4-Phenylcoumarin derivatives as new HIV-1 NNRTIs: Design, synthesis, biological activities, and computational studies

A series of 4-phenylcoumarin derivatives was synthesized and evaluated for their cellular anti-HIV-1 and HIV-2 activities as well as their inhibitory effects against HIV-1 reverse transcriptase (RT). The hydrazone compound 8b and the ethylthiosemicarbazide derivative 4c showed the best inhibition activity against wild-type (WT) HIV-1. The promising compounds were further evaluated against HIV-1 RT and exhibited significant inhibitory activity with compound 8b showing comparable effect to the reference NNRTI Efavirenz (IC50 = 9.01 nM). Structure activity relationship study revealed the importance of 6-chloro and 4-phenyl substituents for optimum activity, as well as the 5-atoms linker (=N-NH-CO-CH2-O-) at position 7 of coumarin scaffold that can support the rotation and flexibility of compound 8b to fit well in the binding pocket. The molecular docking of compound 8b demonstrated a typical seahorse binding mode with better binding interactions that covered more residues when compared to Efavirenz.

Exploration of a library of piperonylic acid-derived hydrazones possessing variable aryl functionalities as potent dual cholinesterase and monoamine oxidase inhibitors

A library of piperonylic acid-derived hydrazones possessing variable aryl moiety was synthesized and investigated for their multifunctional properties against cholinesterases (ChEs) and monoamine oxidases (MAOs). The in vitro enzymatic assay results revealed that the tested hydrazones have exhibited excellent cholinesterase inhibition profile. Compound 4i, (E)-N'-(2,3-dichlorobenzylidene)benzo[d][1,3]dioxole-5-carbohydrazide showed promising dual inhibitory profile against AChE (0.048 ± 0.007 μM), BChE (0.89 ± 0.018 μM), and MAO-B (0.95 ± 0.12 μM) enzymes. SAR exploration revealed that the truncation of the linker connecting both the aryl binding sites of the semicarbazone scaffold, by one atom, has relatively suppressed the AChE inhibitory potential. Kinetic studies disclosed that the compound 4i reversibly inhibited AChE enzyme in a competitive manner (Ki = 8.0 ± 0.076 nM), while it displayed a non-competitive and reversible inhibition profile against MAO-B (Ki = 9.6 ± 0.021 µM). Moreover, molecular docking studies of synthesized compounds against ChEs and MAOs provided the crucial molecular features that enable their close association and interaction with the target enzymes. All atomistic simulation studies confirmed the stable association of compound 4i within the active sites of AChE and MAO-B. In addition, theoretical ADMET prediction studies demonstrated the acceptable pharmacokinetic profile of the dual inhibitors. In summary, the attempted lead simplification study afforded a potent dual ChE-MAO-B inhibitor compound that merits further investigation.

Caging of Bodipy Photosensitizers through Hydrazone Bond Formation and their Activation Dynamics

Three unique hydrazone-based small-molecule-activatable photosensitizers were designed and synthesized. Two of them work efficiently in a low-pH environment, resembling the microenvironment of the cancerous tissues. The activation pathway is unique and based on hydrazone bond cleavage. They were investigated through in vitro cellular studies in aggressive cancer lines, and tumor-specific culture conditions successfully initiated the cleavage and activation of the cytotoxic singlet oxygen generation in the relevant time period. The interesting photophysical characteristics of the α- and β-substituted hydrazone derivatives of the Bodipy structures and their mild hydrolysis methodologies were also investigated successfully.

Investigation of Methyl-5-(pentan-3-yloxy)-7-oxabicyclo[4.1.0]hept-3-ene-3-carboxyhydrazide Derivatives as Potential Inhibitors of COVID-19 Main Protease: DFT and Molecular Docking Study

The search for effective therapeutics to combat COVID-19 has led to the exploration of the biological activity of numerous compounds. In this study, hydrazones derived from oseltamivir intermediate, methyl 5-(pentan-3-yloxy)-7-oxabicyclo[4.1.0]hept-3-ene-3-carboxylate have been investigated for their potential as drug candidates against the COVID-19 virus using computational methods, including density functional theory (DFT) studies, molecular docking, and absorption, distribution, metabolism, excretion and toxicity (ADMET) analysis. The DFT studies provide information on the electronic properties of the compounds while the molecular docking results using AutoDock reported the binding energies between the main protease of COVID-19 and the compounds. The DFT results revealed that the energy gap of the compounds ranged from 4.32 to 5.82 eV while compound HC had the highest energy gap (5.82 eV) and chemical potential (2.90 eV). The electrophilicity index values of the 11 compounds ranged from 2.49 to 3.86, thus they were classified as strong electrophiles. The molecular electrostatic potential (MESP) revealed electron-rich and electron-deficient regions of the compounds. The docking results reveal that all the compounds had better docking scores than remdesivir and chloroquine, frontline drugs employed in combating COVID-19, with HC having the best docking score of -6.5. The results were visualized using Discovery studio, which revealed hydrogen bonding, pi-alkyl interaction, alkyl interaction, salt bridge interaction, halogen interaction as being responsible for the docking scores. The drug-likeness results showed that the compounds qualify as oral drug candidates as none of them violated Vebers and Lipinski's rule. Thus, they could serve as potential inhibitors of COVID-19.

Synthetic Approaches, Biological Activities, and Structure-Activity Relationship of Pyrazolines and Related Derivatives

It has been established that pyrazolines and their analogs are pharmacologically active scaffolds. The pyrazoline moiety is present in several marketed molecules with a wide range of uses, which has established its importance in pharmaceutical and agricultural sectors, as well as in industry. Due to its broad-spectrum utility, scientists are continuously captivated by pyrazolines and their derivatives to study their chemistry. Pyrazolines or their analogs can be prepared by several synthesis strategies, and the focus will always be on new greener and more economical ways for their synthesis. Among these methods, chalcones, hydrazines, diazo compounds, and hydrazones are most commonly applied under different reaction conditions for the synthesis of pyrazoline and its analogs. However, there is scope for other molecules such as Huisgen zwitterions, different metal catalysts, and nitrile imine to be used as starting reagents. The present article consists of recently reported synthetic protocols, pharmacological activities, and the structure-activity relationship of pyrazoline and its derivatives, which will be very useful to researchers.

Design, synthesis, and evaluation of hydrazones as dual inhibitors of ryanodine receptors and acetylcholinesterases for Alzheimer's disease

Alzheimer's disease (AD) implicates neuronal loss, plaque and neurofibrillary tangle formation, and disturbed neuronal Ca²⁺ homeostasis, which leads to severe dementia, memory loss, as well as thinking and behavioral perturbations that could ultimately lead to death. Calcium dysregulation and low acetylcholine levels are two main mechanisms implicated in Alzheimer's disease progression. Simultaneous inhibition of calcium oscillations (store overload-induced Ca²⁺ release [SOICR]) and acetylcholinesterase (AChE) by a single molecule may bring a new breath of hope for AD treatment. Here, we described some dantrolene derivatives as dual inhibitors of the ryanodine receptor and AChE. Two series of acylhydrazone/sulfonylhydrazone derivatives with aromaticgroup were designed and synthesized. In this study, the target compounds were evaluated for their ability to inhibit SOICR and AChE in vitro, using dantrolene and donepezil as positive controls. Compound 22a exhibited excellent and balanced inhibitory potency against SOICR (inhibition (%) = 90.1, IC₅₀ = 0.162 μM) and AChE (inhibition (%) = 93.5, IC₅₀ = 0.372 μM). Docking simulations showed that several preferred compounds could bind to the active sites of both the proteins, further validating the rationality of the design strategy. Potential therapeutic effects in AD were evaluated using the Barnes maze and Morris water maze tests, which demonstrated that compound 22a significantly improved memory and cognitive behavior in AD model mice. Moreover, it was also found that compound 22a could enhance synaptic strength by measuring hippocampal long-term potentiation (LTP) in brain slices. These results suggested that the introduction of a sulfonyl-hydrazone scaffold and aromatic substitution to dantrolene derivatives provided a useful template for the development of potential chemical entities against AD.

