Stability of Carbovir, a Potent Inhibitor of HIV, to Phosphorolysis by Human Purine Nucleoside Phosphorylase

Abstract

Carbovir, a carbocyclic guanosine analogue, is a selective and potent inhibitor of HIV-1 in vitro. The (-)enantiomer of carbovir has been shown, by spectrophotometric and high pressure liquid chromatography (HPLC) analysis, to be stable to phosphorolytic cleavage by purified human erythrocytic purine nucleoside Phosphorylase. Thus depurination, and the salvage reaction via hypoxanthine-guanine phosphoribosyl transferase, would be unlikely to be involved in the metabolism of carbovir. Inhibition of purine nucleoside Phosphorylase interferes with T-lymphocytic function and would be an undesirable activity for any potential antiviral agent. The present study also showed that carbovir, at concentrations up to 300 μM, did not inhibit purine nucleoside Phosphorylase.