Synthesis of novel thiazolyl hydrazone derivatives as potent dual monoamine oxidase-aromatase inhibitors.

The inhibitory effects of 2-thiazolyl hydrazones on monoamine oxidase enzymes are known for a long time. In this study, a new series of 2-thiazolyl hydrazone derivatives were synthesized starting from 6-methoxy-2-naphthaldehyde. All of the synthesized compounds were investigated in terms of their monoamine oxidase (MAO) inhibitory effects and significant results were found. The results showed that compound 2j potently inhibited MAO-A and MAO-B, while compound 2t strongly and selectively inhibited MAO-B compared to standard drugs. Compounds 2k and 2q exhibited selective and satisfying inhibition on MAO-B. In the aromatase inhibition studies of the compounds, it was determined that compounds 2q and 2u had high inhibitory properties. Molecular docking studies on MAO-A, MAO-B, and aromatase enzymes were carried out for the aforementioned compounds. Additionally, molecular dynamics simulation was studied for compound 2q on MAO-B and aromatase complexes. Finally, the Field-based QSAR study was developed and the structure-activity relationship (SAR) was explained. For the first time, dual inhibitors on MAO and aromatase enzyme were investigated together. The aim of this approach is for finding the potential agents that do not cause the cognitive disorders and may even treat neurodegenerative symptoms, thus, the aim was reached successfully.

In-silico modeling and in-vitro studies of 2,1-benzothiazine-2,2-dioxide based hydrazone derivatives as α-glucosidase inhibitors.

Diabetes mellitus (DM) is a metabolic disorder characterized by frequent urination, hunger and high blood sugar level. α-glucosidase inhibitors are considered as a frontline treatment for the DM. This research article deals with the identification of benzothiazine derivatives as α-glucosidase inhibitors through in-silico techniques and then the confirmation through in-vitro analysis. Molecular docking studies were carried out to find out the binding interactions of targeted molecules with receptor molecule i.e., α-glucosidase enzyme. The synthetic compounds 1 (a-n), 2 (a-d) and 3 (a-b) were evaluated for in-vitro alpha glucosidase inhibitory activities that resulted in the discovery of various potent molecules. Majority of the compounds (1c, 1f, 1g, 1k-n, 2a-d and 3a-b) exhibited good inhibitory activity against α-glucosidase. Compounds 1c, 1g, 1k and 1m appeared as the potent active compounds with the IC50 values 17.44, 27.64, 24.43, 42.59 and 16.90 µM respectively. Compounds 1c & 2c were found almost 3-folds more active than the standard acarbose. The study may lead to discover potent drug candidates with less complication for the treatment of the type II diabetes mellitus.

Regioselective hemisynthesis and insecticidal activity of C8-hydrazones/acylhydrazones/sulfonylhydrazones coumarin-type derivatives of osthole.

Osthole, a coumarin-type natural product, is isolated from Chinese traditional herbal medicine Cnidium monnieri. In order to improve the pesticidal activity of osthole, and high value-added application of the plant Cnidium monnieri, a series of new derivatives containing hydrazone/acylhydrazone/sulfonylhydrazone skeletons at the C-8 position of osthole were regioselectively semi-prepared. The steric structure of 3c was determined by the X-ray crystal structure. Against Mythimna separata Walker, benzoylhydrazone 3b (R1 = 4-CH3Ph) showed 1.6 folds potent insecticidal activity of the precursor osthole. Introduction of the acylhydrazones on the 3'-methyl-2'-butylenyl fragment at the C-8 position of osthole can improve the insecticidal activity. These will provide a foundation for future structural modifications of osthole as pesticidal agents.

Synthesis of novel isoindoline-1,3-dione-based oximes and benzenesulfonamide hydrazones as selective inhibitors of the tumor-associated carbonic anhydrase IX.

The synthesis, characterization and biological evaluation of a library of isoindoline-1,3-dione-based oximes and benzenesulfonamide hydrazones is disclosed. The set of hydroxyiminoethyl aromatic derivatives 10-18 was designed to assess the potentiality as zinc-binder for a feebly studied functional group in the field of carbonic anhydrase (CA, EC 4.2.1.1) inhibition. Analogue phenylphthalimmides were linked to benzenesulfonamide scaffold by hydrazone spacers in the second subset of derivatives 20-28 to further investigate the application of the "tail approach" as tool to afford CA selective inhibition profiles. The compounds were assayed for the inhibition of physiologically relevant isoforms of human carbonic anhydrases (hCA, EC 4.2.1.1), the cytosolic CA I and II, and the membrane-bound CA IV and tumor-associated CA IX. The new zinc-binders, both of the oxime and sulfonamide types, showed a striking selective activity against the target hCA IX over ubiquitous hCA I and II, with diverse inhibitory ranges and ratio differing the two subsets. With CA IX being a strongly current antitumor/antimetastatic drug target, these series of compounds may be of interest for the development of new, both conventional and unconventional anticancer drugs targeting hypoxia-induced CA isoforms such as CA IX with minimum ubiquitous CAs-related side effects.

