Synthesis, Characterization, Molecular Docking, and Antimicrobial Evaluation of New Acetylenic Mannich Bases of Isatin–Thiazole Derivatives

The isatin molecule is present in many natural substances, like plants and animals, and it is utilized to prepare compounds with various biological activities. A series of Schiff and Mannich bases derived from isatin were synthesized in this research. First, acetylenic Mannich bases (IIa-e) were prepared by a reaction of isatin with propargyl bromide and different secondary amines (morpholine, piperidine, pyrrolidine, dimethylamine, and diphenylamine) separately, and cuprous chloride (CuCl) was used as a catalyst. Second, these Mannich bases were treated with 2-aminothiazole to obtain the desired final compounds (AM1-AM5). The synthesized compounds were characterized on the basis of their spectral (FT-IR, 1H- NMR) data. All these derivatives had been screened for their antimicrobial activity against two Gram-positive bacteria; “Staphylococcus aureus and Bacillus licheniformis”, and two Gram-negative bacteria; “Escherichia coli and Acinetobacter baumannii”, and one fungus species, “Candida albicans”. Most of the compounds were found to exhibit significant antimicrobial activity and the most active one is compound AM1. The molecular docking was performed for the final synthesized compounds and then compared with the standard drugs (Ciprofloxacin and Fluconazole). Molecular docking has recorded higher docking scores of two final derivatives (AM1 and AM2) in comparison to fluconazole.