the common ciliateTetrahymena pyriformis. Under static conditions all compounds tested are persistent in aqueous solution. Both an increase in methyl substitution and an increase in the number of aromatic rings per compound result in increased growth impairment. Linear positive relationships exist between the log biological response values of the alkyl analog set and each of four hydrophobic indexes: Number of carbon atoms, molecular weight, boiling point, and the log of the 1-octanol/water partition coefficient. No such relationships were found for isomers, for which the crowding of ring-substituted nitrogen has no effect on the number of carbon atoms and molecular weight but causes an increase in boiling point and biological response and a decrease in 1-octanol/ water partition coefficient. In addition, linear positive correlations were demonstrated between the log of the absolute value of the slope of the population growth impairment equation of the alkyl analog set and each of the four hydrophobic parameters. Comparisons of log 1-octanol/water partition coefficients with log biological response or log slope of mononitrogen-substituted cyclic compounds show that similar correlations exist for both mono- and dinitrogen substitution.