Pharmacological characterization of (3-thienylidene)-3,4-methylenedioxybenzoylhydrazide: a novel muscarinic agonist with antihypertensive profile

Colorimetric and Fluorometric N-Acylhydrazone-based Chemosensors for Detection of Single to Multiple Metal Ions: Design Strategies and Analytical Applications

The development of optical sensors for metal ions has gained significant attention due to their broad applications in biology, the environment, and medicine. Colorimetric and fluorometric detection methods are particularly valued for their simplicity, cost-effectiveness, high detection limits, and analytical power. Among various chemical probes, the hydrazone functional group stands out for its extensive study and utility, owing to its ease of synthesis and adaptability. This review provides a comprehensive overview of N-acylhydrazone-based probes, serving as highly effective colorimetric and fluorometric chemosensors for a diverse range of metal ions. Probes are categorized into single-ion, dual-ion, and multi-ion chemosensors, each further classified based on the detected metal(s). Additionally, the review discusses detection modes, detection limits, association constants, and spectroscopic measurements.

Acylhydrazones and Their Biological Activity: A Review

Due to the structure of acylhydrazones both by the pharmacophore -CO-NH-N= group and by the different substituents present in the molecules of compounds of this class, various pharmacological activities were reported, including antitumor, antimicrobial, antiviral, antiparasitic, anti-inflammatory, immunomodulatory, antiedematous, antiglaucomatous, antidiabetic, antioxidant, and actions on the central nervous system and on the cardiovascular system. This fragment is found in the structure of several drugs used in the therapy of some diseases that are at the top of public health problems, like microbial infections and cardiovascular diseases. Moreover, the acylhydrazone moiety is present in the structure of some compounds with possible applications in the treatment of other different pathologies, such as schizophrenia, Parkinson's disease, Alzheimer's disease, and Huntington's disease. Considering these aspects, we consider that a study of the literature data regarding the structural and biological properties of these compounds is useful.

Synthesis of Novel N-Acylhydrazones and Their C-N/N-N Bond Conformational Characterization by NMR Spectroscopy

In this article, a synthesis of N’-(benzylidene)-2-(6-methyl-1H-pyrazolo[3,4-b]quinolin-1-yl)acetohydrazides and their structural interpretation by NMR experiments is described in an attempt to explain the duplication of some peaks in their ¹H- and ¹³C-NMR spectra. Twenty new 6-methyl-1H-pyrazolo[3,4-b]quinoline substituted N-acylhydrazones 6(a–t) were synthesized from 2-chloro-6-methylquinoline-3-carbaldehyde (1) in four steps. 2-Chloro-6-methylquinoline-3-carbaldehyde (1) afforded 6-methyl-1H-pyrazolo[3,4-b]quinoline (2), which upon N-alkylation yielded 2-(6-methyl-1H-pyrazolo[3,4-b]quinolin-1-yl)acetate (3). The hydrazinolysis of 3 followed by the condensation of resulting 2-(6-methyl-1H-pyrazolo[3,4-b]quinolin-1-yl)acetohydrazide (4) with aromatic aldehydes gave N-acylhydrazones 6(a–t). Structures of the synthesized compounds were established by readily available techniques such as FT-IR, NMR and mass spectral studies. The stereochemical behavior of 6(a–t) was studied in dimethyl sulfoxide-d₆ solvent by means of ¹H NMR and ¹³C NMR techniques at room temperature. NMR spectra revealed the presence of N’-(benzylidene)-2-(6-methyl-1H-pyrazolo[3,4-b]quinolin-1-yl)acetohydrazides as a mixture of two conformers, i.e., E_(C=N)(N-N) synperiplanar and E_(C=N)(N-N)antiperiplanar at room temperature in DMSO-d₆. The ratio of both conformers was also calculated and E_{(C=N) (N-N)} syn-periplanar conformer was established to be in higher percentage in equilibrium with the E_{(C=N) (N-N)}anti-periplanar form.

Synthesis of benzimidazole based hydrazones as non-sugar based α-glucosidase inhibitors: Structure activity relation and molecular docking

In search for α-glucosidase inhibitors used in the treatment of diabetes mellitus, a series of unique benzimidazole based hydrazones derivatives were synthesized (5a-5p), which were then investigated for their in vitro α-glucosidase inhibitory potential. The compounds of interest were characterized by modern spectroscopic approaches including CHN, ¹ HNM R, ¹³ CN MR and FTIR. The structure of compound 5n was distinctively authenticated through single crystal X-ray study. All compounds depicted potent enzyme inhibitory potential with IC₅₀ values in the range of 2.25 ± 0.01 to 81.16 ± 0.12 μM except 5n that showed IC₅₀ value of 182.75 ± 0.13 μM. A limited structure-activity correlation demonstrated that substitutions of isatin, aldehydes and ketone in hydrazones moiety had remarkable contribution in the overall activity and that was further supported by molecular docking studies carried out in elucidating the mechanism of binding interaction of these compounds in the catalytic site of α-glucosidase.

