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6-Chloropurine arabinoside (3a) was obtained by treatment of the 2'-O-acetylated congener (2) with ammonia in methanol. The 3',5'-di-O-tritylated riboside (6) was allowed to react with diethylaminosulfur trifluoride (DAST) in the presence of pyridine to give the 2'-deoxy-2'-fluoroarabinoside (7), from which 6-chloro-9-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)purine (3b) was obtained. The antiviral effects of 3a and 3b were assayed against several DNA and RNA viruses. Only 3a displayed potent activity against varicella-zoster virus (VZV). This antiviral activity was dependent on phosphorylation by the VZV-induced thymidine kinase (TK). Compound 3a showed moderate activity against other DNA viruses, herpes simplex type 1 (HSV-1) and type 2 (HSV-2), and vaccinia virus. They were equally active against TK- and TK+ strains of HSV-1, which suggests that the HSV-1-encoded TK does not play a role in the anti-HSV-1 activity. No activity was noted with any of the compounds against various RNA viruses, including human immunodeficiency virus, at subtoxic concentrations.

A novel and highly efficient one-pot three-component synthesis of alpha-aminophosphonates under neat condition was developed. By employing this method, hybrid compounds of aminophosphonate with pyrimidine nucleosides were synthesized in good to excellent yields starting from 5-formyl-2'-deoxyuridine, aniline and dimethyl phosphite. The antiviral and antileishmanial activities of these novel hybrid compounds were also studied but none were found to be active.

Thirty-nine herpes simplex virus (HSV) isolates were assayed for their sensitivity to 10 different antiviral agents. Of these 39 HSV isolates 10 were cultured from recipient buttons obtained at penetrating keratoplasty in patients with inactive stromal scarring due to recurrent herpetic keratitis, 25 were cultured from patients with conjunctival and ulcerative ocular infections, and the remaining four were laboratory strains with known drug sensitivity patterns, thus providing controls for the experiment. All but one of the 35 clinical isolates of HSV were type 1 and all were sensitive to the 10 antiviral agents. A single type 2 isolate from a young man with recurrent conjunctivitis proved to be resistant to a number of the antiviral agents. Since many of the clinical isolates had been exposed to multiple and protracted antiviral drug treatment, it is suggested that antiviral drug resistance in type 1 HSV ocular infection is not a significant problem.

AbstractPurpose. To characterize the anterior segment effects of cidofovir, using an animal model.Methods. Cidofovir drops, at concentrations of 0.04%, 0.4% and 4%, were instilled in eyes of guinea pigs once daily for 10 days. Fellow eyes (controls) received normal saline. The corneal epithelium was debrided at day one and then at every other day for 10 days. Subconjunctival injections of 20 μl of 4% cidofovir were given in another group of animals. A micro-manometer was used to determine the intraocular pressure (IOP). Eyes were studied histopathologically at the conclusion of the study.Results. There was no significant drop in IOP after 10 days, using the 0.04% concentration of cidofovir drops. Histology revealed mild corneal edema and inflammatory infiltrate; iris, ciliary body and retina were normal. There was a statistically significant drop in IOP in the eyes treated with 0.4% and 4.0% cidofovir eye drops at 10 days (p = 0.005 and p < 0.0001, respectively) compared to baseline. Morphological changes included moderate to severe corneal edema, vascularization and inflammatory infiltration. The iris and ciliary body revealed mild inflammatory changes only at the 4% cidofovir dose. No changes were seen in the retina with any doses. No change in IOP was observed following subconjunctival injections of 4% cidofovir, and histologically, only localized inflammatory changes in the conjunctiva were observed.Conclusions. The IOP-decreasing effect of cidofovir occurs at doses below those causing intraocular inflammation and is likely due to an effect on the anterior segment. The anterior segment effects of cidofovir in guinea pigs were similar to those in humans. Thus, the guinea pig appears to be a good animal model for studying the effects of cidofovir on the anterior segment structures. Curr. Eye Res. 17: 560–566, 1998. The authors acknowledge a proprietary interest in cidofovir.Key words: cidofovir (HPMPC)cytomegalovirus (CMV) retinitisguinea pigtopical administrationsubconjunctival administrationintravitreal administrationintraocular pressurehypotony NotesThe authors acknowledge a proprietary interest in cidofovir.