LASSBio-1586, an N-acylhydrazone derivative, attenuates nociceptive behavior and the inflammatory response in mice.

Pain and inflammation are complex clinical conditions that are present in a wide variety of disorders. Most drugs used to treat pain and inflammation have potential side effects, which makes it necessary to search for new sources of bioactive molecules. In this paper, we describe the ability of LASSBio-1586, an N-acylhydrazone derivative, to attenuate nociceptive behavior and the inflammatory response in mice. Antinociceptive activity was evaluated through acetic acid-induced writhing and formalin-induced nociception tests. In these experimental models, LASSBio-1586 significantly (p<0.05) reduced nociceptive behavior. Several methods of acute and chronic inflammation induced by different chemical (carrageenan, histamine, croton oil, arachidonic acid) and physical (cotton pellet) agents were used to evaluate the anti-inflammatory effect of LASSBio-1586. LASSBio-1586 exhibited potent anti-inflammatory activity in all tests (p<0.05). Study of the mechanism of action demonstrated the possible involvement of the nitrergic, serotonergic and histamine signaling pathways. In addition, a molecular docking study was performed, indicating that LASSBio-1586 is able to block the COX-2 enzyme, reducing arachidonic acid metabolism and consequently decreasing the production of prostaglandins, which are important inflammatory mediators. In summary, LASSBio-1586 exhibited relevant antinociceptive and anti-inflammatory potential and acted on several targets, making it a candidate for a new multi-target oral anti-inflammatory drug.

A moderate metal-binding hydrazone meets the criteria for a bioinorganic approach towards Parkinson's disease: Therapeutic potential, blood-brain barrier crossing evaluation and preliminary toxicological studies.

Alzheimer's and Parkinson's diseases share similar amyloidogenic mechanisms, in which metal ions might play an important role. In this last neuropathy, misfolding and aggregation of α-synuclein (α-Syn) are crucial pathological events. A moderate metal-binding compound, namely, 8-hydroxyquinoline-2-carboxaldehyde isonicotinoyl hydrazone (INHHQ), which was previously reported as a potential 'Metal-Protein Attenuating Compound' for Alzheimer's treatment, is well-tolerated by healthy Wistar rats and does not alter their major organ weights, as well as the tissues' reduced glutathione and biometal levels, at a concentration of 200mgkg-1. INHHQ definitively crosses the blood-brain barrier and can be detected in the brain of rats so late as 24h after intraperitoneal administration. After 48h, brain clearance is complete. INHHQ is able to disrupt, in vitro, anomalous copper-α-Syn interactions, through a mechanism probably involving metal ions sequestering. This compound is non-toxic to H4 (human neuroglioma) cells and partially inhibits intracellular α-Syn oligomerization. INHHQ, thus, shows definite potential as a therapeutic agent against Parkinson's as well.

Biological activity of a small molecule indole analog, 1-[(1H-indol-3-yl)methylene]-2-phenylhydrazine (HMPH), in chronic inflammation.

A synthetic small molecule, 1-[(1H-indol-3-yl)methylene]-2-phenylhydrazine (HMPH) was conveniently synthesised by a one-step reaction, purified and characterised by chromatographic and spectroscopic methods. HMPH scavenged free radicals and inhibited lipopolysaccharide (LPS)-induced ROS generation and NO release in RAW-264.7 cells without signs of any detectable cytotoxicity. HMPH inhibited lipid peroxidation (LPO) with IC50 of 135 ± 9 as against 58 ± 8 µM for α-tocopherol. Further, HMPH (>50 µM) significantly reduced the LPS-induced TNF-α release in mouse peritoneal macrophages and in human peripheral blood mononuclear cells (PBMCs). HMPH did not show any visible signs of toxicity in rats up to 400 mg/kg/intraperitoneal and 2000 mg/kg/oral. HMPH at 25 and 50 mg/kg attenuated neutrophil infiltration in air-pouch lavage and bronchoalveolar lavage (BAL) in rat models. HMPH also reduced myeloperoxidase (MPO), nitrite and TNF-α in air-pouch lavage in addition to MPO in plasma. HMPH reduced acute paw-inflammation in carrageenan-induced paw-edema. HMPH consistently decreased both ipsilateral and contralateral paw inflammation, minimised the clinical scores of arthritis, prevented body weight (B.wt.) loss, attenuated serum C-reactive protein (C-RP) and rheumatoid factors (RF) in rat model of adjuvant-induced arthritis. Histopathology and radio-graphical reports show that HMPH reduced bone erosion in both ipsilateral and contralateral paw joints. Failure to inhibit COX suggests that effectiveness of HMPH in both acute and chronic inflammation is mediated by a multimodal mechanism involving modulation of immunity, attenuating TNF-α, protecting bone attrition and reducing oxidative stress.

