Organic acid hydrazides include a vast group of organic derivatives of hydrazines containing the active functional group (-C(=O)NHNH₂). Acid hydrazones were important bidentate ligands and show keto-enol (amido-iminol) tautomerism. They usually exist in keto form in the solid-state while in equilibrium between keto and enol forms in solution state. Such hydrazones were synthesized in the laboratory by heating substituted hydrazides or hydrazines with corresponding aldehydes or ketones in different organic solvents such as ethanol, methanol, butanol, tetrahydrofuran, etc., and some cases with the ethanol-glacial acetic acid or acetic acid alone. Hydrozones are very important intermediates for the synthesis of heterocyclic compounds and also have different biological activities. The organic chemist would have more interest in the synthesis of acid hydrazides and their derivatives because of their properties. These derivatives having wide applications as chemical preservers for plants, drugs, for manufacturing polymers, glues, etc., in industry and many other purposes. These acid hydrazides and their derivatives were found to be useful synthons for various heterocyclic five, six or seven-membered rings with one or more heteroatoms that were exhibited great biological, pharmacological and industrial applications. This paper will present a review of the chemistry and pharmacological potentials of hydrazide-hydrazones. The various synthetic routes for hydrazone, as well as antibacterial, antifungal and antiviral potentials, have been elaborated in brief.

A new series of quinoline hydrazone derivatives and their metal complexes have been synthesized and their biological properties have been evaluated againstMycobacterium tuberculosis(H37 RV strain). Most of the newly synthesized compounds displayed 100% inhibitory activity at a concentration of 6.25–25 μg/mL, againstMycobacterium tuberculosis. Fluorescence properties of all the synthesized compounds have been studied.

: Tuberculosis (TB) is a major cause of mortality and illness as reported by the W.H.O in 2019. The WHO report also mentioned the fact that about 10.0 million people fell ill with tuberculosis in the year 2018. Hydrazide–hydrazones having azomethine group (–NH–N=CH–) connected with carbonyl group is reported for the number of bioactivities like anti-inflammatory, anticonvulsant, anticancer, antiviral and antiprotozoal. Objective: The objective of our current study is to design and synthesis of more potent Hydrazide–hydrazones containing anti-Tubercular agents. Methods: In the current study, we synthesized 10 hydrazones (3a-3j) by stirring corresponding benzohydrazides (2) with substituted aldehydes (1a-j) in ethanol as a solvent and acetic acid as a catalyst at room temperature. All synthesized compounds were characterized by various spectroscopic techniques including elemental analysis, ultraviolet–visible spectroscopy, fluorescence, fourier- transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Compounds (3a-3j) were tested for in vitro anti-TB activity using Microplate Alamar Blue Assay (MABA). Results: All our synthesized compounds (3a-3j) were found to be potent against Mycobacteria tuberculosis (H37RV strain) with MIC (minimum inhibitory concentrations) values of 3.125-50 μg/mL. The hydrazide CO-NH protons in (3a-j) compounds are highly deshielded and showed broad singlet at 9.520-9.168 ppm. All the compounds were found to have more intense emission in the 416 – 429 nm regions and strong absorption in the regions of 316 – 327 nm. Synthesized compounds were also tested for in silico analysis using different software for their Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) analysis. All the compounds were found to be in silico non-carcinogenic. Conclusion: Our current study will definitely help the medicinal chemists for better designing of newer potent anti-Tubercular agents.

Background: For the past several decades, the presence of tuberculosis (TB) is being remarked as the most common infectious disease leading to mortality. Objective: Hydrazone containing azometine group (-NHN=CH-) compounds have been reported for a broad range of bioactivities such as antiplatelet, analgesic, anti-inflammatory, anticonvulsant, antidepressant, antimalarial, vasodilator, antiviral, and antimicrobial, etc. Methods: For the synthesis of compounds (4a-4d) and (6a-6e), aromatic amines were treated with methyl terephthalaldehydate in methanol, giving Schiff’s bases, followed by reductive amination and further treatment with hydrazine hydrate gave acid hydrazides (4a-4d). These acid hydrazides were then treated with different aromatic aldehydes to yield hydrazones (6a-6d). All the synthesized compounds were subjected to FT-IR, NMR, and UV spectroscopic characterization. Results: Compounds (4a-4d) and (6a-6e) were found to have highly potent activity against Mycobacteria tuberculosis (Vaccine strain, H37 RV strains): ATCC No- 27294 (MIC:1.6-6.25 μg/mL) than standard anti-TB drugs. The compounds exhibited good radical scavenging potentials(0- 69.2%), as checked from DPPH protocol. All compounds also demonstrated good in-silico ADMET results. Conclusion: The current study revealed promising in vitro anti-tuberculosis and anti-oxidant profiles of hydrazide-hydrazone analogues.

Background: Antimicrobial resistance is a major global health problem, which is being rapidly deteriorating the quality of human health. Series of substituted N-(benzo[d]thiazol-2-yl)-2- (4-(6-fluorobenzo[d]isoxazol-3-yl) piperidin-1-yl)acetamide (3a-j) were synthesized from substituted N-(benzo[d]thiazol-2-yl)-2-chloroacetamide/bromopropanamide (2a-j) and 6-fluoro-3- (piperidin-4-yl)benzo[d]isoxazole (2) and further evaluated for their docking properties and antimicrobial activity. Methods: All the synthesized compounds were characterized by FT-IR, NMR and Mass spectral analysis. All compounds were allowed to dock against different antimicrobial targets having PDB ID: 1D7U and against common antifungal target having PDB ID: 1EA1. Results: The compounds 3d and 3h showed good activity against Methicillin-resistant Staphylococcus aureus (MRSA, resistance Gram-positive bacteria). All synthesized compounds showed good to moderate activity against selected bacterial and fungal microbial strains. If we compared the actual in-vitro antimicrobial activity and in silico molecular docking study, we found that molecules 3i and 3h were more potent than the others. Conclusion: Our current study would definitely pave the new way of designing and synthesis of more potent 2-aminobenzothiazoles derivatives.