One-pot synthesis and antibacterial screening of new (nicotinonitrile-thiazole)-based mono- and bis(Schiff bases) linked to arene units

Abstract

Two series of (nicotinonitrile-thiazole)-based Schiff bases 1 and their bis(Schiff bases) analogs 2 are efficiently prepared in this study. A one-pot protocol was designed to prepare the target products involved the reaction of the respective nicotinonitrile-based salicylaldehyde, thiosemicarbazide, and the appropriate mono- or bis(α-haloketones). The reaction was heated at 100 °C for 5–8 h in dioxane and mediated by triethylamine to produce the target hybrids in 80–92% yields. Generally, the (nicotinonitrile-thiazole)-based Schiff bases 1 demonstrated superior antibacterial activity over their bis(Schiff bases) analogs 2. The antibacterial activity of Schiff bases 1d and 1e linked to p-tolyl and 4-methoxyphenyl units was the best against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa strains. They had MIC and MBC values ranging from 3.8 to 4.0 and 7.7 to 8.0 µM, respectively. Using SwissADME to predict the physicochemical properties, lipophilicity, and drug-likeness of new products, Schiff bases 1 can be considered as drug-like scaffolds.

Graphical abstract

Keywords:

• Hantzsch thiazole synthesis
• in vitro antibacterial screening
• multicomponent reactions
• Schiff base
• SwissADME