Synthesis, Characterization, X-ray Molecular Structure, Antioxidant, Antifungal, and Allelopathic Activity of a New Isonicotinate-Derived meso-Tetraarylporphyrin.

The present article describes the synthesis of an isonicotinate-derived meso-arylporphyrin, that has been fully characterized by spectroscopic methods (including fluorescence spectroscopy), as well as elemental analysis and HR-MS. The structure of an n-hexane monosolvate has been determined by single-crystal X-ray diffraction analysis. The radical scavenging activity of this new porphyrin against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical has been measured. Its antifungal activity against three yeast strains (C. albicans ATCC 90028, C. glabrata ATCC 64677, and C. tropicalis ATCC 64677) has been tested using the disk diffusion and microdilution methods. Whereas the measured antioxidant activity was low, the porphyrin showed moderate but encouraging antifungal activity. Finally, a study of its effect on the germination of lentil seeds revealed interesting allelopathic properties.

Confronting Tuberculosis: A Synthetic Quinoline-Isonicotinic Acid Hydrazide Hybrid Compound as a Potent Lead Molecule Against Mycobacterium tuberculosis.

The current tuberculosis (TB) treatment is challenged by a complex first-line treatment for drug-sensitive (DS) TB. Additionally, the prevalence of multidrug (MDR)- and extensively drug (XDR)-resistant TB necessitates the search for new drug prototypes. We synthesized and screened 30 hybrid compounds containing aminopyridine and 2-chloro-3-formyl quinoline to arrive at a compound with potent antimycobacterial activity, UH-NIP-16. Subsequently, antimycobacterial activity against DS and MDR Mycobacterium tuberculosis (M.tb) strains were performed. It demonstrated an MIC50 value of 1.86 ± 0.21 µM for laboratory pathogenic M.tb strain H37Rv and 3.045 ± 0.813 µM for a clinical M.tb strain CDC1551. UH-NIP-16 also decreased the MIC50 values of streptomycin, isoniazid, ethambutol, and bedaquiline to about 45, 55, 68, and 76%, respectively, when used in combination, potentiating their activities. The molecule was active against a clinical MDR M.tb strain. Cytotoxicity on PBMCs from healthy donors and on human cell lines was found to be negligible. Further, blind docking of UH-NIP-16 using Auto Dock Vina and MGL tools onto diverse M.tb proteins showed high binding affinities with multiple M.tb proteins, the top five targets being metabolically critical proteins CelA1, DevS, MmaA4, lysine acetyltransferase, and immunity factor for tuberculosis necrotizing toxin. These bindings were confirmed by fluorescence spectroscopy using a representative protein, MmaA4. Envisaging that a pathogen will have a lower probability of developing resistance to a hybrid molecule with multiple targets, we propose that UH-NIP-16 can be further developed as a lead molecule with the bacteriostatic potential against M.tb, both alone and in combination with first-line drugs.

Novel candidates in the clinical development pipeline for TB drug development and their synthetic approaches.

Tuberculosis (TB) is an infection caused by Mycobacterium tuberculosis (Mtb) and one of the deadliest infectious diseases in the world. Mtb has the ability to become dormant within the host and to develop resistance. Hence, new antitubercular agents are required to overcome problems in the treatment of multi-drug-resistant Tb (MDR-Tb) and extensively drug-resistant Tb (XDR-Tb) along with shortening the treatment time. Several efforts are being made to develop very effective new drugs for Tb, within the pharmaceutical industry, the academia and through public-private partnerships. This review will address the antitubercular activities, biological target, mode of action, synthetic approaches and thoughtful concept for the development of several new drugs currently in the clinical trial pipeline (up to October 2019) for tuberculosis. The aim of this review may be very useful in scheming new chemical entities (NCEs) for Mtb.

Synthesis of Highly Potent Anti-Inflammatory Compounds (ROS Inhibitors) from Isonicotinic Acid.

In search of anti-inflammatory compounds, novel scaffolds containing isonicotinoyl motif were synthesized via an efficient strategy. The compounds were screened for their in vitro anti-inflammatory activity. Remarkably high activities were observed for isonicotinates 5-6 and 8a-8b. The compound 5 exhibits an exceptional IC50 value (1.42 ± 0.1 µg/mL) with 95.9% inhibition at 25 µg/mL, which is eight folds better than the standard drug ibuprofen (11.2 ± 1.9 µg/mL). To gain an insight into the mode of action of anti-inflammatory compounds, molecular docking studies were also performed. Decisively, further development and fine tuning of these isonicotinates based scaffolds for the treatment of various aberrations is still a wide-open field of research.