First Isolation of Bicyclic Ditellurides from the Reaction of Camphor Hydrazone with Tellurium Tetrachloride.

Reaction of camphor hydrazone with TeCI4 under basic conditions gave an isomeric mixture of vinyl ditelluride and Wagner-Meerwein rearranged ditelluride. Initially formed tellurocamphor enolized and oxidized to give vinyl telluride, whereas tellurocamphor complexed with TeC4 to afford carbocation, which rearranged in a Wagner-Meerwein manner to afford the rearranged ditelluride. Photolysis of ditelluride in methyl methacrylate solution gave the radical polymerization product, PMMA, in which ditelluride acted as a radical initiator.

Synthesis and biological activity evaluation of hydrazone derivatives based on a Tröger's base skeleton.

We report the design and synthesis of novel anticancer agents based on bis-hydrazones separated by a rigid Tröger's base skeleton. This novel approach combines a biologically active moiety (hydrazone) with this scaffold (Tröger's base) to construct DNA intercalators. Evaluation of the anticancer activity of these agents using seven cancer cell lines and two healthy cell lines found that several derivatives had potent anticancer activity and excellent selectivity indexes toward cancer cells. The antimicrobial activities were tested on a set of thirteen bacterial stains, but the prepared compounds were not active. Complexation studies using biologically important metal ions demonstrated that these compounds are able to bind Cu(2+), Fe(3+), Co(2+), Ni(2+) and Zn(2+). DNA intercalation studies showed that the compounds themselves do not interact with DNA, but their metallocomplexes do interact, most likely via intercalation into DNA.

Novel arylhydrazone derivatives bearing a rhodanine moiety: synthesis and evaluation of their antibacterial activities.

A series of arylhydrazone derivatives bearing a rhodanine moiety have been synthesized, characterized, and evaluated as antibacterial agents. Some of these compounds showed potent antibacterial activities against several different strains of Gram-positive bacteria, including multidrug-resistant clinical isolates. Of the compounds tested, IIk and IIIk were identified as the most effective, with minimum inhibitory concentration values of 2-4 µg/mL against multidrug-resistant Gram-positive organisms, including methicillin-resistant and quinolone-resistant Staphylococcus aureus. None of the compounds exhibited any activity against the Gram-negative bacteria Escherichia coli 1356 at 64 µg/mL.

In silico validation and structure activity relationship study of a series of pyridine-3-carbohydrazide derivatives as potential anticonvulsants in generalized and partial seizures.

A series of twelve compounds (Compounds RNH1-RNH12) of acid hydrazones of pyridine-3-carbohydrazide or nicotinic acid hydrazide was synthesized and evaluated for anticonvulsant activity by MES, scPTZ, minimal clonic seizure and corneal kindling seizure test. Neurotoxicity was also determined for these compounds by rotarod test. Results showed that halogen substitution at meta and para position of phenyl ring exhibited better protection than ortho substitution. Compounds RNH4 and RNH12, were found to be the active analogs displaying 6Hz ED50 of 75.4 and 14.77 mg/kg while the corresponding MES ED50 values were 113.4 and 29.3 mg/kg respectively. In addition, compound RNH12 also showed scPTZ ED50 of 54.2 mg/kg. In the series, compound RNH12 with trifluoromethoxy substituted phenyl ring was the most potent analog exhibiting protection in all four animal models of epilepsy. Molecular docking study has also shown significant binding interactions of these two compounds with 1OHV, 2A1H and 1PBQ receptors. Thus, N-[(meta or para halogen substituted) benzylidene] pyridine-3-carbohydrazides could be used as lead compounds in anticonvulsant drug design and discovery.

Synthesis and evaluation of antimicrobial activity of hydrazones derived from 3-oxido-1H-imidazole-4-carbohydrazides.

