Exploring the purine core of 3'-C-ethynyladenosine (EAdo) in search of novel nucleoside therapeutics.

A series of new nucleoside analogues based on a C-3 branched ethynyl sugar derivative as present in 3'-C-ethynylcytidine (ECyd) and -adenosine (EAdo), combined with modified purine bases was synthetized and evaluated against a broad array of viruses and tumour cell lines. The pronounced cytostatic activity of EAdo was confirmed. EAdo and its 2,6-diaminopurine analogue showed inhibitory activity against vaccinia virus (EC50: 0.31 and 51 μM, respectively). Derivative 10 on the other hand was found active against varicella zoster virus (EC50: 4.68 μM).