A guanosine analog with diverse biological activities; cytotoxic to P338, L5178Y, Sp2/O, HL-60, and Raji cells in vitro (EC50s = 21, 370, 120, 70, and 400 μM, respectively); reduces tumor growth by 60% in S-180 sarcoma and Ehrlich carcinoma solid tumor mouse models at 48 mg/kg per day for 12 days; has been used as an internal standard for the semi-quantitative analysis and comparison of RNA metabolites in MCF-7 breast cancer cells and MCF-10A mammary epithelial cells; decreases the force and rate of contraction in isolated guinea pig atria (EC50s = 2.8 and 17.8 μM, respectively); reduces carotid blood pressure in anesthetized cats at 0.5 μmol/kg