Origin of Glucuronic Acid in the Urine of Rabbits

Abstract

Two theories have been proposed for the origin of glucuronic acid in the urine. Sundwick 1 and Fisher and Piloty 2 suggested that the toxic substance was conjugated with glucose by a glucoside linkage, followed by the oxidation of the terminal alcohol group to a carboxyl group. A second theory 3 states that the body is able to synthesize glucuronic acid from amino acid metabolites as it needs glucuronic acid for detoxification. Quick 4 thinks that the animal body is able to detoxicate itself in both ways. He 5 has reviewed the literature on the subject. One must conclude from reviewing the subject that the results of the investigations are inconclusive.

Glucuronic acid exists preformed in the body, in mucin. It is continuously being digested in the intestine, and its constituents are absorbed and restored to the body. It is reasonable to think that glucuronic acid would be one of the digestion products and that it is a normal constituent of the blood stream. It seemed to us that the glucuronic acid arising from mucin metabolism would be available for use by the body in detoxication when needed and that it is unnecessary to assume that the glucuronic acid appearing in the urine as conjugated glucuronic acids arises from the oxidation of carbohydrates or by synthesis from amino acid metabolites. Our experiments were carried out to see if mucin feeding had any significant effect upon the conjugation of glucuronic acid as indicated by the quantity excreted.

A group of 11 rabbits was fed a diet of oats, carrots, and water and each given 2 gm. of menthol in water by stomach tube for 3 days.