Synthetic hydrazones: In silico studies and in vitro evaluation of the antileishmania potential

Bioprospecting and synthesis of strategically designed molecules have been used in the search for drugs that can be in leishmaniasis. Hydrazones (HDZ) are promising compounds with extensive biological activities. The objective of this work was to perform in silico studies of hydrazones 1-5 and to evaluate their antileishmanial, cytotoxic and macrophage immunomodulatory potential in vitro. Hydrazones were subjected to prediction and molecular docking studies. Antileishmanial protocols on promastigotes and amastigotes of Leishmania amazonensis, cytotoxicity and macrophage immunomodulatory activity were performed. Hydrazones showed a good pharmacokinetic profile and hydrazone 3 and hydrazone 5 were classified as non-carcinogenic. Hydrazone 5 obtained the best conformation with trypanothione reductase. Hydrazone 1 and hydrazone 3 obtained the best mean inhibitory concentration (IC₅₀) values for promastigotes, 4.4-61.96 μM and 8.0-58.75 μM, respectively. It also showed good activity on intramacrophagic amastigotes, with hydrazone 1 being the most active (IC₅₀ = 6.79 μM) with selectivity index of 56. In cytotoxicity to macrophages hydrazone 3 was the most cytotoxic (CC₅₀ = 256.3 ± 0,04 μM), while hydrazone 4 the least (CC₅₀ = 1055.9 ± 0.03 μM). It can be concluded that the hydrazones revealed important pharmacokinetic and toxicological properties, in addition to antileishmania potential in reducing infection and infectivity in parasitized macrophages.

Electrochemical Synthesis of Pyrazolines and Pyrazoles via [3+2] Dipolar Cycloaddition

Pyrazolines and pyrazoles are common and important motifs of pharmaceutical agents and agrochemicals. Herein, the first electrochemical approach for their direct synthesis from easily accessible hydrazones and dipolarophiles up to decagram scale is presented. The application of a biphasic system (aqueous/organic) even allows for the conversion of highly sensitive alkenes, wherein inexpensive sodium iodide is employed in a dual role as supporting electrolyte and mediator. In addition, mechanistic insight into the reaction is given by the isolation of key step intermediates. The relevance of the presented reaction is underlined by the synthesis of commercial herbicide safener mefenpyr-diethyl in good yields.

Photocatalytic Alkylation of C(sp3 )-H Bonds Using Sulfonylhydrazones

The ability to construct C(sp³ )-C(sp³ ) bonds from easily accessible reagents is a crucial, yet challenging endeavor for synthetic organic chemists. Herein, we report the realization of such a cross-coupling reaction, which combines N-sulfonyl hydrazones and C(sp³ )-H donors through a diarylketone-enabled photocatalytic hydrogen atom transfer and a subsequent fragmentation of the obtained alkylated hydrazide. This mild and metal-free protocol was employed to prepare a wide array of alkyl-alkyl cross-coupled products and is tolerant of a variety of functional groups. The application of this chemistry further provides a preparatively useful route to various medicinally-relevant compounds, such as homobenzylic ethers, aryl ethyl amines, β-amino acids and other moieties which are commonly encountered in approved pharmaceuticals, agrochemicals and natural products.

Synthesis, characterization, DFT, antioxidant, antibacterial, pharmacokinetics and inhibition of SARS-CoV-2 main protease of some heterocyclic hydrazones

Three hydrazone derivatives have been synthesized using condensation reaction of 4-hydrazinylbenzoic acid with three aromatic aldehydes namely: thiophene-2-carbaldehyde, thiophene-3-carbaldehyde and 2-furaldehyde in ethanol at 78 °C reflux. The synthesized molecules have been characterized using spectroscopic and physicochemical methods including UV-Vis, IR, ¹H NMR, ¹³C NMR, ¹⁵N NMR and melting point determination. Optimized molecular structures, UV-Vis and IR spectra modeling, the reactivity, the stability and some quantum chemical parameters of the synthesized molecules were modeled utilizing density functional theory (DFT). The obtained theoretical results were found in good agreement with the experimental results. On the other hand, the antioxidant and antibacterial activities of the molecules under study were evaluated to better understand the associated mechanisms of action specifically. Also, predicted ADME-T and pharmacokinetic parameters indicated that these compounds showed good oral bioavailability. Finally, molecular docking has been used to predict the inhibitory activity of the studied hydrazone derivatives on the SARS-CoV-2 main protease (Mpro).

Synthesis and Antimycobacterial Activity of Isoniazid Derivatives Tethered with Aliphatic Amines

BACKGROUND

There is an urgent need for new antitubercular compounds. Modification of antimycobacterial isonicotinohydrazide at hydrazide N2 provided antimycobacterial active compounds.

OBJECTIVE

Combining this scaffold with various aliphatic amines that are also frequently present in antitubercular compounds, we have designed, synthesized, and evaluated twenty-three N- (cyclo)alkyl-2-(2-isonicotinoylhydrazineylidene)propanamides and their analogues as potential antimycobacterial compounds. By increasing lipophilicity, we intended to facilitate the penetration of mycobacteria's highly impermeable cell wall.

METHODS

The target amides were prepared via condensation of isoniazid and pyruvic acid, followed by carbodiimide-mediated coupling with yields from 35 to 98 %. The compounds were screened against Mycobacterium tuberculosis H37Rv and two nontuberculous mycobacteria (M. avium, M. kansasii).

RESULTS

All the derivatives exhibited low minimum inhibitory concentrations (MIC) from ≤0.125 and 2 μM against M. tuberculosis and nontuberculous mycobacteria, respectively. The most active molecules were substituted by a longer n-alkyl from C8 to C14. Importantly, the compounds showed comparable or even several-fold lower MIC than parent isonicotinohydrazide. Based on in silico predictions, a vast majority of the derivatives share suitable physicochemical properties and structural features for drug-likeness.

CONCLUSION

Presented amides are promising antimycobacterial agents.

Photocatalytic remediation of methylene blue and antibacterial activity study using Schiff base-Cu complexes

This work describes the design of novel Cu(II) complexes and their application in the photocatalytic degradation of methylene blue (MB). The same photocatalyst exhibits antibacterial activity against Escherichia coli (gram-negative) and Bacillus circulans (gram-positive). The characterisation of the photocatalysts has been done by several up-to-date physical methods. The rationale behind the photocatalysts' beneficial intervention is discussed in this study. Statistical analysis of the degradation of MB is done using a one-way ANOVA, and the significance of means is determined by a multiple comparison test using Turkey HSD. Also, the degradation of MB follows pseudo first-order kinetics with high correlation coefficient values (R² > 0.95), making them useful as simple and low-cost organic dye degradation agents.

Neuroprotective evaluation of novel substituted 1,3,4-oxadiazole and aroylhydrazone derivatives

The paper reports on the facile and convenient synthesis of a series of novel 2,5-substituted 1,3,4-oxadiazoles 3a-f and that of aroylhydrazone-based molecular hybrids 5a-g from readily available starting materials. The structure of the compounds was confirmed by IR, ¹H-NMR, ¹³C-NMR and HRESI-MS spectral data. The toxicological potential of the compounds was evaluated by monitoring the synaptosomal viability and the levels of reduced glutathione in rat brain synaptosomes, isolated by Percoll gradient. The neuroprotective effects were assessed in vitro in a model of 6-hydroxydopamine-induced neurotoxicity. Administered alone, at a concentration of 40 µM, most of the 1,3,4-oxadiazole derivatives and all of the hydrazone derivatives exhibited weak statistically significant neurotoxic effects, compared to the control. Two of the compounds from the novel oxadiazoles 3a and 3d did not have any toxicity. In a model of 6-OHDA-induced oxidative stress, again 3a and 3d and all aroylhydrazone derivatives 5a-g revealed statistically significant neuroprotective effect by preserving the synaptosomal viability and the level of reduced glutathione, against the toxic agent. Some of the compounds may have neuroprotective effects due to possible stabilization of the synaptosomal membrane and/or because of the preserved reduced glutathione. Additionally, all the compounds display a good predicted ADME profile.

