Absorption of benzene derivatives through the body surface and gill membranes of goldfish: substitutent and intramolecular interaction effects

Abstract

The substituent effects on the absorption rate constants ( k fish) of 35 benzene derivatives at pH 6.0 through the body surface and gill membranes of the goldfish were examined in terms of the substituent constant ( K s) and the intramolecular interaction constant ( K I), and the substituent effects were compared with those reported for the rat intestinal absorption rate constants ( k rat) at pH 6.0. The substituent groups giving positive or negative K s values were the same for the two goldfish membranes and the rat intestine. All the K I values were positive for the two goldfish membranes as well as for the rat intestine. The logarithmic values of k rat showed good correlations with those of k fish in both body surface ( r = 0.870, n = 34) and gills ( r = 0.860, n = 35). However, the k fish values of salicylic acid, p-hydroxybenzamide, and phenol in the body surface and those of the former two in the gills were significantly outside the critical region ( P < 0.05). The effects of substituent groups (increase or decrease) and intramolecular interaction (increase) on the k fish values were qualitatively the same as those on the k rat values and quantitatively correlated well with those on the k rat values, except in the cases of salicylic acid, phenol, and p-hydroxybenzamide. It was concluded that the substituent effects on the k fish values can be explained in terms of K S and K I, as in the case of rat intestine, but the effects on the k fish values of salicylic acid, phenol, and p-hydroxybenzamide can not.