Reduction of cardiac and renal dysfunction by new inhibitor of DPP4 in diabetic rats

BACKGROUND

Increased mortality due to type 2 diabetes mellitus (T2DM) has been associated with renal and/or cardiovascular dysfunction. Dipeptidyl dipeptidase-4 inhibitors (iDPP-4s) may exert cardioprotective effects through their pleiotropic actions via glucagon-like peptide 1-dependent mechanisms. In this study, the pharmacological profile of a new iDPP-4 (LASSBio-2124) was investigated in rats with cardiac and renal dysfunction induced by T2DM.

METHODS

T2DM was induced in rats by 2 weeks of a high-fat diet followed by intravenous injection of streptozotocin. Metabolic disturbance and cardiac, vascular, and renal dysfunction were analyzed in the experimental groups.

RESULTS

Sitagliptin and LASSBio-2124 administration after T2DM induction reduced elevated glucose levels to 319.8 ± 13.2 and 279.7 ± 17.8 mg/dL, respectively (p < 0.05). LASSBio-2124 also lowered the cholesterol and triglyceride levels from 76.8 ± 8.0 to 42.7 ± 3.2 mg/dL and from 229.7 ± 25.4 to 100.7 ± 17.1 mg/dL, in diabetic rats. Sitagliptin and LASSBio-2124 reversed the reduction of the plasma insulin level. LASSBio-2124 recovered the increased urinary flow in diabetic animals and reduced 24-h proteinuria from 23.7 ± 1.5 to 13.3 ± 2.8 mg (p < 0.05). It also reduced systolic and diastolic left-ventricular dysfunction in hearts from diabetic rats.

CONCLUSION

The effects of LASSBio-2124 were superior to those of sitagliptin in the cardiovascular systems of T2DM rats. This new prototype showed promise for the avoidance of comorbidities in a T2DM experimental model, and thus may constitute an innovative therapeutic agent for the treatment of these conditions in the clinical field in future.

Gastroprotective effects of N-acylarylhydrazone derivatives on ethanol-induced gastric lesions in mice are dependent on the NO/cGMP/KATP pathway

The gastroprotective effects of N-acylarylhydrazone derivatives on ethanol-induced gastric lesions in mice were investigated with respect to the NO/cGMP/K_ATP pathway. To investigate our hypothesis, the mice were intraperitoneally pretreated with glibenclamide, L-NAME, or ODQ 30 min before treatment with DMSO, LASSBio-294 (1, 2, and 4 mg/kg, p.o.), LASSBio-897 (0.5, 1, and 2 mg/kg, p.o.), or omeprazole. After 1 h, the mice received absolute ethanol (4 ml/kg) by gavage to induce gastric mucosal lesions, and the microscopic and macroscopic parameters were evaluated. GSH (non-protein sulfhydryl groups) and MDA (malondialdehyde) concentrations, hemoglobin levels, nitric oxide production, myeloperoxidase (MPO) activity, and TNF-α and IL-1β levels were also analyzed in the stomach after absolute ethanol administration. Pretreatment with LASSBio-294 or LASSBio-897 significantly reduced the microscopic and macroscopic lesion area. The compounds restored the GSH, MDA, and hemoglobin levels and reduced MPO activity. Moreover, the compounds significantly reduced nitrate and nitrite concentrations in the stomach samples after ethanol administration. Molecular docking studies revealed that LASSBio-294 and LASSBio-897 interact with active sites of the eNOS (endothelial nitric oxide synthase) enzymes through hydrogen bonds. LASSBio-294 and LASSBio-897 also reduced TNF-α and IL-1β levels. It was observed that a NO synthase inhibitor, an ATP-sensitive potassium channel blocker, and a guanylate cyclase inhibitor significantly reversed the gastroprotective effects of these compounds. Thus, the gastroprotective effect of LASSBio-294 and LASSBio-897 against gastric lesions is mediated through the NO/cGMP cascade, followed by blocking of the K_ATP channels.

Theoretical and experimental characterization of 1,4-N⋯S σ-hole intramolecular interactions in bioactive N-acylhydrazone derivatives

Sigma-hole (σ-hole) bonds are interactions that are gaining special attention in medicinal chemistry.