Synthesis, characterization, computational, antioxidant and fluorescence properties of novel 1,3,5-trimesic hydrazones derivatives

New photophysical and antioxidant materials of trimesic trihydrazide derivatives were synthesized by one-pot stage of trimesic trihydrazide and different aromatic aldehydes. All compounds were characterized by spectroscopic techniques (NMR, MS, and IR) and elemental analysis. The absorption and emission spectral characteristics of hydrazone derivatives were investigated. The absorption maxima showed red shift relative to the starting compound. While the emission maxima showed clear dependent on the type of substituents. The electron donating and electron withdrawing showed red and blue shifts relative to the starting compound, respectively. The compounds’ effectiveness as antioxidant was estimated by DPPH radical scavenging and ABTS radical cation assays in vitro which indicated that the derivatives could be used as potential antioxidants. In addition, compounds 3g, and 3i showed strong antioxidant activities according to the DPPH assay and compounds 3c and 3m exhibited good antioxidant activities in ABTS assay. Antimicrobial activity of the derivatives was estimated using a micro-broth dilution method. Furthermore, molecular geometries of all prepared derivatives were fully optimized using density functional theory (DFT) calculations at the 6-31G(d)/B3LYP level of theory.

Evaluation of N-aryl-β-alanine derivatives as anticancer agents in triple-negative breast cancer and glioblastoma in vitro models

Synthesis of β-amino acid derivatives containing hydrazone and azole moieties is described. For this purpose, the appropriate hydrazide was treated with aromatic aldehydes, ketones and phenyl iso(thio)cyanates to obtain the desired outcome. The synthesized target compounds were evaluated for their anticancer properties. The assay displayed 3,3'-((2,6-diethylphenyl)azanediyl)bis(N'-(benzylidene)propanehydrazide) to possess the convincing anticancer effect against triple-negative breast cancer cells in vitro. To further study the anticancer properties of compounds containing a hydrazone moiety in breast cancer, series of previously and newly prepared dihydrazones were investigated. It was determined that derivatives with the bis(N'-(4-bromobenzylidene) fragment in the structure are exclusively cytotoxic to cancer cells. The most active compounds against both cell lines were those containing electron withdrawing 4-BrPh or 4-ClPh moieties, together with either chlorine, bromine or iodine groups in para position of phenyl ring. Selected two representative compounds showed migrastatic activity in MDA-MB-231 cell line, where both of them reduced the growth of breast cancer and glioblastoma cell 3D cultures and inhibited cell colony formation. 2009 Elsevier Ltd. All rights reserved.

Virtual and experimental high throughput screening of substituted hydrazones on β-Tubulin polymerization

Microtubule targeting agents that disrupt the dynamic functioning of the mitotic spindle are some of the best chemotherapeutic agents. Interruption of microtubule dynamics through polymerization or depolymerization causes cell arrest leading to apoptosis. We report a novel class of aroylhydrazones with anticancer properties. Tubulin inhibition studies were performed using both computational and biological methods. Docking and pharmacophore mapping showed efficient binding between the ligands and the protein. Tubulin inhibition assay showed the aroylhydrazones to be inhibitors of tubulin polymerization. DFT studies explains the geometrical and electronic properties of the compounds. Furthermore, anticancer studies using lung and liver cancer cell lines gave low IC₅₀ values with the methyl substituted hydrazone MH-2 being the most potent. (IC₅₀ of 0.0896 and 0.1040 µM respectively). The methyl group is responsible for the effective binding to the protein. Thus, a new class of tubulin binding agents have been identified as potential agents in cancer therapy.

4-Chlorophenylthioacetone-derived thiosemicarbazones as potent antitrypanosomal drug candidates: Investigations on the mode of action

Chagas disease (ChD), caused by Trypanosoma cruzi, remains a challenge for the medical and scientific fields due to the inefficiency of the therapeutic approaches available for its treatment. Thiosemicarbazones and hydrazones present a wide spectrum of bioactivities and are considered a platform for the design of new anti-T. cruzi drug candidates. Herein, the potential antichagasic activities of [(E)-2-(1-(4-chlorophenylthio)propan-2-ylidene)-hydrazinecarbothioamides] (C1, C3), [(E)-N'-(1-((4-chlorophenyl)thio)propan-2-ylidene)benzohydrazide] (C2), [(E)-2-(1-(4-, and [(E)-2-(1-((4-chlorophenyl)thio)propan-2-ylidene)hydrazinecarboxamide] (C4) were investigated. Macrophages (MOs) from C57BL/6 mice stimulated with C1 and C3, but not with C2 and C4, reduced amastigote replication and trypomastigote release, independent of nitric oxide (NO) and reactive oxygen species production and indoleamine 2,3-dioxygenase activity. C3, but not C1, reduced parasite uptake by MOs and potentiated TNF production. In cardiomyocytes, C3 reduced trypomastigote release independently of NO, TNF, and IL-6 production. C1 and C3 were non-toxic to the host cells. A reduction of parasite release was found during infection of MOs with trypomastigotes pre-incubated with C1 or C3 and MOs pre-stimulated with compounds before infection. Moreover, C1 and C3 acted directly on trypomastigotes, killing them faster than Benznidazole, and inhibited T. cruzi proliferation at various stages of its intracellular cycle. Mechanistically, C1 and C3 inhibit parasite duplication, and this process cannot be reversed by inhibiting the DNA damage response. In vivo, C1 and C3 attenuated parasitemia in T. cruzi-infected mice. Moreover, C3 loaded in a lipid nanocarrier system (nanoemulsion) maintained anti-T. cruzi activity in vivo. Collectively, these data suggest that C1 and C3 are candidates for the treatment of ChD and present activity in both the host and parasite cells.

Novel Iodinated Hydrazide-hydrazones and their Analogues as Acetyl- and Butyrylcholinesterase Inhibitors

BACKGROUND

Hydrazide-hydrazones have been known as scaffold with various biological activities including inhibition of acetyl- (AChE) and butyrylcholinesterase (BuChE). Cholinesterase inhibitors are mainstays of dementias' treatment.

OBJECTIVE

Twenty-five iodinated hydrazide-hydrazones and their analogues were designed as potential central AChE and BuChE inhibitors.

METHODS

Hydrazide-hydrazones were synthesized from 4-substituted benzohydrazides and 2-/4- hydroxy-3,5-diiodobenzaldehydes. The compounds were investigated in vitro for their potency to inhibit AChE from electric eel and BuChE from equine serum using Ellman's method. We calculated also physicochemical and structural parameters for CNS delivery.

RESULTS

The derivatives exhibited a moderate dual inhibition with IC50 values ranging from 15.1-140.5 and 35.5 to 170.5 μmol.L-1 for AChE and BuChE, respectively. Generally, the compounds produced a balanced or more potent inhibition of AChE. N'-[(E)-(4-Hydroxy-3,5-diiodophenyl)methylidene]-4- nitrobenzohydrazide 2k and 4-fluoro-N'-(2-hydroxy-3,5-diiodobenzyl)benzohydrazide 3a were the most potent inhibitors of AChE and BuChE, respectively. Structure-activity relationships were established, and molecular docking studies confirmed interaction with enzymes.

CONCLUSION

Many novel hydrazide-hydrazones showed lower IC50 values than rivastigmine against AChE and some of them were comparable for BuChE to this drug used for the treatment of dementia. They interact with cholinesterases via non-covalent binding into the active site. Based on the BOILEDEgg approach, the majority of the derivatives met the criteria for blood-brain-barrier permeability.

Iodinated 1,2-diacylhydrazines, benzohydrazide-hydrazones and their analogues as dual antimicrobial and cytotoxic agents

Hydrazide-hydrazones have been described as a scaffold with antimicrobial and cytotoxic activities as well as iodinated compounds. A resistance rate of bacterial and fungal pathogens has increased considerably. That is why we synthesized and screened twenty-two iodinated hydrazide-hydrazones 1 and 2, ten 1,2-diacylhydrazines 3 and their three reduced analogues 4 for their antibacterial, antifungal, and cytotoxic properties. Hydrazide-hydrazones were prepared by condensation of 4-substituted benzohydrazides with 2-/4-hydroxy-3,5-diiodobenzaldehydes, diacylhydrazines from identical benzohydrazides and 3,5-diiodosalicylic acid via its chloride. These compounds were investigated in vitro against eight bacterial and eight fungal strains. The derivatives were found potent antibacterial agents against Gram-positive cocci including methicillin-resistant Staphylococcus aureus with the lowest values of minimum inhibitory concentrations (MIC) of 7.81 µM. Four compounds inhibited also human pathogenic fungi (MIC of ≥1.95 µM). The derivatives had different degrees of cytotoxicity for HepG2 and HK-2 cell lines (IC₅₀ values from 11.72 and 26.80 µM, respectively). Importantly, normal human cells exhibited lower sensitivity. The apoptotic effect was also investigated. In general, the presence of 3,5-diiodosalicylidene scaffold (compounds 1) is translated into enhanced both antimicrobial and cytotoxic properties whereas its 4-hydroxy isomers 2 share a low biological activity. N'-Benzoyl-2-hydroxy-3,5-diiodobenzohydrazides 3 have a non-homogeneous activity profile. Focusing on 4-substituted benzohydrazide part, the presence of an electron-withdrawing group (F, Cl, CF₃, NO₂) was found to be beneficial.

