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

Abstract

A series of tetrahydropyrimidinethiones were synthesized from thiourea, β-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 6.76–15.68 nM, respectively. hCA I and II were effectively inhibited by these compounds, with Ki values in the range of 47.40–76.06 nM for hCA I, and of 30.63–76.06 nM 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, Cu2+and Fe3+reducing, and Fe2+chelating activities.