Exploration of Structure-Activity Relationship of Aromatic Aldehydes Bearing Pyridinylmethoxy-Methyl Esters as Novel Antisickling Agents.

Aromatic aldehydes elicit their antisickling effects primarily by increasing the affinity of hemoglobin (Hb) for oxygen (O2). However, challenges related to weak potency and poor pharmacokinetic properties have hampered their development to treat sickle cell disease (SCD). Herein, we report our efforts to enhance the pharmacological profile of our previously reported compounds. These compounds showed enhanced effects on Hb modification, Hb-O2 affinity, and sickling inhibition, with sustained pharmacological effects in vitro. Importantly, some compounds exhibited unusually high antisickling activity despite moderate effects on the Hb-O2 affinity, which we attribute to an O2-independent antisickling activity, in addition to the O2-dependent activity. Structural studies are consistent with our hypothesis, which revealed the compounds interacting strongly with the polymer-stabilizing αF-helix could potentially weaken the polymer. In vivo studies with wild-type mice demonstrated significant pharmacologic effects. Our structure-based efforts have identified promising leads to be developed as novel therapeutic agents for SCD.

Sulfamic acid catalyzed synthesis of new 3,5-[(sub)phenyl]-1H-pyrazole bearing N1-isonicotinoyl: And their pharmacological activity evaluation.

A sustainable synthesis of new 3,5-[(sub)phenyl]-1H-pyrazole bearing N1-isonicotinoyl derivatives from substituted chalcones and isoniazid by using sulfamic acid and their pharmacological activity evaluation is reported. An anti-oxidant study is performed by using DPPH assay. In vitro anti-mycobacterial activity of compounds bearing R/R' = 4-CH3/4-F and 3-OCH3/4-Cl showed complete inhibition (99%) at the MIC of 31 and 34 µM respectively. Antibacterial screening of compounds bearing R/R' = 4-CH3/4-F; 4-OCH3/4-Br; and 4-OCH3/4-Cl has shown noticeable inhibition (27 mm) against Staphylococcus aureus. The anti-cancer bioassay demonstrated that the five compounds were active on human breast cancer cell line MCF-7; however on HeLa cervical cancer cells only two compounds are active in comparison to standard drug Doxorubicin. Higher inhibitory effects observed in this study appear to be dependent on the chloro, bromo, fluoro and methoxy functionality present on the aromatic nucleus. The structures of all the compounds are established using NMR (1H and 13C), FT-IR, Mass and elemental analysis.

Synthetic nicotinic/isonicotinic thiosemicarbazides: In vitro urease inhibitory activities and molecular docking studies.

Nicotinic and isonicotinic thiosemicarbazide or hydrazine carbothioamides 3-27 were synthesized and the structures of synthetic compounds were elucidated by various spectroscopic techniques such as EI-MS, 1H-, and 13C NMR. Synthetic derivatives were evaluated for their urease inhibitory activity which revealed that except few all derivatives demonstrated excellent inhibition in the range of IC50 values of 1.21-51.42 µM as compared to the standard thiourea (IC50 = 21.25 ±â€¯0.13 µM). Among the twenty-five synthetic derivatives nineteen 1-5, 7, 8, 10, 12, 14-18, 20-22, 24-27 were found to be more active showing IC50 values between 1.13 and 19.74 µM showing superior activity than the standard. Limited structure-activity relationship demonstrated that the positions of substituent as well as position of nitrogen in pyridine ring are very important for inhibitory activity of this class of compound. To verify these interpretations, in silico study was also performed. A good correlation was obtained between the biological evaluation of active compounds and docking study.

New hydrazide-hydrazones of isonicotinic acid: synthesis, lipophilicity and in vitro antimicrobial screening.

This study describes the synthesis, lipophilicity and in vitro antimicrobial assays of 15 new hydrazide-hydrazones of isonicotinic acid. New derivatives were obtained on the basis of the condensation reaction of isonicotinic acid hydrazide with different aromatic aldehydes. The chemical structure of synthesized compounds was confirmed by spectral methods. Experimental lipophilicity of new isonicotinic acid derivatives was determined using reversed-phase thin-layer chromatography. All synthesized compounds were subjected to in vitro antimicrobial assays against reference strains of Gram-positive bacteria, Gram-negative bacteria and fungi belonging to Candida spp. Some of the synthesized hydrazide-hydrazones proved to be significant antibacterial compounds and more potent than commonly used chemotherapeutic agents.

Pharmacological Evaluation of Novel Isonicotinic Carboxamide Derivatives as Potential Anti-Hyperlipidemic and Antioxidant Agents.