In vitro and in vivo antiplasmodial activity of novel quinoline derivative compounds by molecular hybridization

Chloroquine (CQ) has been the main treatment for malaria in regions where there are no resistant strains. Molecular hybridization techniques have been used as a tool in the search for new drugs and was implemented in the present study in an attempt to produce compound candidates to treat malarial infections by CQ-resistant strains. Two groups of molecules were produced from the 4-aminoquinoline ring in conjugation to hydrazones (HQ) and imines (IQ). Physicochemical and pharmacokinetic properties were found to be favorable when analyzed in silico and cytotoxicity and antiplasmodial activity were assayed in vitro and in vivo showing low cytotoxicity and selectiveness to the parasites. Candidates IQ5 and IQ6 showed important values of parasite growth inhibition in vivo on the 5th day after infection (IQ5 15 mg/kg = 72.64% and IQ6 15 mg/kg = 71.15% and 25 mg/kg = 93.7%). IQ6 also showed interaction with ferriprotoporphyrin IX similarly to CQ. The process of applying condensation reactions to yield imines is promising and capable of producing molecules with antiplasmodial activity.

Design, synthesis, molecular docking, in silico ADMET profile and anticancer evaluations of sulfonamide endowed with hydrazone-coupled derivatives as VEGFR-2 inhibitors

A new series of sulfonamide endowed with hydrazone coupled to dimethyl and/or diethyl malonates were prepared. Various sulfa drugs were diazotized and followed by coupling with active methylene of dimethyl and/or diethyl malonate to afford the new intermediates hydrazones 3_a-c and 4_a-c. The reactivity of hydrazone derivatives towards hydrazines was investigated. Thus, a novel series of 3,5-dioxopyrazolidine7_a-cwere obtained by treatment with hydrazine hydrate. When hydrazones were allowed to react with phenyl hydrazine, the alkyl 2-((4-(N-(substituted)sulfamoyl)phenyl)diazenyl)-3-oxo-3-(2-phenylhydrazinyl)propanoateswere obtained 8_a-c and/or 10_a-c. Their anticancer activities were evaluated against HepG2, HCT-116 and MCF-7. HepG2 was the most sensitive one. In particular, compounds 7_c, 7_b and 10_c were found to be the most potent derivatives with IC₅₀ = 6.43 ± 0.5, 9.66 ± 0.8, 10.57 ± 0.9 µM, 8.65 ± 0.7, 7.49 ± 0.6, 14.29 ± 1.3 µM and 8.97 ± 0.7, 10.13 ± 0.9, 13.82 ± 1.1 µM respectively. Sorafenib and doxorubicin were used as reference drugs. The most potent derivatives 7_a, 7_b, 7_c, 8_c and 10_c were tested for their cytotoxicity against normal VERO cell lines. Compounds 7_a, 7_b, 7_c, 8_c and 10_c are respectively, 2.41, 4.85, 4.08, 3.23 and 5.89 fold times more toxic in HCT116 than in VERO normal cells. Moreover, the most active anti-proliferative derivatives 7_a, 7_b, 7_c, 8_c and 10_c were subjected to further biological study to evaluate their inhibitory potentials against VEGFR-2. The tested compounds displayed high to good inhibitory activity with IC₅₀ values ranging from 0.14 ± 0.02 to 0.23 ± 0.03 µM. Among them, compounds 7_c, 7_b and 10_c were found to be the most potent derivative that inhibited VEGFR-2 at IC₅₀ values of 0.14 ± 0.02, 0.15 ± 0.02 and 0.15 ± 0.02 µM respectively. sorafenib was used as reference drug. Furthermore, ADMET profile was evaluated for the four most active compounds in comparison to doxorubicin as a reference drug. The data obtained from docking studies were highly correlated with that obtained from the biological screening.

Synthesis of non-nucleoside anti-viral cyclopropylcarboxacyl hydrazones and initial anti-HSV-1 structure-activity relationship studies

The synthesis of a lead anti-viral cyclopropyl carboxy acyl hydrazone 4F17 (5) and three sequential arrays of structural analogues along with the initial assessment and optimization of the antiviral pharmacophore against the herpes simplex virus type 1 (HSV-1) are reported.

Synthesis and Biological Activity of Hydrazones and Derivatives: A Review

Hydrazones and their derivatives are very important compounds in medicinal chemistry due to their reported biological activity for the treatment of several diseases, like Alzheimer's, cancer, inflammation, and leishmaniasis. However, most of the investigations on hydrazones available in literature today are directed to the synthesis of these molecules with little discussion available on their biological activities. With the purpose of bringing lights into this issue, we performed a revision of the literature and wrote this review based on some of the most current research reports of hydrazones and derivatives, making it clear that the synthesis of these molecules can lead to new drug prototypes. Our goal is to encourage more studies focused on the synthesis and evaluation of new hydrazones, as a contribution to the development of potential new drugs for the treatment of various diseases.

In vitro Assessment of Camphor Hydrazone Derivatives as an Agent Against Leishmania amazonensis

PURPOSE

Due to serious problems with the treatment of leishmaniasis all around the world, here is an urgent need in the search for new drugs that are more effective and safer for the treatment of the various forms of leishmaniasis. Actual therapy is limited and lacks sufficient efficacy due to incomplete elimination of the parasites form of patients. In this sense, we decided to evaluate, by first-time, a series of seventeen camphor hydrazone derivatives (2a-2p) against Leishmania amazonensis.

METHODS

The compounds previously synthesized from camphor, an abundant natural compound, were evaluated in vitro against the extra and intracellular forms of Leishmania amazonensis, and murine macrophages.

RESULTS

The majority of compounds, fourteen, displayed activity against the intracellular form of the parasite (amastigote) with IC₅₀ values ranging from 21.78 to 58.23 µM, being six compounds active for both forms of the parasite. The compound 2i exhibited higher activity against the amastigote form with the value of IC₅₀ (21.78 µM) close to standard utilized miltefosine (12.74 µM) and selectivity index of at least 6.9. Six compounds displayed activity against promastigote form of Leishmania amazonensis 2g, 2j-2n (41.17-69.59 µM), with the compound 2m being the more active with IC₅₀ = 41.17 µM, 1.9 times less active than the reference drug (IC₅₀ = 21.39 µM). The compound 2m was the more selective to this form, with a selectivity index of at least 3.6. All the compounds were non-cytotoxic to macrophages.

CONCLUSIONS

Most compounds showed activity against amastigote form of Leishmania amazonensis, being that they were not cytotoxic to macrophage at the maximum tested concentration, showing the selective property of these compounds. Since amastigotes are the parasite stages that cause the disease in humans, these results highlight the antileishmanial effect of the compounds. This study indicates the possible development of candidates to leishmanicidal drugs from an abundant natural compound of easy access.

Design, synthesis, in vitro antimicrobial evaluation and molecular docking studies of indol-2-one tagged with morpholinosulfonyl moiety as DNA gyrase inhibitors

A series of Schiff bases 3, 5, 7 and hydrazones 9 were achieved via reaction of 5-(morpholinosulfonyl)indol-2,3-dione (1) with appropriate amines and/or hydrazide derivatives. Representative compounds of the synthesized products were tested and evaluated as antimicrobial agents. According to MIC and MBC results from compounds 9a, 9c, 7a, 3b, 3c, and 5b were able to exhibit significant antibacterial activity against both Gram-positive and Gram-negative bacteria together with moderate antifungal activities. Also, a multi-drug resistance study (MDRS) was carried out to evaluate the activity of most potent compounds, and these compounds showed considerable results compared with Norfloxacin and Tetracycline which observed no results against strains used in this study. The inhibitory activity of most potent compounds (3b, 3c, 5b, 7a, 9a, and 9c) against DNA gyrase isolated from S. aureus was examined. The results indicated that all of these derivatives inhibiting DNA gyrase and therefore lead to separate bacterial DNA and inhibit cell division. Compounds 3b, 9c showed to be very potent inhibitors towards S. aureus DNA gyrase with IC₅₀ values (18.75 ± 1.2 and 19.32 ± 0.99 µM) respectively, compared with Ciprofloxacin (26.43 ± 0.64 µM). Molecular docking studies indicated that the synthesized compounds observed good binding with the enzyme and showed lower binding energy of the most promising compounds than a standard drug used, and enabled a better understanding of their structural features.

