Synthesis, Antiviral and Cytotoxic Activities of Some Novel 2, 3-Disubstituted Quinazolin-4(3H)-Ones

2-substituted benzoxazin-4-ones were condensed with trimethoprim and pyrimethamine to form the 2, 3-disubstituted quinazolin-4(3H)-ones. Their chemical structure was elucidated by means of spectral (FT-IR, IH-NMR, MS) and elemental analysis. The antiviral activity and cytotoxicity of the compounds were tested in HeLa cells (Vesicular stomatitis virus and Respiratory syncytial virus), HEL cells (Herpes simplex- l and -2), Vero cells(Parainfluenza-3 , Reovirus-l , Sindbis virus, Coxsackie virus B4 and Punta Toro Virus) and MT-4 cells (HIV-l and 2) cell cultures. Among the new derivatives evaluated, 3-[4-amino5(4-chlorophenyl)-6-ethylpyrimidin-2-yl ]-2-ethyl/phenyl-quinazolin-4(3H)-one (5b andSa) exhibited some activity with an MIC of 9.6 ug/ml, against Parainfluenza-3 virus, Reo-lvirus and Punta Toro virus in Vero cells. Compounds 5a, Sb and 5c also displayed markedcytostatic activity in lymphocyte (MT-4) cells. They were not active against HIV-l or -2 atnon-cytostatic concentrations.