FLUOROMETRIC ASSAY OF QUINDONIUM BROMIDE AND IDENTIFICATION OF A GLUCURONIDE AS THE MAJOR METABOLITE

¹ Warner-Lambert Research Institute, Morris Plains, New Jersey

An assay procedure for quindonium bromide (W3366A, an octahydro-8-hydroxy-benzo-cyclopenta-quinolizinium bromide) bsed on its pH-dependent fluorescence is described. Tissues are homogenized in pH 10 borate to prevent breakdown of quindonium glucuronide and are extracted at that pH with butanol-1. The quindonium is reextracted from the butanol-1 into a small volume of 0.1 N HCl. After adjustment of the aqueous extract back to pH 10, fluorescence at 420 mµ is measured upon activation at 360 mµ. The identification of a biotransformation product, which is the major metabolite appearing in the urine, as a monoglucuronide was based on its hydrolysis catalyzed by -glucuronidase, its incorporation of C¹⁴ from radioactive glucose, the purification by column chromatography of a material containing conjugated quindonium and glucuronic acid in a molar ratio of 1:1 and the reaction of quindonium with uridine-5'-diphospho-glucosidouronate catalyzed by microsomes.