Synthesis and biological evaluation of some thiazole derivatives as new cholinesterase inhibitors

In the present study, some thiazole derivatives were synthesized via the ring closure reaction of 1-2-(2-oxobenzod]thiazol-3(2H)-yl)acetyl]thiosemicarbazide with various phenacyl bromides. The chemical structures of the compounds were elucidated by ¹H NMR, ¹³C NMR and mass spectral data and elemental analyses. Each derivative was evaluated for its ability to inhibit acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) using a modification of Ellman’s spectrophotometric method. The compounds were also investigated for their cytotoxic properties using MTT assay. The most potent AChE inhibitor was found as compound 4e (IC₅₀?=?25.5?±?2.12 µg/mL) followed by compounds 4i (IC₅₀?=?38.50?±?2.12 µg/mL), 4c (IC₅₀?=?58.42?±?3.14 µg/mL) and 4g (IC₅₀?=?68?±?2.12 µg/mL) when compared with eserine (IC₅₀?=?0.025?±?0.01 µg/mL). Effective compounds on AChE exhibited weak inhibition on BuChE (IC₅₀ > 80 µg/mL). MTT assay indicated that the cytotoxic dose (IC₅₀?=?71.67?±?7.63 µg/mL) of compound 4e was higher than its effective dose.