Synthesis, Spectroscopic Characterization and Antimicrobial Potential of Certain New Isatin-Indole Molecular Hybrids

Molecular hybridization has a wide application in medicinal chemistry to obtain new biologically active compounds. New isatin-indole molecular hybrids 5a–n have been synthesized and characterized by various spectroscopic tools. The in vitro antimicrobial potential of the prepared compounds 5a–n was assessed using diameter of the inhibition zone (DIZ) and minimum inhibitory concentration (MIC) assays against a panel of Gram-negative bacteria, Gram-positive bacteria and fungi. Most of the synthesized compounds 5a–n showed weak activities against Gram-negative bacteria while compounds 5b and 5c exhibited good activities against Gram-positive bacteria. On the other hand, compound 5j emerged as the most active compound towards Candida albicans (C. albicans), with an MIC value of 3.9 µg/mL, and compound 5g as the most active congener towards Asperagillus niger (A. niger), with an MIC value of 15.6 µg/mL. Moreover, compound 5h manifested the best anti-P. notatum effect, with an MIC value of 7.8 µg/mL, making it equipotent with compound 5g.