Transformation kinetics of the 5 '-chloro-5 '-deoxy analogue of arabinosylcytosine

5'-Chloro-5'-deoxy arabinosylcytosine (Cl-araC) is a more lipophilic analog of the clinically used drug - arabinosylcytosine (araC). The resistance to ward the enzyme cytidine-deaminase action was described as an characteristi c feature of this synthetic nucleoside. The kinetics of the Cl-araC transfo rmation in acid and alkaline solutions was studied at various temperatures. When compared with parent compound araC, the chlorine atom at the 5' posit ion of the nucleoside sugar moiety increases the Cl-araC stability. The chl orine atom stabilizing effect is higher in acidic conditions. Cl-araC incre ased stability, antileukemic activity accompanied by higher lipophilicity c onfirm the fact that Cl-araC belong among interesting compounds from the po int of view of cancer chemotherapy.