Hyperlipidemia and oxidative stress have been implicated as contributing factors to the development of atherosclerosis and cardiovascular diseases (CVDs). Currently, a large number of antihyperlipidemic medications are conveniently available in the market. Nonetheless, the majority of antihyperlipidemics lack the desired safety and efficacy. Thus, the present study was undertaken to evaluate the potential effect of novel N-(benzoylphenyl)pyridine-4-carboxamide and N-(9,10-dioxo-9,10-dihydroanthracenyl)pyridine-4-carboxamide derivatives in controlling hyperlipidemia and oxidative stress using the Triton WR-1339-induced hyperlipidemic rat model for antihyperlipidemic activity and the DPPH radical scavenging assay for antioxidant activity. This study revealed the antihyperlipidemic activities of some of the newly synthesized, novel carboxamide derivatives, mainly C4 and C12 (p < 0.05). The majority of the compounds displayed a relatively low or no DPPH radical scavenging effect, with C20 possessing the best radical scavenging effect (22%) among all. This research opens the door for new potential antihyperlipidemic compounds derived from isonicotinic acid. N-(3-Benzoylphenyl)pyridine-4-carboxamide (C4) was found to have promising lipid-lowering and antioxidant effects, which may create a protective effect against CVDs, by reducing the LDL-C levels and diminishing the generation of reactive oxygen species.

QSAR, docking studies of 1,3-thiazinan-3-yl isonicotinamide derivatives for antitubercular activity.

The enzyme - enoyl acyl carrier protein reductase (enoyl ACP reductase) is a validated target for antitubercular activity. Inhibition of this enzyme interferes with mycolic acid synthesis which is crucial for Mycobacterium tuberculosis cell growth. In the present work 2D and 3D quantitative structure activity relationship (QSAR) studies were carried out on a series of thiazinan-Isoniazid pharmacophore to design newer analogues. For 2D QSAR, the best statistical model was generated using SA-MLR method (r2=0.958, q2=0.922) while 3D QSAR model was derived using the SA KNN method (q2=0.8498). These studies could guide the topological, electrostatic, steric, hydrophobic substitutions around the nucleus based on which the NCEs were designed. Furthermore, molecular docking was performed to gauze the binding affinity of the designed analogues for enoyl ACP reductase enzyme. Amongst all the designed analogues the binding energies of SKS 01 and SKS 05 were found to be -5.267kcal/mol and -5.237kcal/mol respectively which was comparable with the binding energy of the standard Isoniazid (-6.254kcal/mol).

Substituted 2-(2-aminopyrimidin-4-yl)pyridine-4-carboxylates as potent inhibitors of JumonjiC domain-containing histone demethylases.

BACKGROUND: Aberrant expression of iron(II)- and 2-oxoglutarate-dependent JumonjiC histone demethylases has been linked to cancer. Potent demethylase inhibitors are drug candidates and biochemical tools to elucidate the functional impact of demethylase inhibition. METHODS & RESULTS: Virtual screening identified a novel lead scaffold against JMJD2A with low-micromolar potency in vitro. Analogs were acquired from commercial sources respectively synthesized in feedback with biological testing. Optimized compounds were transformed into cell-permeable prodrugs. A cocrystal x-ray structure revealed the mode of binding of these compounds as competitive to 2-oxoglutarate and confirmed kinetic experiments. Selectivity studies revealed a preference for JMJD2A and JARID1A over JMJD3. CONCLUSION: Virtual screening and rational structural optimization led to a novel scaffold for highly potent and selective JMJD2A inhibitors.

New Antimycobacterial Leads from Multicomponent Hydrazino-Ugi Reaction.

BACKGROUND: Previously, modification of isoniazide- and pyrazinamide-derived pharmacophores via the Ugi multicomponent reaction proved to be an effective strategy to obtain efficacious and non-cytotoxic antimycobacterial leads. OBJECTIVE: To apply the hydrazino-Ugi reaction developed in our group toward modifying these pharmacophores with similar appendages as reported previously; to create hydrolytically more stable compounds which are based on acyl hydrazine, rather than diamide backbone. METHOD: Six hydrazino-Ugi products were synthesized and modified at the reactive nitrogen atom via reductive alkylation. Additionally, by conducting the hydrazino-Ugi reaction in methanol, three methyl ester by-products were obtained and tested alongside the main library. Compounds were screened against M. tuberculosis H37Rv strain and checked for cytotoxicity vs. HEK293 cells. Hydrolytic stability of a model Ugi and one of the newly synthesized hydrazino-Ugi products was compared in rat plasma stability experiments. RESULTS: 6 out of 20 compounds prepared and tested, displayed potent inhibition of M. tuberculosis growth and virtually no cytotoxicity in the testing concentration range. The stability of a sample hydrazino-Ugi product in rat plasma was over 3 times higher compared to that of one of the Ugi products reported earlier. CONCLUSION: Hydrazino-Ugi reaction represents an effective way to modify classical antitubercular chemotypes and generate compounds endowed with specific antimycobacterial activity. These are new, hydrolytically stable leads for the future antitubercular therapy development.

