Antiviral activity of tetrahydro-2(1H)-pyrimidinones and related compounds.

24 derivatives of tetrahydro-2(1H)-pyrimidinone and related compounds were tested in vitro for antiviral activity against representatives of six viral taxonomic groups. The screening was carried out by a two-stage procedure including the agar-diffusion plaque-inhibition test and the one-step growth cycle setup. A distinct activity of three mono- and bis-morpholinomethyl derivatives of tetrahydro-2(1H)-pyrimidinone (THP), 1,3-bis(piperidinomethyl)-THP, the 1-morpholinomethyl derivative of tetrahydro-2(1H)-pyrimidinethione (THPT) and the related N,N'-bis(morpholinomethyl)-urea against the fowl plague virus was established. In the one-step growth cycle setup these compounds inhibited 87.5-99.6% of the infectious virus yield. Two of the compounds, namely 1-morpholinomethyl derivatives of THP and THPT manifested a strong inhibitory effect on the reproduction of Semliki Forest virus as well, exceeding 99.9% in the one-step growth cycle test. A borderline effect was observed in some derivatives against vaccinia virus and Newcastle disease virus. The structure-activity relationship of this group of compounds is discussed.