In Vitro Antiherpesviral Activity of 5-Alkyl Derivatives of 1-β- d -Arabinofuranosyluracil

Several 5-alkyl derivatives of 1-β-d -arabinofuranosyluracil (araU) were tested for antiherpesviral activity and inhibitory action on cell growth in human embryonic lung fibroblasts. 1-β-d -Arabinofuranosylcytosine, 9-β-d -arabinofuranosyladenine, and 5-iododeoxyuridine (IUdR) were included as reference materials. Among the 5-alkyl derivatives of araU, arabinosylthymine was the most active, followed by 5-ethyl- and 5-propyl-araU. 5-Ethyl-araU was as active as IUdR and more active than 9-β-d -arabinofuranosyladenine against herpes simplex virus (HSV) type 1 and did not inhibit cell growth at a concentration as high as 1,000 μg/ml. 5-Butyl- and 5-methoxymethyl-araU, as well as araU, exhibited relatively low activity. The araU derivatives tested were as active against HSV WT-34, an isolate from a patient with keratitis, as against HSV type 1. Against an IUdR-resistant isolate, HSV WT-20, arabinosylthymine was less inhibitory than IUdR. Deoxyribonucleic acid synthesis in HSV type 1-infected cells was markedly inhibited by arabinosylthymine, IUdR, and 5-ethyl-araU, whereas cellular deoxyribonucleic acid synthesis in uninfected cells was significantly inhibited by IUdR but not by arabinosylthymine or 5-ethyl-araU.