Synthesis and evaluation of antibacterial activity of (R)-2-methylheptyl isonicotinate, a putative naturally occurring bioactive agent.

A putative antibacterial and antifungal compound, (R)-2-methylheptyl isonicotinate, was synthesized via reductive lactone alkylation of (R)-4-methyldihydrofuran-2(3H)-one. Structural characterisation data as well as bioassay results (with Bacillus subtilis or Escherichia coli) contradict those previously reported.

A multifunctional, light-activated prochelator inhibits UVA-induced oxidative stress.

UVA radiation can damage cells and tissues by direct photodamage of biomolecules as well as by initiating metal-catalyzed oxidative stress. In order to alleviate both concerns simultaneously, we synthesized a multifunctional prochelator PC-HAPI (2-((E)-1-(2-isonicotinoylhydrazono)ethyl)phenyl (trans)-3-(2,4-dihydroxyphenyl)acrylate) that contains a trans-(o-hydroxy)cinnamate ester photocleavable protecting group that is cleaved upon UVA exposure to release a coumarin, umbelliferone, and an aroylhydrazone metal chelator, HAPI (N'-[1-(2-hydroxyphenyl)ethyliden]isonicotinoylhydrazide). While the prochelator PC-HAPI exhibits negligible affinity for iron, it responds rapidly to UVA irradiation and converts to an iron-binding chelator that inhibits iron-catalyzed formation of reactive oxygen species and protects cells from UVA damage.

A novel colorimetric probe derived from isonicotic acid hydrazide for copper (II) determination based on internal charge transfer (ICT).

A novel isonicotic acid hydrazide Schiff base derivative N'-(3,5-di-tert-butyl-2-hydroxy-benzylidene) isonicotinohydrazide (DHIH) has been synthesized and developed as a high selective and sensitive colorimetric probe for Cu(2+) determination. Addition of Cu(2+) to the solution of DHIH resulted in a rapid color change from colorless to yellow together with an obvious new absorption band appeared at the range of 400-440 nm by forming a 1:1 complex. Experimental results indicated that the DHIH could provide absorption response to Cu(2+) with a linear dynamic range from 1.0×10(-5) to 1.0×10(-4)mol/L. The detection limit of Cu(2+) was 5.24×10(-7)mol/L with good tolerance of other metal ions.

Synthesis, crystal structure, characterization and biological activity of 2,5-hexanedione bis(isonicotinylhydrazone) and N-(2,5-dimethyl-1H-pyrrol-1-yl)isonicotinamide complexes.

The reaction between 2,5-hexanedione and isonicotinic acid hydrazide in EtOH gave two products. The ethanol insoluble product was identified as 2,5-hexanedione bis(isonicotinylhydrazone) [HINH] and the soluble ethanol product as N-(2,5-dimethyl-1H-pyrrol-1-yl)isonicotinamide [DINA]. A series of Cr(3+), Fe(3+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Pd(2+) complexes of HINH and Co(2+), Cu(2+), Zn(2+) and Hg(2+) complexes of DINA have been synthesized and structurally characterized. Based on the elemental analysis, mass spectra and molar conductance, the complexes have assigned the proposed imperical formulae. The crystal structures of N-(2,5-dimethyl-1H-pyrrol-1-yl)isonicotinamide and its Zn(2+) and Hg(2+) complexes have been solved by X-ray diffraction having [Zn(DINA)2Cl2] and [Hg(DINA)2Cl2] in a tetrahedral structure. In the DINH complexes, the ligand coordinates as a monodentate through the pyridine nitrogen. On the other hand, HINH behaves as a tetradentate (neutral or binegative) manner with the two metal ions. The magnetic moments and electronic spectra of all complexes provide tetrahedral, square-planar, trigonal biyramid and/or octahedral structure. The thermal decomposition of the complexes revealed the outer and inner solvents as well as the end product. The steady part of [Zn(DINA)2Cl2] and [Hg(DINA)2Cl2] thermograms till 303 and 286 °C indicates the absence of any outside solvents. All compounds have activity against bacteria more than fungi. [Cd4(HINH)Cl8]·3H2O has the highest values.

