IMMUNOMODULATORY AND ANTIVIRAL ACTIVITIES OF 2',3'-DIDEOXY-BETA-L-CYTIDINE AND 2',3'-DIDEOXY-BETA-L-5-FLUOROCYTIDINE

Two dideoxynucleosides, 2',3'-dideoxy-beta-L-cytidine and 2',3'-dideox y-beta-L-5-fluorocytidine, containing unnatural L-configuration in the ir sugar moieties, were synthesized and assayed for antiviral activiti es. Both compounds were shown to possess potent anti-human immunodefic iency virus type 1 and antihepatitis B virus activities, while demonst rating no anti-herpes simplex viruses 1 and 2 activity, These two comp ounds exhibited in vitro cellular toxicities for several leukocytic ce ll lines and were shown to inhibit phytohemagglutinin-stimulated human peripheral blood mononuclear leukocyte proliferations. At inhibitory concentrations, both compounds caused accumulations of cells in the S phase. While demonstrating no obvious morphological toxicity in vivo i n mice at concentrations of 75 and 150 mg/kg, 2',3'-dideoxy-beta-L-5-f luorocytidine-treated animals were shown to have considerable increase s in CD4/CD8 double positive T lymphocyte population in their blood ci rculation.