In this work we reported the synthesis and evaluation of in vitro antimicrobial activities of hydrazones 6 obtained from 3-oxido-1H-imidazole-4-carbohydrazides 4. All new compounds were characterized by spectroscopic methods. Hydrazones 6 were tested for their in vitro antimicrobial activity against four Gram-positive and four Gram-negative strains of bacteria as well as one fungal species. Three of the tested compounds appeared to be promising agents against reference strains of Escherichia coli, Staphylococcus aureus and Staphylococcus epidermidis. They were also tested against twelve clinical isolates of S. aureus and their cytotoxic effect on murine fibroblasts and HeLa human tumor cell line was determined.

Synthesis of 2-methoxybenzoylhydrazone and evaluation of their antileishmanial activity.

Compounds 1-25 showed varying degree of antileishmanial activities with IC50 values ranging between 1.95 and 88.56 µM. Compounds 2, 10, and 11 (IC50=3.29±0.07 µM, 1.95±0.04 µM, and 2.49±0.03 µM, respectively) were found to be more active than standard pentamidine (IC50=5.09±0.04 µM). Compounds 7 (IC50=7.64±0.1 µM), 8 (IC50=13.17±0.46 µM), 18 (IC50=13.15±0.02 µM), and 24 (IC50=15.65±0.41 µM) exhibited good activities. Compounds 1, 3, 4, 5, 9, 12, 15, 18, and 19 were found to be moderately active. Compounds 13, 14, 16, 17, 20-25 showed weak activities with IC50 values ranging between 57 and 88 µM.

Diaryl hydrazones as multifunctional inhibitors of amyloid self-assembly.

The design and application of an effective, new class of multifunctional small molecule inhibitors of amyloid self-assembly are described. Several compounds based on the diaryl hydrazone scaffold were designed. Forty-four substituted derivatives of this core structure were synthesized using a variety of benzaldehydes and phenylhydrazines and characterized. The inhibitor candidates were evaluated in multiple assays, including the inhibition of amyloid ß (Aß) fibrillogenesis and oligomer formation and the reverse processes, the disassembly of preformed fibrils and oligomers. Because the structure of the hydrazone-based inhibitors mimics the redox features of the antioxidant resveratrol, the radical scavenging effect of the compounds was evaluated by colorimetric assays against 2,2-diphenyl-1-picrylhydrazyl and superoxide radicals. The hydrazone scaffold was active in all of the different assays. The structure-activity relationship revealed that the substituents on the aromatic rings had a considerable effect on the overall activity of the compounds. The inhibitors showed strong activity in fibrillogenesis inhibition and disassembly, and even greater potency in the inhibition of oligomer formation and oligomer disassembly. Supporting the quantitative fluorometric and colorimetric assays, size exclusion chromatographic studies indicated that the best compounds practically eliminated or substantially inhibited the formation of soluble, aggregated Aß species, as well. Atomic force microscopy was also applied to monitor the morphology of Aß deposits. The compounds also possessed the predicted antioxidant properties; approximately 30% of the synthesized compounds showed a radical scavenging effect equal to or better than that of resveratrol or ascorbic acid.

Synthesis and biological evaluation of biotinyl hydrazone derivatives of muramyl peptides.

Muramyl peptides derived from bacterial peptidoglycan have long been known for their ability to trigger host innate immune responses, including inflammation and antimicrobial defense. Muramyl peptides have also been widely studied for their role as immune adjuvants. In mammals, the nucleotide-binding oligomerization domain (Nod) proteins Nod1 and Nod2 detect distinct muramyl peptide structures and mediate their biological activity. Because of the poor immunogenicity of these small peptidoglycan derivatives, research in this field is currently limited by the lack of reagents to track or immobilize specific muramyl peptides. We present here the generation and initial biological characterization of synthetic muramyl peptides covalently coupled to dansyl or biotinyl derivatives and demonstrate that biotinyl coupling on the muramyl moiety results in derivatives that can be tracked by immunofluorescence and maintain full biological activity, as observed by their capacity to trigger Nod signaling. Moreover, using digitonin-mediated permeabilization techniques on live cells, we also demonstrate that biotinylated muramyl peptides efficiently reach the host cytosol, where they activate Nod signaling. Therefore, these derivatives represent useful probes to study the cell biology and the biochemistry of host responses to muramyl peptides.

Design and evaluation of a novel fluorescent CB2 ligand as probe for receptor visualization in immune cells.

Cannabinoid CB2 receptor has emerged as a very promising target over the last decades. We have synthesized and evaluated a new fluorescent probe designated NMP6 based on 6-methoxyisatin scaffold, which exhibited selectivity and K(i) value at hCB2 of 387 nM. We have demonstrated its ability to be an effective probe for visualization of CB2 receptor binding using confocal microscopy and a flow cytometry probe for the analysis of CB2 protein expression. Furthermore, NMP6 was easily obtained in two chemical steps from commercially available building blocks.

