Synthesis of 4,5-disubstituted-2-thioxo-1,2,3,4-tetrahydropyrimidines and investigation of their acetylcholinesterase, butyrylcholinesterase, carbonic anhydrase I/II inhibitory and antioxidant activities

A series of tetrahydropyrimidinethiones were synthesized from thiourea, -diketones and aromatic aldehydes, such as p-tolualdehyde, p-anisaldehyde, o-tolualdehyde, salicylaldehyde and benzaldehyde. These cyclic thioureas showed good inhibitory action against acetylcholine esterase (AChE), butyrylcholine esterase (BChE), and human (h) carbonic anhydrase (CA) isoforms I and II. AChE and BChE inhibitions were in the range of 6.11-16.13 and 6.76-15.68nM, respectively. hCA I and II were effectively inhibited by these compounds, with K-i values in the range of 47.40-76.06nM for hCA I, and of 30.63-76.06nM for hCA II, respectively. The antioxidant activity of the cyclic thioureas was investigated by using different in vitro antioxidant assays, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, Cu(2+)and Fe(3+)reducing, and Fe(2+)chelating activities.