Synthesis of New Hydrazone Derivatives and Evaluation of their Efficacy as Proliferation Inhibitors in Human Cancer Cells

BACKGROUND

Hydrazine-hydrazones represent a group of bioactive compounds that display antibacterial, anti-inflammatory, antiviral or anticancer activities.

OBJECTIVE

In this study, we designed new derivative compounds from groups of hydrazones.

METHODS

The group of new derivatives was evaluated by the viability assay in human cancer and normal cells.

RESULTS

The dimethylpyridine hydrazones showed potent inhibition of cell proliferation of breast, colon cancer cells, human melanoma and glioblastoma. Compound 12 inhibited proliferation of cancer cells exhibiting a drug-resistant phenotype (MCF-7/DX and LoVoDX) at low millimolar concentrations. Whereas, antimelanoma activity was revealed by Compounds 2, 4, 7 and 12.

CONCLUSION

The present results highlighted newly synthetized hydrazine derivatives an excellent base for the design of new anticancer agents and resistance inhibitors.

Anticancer, antimicrobial activities of quinoline based hydrazone analogues: Synthesis, characterization and molecular docking

Based on the biologically active heterocycle quinoline, a series (18a-p) of quinoline hydrazone analogues were prepared, starting from 6-bromo/6-chloro-2-methyl-quinolin-4-yl-hydrazines. For all the newly synthesized compounds cytotoxic activities were carried out at the National Cancer Institute (NCI), USA, against full NCI 60 human cancer cell lines. Amongst all the tested compounds, nine compounds (18b, 18d, 18e, 18f, 18g, 18h, 18i, 18j, 18l) exhibited important anti-proliferative activity at 10 µM concentration and were further screened at 10-fold dilutions of five different concentrations (0.01, 0.1, 1, 10 and 100 µM) with GI₅₀ values ranging from 0.33 to 4.87 µM and LC₅₀ values ranging from 4.67 µM to >100j µM. Further, the mean values of GI₅₀, TGI and LC₅₀ of the most potent compound 18j were compared with the clinically used anticancer agents bendamustine and chlorambucil, revealed that the quinolyl hydrazones holds promise as a potential anticancer agents. Further all the newly prepared compounds were screened for their antimicrobial activity. All the quinolyl hydrazones displayed good to excellent antimicrobial activity with MIC values ranging from 6.25 to 100 µg/mL against the tested pathogenic strains. Molecular docking of the synthesized compounds into the active binding site of human DNA topoisomerase I (htopoI) was carried out to predict the binding mode to the DNA topoisomerase I inhibitors. Hopefully in future, compounds based on quinoline core could be used as a lead compounds for designing new anticancer agents.

Monitoring the extraction of copper from chicken dung leachate using an aluminium electrode as an indicator

Copper is found in several minerals in the earth's crust with varying the elemental and mineralogical composition. Several techniques of extraction have been investigated all in the effort of obtaining a cheaper and viable method. This paper reports on further works done on copper extraction using a wet chemical method. According to the method, reduction of copper (II) ions using hydrazones from chlorinated chicken waste leachate was stoichiometrically driven. The chicken dung leachate used was an impure bio-material in which the concentration could not be determined. It was, therefore, difficult to quantify the stoichiometric ratios of species in that reaction. This paper reports on a method of monitoring the extent of copper reduction by chlorinated chicken dung leachate using an aluminum electrode as an indicator. Mineral rocks were obtained from Maragwa Location in Tharaka Nithi County in Kenya. The samples were ground into a fine powder of 250 micro millimeters. The samples were then subjected to mineralogical analysis using X-ray diffraction (XRD). Chemical analysis was done using atomic absorption spectroscopy (AAS) and X-ray fluorescence spectroscopy (XRFS). Ground samples were leached using 1.0 M hydrochloric acid. The resulting leachate was treated with chicken dung leachate prepared from chicken dung in which chlorine gas was bubbled at a constant temperature of 28 °C. The pH of the resultant chicken dung leachate was adjusted from 4 to 12 using 1.0 M sodium hydroxide and then used as an electrolyte. An electrochemical cell was set up consisting of aluminum and graphite rods. The aluminum electrode was found not to corrode at pH above 11 while it was able to displace available copper ions. This property of the aluminum electrode was used to monitor when all copper ions were displaced. The recovered copper was analyzed using XRFS. The copper recovery rate from the samples ranged from 7.0 to 20.0 at level A and 7.4-26.8% at level B with a purity range of 84.9 level A to 88.6% level B. An overall positive potential in the reduction process confirmed the greater the tendency of copper reduction without an external source of electricity. The corrosion of the aluminium electrode in the process was not observed and therefore does not require frequent replacement. Therefore, a large scale extraction process needs to be investigated.

Novel steroidal 1,3,4-thiadiazines: Synthesis and biological evaluation in androgen receptor-positive prostate cancer 22Rv1 cells

A flexible approach to previously unknown spirofused and linked 1,3,4-thiadiazine derivatives of steroids with selective control of heterocyclization patterns is disclosed. (N-Arylcarbamoyl)spiroandrostene-17,6' [1,3,4]thiadiazines and (N-arylcarbamoyl)17-[1',3',4']thiadiazine-substituted androstenes, novel types of heterosteroids, were prepared from 16β,17β-epoxypregnenolone and 21-bromopregna-5,16-dien-20-one in good to high yields by the treatment with oxamic acid thiohydrazides. The synthesized compounds were screened for antiproliferative activity against the human androgen receptor-positive prostate cancer cell line 22Rv1. Most of (N-arylcarbamoyl)17-[1',3',4']thiadiazine-substituted androstenes exhibit better antiproliferative potency (IC₅₀ = 2.1-6.6 µM) than the antiandrogen bicalutamide. Compounds 7d with IC₅₀ = 3.0 μM and 7j with IC₅₀ = 2.1 μM proved to be the most active in the series under study. Lead synthesized compound 7j downregulates AR expression and activity in 22Rv1 cells. NF-κB activity is also blocked in 7j-treated 22Rv1 cells. Apoptosis is considered as a possible mechanism of 7j-induced cell death.

Pd(II) complexes with N-heteroaromatic hydrazone ligands: Anticancer activity, in silico and experimental target identification

Anticancer activity of Pd complexes 1-5 with bidentate N-heteroaromatic hydrazone ligands was investigated on human acute monocytic leukemia (THP-1; cells in a suspension) and human mammary adenocarcinoma (MCF-7; two-dimensional layer and three-dimensional spheroid tumor model) cell lines. For the Pd(II) complexes with condensation products of ethyl hydrazainoacetate and quinoline-8-carboxaldehyde (complex 1) and 2-formylpyridine (complex 3), for which apoptosis was determined as a mechanism of anticancer activity, further investigation revealed that they arrest the cell cycle in G0/G1 phase, induce generation of reactive oxygen species and inhibit Topoisomerase I in vitro. In silico studies corroborate experimental findings that these complexes show topoisomerase inhibition activity in the micromolar range and indicate binding to a DNA's minor groove as another potential target. Based on the results obtained by circular dichroism and fluorescence spectroscopy measurements, the most active complexes are suitable to be delivered to a blood stream via human serum albumin.