LASSBio-897 Reduces Lung Injury Induced by Silica Particles in Mice: Potential Interaction with the A2A Receptor

Silicosis is a lethal fibro-granulomatous pulmonary disease highly prevalent in developing countries, for which no proper therapy is available. Among a small series of N-acylhydrazones, the safrole-derived compound LASSBio-897 (3-thienylidene-3, 4-methylenedioxybenzoylhydrazide) raised interest due to its ability to bind to the adenosine A_2A receptor. Here, we evaluated the anti-inflammatory and anti-fibrotic potential of LASSBio-897, exploring translation to a mouse model of silicosis and the A_2A receptor as a site of action. Pulmonary mechanics, inflammatory, and fibrotic changes were assessed 28 days after intranasal instillation of silica particles in Swiss–Webster mice. Glosensor cAMP HEK293G cells, CHO cells stably expressing human adenosine receptors and ligand binding assay were used to evaluate the pharmacological properties of LASSBio-897 in vitro. Molecular docking studies of LASSBio-897 were performed using the genetic algorithm software GOLD 5.2. We found that the interventional treatment with the A_2A receptor agonist CGS 21680 reversed silica particle-induced airway hyper-reactivity as revealed by increased responses of airway resistance and lung elastance following aerosolized methacholine. LASSBio-897 (2 and 5 mg/kg, oral) similarly reversed pivotal lung pathological features of silicosis in this model, reducing levels of airway resistance and lung elastance, granuloma formation and collagen deposition. In competition assays, LASSBio-897 decreased the binding of the selective A_2A receptor agonist [³H]-CGS21680 (IC₅₀ = 9.3 μM). LASSBio-897 (50 μM) induced modest cAMP production in HEK293G cells, but it clearly synergized the cAMP production by adenosine in a mechanism sensitive to the A_2A antagonist SCH 58261. This synergism was also seen in CHO cells expressing the A_2A, but not those expressing A_2B, A₁ or A₃ receptors. Based on the evidence that LASSBio-897 binds to A_2A receptor, molecular docking studies were performed using the A_2A receptor crystal structure and revealed possible binding modes of LASSBio-897 at the orthosteric and allosteric sites. These findings highlight LASSBio-897 as a lead compound in drug development for silicosis, emphasizing the role of the A_2A receptor as its putative site of action.

Beneficial effects of a novel agonist of the adenosine A2A receptor on monocrotaline-induced pulmonary hypertension in rats

BACKGROUND AND PURPOSE

Pulmonary arterial hypertension (PAH) is characterized by enhanced pulmonary vascular resistance, right ventricular hypertrophy and increased right ventricular systolic pressure. Here, we investigated the effects of a N-acylhydrazone derivative, 3,4-dimethoxyphenyl-N-methyl-benzoylhydrazide (LASSBio-1359), on monocrotaline (MCT)-induced pulmonary hypertension in rats.

EXPERIMENTAL APPROACH

PAH was induced in male Wistar rats by a single i.p. injection of MCT (60 mg·kg(-1)) and 2 weeks later, oral LASSBio-1359 (50 mg·kg(-1)) or vehicle was given once daily for 14 days. Echocardiography was used to measure cardiac function and pulmonary artery dimensions, with histological assay of vascular collagen. Studies of binding to human recombinant adenosine receptors (A1, A2A, A3) and of docking with A2A receptors were also performed.

KEY RESULTS

MCT administration induced changes in vascular and ventricular structure and function, characteristic of PAH. These changes were reversed by treatment with LASSBio-1359. MCT also induced endothelial dysfunction in pulmonary artery, as measured by diminished relaxation of pre-contracted arterial rings, and this dysfunction was reversed by LASSBio-1359. In pulmonary artery rings from normal Wistar rats, LASSBio-1359 induced relaxation, which was decreased by the adenosine A2A receptor antagonist, ZM 241385. In adenosine receptor binding studies, LASSBio-1359 showed most affinity for the A2A receptor and in the docking analyses, binding modes of LASSBio-1359 and the A2A receptor agonist, CGS21680, were very similar.

CONCLUSION AND IMPLICATIONS

In rats with MCT-induced PAH, structural and functional changes in heart and pulmonary artery were reversed by treatment with oral LASSBio-1359, most probably through the activation of adenosine A2A receptors.

Characterization of amide bond conformers for a novel heterocyclic template of N-acylhydrazone derivatives

Herein we describe NMR experiments and structural modifications of 4-methyl-2-phenylpyrimidine-N-acylhydrazone compounds (aryl-NAH) in order to discover if duplication of some signals in their ¹H- and ¹³C-NMR spectra was related to a mixture of imine double bond stereoisomers (E/Z) or CO-NH bond conformers (syn and anti-periplanar). NMR data from NOEdiff, 2D-NOESY and ¹H-NMR spectra at different temperatures, and also the synthesis of isopropylidene hydrazone revealed the nature of duplicated signals of a 4-methyl-2-phenylpyrimidine-N-acylhydrazone derivative as a mixture of two conformers in solution. Further we investigated the stereoelectronic influence of substituents at the ortho position on the pyrimidine ring with respect to the carbonyl group, as well as the electronic effects of pyrimidine by changing it to phenyl. The conformer equilibrium was attributed to the decoplanarization of the aromatic ring and carbonyl group (generated by an ortho-alkyl group) and/or the electron withdrawing character of the pyrimidine ring. Both effects increased the rotational barrier of the C-N amide bond, as verified by the ΔG^≠ values calculated from dynamic NMR. As far as we know, it is the first description of aryl-NAH compounds presenting two CO-NH bond- related conformations.

