Synthesis, SAR Study and Evaluation of Mannich and Schiff Bases of Pyrazol-5(4H)-one Moiety Containing 3-(Hydrazinyl)-2-phenylquinazolin-4(3H)-one

Pyrazolone structural motif in medicinal chemistry: Retrospect and prospect

The pyrazolone structural motif is a critical element of drugs aimed at different biological end-points. Medicinal chemistry researches have synthesized drug-like pyrazolone candidates with several medicinal features including antimicrobial, antitumor, CNS (central nervous system) effect, anti-inflammatory activities and so on. Meanwhile, SAR (Structure-Activity Relationship) investigations have drawn attentions among medicinal chemists, along with a plenty of analogues have been derived for multiple targets. In this review, we comprehensively summarize the biological activity and SAR for pyrazolone analogues, wishing to give an overall retrospect and prospect on the pyrazolone derivatives.

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The pyrazolone structural motif is a critical element of drugs aimed at different biological end-points.

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The pyrazolone analogues have been carried out to drug-like candidates with broad range of medicinal properties.

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This review wishes to give an overall retrospect and prospect on the pyrazolone derivatives.

Design, Synthesis, and Characterization of Some Hybridized Pyrazolone Pharmacophore Analogs against Mycobacterium tuberculosis

Twenty-seven hybridized pyrazolone analogs were designed, docked, synthesized in two series and evaluated for their in vitro antimycobacterial properties. In the first series, four Schiff base derivatives, 6b, 7b, 7h, and 7i, show good antitubercular activity with minimum inhibition concentration (MIC) values in the range of 32.56-42.55 µM. In the second series, two compounds, 8b and 8c, possessed significant antitubercular activity with MIC <0.37 and <0.44 μM, respectively; they were even more potent than the standards pyrazinamide (12.99 μM), ciprofloxacin (4.82 μM), and streptomycin (5.36 μM), with a selectivity index of >630. Compounds 8b and 8c showed shikimate kinase inhibition activity at 5.84 and 6.93 µM, respectively. The activity and docking results lead to the conclusion that the compounds without double bond in the imine side chain and hydrophobic clashes at the pyrazolone end are necessary for good accommodation in the binding pocket and for imparting flexibility. All the compounds were also tested for antimicrobial activity (antibacterial and antifungal) and show highly significant activities against all the microorganisms tested.

Mannich bases in medicinal chemistry and drug design

The biological activity of Mannich bases, a structurally heterogeneous class of chemical compounds that are generated from various substrates through the introduction of an aminomethyl function by means of the Mannich reaction, is surveyed, with emphasis on the relationship between structure and biological activity. The review covers extensively the literature reports that have disclosed Mannich bases as anticancer and cytotoxic agents, or compounds with potential antibacterial and antifungal activity in the last decade. The most relevant studies on the activity of Mannich bases as antimycobacterial agents, antimalarials, or antiviral candidates have been included as well. The review contains also a thorough coverage of anticonvulsant, anti-inflammatory, analgesic and antioxidant activities of Mannich bases. In addition, several minor biological activities of Mannich bases, such as their ability to regulate blood pressure or inhibit platelet aggregation, their antiparasitic and anti-ulcer effects, as well as their use as agents for the treatment of mental disorders have been presented. The review gives in the end a brief overview of the potential of Mannich bases as inhibitors of various enzymes or ligands for several receptors.