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 series of multistep synthesis protocols was adopted to synthesize substituted imidazopyridines (IMPs) (SM-IMP-01 to SM-IMP-13, and DA-01-05). All substituted IMPs were then characterized using standard spectroscopic techniques such as ¹H-NMR, ¹³C-NMR, elemental analyses, and mass spectrometry. Our both in vitro qualitative and quantitative results for antibacterial analysis, against Klebsiella pneumoniae ATCC 4352 and Bacillus subtilis ATCC 6051 suggested that all compounds essentially exhibited activity against selected strains of bacteria. Our DFT analyses suggested that the compounds of the SM-IMP-01–SM-IMP-13 series have HOMO/LUMO gaps within 4.43–4.69 eV, whereas the compounds of the DA-01–DA-05 series have smaller values of the HOMO/LUMO gaps, 3.24–4.17 eV. The lowest value of the global hardness and the highest value of the global softness, 2.215 and 0.226 eV, respectively, characterize the compound SM-IMP-02; thus, it is the most reactive compound in the imidazopyridine carboxamide series (except hydrazide series). This compound also depicted lesser MIC values against Klebsiella pneumoniae ATCC 4352 and Bacillus subtilis ATCC 6051 as 4.8 µg/mL, each. In terms of another series, hydrazide DA-05 depicted strong antimicrobial actions (MIC: 4.8 µg/mL against both bacterial strains) and also had the lowest energy gap (3.24 eV), higher softness (0.309 eV), and lesser hardness (1.62 eV). Overall, when we compare qualitative and quantitative antimicrobial results, it is been very clear that compounds with dibromo substitutions on imidazopyridine (IMP) rings would act as better antimicrobial agents than those with -H at the eighth position on the IMP ring. Furthermore, substituents of higher electronegativities would tend to enhance the biological activities of dibromo-IMP compounds. DFT properties were also well comparable to this trend and overall, we can say that the electronic behavior of compounds under investigation has key roles in their bioactivities.

Artemisinin-resistant plasmodium strains are becoming increasingly common in malaria patients, posing a serious threat to successful malaria management. Brosimone, a significant polyphenolic ingredient of Artocarpus lakoocha, has previously been shown to have antimalarial activity in vitro. However, research into the precise mechanism of interactions is still in progress. The present study explored molecular modeling research in order to elucidate the likely mechanism of its anti-malarial effect in terms of Falcipain-2 (FP-2) inhibition. Brosimone shows a maximum binding affinity (docking score: −8.1 Kcal/mol) against FP-2 from Plasmodium falciparum, according to our molecular docking analysis of 50 lakoocha bioactive chemicals. For numerous Artocarpus lakoocha polyphenols (ALP), we used in-silico pharmacokinetics and toxicities, leading to critical insights into the mechanism of action of brosimone and other ALPs as potential therapeutic agents (2GHU) against malaria.