NDMA formation mechanisms from typical hydrazines and hydrazones during ozonation: A computational study

N-nitrosodimethylamine (NDMA) as the most frequently detected disinfection by-product has aroused widespread concern due to its unusually high carcinogenicity, however, there is still limited understanding of its formation mechanisms. In this study, the formation mechanisms of NDMA from some typical hydrazines and hydrazones with high NDMA conversion yields (60%∼90%) during ozonation, i.e., unsymmetrical dimethylhydrazine (UDMH), 1-formyl-2,2-dimethylhydrazine (FDMH), formaldehyde dimethylhydrazone (FDH) and acetone dimethylhydrazone (ADMH), were investigated by using DFT method with the M05 functional. A new NDMA formation mechanism from hydrazines during ozonation was proposed, in which the initial step is hydrogen abstraction rather than previously reported oxygen addition. For hydrazones, the C atom of the -N = C moiety in hydrazones is preferred to be attacked by ozone to generate N,N-dimethylaminonitrene (DMAN), which is an important intermediate in NDMA formation during ozonation. Moreover, the reactivity order of the following H atoms in hydrogen/hydride ion abstraction (HA) by ozone is -NH₂ > -N(CH₃)₂ > -CO-NH ∼ =C(CH₃)₂ > =CH-. Additionally, formation pathways of some experimentally detected compounds, i.e., HOOOH, HOOH and HCOH, in the ozonation of hydrazine were elucidated in this study. The results are expected to expand our understanding of NDMA formation mechanisms and ozone reaction characteristics.

Crystal structures and Hirshfeld surface analyses of the di- and tri-hydrates of (5α,17E)-17-hydrazonoandrostan-3-ol: Significant differences in the hydrogen bonding patterns and supramolecular arrangements

The crystal structures, Hirshfeld surface analyses and electrostatic potential surfaces of the di- and tri-hydrates of (5α,17E)-17-hydrazonoandrostan-3-ol, 3, namely [3·(H₂O)₂] and [3·(H₂O)₃], are reported. The trihydrate, isolated from a solution of 3 in moist methanol, recrystallizes in the orthorhombic space group, P2₁2₁2₁, while that of the dihydrate, isolated from a 1:1 aqueous methanol solution, recrystallizes in the monoclinic space group, P2₁. The asymmetric unit of the trihydrate involves one steroid and three water molecules, while that of the dihydrate has two similar but independent steroid molecules and four hydrate molecules. Very similar conformations are found for the steroid molecules in both hydrates. As expected, the different mole ratios of water: steroid have major influences on the structures. In both cases, complex crystal structures are constructed from various classical hydrogen bonds, involving the hydrate molecules and the hydroxy and hydrazonyl moieties of the steroid. In the trihydrate, there are no direct connections between the steroid molecules, instead the water molecules link the steroid molecules, with only weak van der Waals forces between the steroid molecules. There are some direct links between the steroid molecules in the dihydrate, involving OH(steroid hydroxyl)⋯O(steroid oxo) hydrogen bonds, in a head to head fashion, and OH⋯N(hydrazonyl) hydrogen bonds, in a head to tail fashion. However, the major occurrence throughout the structure is of steroid molecules linked by water molecules.

Novel amphiphilic pyridinium ionic liquids-supported Schiff bases: ultrasound assisted synthesis, molecular docking and anticancer evaluation

Background

Pyridinium Schiff bases and ionic liquids have attracted increasing interest in medicinal chemistry.

Results

A library of 32 cationic fluorinated pyridinium hydrazone-based amphiphiles tethering fluorinated counteranions was synthesized by alkylation of 4-fluoropyridine hydrazone with various long alkyl iodide exploiting lead quaternization and metathesis strategies. All compounds were assessed for their anticancer inhibition activity towards different cancer cell lines and the results revealed that increasing the length of the hydrophobic chain of the synthesized analogues appears to significantly enhance their anticancer activities. Substantial increase in caspase-3 activity was demonstrated upon treatment with the most potent compounds, namely 8, 28, 29 and 32 suggesting an apoptotic cellular death pathway.

Conclusions

Quantum-polarized ligand docking studies against phosphoinositide 3-kinase α displayed that compounds 2–6 bind to the kinase site and form H-bond with S774, K802, H917 and D933.

Electronic supplementary material

The online version of this article (10.1186/s13065-018-0489-z) contains supplementary material, which is available to authorized users.

A novel binuclear hydrazone-based Cd(II) complex is a strong pro-apoptotic inducer with significant activity against 2D and 3D pancreatic cancer stem cells

A novel binuclear Cd complex (1) with hydrazone-based ligand was prepared and characterized by spectroscopy and single crystal X-ray diffraction techniques. Complex 1 reveals a strong pro-apoptotic activity in both human, mammary adenocarcinoma cells (MCF-7) and pancreatic AsPC-1 cancer stem cells (CSCs). While apoptosis undergoes mostly caspase-independent, 1 stimulates the activation of intrinsic pathway with noteworthy down regulation of caspase-8 activity in respect to non-treated controls. Distribution of cells over mitotic division indicates that 1 caused DNA damage in both cell lines, which is confirmed in DNA interaction studies. Compared to 1, cisplatin (CDDP) does not achieve cell death in 2D cultured AsPC-1 cells, while induces different pattern of cell cycle changes and caspase activation in 2D cultured MCF-7 cells, implying that these two compounds do not share similar mechanism of action. Additionally, 1 acts as a powerful inducer of mitochondrial superoxide production with dissipated trans-membrane potential in the majority of the treated cells already after 6 h of incubation. On 3D tumors, 1 displays a superior activity against CSC model, and at 100 μM induces disintegration of spheroids within 2 days of incubation. Fluorescence spectroscopy, along with molecular docking show that compound 1 binds to the minor groove of DNA. Compound 1 binds to the human serum albumin (HSA) showing that the HSA can effectively transport and store 1 in the human body. Thus, our current study strongly supports further investigations on antitumor activity of 1 as a drug candidate for the treatment of highly resistant pancreatic cancer.

Crystal structures and Hirshfeld surface analyses of the hemi-hydrate and hemi-methanolate of 3α-hydroxy-16α-bromoandrostan-17-one, 3: Differences in supramolecular arrangements

The crystal structures and Hirshfeld surface analyses of two hemi-solvates of 3α-hydroxy-16α-bromoandrostan-17-one, 3, namely [(3)₂.(H₂O)] and [(3)₂.(MeOH)], are reported. Both solvates crystallize in the monoclinic space group, P2₁, with Z = 4._. The asymmetric unit of the hemi-hydrate [(3)₂.(H₂O)] contains two independent but similar steroid molecules and a water molecule, while that of the hemi-methanoate [(3)₂.(MeOH)] has four similar but independent steroid molecules and two methanol molecules. Very similar conformations are found for the steroid molecules in both solvates. In both solvates, the strongest intermolecular interactions are OH···O hydrogen bonds, involving hydroxyl groups of the steroid and the solvate molecule, which result in head-to-head directly linked steroid molecules and solvate separated steroid molecules. In both cases, the oxygen atoms of the carbonyl groups of the steroids are involved in weaker CH···O hydrogen bonds which directly link steroid molecules in tail-to-tail fashions. Combinations of the hydrogen bonds, both OH···O and CH···O, result in two-molecule wide sheets in the hemi-hydrate, which are further weakly linked in the hemi--methanoate into a 3-dimensional array. Very different hydrogen bonded chains are found in the two solvates. There is a higher proportion of CH···O to OH···O hydrogen bonds in the hemi-methanoate, [8-6], compared to that in the hemi-hydrate [1-4]: this is an indication of the weaker solvating influence of methanol compared to water.

Generation of Dynamic Combinatorial Libraries Using Hydrazone-Functionalized Surface Mimetics

Dynamic combinatorial chemistry (DCC) represents an approach, whereby traditional supramolecular scaffolds used for protein surface recognition might be exploited to achieve selective high affinity target recognition. Synthesis, in situ screening and amplification under selection pressure allows the generation of ligands, which bear different moieties capable of making multivalent non‐covalent interactions with target proteins. Generic tetracarboxyphenyl porphyrin scaffolds bearing four hydrazide moieties have been used to form dynamic combinatorial libraries (DCLs) using aniline‐catalyzed reversible hydrazone exchange reactions, in 10 % DMSO, 5 mm NH₄OAc, at pH 6.75. High resolution mass spectrometry (HRMS) was used to monitor library composition and establish conditions under which equilibria were established.