Vasodilator activity of the essential oil from aerial parts of Pectis brevipedunculata and its main constituent citral in rat aorta

The essential oil of Pectis brevipedunculata (EOPB), a Brazilian ornamental aromatic grass, is characterized by its high content of citral (81.9%: neral 32.7% and geranial 49.2%), limonene (4.7%) and α-pinene (3.4%). Vasodilation induced by EOPB and isolated citral was investigated in pre-contracted vascular smooth muscle, using thoracic aorta from Wistar Kyoto (WKY) rats which was prepared for isometric tension recording. EOPB promoted intense relaxation of endothelium-intact and denuded aortic rings with the concentration to induce 50% of the maximal relaxation (IC50) of 0.044% ± 0.006% and 0.093% ± 0.015% (p < 0.05), respectively. The IC50 values for citral in endothelium-intact and denuded rings were 0.024% ± 0.004% and 0.021% ± 0.004%, respectively (p > 0.05). In endothelium-intact aorta, EOPB-induced vasorelaxation was significantly reduced by L-NAME, a nitric oxide synthase inhibitor. The vasodilator activity of citral was increased in the KCl-contracted aorta and citral attenuated the contracture elicited by Ca2+ in depolarized aorta. EOPB and citral elicited vasorelaxation on thoracic aorta by affecting the NO/cyclic GMP pathway and the calcium influx through voltage-dependent L-type Ca2+ channels, respectively.

Synthesis and antibacterial evaluation of New N-acylhydrazone derivatives from dehydroabietic acid

A series of new N-acylhydrazone derivatives were synthesized in good yields through the reactions of dehydroabietic acid hydrazide with a variety of substituted arylaldehydes. The structures of the synthesized compounds were confirmed by IR, 1H- and 13C-NMR, ESI-MS, elemental analysis and single crystal X-ray diffraction. From the crystal structure of compound 4l, the C=N double bonds of these N-acylhydrazones showed (E)-configuration, while the NMR data of compounds 4a-q indicated the existence of two rotamers for each compound in solution. The target compounds were evaluated for their antibacterial activities against four microbial strains. The result suggested that several compounds exhibited pronounced antibacterial activities. Particularly, compound 4p exhibited good antibacterial activity against Staphylococcus aureus and Bacillus subtilis comparable to positive control. The possible antibacterial metabolism and the strategy for further optimization of this compound were also discussed.

Role of M1, M3, and M5 muscarinic acetylcholine receptors in cholinergic dilation of small arteries studied with gene-targeted mice

Acetylcholine regulates perfusion of numerous organs via changes in local blood flow involving muscarinic receptor-induced release of vasorelaxing agents from the endothelium. The purpose of the present study was to determine the role of M₁, M₃, and M₅ muscarinic acetylcholine receptors in vasodilation of small arteries using gene-targeted mice deficient in either of the three receptor subtypes (M1R(-/-), M3R(-/-), or M5R(-/-) mice, respectively). Muscarinic receptor gene expression was determined in murine cutaneous, skeletal muscle, and renal interlobar arteries using real-time PCR. Moreover, respective arteries from M1R(-/-), M3R(-/-), M5R(-/-), and wild-type mice were isolated, cannulated with micropipettes, and pressurized. Luminal diameter was measured using video microscopy. mRNA for all five muscarinic receptor subtypes was detected in all three vascular preparations from wild-type mice. However, M(3) receptor mRNA was found to be most abundant. Acetylcholine produced dose-dependent dilation in all three vascular preparations from M1R(-/-), M5R(-/-), and wild-type mice. In contrast, cholinergic dilation was virtually abolished in arteries from M3R(-/-) mice. Deletion of either M₁, M₃, or M₅ receptor genes did not affect responses to nonmuscarinic vasodilators, such as substance P and nitroprusside. These findings provide the first direct evidence that M₃ receptors mediate cholinergic vasodilation in cutaneous, skeletal muscle, and renal interlobar arteries. In contrast, neither M₁ nor M₅ receptors appear to be involved in cholinergic responses of the three vascular preparations tested.