Bacterial infections often produce pain and inflammation. In normal practice, two groups of agents (chemotherapeutic, analgesic and anti-inflammatory) are prescribed simultaneously. The compounds possessing all three activities are not common. Quinazolines and condensed quinazolines exhibit potent antimicrobial 1) and CNS activities like analgesic, 2) anti-inflammatory 3) and anticonvulsant 4) activities. In view of these facts and to develop our earlier reported 2-phenyl-3-substituted quinazolines, 5) 2,3-disubstituted quinazolines 6) and 2-methyl-3-substituted quinazolin-4-(3H)-ones 7) that exhibited good analgesic and anti-inflammatory activities, in the present study we aimed to synthesize some 2-methylthio-3-substituted quinazolin-4(3H)-ones. The title compounds were synthesized by nucleophilic substitution of (2-methylthio-4-oxo-3H-quinazolin-3-yl)dithiocarbamic acid methyl ester with different amines. The (2-methylthio-4-oxo-3H-quinazolin-3-yl)dithiocarbamic acid methyl ester was synthesized by reacting the amino group of 3-amino-2-methylthioquinazoline with carbondisulphide and dimethyl sulphate. The 3-amino-2-methylthio quinazoline was synthesized from anthranilic acid (Chart 1). Spectral data (IR, NMR, and mass spectra) confirmed the structures of the synthesized compounds, the purity of these compounds was ascertained by microanalysis (Table 1). The synthesized compounds were tested for their analgesic, anti-inflammatory and antibacterial activities. CHEMISTRYMelting points were determined in open capillary tubes on a Thomas Hoover apparatus and are uncorrected. IR spectra were recorded in KBr on a Perkin Elmer-841 grating spectrometer (cm Ϫ1 ), mass spectra on a varian Atlas CH-7 mass spectrometer at 70 eV and NMR spectra on a varian A-60 or EM-360 spectrometer, using tetramethylsilane as internal standard. Elemental analysis were performed on Carlo erba 1108.Synthesis of 3-Amino-2-mercaptoquinazolin-4(3H)-one To a vigorously stirred solution of methylanthranilate 3.02 g (0.02 mol) in dimethylsulfoxide (10 ml) at room temperature, carbondisulphide (1.6 ml, 0.026 mol) and aqueous sodium hydroxide 1.2 ml (20 mol solution) was added dropwise simultaneously during 30 min and it was stirred for 30 min more. Dimethyl sulphate 2.5 g (0.02 mol) was added dropwise under cooling with an ice bath. Stirring was continued for 3 h, the reaction mixture was poured into ice-water and then it was extracted with chloroform. The solvent was removed by distillation under reduced pressure. Thus the obtained crude methyl N-(2-methoxycarbonylphenyl)dithiocarbamate was used for further reaction without purification. * To whom correspondence should be addressed. A variety of novel 2-methylthio-3-substituted quinazolin-4-(3H)-ones have been synthesized by reacting (2-methylthio-4-oxo-3H-quinazolin-3-yl)dithiocarbamic acid methyl ester with a variety of amines, the starting material dithiocarbamate was synthesized from methylanthranilate. The title compounds were investigated for analgesic, anti-inflammatory and antibacterial ...