N-GLUCOSYL CONJUGATES OF CHLORINATED ANILINES - SPONTANEOUS FORMATION AND CLEAVAGE

N-Glucosides are known plant metabolites of chlorinated anilines, which are formed by N-glucosyltransferases utilizing UDP-glucose. Free D-glucose and free 3,4-dichloroaniline have now been found to also conjugate spontaneously under physiological conditions of pH and temperature. Rate constants for spontaneous formation and cleavage of the N-glucosyl conjugate of 3,4-dichloroaniline were determined. The dissociation equilibrium constant calculated from the two rate constants (K(diss) almost-equal-to 0.1 M) was confirmed by direct measurement. Formation as well as cleavage of the N-glucoside showed general acid catalysis in the pH range of about 3-8. A previously proposed reaction mechanism is applied to interpret these results and to explain the known broad range of acid sensitivity of pesticidal N-glucosides. It should thereby become possible to predict the degree of cleavage of N-glucosyl conjugates under stomach conditions (pH 1-2, 37-degrees-C), thus providing a first estimate of animal bioavailability of the pesticidal aglycon.