Synthesis and antitubercular activities of substituted benzoic acid N'-(substituted benzylidene/furan-2-ylmethylene)-N-(pyridine-3-carbonyl)-hydrazides.

A series of benzoic acid hydrazones and its nicotinyl derivatives (1-10) were prepared and evaluated for their antitubercular activity towards a strain of Mycobacterium tuberculosis (MTB). The structures of newly synthesized compounds were confirmed by infrared (IR) and 1H-nuclear magnetic resonance (NMR) spectral data and elemental analysis. The in vitro antitubercular activity of synthesized compounds against MTB was carried out in Middlebrook 7H11agar medium supplemented with OADC by agar dilution method. The antitubercular activity results indicated that nicotinic acid N-(3,5-dinitro-benzoyl)-N'-(4-methoxy-benzylidene)-hydrazide (1) is the most potent among the synthesized compounds with MIC of 3.5×10(-3) µM.

Synthesis and antiviral evaluation of some sugar arylglycinoylhydrazones and their oxadiazoline derivatives.

Sugar N-arylaminoacetylhydrazones 2-5 were prepared by the reaction of N-arylaminoacetylhydrazides 1 with equivalent amounts of the corresponding monosaccharides. Per-O-acetyl derivatives 6-9 of sugar hydrazones 2-5 were prepared by using acetic anhydride in pyridine at room temperature, while on boiling with acetic anhydride, cyclization had taken place to give the oxadiazolines 10-12. The prepared compounds were tested for antiviral activity against Herpes Simplex virus type-1 (HSV-1) and hepatitis-A virus (HAV, MBB-cell culture adapted strain). Plaque reduction infectivity assay was used to determine virus count reduction as a result of treatment with tested compounds.

Design and synthesis of 3,4-methylenedioxy-6-nitrophenoxyacetylhydrazone derivatives obtained from natural safrole: new lead-agents with analgesic and antipyretic properties.

In this work, we reported the synthesis and evaluation of the analgesic, anti-inflammatory, and antipyretic properties of new 2-(6-nitro-benzo[1,3]dioxol-5-yloxy)-acetylhydrazone derivatives (3), designed exploring molecular hybridization and isosteric replacement approaches between nimesulide (1) and carbanalogue NAH series (2) developed at LASSBio. Target compounds were synthesized in very good yields exploiting abundant Brazilian natural product safrole (4) as starting material. The evaluation of the antinociceptive properties of this series led us to discover a new potent prototype of analgesic and antipyretic agent, that is, NAH derivative 3c, named LASSBio-891, which showed to be more potent than dipyrone used as standard.

Synthesis and preliminary screening of carbohydrazides and hydrazones of pyrrole derivatives as potential tuberculostatics.

Five carbohydrazides and 19 hydrazones of carboxylic acids of pyrrole were synthesized as new structural analogs of known tuberculostatics, such as isoniazid (CAS 54-85-3) and its popular hydrazones. The preliminary screening against Mycobacterium tuberculosis H37Rv (ATCC 27294) at 6.25 microg/mL in 12B medium using a broth microdilution assay, the Microplate Alamar Blue Assay (MABA) registered higher inhibitory activity within the hydrazones series (up to 68 % inhibition) compared with that of the carbohydrazides (0-34 %). No simple relationship between the activity of a particular hydrazone and that of the parent carbohydrazide, or correlations with the structural features introduced by the carbonyl partner could be observed. So both most active hydrazones diethyl 5-(2-[(2,4-dimethyl-1H-3-pyrrolyl)carbonyl]hydrazonomethyl)-3-methyl-1H-2,4-pyrroledicarboxylate (22, 68 % inhibition) and ethyl 5-(4-chlorophenyl)-2-methyl-1-(2-2-1-(5-nitro-2-furyl)methylidene]hydrazino-2-oxoethyl)-1H-3-pyrrolecarboxylate (32, 55 %) originated from inactive carbohydrazides (1, 0 % and 7, 10 % respectively); ethyl 1-(2-2-[1-(3-ethoxy-4-hydroxyphenyl) methylidene] hydrazino-2-oxoethyl)-2-methyl-5-(4-nitrophenyl)-1H-3-pyrrolecarboxylate (30) showed 0 % inhibition, although derived from a hydrazide with 34 % activity. The condensation of six carbohydrazides with the same carbonyl reagent 5-nitrofurfural yielded hydrazones whose activity covered the wide range of 0-55 % inhibition.