SYNTHESIS AND CHARACTERIZATION OF NEW COUMARIN DERIVATIVES CONTAINING VARIOUS MOIETIES WITH ANTIBACTERIAL ACTIVITIES

Objective: The purpose of this research is to evaluate the antibacterial activity of different moieties (Schiff bases, chalcones, hydrazones and hydrazinyl thiazole) derivatives, inserted at carbon 8 of 7-hydroxy-4-methyl coumarin, using in vitro, serial broth dilution method.Methods: A series of new coumarin derivatives, including (Schiff bases, chalcones, hydrazones and hydrazinyl thiazole), were prepared from 7-hydroxy-4-methyl coumarin, by insertion of the formyl group, at carbon number 8 using Duff reaction. The structure of the new synthesized derivatives elucidated and confirmed utilizing the corresponding analytical and spectroscopic data; including FT-IR, 13C-NMR, and mass spectroscopy. All new coumarin derivatives have been screened for their preliminary antibacterial activity, by serial broth dilution method against two Gram-positive bacteria (Staphylococcus epidermidis and Staphylococcus hemolyticus) and two Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae).Results: All the synthesized compounds have been found to exhibit considerable antibacterial activity in vitro. Among all the derivatives, compound (5a), showed the highest rate of inhibition, against (Escherichia coli), while compound (6a), showed the greatest anti-bacterial activity against (Staphylococcus hemolyticus), each with minimum inhibitory concentration of (25µg/ml), and the highest MIC of 200 µg/ml for compound 2, against. Klebsiella pneumoniae.Conclusion: Our results displayed a substantial preliminary antibacterial activity of the new coumarin moieties, especially some hydrazones and chalcones at C8 of the coumarin nucleus, against Gram-positive and a Gram-negative bacteria with distinguished MIC.Â