Nebularine is a purine ribonucleoside and an adenosine analog that has been found inL. nebularisand has diverse biological activities.^1,2,3,4,5It reduces herpes simplex virus 1 (HSV-1) viral plaque formation in Vero cells (IC₅₀= 0.6 µM) and is active againstM. phlei,M. avium,M. tuberculosis, andB. abortus.^1,2Nebularine (10 and 100 µM) is cytotoxic to COS-7 cells and induces pyknosis in mouse sarcoma 180 cells and mouse embryonic skin explants in a concentration-dependent manner.^3,4It inhibits root growth of wheat seedlings when used at concentrations ranging from 0.1 to 2 mM.²Nebularine also inhibits adenosine deaminase (K_i= 16 µM).⁵

1.JuliÁn-Ortiz, J.V., GÁlvez, J., MuÑoz-Collado, C., et al.Virtual combinatorial syntheses and computational screening of new potential anti-herpes compoundsJ. Med. Chem.42(17)3308-3314(1999) 2.Brown, E.G., and Konuk, M.Plant cytotoxicity of nebularine (purine riboside)Phytochemistry37(6)1589-1592(1994) 3.Tkacz, K., Cioroch, M., Skladanowski, A.C., et al.The cytotoxic effect of purine riboside on COS-7 cellsPurine and Pyrimidine Metabolism in Man X. Advances in Experimental Medicine and Biology486355-359(2000) 4.Biesele, J.J., Slautterback, C., and Margolis, M.Unsubstituted purine and its riboside as toxic antimetabolites in mouse tissue culturesCancer8(1)87-96(1955) 5.Shewach, D.S., Krawczyk, S.H., Acevedo, O.L., et al.Inhibition of adenosine deaminase by azapurine ribonucleosidesBiochem. Pharmacol.44(9)1697-1700(1992)