Synthesis and Biological Screening of New 2-(5-Aryl-1-phenyl-1H-pyrazol-3-yl)-4-aryl Thiazole Derivatives as Potential Antimicrobial Agents

A new series of 2-(5-aryl-1-phenyl-1H-pyrazol-3-yl)-4-aryl thiazoles (10a-ab) have been synthesized by a cyclocondensation reaction of 5-aryl-1-phenyl-1H-pyrazole-3-car-bothioamide (7a-d) with substituted phenacyl bromide (8a-f). The structure of newly synthesized 2-(5-aryl-1-phenyl-1H-pyrazol-3-yl)-4-aryl thiazole (10a-ab) derivatives was characterized by spectroscopic analysis. The compounds 10a-ab were evaluated for in vitro antibacterial activity against Escherichia coli (NCIM 2574), Proteus mirabilis (NCIM 2388), Bacillus subtilis (NCIM 2063), Staphylococcus aureus (NCIM 2178), and in vitro antifungal activity against Aspergillus niger (ATCC 504) and Candida albicans (NCIM 3100). Among the twenty-eight pyrazolyl-thiazole derivatives, six compounds, 10g, 10h, 10i, 10j, 10o, and 10t, showed good activity against P. mirabilis; four compounds 10q, 10u, 10y, and 10z showed good activity against S. aureus; and twenty-four derivatives showed good antifungal activity against A. niger. Compounds 10g, 10q, 10r, 10s, and 10ab showed comparable activity with respect to the reference drug Ravuconazole. Thus, the significant antimicrobial activity of 2-(5-aryl-1-phenyl-1H-pyrazol-3-yl)-4-aryl thiazole (10a-ab) derivatives prompted that these scaffolds could assist in the development of lead compounds to treat microbial infections.