The Synthesis of Menthol Glycuronic Acid in the Rabbit

The lack of a trustworthy analytical method for conjugated glycuronic acids heretofore has left many problems concerning their synthesis in the body unsolved.Before attempting, however, any specialized phase of the problem, it seemed necessary to study the excretion of conjugated glycuronic acids following the feeding of a substance like menthol from the point of view of: the effect of dosage; the rate of excretion; and the effect of prolonged feeding.Fromm and Clemens (1) state that a strong rabbit can tolerate as much as 5 gm. of menthol, and Biberfeld (2) reports that a rabbit can be fed 2 gm.daily for a period of over a month provided greens are included in the diet.No reference was found concerning the relative amount of menthol conjugated.Von Fenyvessy (3) from polariscopic measurement determined that 2.6 to 2.8 gm. of camphor01 glycuronic acid were produced following the administration of 2 gm. of camphor.In the experiments carried out, it was found that the rabbit conjugated somewhat less than one-half of the menthol fed up to a certain amount after which the amount conjugated decreased as the dose was increased, but that, nevertheless, the amount conjugated was high even for the lethal dose provided the animal lived 10 hours after the feeding.There seemed to be only slight variations between rabbits as to the amount of menthol they could conjugate.Somewhat less than 3 gm. of menthol glycuronic acid were the maximum amount that a 2 kilo rabbit could excrete, and this was obtained by feeding about 3.5 gm. of menthol.No information was obtained concerning the elimina-679