cis-trans-Isomerization of [E]-5-(2-bromovinyl)-2,2′-anhydrouridine in vivo in rats

1. [E]-5-(2-bromovinyl)-2,2′-anhydrouridine ([E]BVANUR) has considerable antiviral activity against herpes simplex virus type 1 (HSV-1).2. [E]BVANUR is not a substrate of pyrimidine nucleoside phosphorylases, but it is an inhibitor of uridine phosphorylase (Ki=450 nM).3. [E]BVANUR (trans-isomer, parent compound) undergoes isomerization to [Z]BVANUR (cis-isomer), the only metabolite in rat, which was identified by h.p.l.c., mass spectra and n.m.r. spectroscopy.4. Absorption of the drug from the gastrointestinal tract after oral administration is minimal. Absorption of [E]BVANUR from the abdominal cavity after i.p. administration was slow.