The main aim of the present study was to synthesize new leads with potential antimicrobial and antioxidant activities. As a part of systematic investigation of synthesis and biological activity, some new indole compounds
The emergence and spread of antimicrobial resistance have become one of the most serious public health concerns across the world. In last few years it was reported that indole, its bioisosteres, and derivatives had antimicrobial activity against Gram-negative, Gram-positive bacteria especially against
Thiazolidinone, a saturated form of thiazole with carbonyl group on fourth carbon, has been considered as a magic moiety (wonder nucleus) because it gives out novel derivatives with different types of biological activities. This diversity in the biological response profile has attracted the attention of many researchers to explore the potential biological activity (such as antibacterial [
We have reported earlier the synthesis, antioxidant, and antimicrobial activities of indole analogues containing thiazolidinone derivatives such as 3-[4-(4-substituted)thiazol-2-yl]-2-(2-phenyl-1H-indol-3-yl)thiazolidin-4-ones (
Motivation for synthesis of antimicrobial and antioxidant active compounds.
The pathway for the synthesis of title compounds is illustrated in Scheme
Synthetic pathways for indole analogues (
All the synthesized compounds (
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Std.: streptomycin.
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Std.: fluconazole.
Antibacterial screening revealed that compound
Antifungal activity assay revealed that the compounds
Antioxidants are intimately involved in the prevention of cellular damage, cancer, aging, and a variety of diseases. DPPH is stable free radical that can accept an electron or hydrogen atom, and its stability originates from delocalization of the unpaired electron over the molecule.
Free radicals are highly reactive species with one or more unpaired electrons in their last orbital. Reactive oxygen species (ROS), important in biological systems, include superoxide (
DPPH RSA of the compounds (
The RSA results revealed that the compound
Ferric ion (Fe3+) is relatively biologically inactive form of iron. However, it can be reduced to the active Fe2+ depending on the condition, particularly pH [
Ferric (Fe3+) ions reducing capacity of the compounds (
Determination of the reducing power of the compounds was conducted by a method described in [
Metal chelating capacity reduces the concentration of the catalyzing transition metal in lipid peroxidation. It was reported that chelating agents, which form
Determination of ferrous ion (Fe2+) chelating activity of the synthesized compounds was carried out as described in Dinis’ method [
Metal chelating activity of the compounds (
In this study, we have demonstrated the synthesis of some novel indole derivatives incorporating 5H-dibenzo[b,f]azepine and thiazolidine heterocycles in a single structure. Some of the chloro- and methyl-substituted compounds exhibited promising antimicrobial and antioxidant activities.
All reagents were obtained commercially and used by further purification. Melting points were determined by an open capillary method, and uncorrected melting points are reported in this study. Purity of the compounds was checked by thin layer chromatography (TLC) using silica gel-G coated aluminium plates (Merck), and spots were visualized by exposing the dry plates to iodine vapours. The infrared (IR) (KBr) spectra were recorded with a Perkin-Elmer spectrum one Fourier transform infrared spectroscopy (FT-IR) spectrometer. The 1H nuclear magnetic resonance (NMR) (dimethysulphoxide-
A solution of
A mixture of compounds
The
The radical scavenging activity (RSA) of test compounds (
The reducing power of the synthesized compounds (
The ferrous ion chelating activities of synthesized compounds (
Since The authors have procured the IR, NMR, and mass spectra of the synthesized compounds from the Sophisticated Analytical Instrument facility, namely, The Indian Institute of Technology, Madras, Chennai, India, as per the condition of institution, authors should acknowledge their services in the research paper while publishing the work, which includes the data provided by them in the research paper. The same has been acknowledged in the acknowledgment section. The authors do not have any agreement, financial assistance, or sponsorship from Perkin-Elmer spectrum, Brucker NMR, and so forth. These names are mentioned in the experimental protocol as these are the instrument models, and it is mandatory for authors to mention the instrument models used to scan the spectra of unknown compounds. Otherwise the corresponding author or coauthors have nodirect financial relationship with the commercial identity mentioned in their paper in any form.
The authors are thankful to the Chairman, Department of Chemistry, Gulbarga University, Gulbarga, for providing laboratory facilities, to the Chairman, Department of Microbiology, Gulbarga University, Gulbarga, for providing facilities to carry out antimicrobial activity tests, and to the Director, Indian Institute of Technology, Madras, Chennai, for providing spectral data. Vijaykumar Tukaram Katkar is thankful to University grants Commission, New Delhi, India, for providing financial assistance through Research Fellowship in Science Meritorious Students (RFSMS).