Synthesis, Characterization And Microbial Activity Of New Thiazole, Thiazolidinone, Thiadiazole And Phenylacrylohydrazide Substituted Coumarin Derivatives
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Date
2015-07
Authors
Yusuf Zai, Samina Khan
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Abstract
Thiazoles, thiazolidinones, thiadiazoles, phenylacrylohydrazides and
coumarins, are few of the very important classes of heterocyclic compounds having
great medicinal and pharmacological importance. In the present study, six series of
67 new biologically active coumarin derived compounds have been synthesized by
substituting thiazole, thiazolidinone, thiadiazole and phenylacrylohydrazide units
into the coumarin core, in order to increase their use as important therapeutic agents.
The structures of all the new compounds were characterized by spectroscopic
techniques such as, IR, 1D NMR (1H and 13C) and CHN analysis together with LCMS.
The structures of the selective compounds from each series were further
confirmed by 2D NMR (COSY, HMQC and HMBC) spectroscopic techniques. In
addition to this X-Ray diffraction analysis was used to confirm, the structures for
those compounds obtained as single crystals. The structures of all the synthesized
starting materials were confirmed by the comparison of their spectroscopic data with
those already reported in literature. Melting point measurements was done for all the
synthesized compounds, in order to check their purity. All the synthesized coumarin
analogues were screened in vitro for their antibacterial activity against two Grampositive
bacteria Streptococcus pneumoniae and Staphylococcus aureus and three
Gram-negative bacteria Escherichia coli, Enterobacter aerogenes and Salmonella
typhi, including Mycobacterium tuberculosis, a bacterium which causes tuberculosis
disease. Significant activity against Mycobacterium tuberculosis was shown by
almost all the compounds. Strongest inhibition was shown by the halogenated compound 29g with the lowest MIC value of 60.0 M, while its analogue 29f and the
other coumarins 27b, 30a and 26 also revealed good activities with MIC values of
83, λ3, 83 and λ3 M, respectively as compared to that of the control drug, Isoniazid.
Moreover, in antibacterial activity the strongest inhibition against the aforementioned
bacteria strains were observed again by the group of halogenated compounds (27b,
28b, 28i, 28p, 29d, 29h, 30b, 31b, and 32d), with MIC values ranging from 34 to
233 M as compared to those of the standard drugs streptomycin, kanamycin and
vancomycin. Rest other coumarin derivatives were also found to exhibit significant
anti bacterial activities. The results of this study concluded the potential uses of
coumarin derived compounds, in medicine and drug discovery.
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Chemistry