Synthesis, characterization, monoamine oxidase inhibition, molecular docking and dynamic simulations of novel 2,1-benzothiazine-2,2-dioxide derivatives

In this research work, we report the synthesis and biological evaluation of two new series of 1-benzyl-4-(benzylidenehydrazono)-3,4-dihydro-1H-benzo[c] [1,2]thiazine 2,2-dioxides and 1-benzyl-4-((1-phenylethylidene)hydrazono)-3,4-dihydro-1H-benzo[c][1,2]thiazine 2,2-dioxides. The synthetic plan involves the mesylation of methyl anthranilate with subsequent N-benzylation of the product. The methyl 2-(N-benzylmethylsulfonamido)benzoate was subjected to cyclization reaction in the presence of sodium hydride to obtain 1-benzyl-1H-benzo[c][1,2]thiazin-4(3H)-one 2,2-dioxide which was treated with hydrazine hydrate to get corresponding hydrazone precursor. Finally, the titled compounds were obtained by reaction of hydrazone with various substituted aldehydes and ketones. The synthesized derivatives were subjected to carry out their inhibition activities against monoamine oxidases along with modelling investigations to evaluate their binding interactions and dynamic stability during the docking studies. The inhibition profile of potent compounds was found as competitive for both the isozymes. The compounds were more selective inhibitors of MAO-A as compared to MAO-B. Moreover, drug likeness profile of the derivatives was evaluated to have an additional insight into the physicochemical properties. The molecular dynamic simulations predicted the behaviour of amino acids with the active site residues.

Potential antioxidant activity of Morita-Baylis-Hillman adducts

The wide variety of potent biological activities of Morita-Baylis-Hillman adducts (MBH) encouraged us to synthesize new series of products belonging to this class of compounds, possessing different functionalities and exhibiting potential antioxidant activity. As part of our on-going program on targeting molecules with antioxidant activity, we describe herein different DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging activities of MBH alcohols and their derivatives including acetates, phosphonates and hydrazonophosphonates. The obtained results showed that the strongest DPPH radical scavenging activity was observed in the case of hydrazonophosphonates in comparison to the other MBH derivatives.

Metallomics for Alzheimer's disease treatment: Use of new generation of chelators combining metal-cation binding and transport properties

Alzheimer's disease (AD) is a progressive neurodegenerative disorder affecting tens of million people. Currently marketed drugs have limited therapeutic efficacy and only slowing down the neurodegenerative process. Interestingly, it has been suggested that biometal cations in the amyloid beta (Aβ) aggregate deposits contribute to neurotoxicity and degenerative changes in AD. Thus, chelation therapy could represent novel mode of therapeutic intervention. Here we describe the features of chelators with therapeutically relevant mechanism of action. We have found that the tested compounds effectively reduce the toxicity of exogenous Aβ and suppress its endogenous production as well as decrease oxidative stress. Cholyl hydrazones were found to be the most active compounds. In summary, our data show that cation complexation, together with improving transport efficacy may represent basis for eventual treatment strategy in AD.

N-Sulfamoylphenyl- and N-sulfamoylphenyl-N-thiazolyl-β-alanines and their derivatives as inhibitors of human carbonic anhydrases

A series of N-substituted and N,N-disubstituted β-amino acids and their derivatives bearing benzenesulfonamide moiety were designed and synthesized in search of compounds that would be high-affinity and selective inhibitors of human carbonic anhydrases (CA). There are 12 catalytically active human CA isoforms, the cytosolic CA I, CA II, CA III, CA VII, and CA XIII, secreted CA VI, the mitochondrial CA VA and CA VB, membrane-associated CA IV, and transmembrane CA IX, CA XII, and CA XIV. The di-bromo meta-substituted compounds exhibited low nanomolar dissociation constants and over 10-fold selectivity for mitochondrial isozyme CA VB, implicated in diseases of the central nervous system and obesity. These compounds can be used for further development as inhibitors of significant binding affinity and selectivity towards CA VB isozyme.

Silver(I) complexes with chromone-derived hydrazones: investigation on the antimicrobial and cytotoxic effects

Complexes [Ag(HCrPh)₂]NO₃·2H₂O (1) and [Ag(HCrpClPh)₂]NO₃ (2) were obtained with 3-formyl-6-methylchromone-phenyl hydrazone (HCrPh, HL1) and 3-formyl-6-methylchromone-para-chloro-phenyl hydrazone (HCrpClPh, HL2). Although the hydrazones were inactive, upon coordination to silver(I) antifungal activity significantly improved against several Candida strains. Complexes (1-2) revealed to be more active than silver nitrate, silver sulfadiazine and the reference drug nystatin against Candida parapsilosis. The cytotoxic activities of the hydrazones and their silver(I) complexes were evaluated in comparison with cisplatin on B16F10 (metastatic melanoma) and Melan-a (non-tumorigenic melanocyte) cells. The hydrazones showed low cytotoxicity against B16F10 cells, reducing only about 20% of cell viability at the concentration of 10 μM. Upon coordination to silver(I) the cytotoxic effect did not appreciably change in complex (1) while complex (2) proved to be as cytotoxic as cisplatin and much more cytotoxic than both the free ligand and silver nitrate at 1 μM. Both complexes (1) and (2) were less active than cisplatin on non-malignant Melan-a cells, indicating that these compounds might promote less damage on normal cells.

3-methoxy aroylhydrazones - free radicals scavenging, anticancer and cytoprotective potency

OBJECTIVE

This study aimed to determine the capability of newly designed 3-methoxy derivatives of salicylaldehyde benzoylhydrazone to influence the oxidative stress processes and to test their in vitro cytotoxicity.

METHODS

We have used chemiluminescent and spectrophotometric model systems containing different types of reactive oxygen species (OH^●, OCl^─ and O₂^─●). The hydrazones effect on the viability of Hep-G2, HEK-293 and SH-SY5Y cell lines was determined via MTT assay.

RESULTS

The comparative analysis of the C₅₀ values of the chemiluminescent investigation demonstrated moderate activity against the hydroxyl radicals (C₅₀ > 50 μmol/L) and remarkable reactivity in the systems containing a superoxide radical and a hypochlorous anion (C₅₀ < 3.7 μmol/L). Further experiments in the spectrophotometric system of UV-induced OH^● generation and consequent 2'-deoxyribose oxidative damage excluded the possibility of quenching effect and proved the direct interaction of the studied compounds with that generated in the system reactive oxygen species (ROS). The encapsulation of the studied derivatives into chitosan-alginate particles led to the protection and stabilization of their antioxidant activity as revealed by a one-month study using the ABTS ^●+ method. The cytotoxic study revealed less pronounced effects against the non-malignant cell line (HEK-293) compared to Hep-G2 and SH-SY-5Y cells.

DISCUSSION

The incorporation of a hydroxyl group in the hydrazide part of a parent molecule which relates to better antioxidant effect in most of the studied systems is associated with higher IC₅₀ values in all cytotoxicity experiments and relates to the cytoprotective effect against N-methyl-D-aspartate-induced excitotoxicity in SH-SY5Y human neuronal cells.

Substituted tetrazoles as multipurpose screening compounds

Tetrazoles are small functional heterocycles that are suited to serve simultaneously as aromatic platform for diversity and as functional interaction motif. Furthermore, the tetrazole ring and its deprotonated tetrazolate counterpart are metal ion complexing ligands that possess a rich variety of binding and bridging modes. We recently demonstrated that fragments containing the tetrazole moiety and a metal chelating hydrazide group are well suited to discover selective screening hits with high ligand efficiency for a given protein target. Here, we report the synthesis and characterization of new polydentate tetrazole-containing screening compounds and their synthetic precursors as well as their deposition in a multipurpose screening library in the frame of the EU-OPENSCREEN network. The pure and well-characterized screening compounds could be useful to aid drug discovery programs for multiple or hitherto undruggable targets by enclosure of under-represented tetrazole derivatives.

