Yoko Sakiya

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

The substituent effects on the absorption rate constants (kfish) 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 (Ks) and the intramolecular interaction constant (KI), and the substituent effects were compared with those reported for the rat intestinal absorption rate constants (krat) at pH 6.0. The substituent groups giving positive or negative Ks values were the same for the two goldfish membranes and the rat intestine. All the KI values were positive for the two goldfish membranes as well as for the rat intestine. The logarithmic values of krat showed good correlations with those of kfish in both body surface (r = 0.870, n = 34) and gills (r = 0.860, n = 35). However, the kfish 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 kfish values were qualitatively the same as those on the krat values and quantitatively correlated well with those on the krat values, except in the cases of salicylic acid, phenol, and p-hydroxybenzamide. It was concluded that the substituent effects on the kfish values can be explained in terms of KS and KI, as in the case of rat intestine, but the effects on the kfish values of salicylic acid, phenol, and p-hydroxybenzamide can not.