Design and structural analysis of aromatic inhibitors of type II dehydroquinase from Mycobacterium tuberculosis.

3-Dehydroquinase, the third enzyme in the shikimate pathway, is a potential target for drugs against tuberculosis. Whilst a number of potent inhibitors of the Mycobacterium tuberculosis enzyme based on a 3-dehydroquinate core have been identified, they generally show little or no in vivo activity, and were synthetically complex to prepare. This report describes studies to develop tractable and drug-like aromatic analogues of the most potent inhibitors. A range of carbon-carbon linked biaryl analogues were prepared to investigate the effect of hydrogen bond acceptor and donor patterns on inhibition. These exhibited inhibitory activity in the high-micromolar range. The addition of flexible linkers in the compounds led to the identification of more potent 3-nitrobenzylgallate- and 5-aminoisophthalate-based analogues.

Synthesis, structure, spectral, thermal and first-order molecular hyperpolarizability of 4-benzoylpyridine isonicotinyl hydrazone monohydrate single crystals.

Single crystals of 4-benzoylpyridine isonicotinyl hydrazone monohydrate were grown by slow evaporation solution growth technique from ethanol at room temperature. It belongs to triclinic system with space group P1¯ and the cell parameters are, a=8.9250(2) Å, b=9.1540(2) Å, c=10.87500(10) Å and V=797.88(3) Å(3). Powder XRD closely resembles with that of simulated pattern from single crystal XRD. The characteristic functional groups present in the molecule are confirmed by FT-IR and FT-Raman analyses. The crystal is transparent in the visible region having a lower optical cut-off at ∼420 nm and the band gap energies are estimated by the application of Kubelka-Munk algorithm. Thermal analysis by TG/DTA indicates the stability of the material. The scanning electron microscopy studies reveal the surface morphology of the as-grown crystal. Mass spectrometry provides information pertaining to the structure and molecular weight of the compound. Theoretical calculations were performed using Hartree-Fock method with 6-31G(d,p) as the basis set for to derive the optimized geometry, dipole moment and first-order molecular hyperpolarizality (ß) values.

Peroxisome proliferator-activated receptor-γ mediates the anti-inflammatory effect of 3-hydroxy-4-pyridinecarboxylic acid derivatives: synthesis and biological evaluation.

Seven 3-hydroxy-4-pyridinecarboxylic acid derivatives (HPs), aza-analogues of salicylic acid and structurally close to other potent inflammatory pyridine compounds such as aminopyridinylmethanols and aminopyridinamines, were synthesized, and their anti-inflammatory activity was evaluated. The synthesis was performed by adopting a general procedure involving an intramolecular Diels-Alder cycloaddition of oxazoles with acrylic acid to form various substituted pyridinic acids. The newly synthesized HPs did not exhibit cytotoxic activity on human monocytes-derived macrophages at concentrations up to 10(2) µM. Anti-inflammatory activity of the compounds was screened in vitro by evaluating the capability to inhibit cytokines release from lipopolysaccharide (LPS) stimulated human macrophages. 3-Hydroxy-1-methyl-4-pyridinecarboxylic acid (24) was found to be the most active HP. At 10 µM concentration, HP 24 reduced LPS-induced and nuclear factor-κB activation and cyclooxygenase-2 expression, while increased intracellular reactive oxygen species generation and peroxisome proliferator-activated receptor (PPAR-γ) mRNA transcript level. Indeed, pre-treatment of LPS-exposed human macrophages with PPAR-γ specific antagonist completely prevented HP 24-induced TNF-α and IL8 down regulation, demonstrating that the PPARγ pathway is mandatory for the HP 24 anti-inflammatory effect. Finally, daily treatment with HP 24 ameliorated the outcome of DSS-induced colitis in mice, significantly reducing colonic MPO activity and IL-1ß tissue levels.

New 1,4-di-N-oxide-quinoxaline-2-ylmethylene isonicotinic acid hydrazide derivatives as anti-Mycobacterium tuberculosis agents.

The increase in the prevalence of drug-resistant tuberculosis cases demonstrates the need of discovering new and promising compounds with antimycobacterial activity. As a continuation of our research and with the aim of identifying new antitubercular drugs candidates, a new series of quinoxaline 1,4-di-N-oxide derivatives containing isoniazid was synthesized and evaluated for in vitro anti-tuberculosis activity against Mycobacterium tuberculosis H37Rv strain. Moreover, various drug-like properties of new compounds were predicted. Taking into account the biological results and the promising drug-likeness profile of these compounds, make them valid leads for further experimental research.