Synthesis and antimicrobial activity of tetradentate ligands bearing hydrazone and/or thiosemicarbazone motifs and their diorganotin(IV) complexes

Four novel ligands derived from 2,3-butanedione have been synthesized, two dissymmetric thiosemicarbazone/3-hydroxy-2-naphthohydrazone ligands, H₂L¹ (bearing 4-isopropyl-3-thiosemicarbazone) and H₂L² (containing 4-cyclohexyl-3-thiosemicarbazone) and the symmetric H₂L³, diacetyl bis(3-hydroxy-2-naphthohydrazone), and H₂L⁴, diacetyl bis(4-cyclohexyl-3-thiosemicarbazone). Their reactivity with SnR₂Cl₂ (R=methyl, n-butyl and phenyl) was explored and the resulting complexes were characterized by elemental analysis, molar conductivity, mass spectrometry, IR, ¹H, ¹³C and ¹¹⁹Sn NMR and seven of them also by single crystal X-ray diffraction. The results showed that the reactivity of the dissymmetric ligands is strongly different and while the cyclohexyl derivative is very stable, with isopropyl easily undergoes a symmetrization reaction to yield the corresponding symmetric ligands. The antimicrobial activity of the ligands and the corresponding diorganotin(IV) complexes was investigated in vitro against seven species of microorganisms and minimum inhibitory concentrations (MICs) were determined. The results showed that the ligand H₂L² and several of its derivatives, together with methyl and phenyl complexes of H₂L¹, have the ability of inhibiting the growth of tested bacteria and fungi to different extents. Bacillus subtilis and Staphylococcus aureus Gram positive strains were the most sensitive microorganisms.

Synthesis and in vitro antifungal activity of isoniazid-derived hydrazones against Coccidioides posadasii

Coccidioidomycosis is a potentially severe infection caused by dimorphic fungi Coccidioides immitis and Coccidioides posadasii. Although guidelines are well established, refractory disease is a matter of concern in the clinical management of coccidioidomycosis. In the present study three isoniazid-derived hydrazones N'-[(E)-1-(4-methoxyphenyl)ethylidene]pyridine-4-carbohydrazide, N'-[(E)-1-(4-methylphenyl)ethylidene]pyridine-4-carbohydrazide, and N'-[(E)-1-(phenyl)ethylidene]pyridine-4-carbohydrazide were synthesized and evaluated for antifungal activity against C. posadasii. Susceptibility assays were performed by macrodilution testing. Interactions between the hydrazones and amphotericin B or itraconazole were evaluated by the checkerboard method. We also investigated the impairment of such compounds on cell ergosterol and membrane integrity. The synthesized molecules were able to inhibit C. posadasii in vitro with MIC values that ranged from 25 to 400 μg/mL. Drug interactions between synthesized molecules and amphotericin B proved synergistic for the majority of tested isolates; regarding itraconazole, synergism was observed only when strains were tested against N'-[(E)-1-(phenyl)ethylidene]pyridine-4-carbohydrazide. Reduction of cellular ergosterol was observed when strains were challenged with the hydrazones alone or combined with antifungals. Only N'-[(E)-1-(4-methylphenyl)ethylidene]pyridine-4-carbohydrazide altered membrane permeability of C. posadasii cells. Isoniazid-derived hydrazones were able to inhibit C. posadasii cells causing reduction of ergosterol content and alterations in the permeability of cell membrane. This study confirms the antifungal potential of hydrazones against pathogenic fungi.

New 1,3-thiazole derivatives and their biological and ultrastructural effects on Trypanosoma cruzi

In previous studies, the compound 3-(bromopropiophenone) thiosemicarbazone was described as a potent anti-Trypanosoma cruzi and cruzain inhibitor. In view to optimize this activity, 1,3-thiazole core was used as building-block strategy to access new lead generation of anti T. cruzi agents. In this way a series of thiazole derivatives were synthesized and most of these derivatives exhibited antiparasitic activity similar to benznidazole (Bzd). Among them, compounds (1c) and (1g) presented better selective index (SI) than Bzd. In addition, compounds showed inhibitory activity against the cruzain protease. As observed by electron microscopy, compound (1c) treatment caused irreversible and specific morphological changes on ultrastructure organization of T. cruzi, demonstrating that this class of compounds is killing parasites.

Synthesis, spectral characterization, DNA interaction, radical scavenging and cytotoxicity studies of ruthenium(II) hydrazone complexes

Three new ruthenium(II) complexes with hydrazone ligands, furan-2-carboxylic acid (2,4-dihydroxy-benzylidene)-hydrazide (HL(1)), furan-2-carboxylic acid [4-(ethyl-propyl-amino)-2-hydroxy-benzylidene]-hydrazide (HL(2)) and furan-2-carboxylic acid (3-ethoxy-2-hydroxy-benzylidene)-hydrazide (HL(3)) were synthesized and characterized by various spectro-analytical techniques. The hydrazone ligands act as a tridendate ligand with ONO as the donor sites and are preferably found in the enol form in all the complexes. The molecular structure of the ligands was determined by single crystal X-ray diffraction technique. The interaction of the ligands and the complexes with CT-DNA were evaluated by an absorption titration method which revealed that the compounds interact with CT-DNA through intercalation. Gel electrophoresis assay demonstrated the ability of the complexes to cleave the calf thymus DNA hydrolytically. Antioxidant studies showed that the ruthenium(II) complexes have a strong radical-scavenging properties. Further, the cytotoxic effect of the compounds examined on cancerous cell lines showed that the complexes exhibited substantial anticancer activity.

Spectral, thermal, molecular modeling and biological studies on mono- and binuclear complexes derived from oxalo bis(2,3-butanedionehydrazone)

Background

Hydrazones and their metal complexes were heavily studied due to their pharmacological applications such as antimicrobial, anticonvulsant analgesic, anti-inflammatory and anti-cancer agents. This work aims to synthesize and characterize novel complexes of VO²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Zr⁴⁺and Pd²⁺ ions with oxalo bis(2,3-butanedione-hydrazone). Single crystals of the ligand have been grown and analyzed.

Results

Oxalo bis(2,3-butanedionehydrazone) [OBH] has a monoclinic crystal with P 1 21/n 1 space group. The VO²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Zr⁴⁺ and Pd²⁺ complexes have the formulas: [VO(OBH–H)₂]·H₂O, [Co(OBH)₂Cl]Cl·½EtOH, [Ni₂(OBH)Cl₄]·H₂O·EtOH, [Cu(OBH)₂Cl₂]·2H₂O, [Zn(OBH–H)₂], [Zr(OBH)Cl₄]·2H₂O, and [Pd₂(OBH)(H₂O)₂Cl₄]·2H₂O. All complexes are nonelectrolytes except [Co(OBH)₂Cl]Cl·½EtOH. OBH ligates as: neutral tetradentate (NNOO) in the Ni²⁺ and Pd²⁺ complexes; neutral bidentate (OO) in [Co(OBH)₂Cl]Cl·½EtOH, [Zr(OBH)Cl₄]·2H₂O and [Cu(OBH)₂Cl₂]·2H₂O and monobasic bidentate (OO) in the Zn²⁺ and VO²⁺ complexes. The NMR (¹H and ¹³C) spectra support these data. The results proved a tetrahedral for the Zn²⁺ complex; square-planar for Pd²⁺; mixed stereochemistry for Ni²⁺; square-pyramid for Co²⁺ and VO²⁺ and octahedral for Cu²⁺ and Zr⁴⁺ complexes. The TGA revealed the outer and inner solvents as well as the residual part. The molecular modeling of [Ni₂(OBH)Cl₄]·H₂O·EtOH and [Co(OBH)₂Cl]Cl·½EtOH are drawn and their molecular parameters proved that the presence of two metals stabilized the complex more than the mono metal. The complexes have variable activities against some bacteria and fungi. [Zr(OBH)Cl₄]·2H₂O has the highest activity. [Co(OBH)₂Cl]Cl·½EtOH has more activity against Fusarium.

Conclusion

Oxalo bis(2,3-butanedionehydrazone) structure was proved by X-ray crystallography. It coordinates with some transition metal ions as neutral bidentate; mononegative bidentate and neutral tetradentate. The complexes have tetrahedral, square-planar and/or octahedral structures. The VO²⁺ and Co²⁺ complexes have square-pyramid structure. [Cu(OBH)₂Cl₂]·2H₂O and [Ni₂(OBH)Cl₄]·H₂O·EtOH decomposed to their oxides while [VO(OBH–H)₂]·H₂O to vanadium. The energies obtained from molecular modeling calculation for [Ni₂(OBH)Cl₄]·H₂O·EtOH are less than those for [Co(OBH)₂Cl]Cl·½EtOH indicating the two metals stabilized the complex more than mono metal. The Co(II) complex is polar molecule while the Ni(II) is non-polar.

Graphical abstract

Electronic supplementary material

The online version of this article (doi:10.1186/s13065-015-0135-y) contains supplementary material, which is available to authorized users.

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