Synthesis,antibacterial and antioxidant activity of novel 2,3-dihydroquinazolin-4(1H)-one derivatives of dehydroabietylamine diterpene

A series of novel 2,3-dihydroquinazolin-4(1H)-ones was synthesized by a three-component reaction between dehydroabietylamine (DHA) diterpene, isatoic anhydride and different aromatic aldehydes in the presence of a catalytic amount of p-toluenesulfonic acid (13 mol%). Diastereomeric products were separated by preparative thin-layer chromatography and their structures were characterized by ¹H and ¹³C NMR, HMQC, IR and HR-ESI-MS. Antioxidant activities of the synthesized compounds were assessed by two different methods including DPPH and β-carotene-linoleic acid bleaching assays. Antibacterial activities of the compounds were also evaluated against two Gram-positive and one Gram-negative bacterial strains and in the case of Bacillus cereus a considerable inhibitory effect (MIC 4–16 μg/ml) was observed.