BIOTRANSFORMATION OF CL-937 IN PRIMARY CULTURES OF RAT HEPATOCYTES - FORMATION OF GLUTATHIONE CONJUGATES

The anticancer drug 7,10-dihydroxy-2-[2-[(2-hydroxyethyl)amino] mino)e thyl]amino]anthra[1.9-c,d]pyrazole-6(2H)-one dihydrochloride (Cl-937) is 1 of 3 anthrapyrazole derivatives chosen for phase I and phase II c linical trials. Although the chemical structure of Cl-937 signals a co ntribution of redox reactions in the pharmacology of the drug, a study concerning the biotransformation of Cl-937 is still missing. Incubati ons of primary cultures of rat hepatocytes with Cl-937 result in the f ormation of three glutathione conjugates and a glucuronic acid conjuga te. The structures of the glutathione conjugates have been established by reference synthesis with activated horseradish peroxidase and HPLC -MS-MS and two-dimensional NMR measurements. The glucuronic acid deriv ative of Cl-937 has been identified by MS. The formation of the glutat hione conjugates in cells establishes the ability of the drug to form covalent bonding to intracellular nucleophilic targets. The conjugatio n with glutathione has been rationalized by oxidative activation of Cl -937, yielding an electrophilic intermediate that finally reacts with glutathione.