Guri L.V. Damu

Comprehensive Review in Current Developments of Imidazole-Based Medicinal Chemistry

Imidazole ring is an important five‐membered aromatic heterocycle widely present in natural products and synthetic molecules. The unique structural feature of imidazole ring with desirable electron‐rich characteristic is beneficial for imidazole derivatives to readily bind with a variety of enzymes and receptors in biological systems through diverse weak interactions, thereby exhibiting broad bioactivities. The related research and developments of imidazole‐based medicinal chemistry have become a rapidly developing and increasingly active topic. Particularly, numerous imidazole‐based compounds as clinical drugs have been extensively used in the clinic to treat various types of diseases with high therapeutic potency, which have shown the enormous development value. This work systematically gives a comprehensive review in current developments of imidazole‐based compounds in the whole range of medicinal chemistry as anticancer, antifungal, antibacterial, antitubercular, anti‐inflammatory, antineuropathic, antihypertensive, antihistaminic, antiparasitic, antiobesity, antiviral, and other medicinal agents, together with their potential applications in diagnostics and pathology. It is hoped that this review will be helpful for new thoughts in the quest for rational designs of more active and less toxic imidazole‐based medicinal drugs, as well as more effective diagnostic agents and pathologic probes.

Current Developments of Coumarin Compounds in Medicinal Chemistry

Coumarin compounds represent an important type of naturally occurring and synthetic oxygen-containing heterocycles with typical benzopyrone framework. This type of special benzopyrone structure enables its derivatives readily interact with a diversity of enzymes and receptors in organisms through weak bond interactions, thereby exhibit wide potentiality as medicinal drugs. So far, some coumarin-based drugs such as anticoagulant and antineurodegenerative agents have been extensively used in clinic. Coumarin-containing supramolecular medicinal agents as a new increasing expansion of supramolecular chemistry in pharmaceutical science have also been actively investigated in recent years. Coumarin-derived artificial ion receptors, fluorescent probes and biological stains are growing quickly and have a variety of potential applications in monitoring timely enzyme activity, complex biological events as well as accurate pharmacological and pharmacokinetic properties. This review provides a systematic summary and insight of the whole range of medicinal chemistry in the current developments of coumarin compounds as anticoagulant, antineurodegenerative, anticancer, antioxidative, antibacterial, antifungal, antiviral, antiparasitic, antiinflammatory and analgesic, antidiabetic, antidepressive and other bioactive agents as well as supramolecular medicinal drugs, diagnostic agents and pathologic probes, and biological stains. Some rational design strategies, structure-activity relationships and action mechanisms are discussed. The perspectives of the future development of coumarinbased medicinal chemistry are also presented.

Design, synthesis and evaluation of clinafloxacin triazole hybrids as a new type of antibacterial and antifungal agents

A series of clinafloxacin triazole hybrids as a new type of antibacterial and antifungal agents were synthesized for the first time and screened for their antimicrobial efficacy against four Gram-positive bacteria, four Gram-negative bacteria and two fungi by two fold serial dilution technique. The bioactive assay indicated that most of the target compounds displayed broad antimicrobial spectrum and good antibacterial and antifungal activities with low MIC values ranging from 0.25 to 2 μg/mL against all the tested strains which exhibited comparable or even better efficiency in comparison with the reference drugs Chloramphenicol, Clinafloxacin and Fluconazole, respectively. Notably, some synthesized clinafloxacin triazoles showed stronger efficacy against methicillin-resistant Staphylococcus aureus than their parent Clinafloxacin.

Synthesis and biological evaluation of a class of quinolone triazoles as potential antimicrobial agents and their interactions with calf thymus DNA

A novel series of quinolone triazoles were synthesized and characterized by IR, NMR, MS and HRMS spectra. All the newly prepared compounds were screened for their antimicrobial activities against seven bacteria and four fungi. Bioactive assay manifested that most of new compounds exhibited good or even stronger antibacterial and antifungal activities against the tested strains including multi-drug resistant MRSA in comparison with reference drugs Norfloxacin, Chloromycin and Fluconazole. The preliminary interactive investigations of compound 6b with calf thymus DNA by fluorescence and UV-vis spectroscopic methods revealed that compound 6b could effectively intercalate DNA to form compound 6b-DNA complex which might block DNA replication and thus exert its antimicrobial activities.

Novel berberine triazoles: Synthesis, antimicrobial evaluation and competitive interactions with metal ions to Human Serum Albumin

A series of novel berberine triazoles were synthesized and characterized by IR, NMR, MS and HRMS spectra. All target compounds and their precursors were screened for antimicrobial activities in vitro against four Gram-positive bacteria, four Gram-negative bacteria and two fungal strains. Bioactive assay indicated that most of the prepared compounds exhibited good antibacterial and antifungal activities with low MIC values ranging from 2 to 64 μg/mL, which were comparable to or even better than the reference drugs Berberine, Chloromycin, Norfloxacin and Fluconazole. The competitive interactions between compound 5a and metal ions to Human Serum Albumin (HSA) revealed that the participation of Mg(2+) and Fe(3+) ions in compound 5a-HSA association could result in the concentration increase of free compound 5a, shorten the storage time and half-life of compound 5a in the blood, thus improving its antimicrobial efficacy.

Synthesis and bioactive evaluation of novel hybrids of metronidazole and berberine as new type of antimicrobial agents and their transportation behavior by human serum albumin

A series of novel hybrids of metronidazole and berberine as new type of antimicrobial agents were synthesized and characterized by (1)H NMR, (13)C NMR, IR, MS and HRMS spectra. Bioactive assay manifested that most of the prepared compounds exhibited effective antibacterial and antifungal activities and some showed comparable or superior potency against Methicillin-resistant Staphylococcus aureus to reference drugs Norfloxacin, Chloromycin and Berberine. The transportation behavior of human serum albumin (HSA) to the highly active compound 5g was evaluated and revealed that the association of imidazole derivative 5g with HSA was spontaneous and the electrostatic interactions played important roles in the transportation of HSA to 5g. The calculated parameters indicated that compound 5g could be effectively stored and carried by HSA.

Synthesis and bioactive evaluation of a novel series of coumarinazoles

A series of novel coumarinazoles were designed, synthesized, and characterized by IR, NMR, MS and HRMS spectra. The bioactive assay for the newly prepared compounds against six bacteria and five fungi manifested that most new compounds exhibited good or even stronger antibacterial and antifungal activities in comparison with reference drugs Chloromycin, Norfloxacin and Fluconazole. Bis-azole alcohols 7a and 7d-e showed better anti-Candida utilis activity than mono-azole derivatives 4a and 4d-e at the tested concentrations, and they were more potent than the clinical Fluconazole. While triazole alcohol 7a gave comparable anti-Candida albicans and anti-Candida mycoderma activity to Fluconazole and better anti-MRSA activity than mono-triazole one 4a and clinical Norfloxacin. 1H-Benzoimidazol-2-ylthio coumarin derivatives 4e and 7e gave the strongest anti-Escherichia coli JM109 efficacy. Oxiran-2-ylmethoxy moiety was found to be a beneficial fragment to improve antibacterial and antifungal activity to some extent.

Current developments in the syntheses of 1,2,4-triazole compounds

Heterocyclic 1,2,4-triazole derivatives possess unusually spacious potentiality as medicinal agents, agricultural chemicals, functional materials, ionic liquids, supramolecular catalysts as well as artificial enzymes and receptors for supramolecular recognition and biomimetic catalysis, and their various researches and developments have been being a quite rapidly developing and active highlight topic with an infinite space. Numerous efforts have been directed toward various types of possible applications of 1,2,4-triazole-based compounds and a lot of important progress has been made, especially their preparations have attracted increasing attention. This review systematically summarized the recent advances in the syntheses of 1,2,4-triazole derivatives, including: (1) Cyclizations to form triazole ring; (2) Transformations of heterocyclic compounds to construct triazole ring; (3) Substitutions on 1,2,4-triazole ring; (4) Structural modifications in side chains of 1,2,4-triazole ring. It was hoped that this review would be helpful for the design and development of highly efficient preparation of 1,2,4-triazole derivatives with various sorts and varieties of extensively potential applications in medicine, agriculture, chemistry, materials, supramolecular sciences and so on.

Coumarin-derived azolyl ethanols: synthesis, antimicrobial evaluation and preliminary action mechanism

A series of coumarin-derived azolyl ethanols including imidazolyl, triazolyl, tetrazolyl, benzotriazolyl, thiol-imidazolyl and thiol-triazolyl ones were conveniently synthesized and characterized by IR, 1H NMR, 13C NMR and high-resolution mass spectra (HRMS) spectra. Some of the prepared compounds showed appropriate logPow values and effective antibacterial and antifungal activities. Noticeably, compound 14 with bis-triazolyl ethanol group exhibited low minimal inhibitory concentration (MIC) value of 8 mg/mL against MRSA, which was comparable or even superior to reference drugs Norfloxacin (MIC=8 mg/mL) and Chloramphenicol (MIC=16 mg/mL). It could also effectively inhibit the growth of the tested fungal strains compared to Fluconazole. Further binding studies of coumarin 14 with calf thymus DNA were investigated by UV-Vis absorption and fluorescence spectroscopy. It was found that compound 14 could interact with calf thymus DNA by groove binding to form 14-DNA complex via both hydrogen bonds and van der Waals force, which might be the factor to exert the powerful antimicrobial activity.

1H-1,2,4-Triazol-4-ium (3,4-dichloro-phen-yl)methane-sulfonate.

In the title molecular salt, C2H4N3 +·C7H5Cl2O3S−, C—C—S angle [112.25 (18)°] deviates slightly from that expected for ideal sp 3-hybridization geometry. In the crystal, the components are linked by N—H⋯O and bifurcated N—H⋯(O,O) hydrogen bonds into chains parallel to [110].