Synthesis, biological evaluation, and computational investigation of ethyl 2,4,6-trisubstituted-1,4-dihydropyrimidine-5-carboxylates as potential larvicidal agents against Anopheles arabiensis

Malaria is one of the most known vector-borne diseases caused by female Anopheles mosquito bites. According to WHO, about 247 million cases of malaria and 619,000 deaths were estimated worldwide in 2021, of which 95% of the cases and 96% of deaths occurred in the African region. Sadly, about 80% of all malaria deaths were of children under five years old. Despite the availability of different insecticides used to control this disease, the emergence of drug-resistant mosquitoes threatens public health. This, in turn, highlighted the need for new larvicidal agents that are effective at different larval life stages. This study aimed to identify novel larvicidal agents. To this end, a series of ethyl 2,4,6-trisubstituted-1,4-dihydropyrimidine-5-carboxylates 8a-i was synthesized using a three-step chemical synthetic approach via a Biginelli reaction employed as a key step. All title compounds were screened against Anopheles arabiensis to determine their larvicidal activities. Among them, two derivatives, ethyl 2-((4-bromophenyl)amino)-4-(4-fluorophenyl)-6-methyl-1,4-dihydropyrimidine-5-carboxylate 8b and ethyl 2-((4-bromo-2-cyanophenyl)amino)-4-(4-fluorophenyl)-6-methyl-1,4-dihydropyrimidine-5-carboxylate 8f, showed the highest larvicidal activity, with mortality of 94% and 91%, respectively, and emerged as potential larvicidal agents. In addition, computational studies, including molecular docking and molecular dynamics simulations, were carried out to investigate their mechanism of action. The computational results showed that acetylcholinesterase appears to be a plausible molecular target for their larvicidal property.Communicated by Ramaswamy H. Sarma.

Design, synthesis and characterization of ethyl 3-benzoyl-7-morpholinoindolizine-1-carboxylate as anti-tubercular agents: In silico screening for possible target identification

A thorough search for the development of innovative drugs to treat tuberculosis, especially considering the urgent need to address developing drug resistance, we report here a synthetic series of ethyl 3-benzoyl-7-morpholinoindolizine-1-carboxylate analogues (5a-o) as potent anti-tubercular agents. These morpholino-indolizines were synthesized by reacting 4-morpholino pyridinium salts, with various electron-deficient acetylenes to afford the ethyl 3-benzoyl-7-morpholinoindolizine-1-carboxylate analogues (5a-o). All synthesized intermediate and final compounds are characterized by spectroscopic methods such as 1H NMR, 13C NMR and HRMS and further examined for their anti-tubercular activity against the M. tuberculosis H37Rv strain (ATCC 27294-American type cell culture). All the compounds screened for anti-tubercular activity in the range of 6.25-50 μM against the H37Rv strain of Mycobacterium tuberculosis. Compound 5g showed prominent activity with MIC99 2.55 μg/mL whereas compounds 5d and 5j showed activity with MIC99 18.91 μg/mL and 25.07 μg/mL, respectively. In silico analysis of these compounds revealed drug-likeness. Additionally, the molecular target identification for Malate synthase (PDB 5CBB) is attained by computational approach. The compound 5g with a MIC99 value of 2.55 μg/mL against M. tuberculosis H37Rv emerged as the most promising anti-TB drug and in silico investigations suggest Malate synthase (5CBB) might be the compound's possible target.

Synthesis, characterization, and anti-inflammatory properties of novel ethyl 3-benzoyl-7-(trifluoromethyl)indolizine-1-carboxylate derivatives: In silico and in vitro analysis

Series of 7-(Trifluoromethyl) substituted indolizine 4a-g was synthesized using the one-pot method. Spectroscopic techniques such as IR, 1H-NMR, 13C-NMR, and HRMS were used for the structure confirmation of newly synthesized compounds. These 4a-g compounds were tested for their anti-inflammatory activity. In this study, we identified novel indolizine derivative compounds 4a-g selectively targeting COX-2 enzyme, tumor necrosis factor-α (TNF-α) and, interleukin-6 (IL-6). The in silico docking studies of 4a-g showed that these compounds have a higher affinity for COX-2 enzyme, TNF- α, and IL-6. In silico ADME profile analysis predicts that these compounds have good gastrointestinal tract and blood-brain barrier absorption. In vitro studies showed that compound 4d significantly reduces the level of COX-2 enzymes as compared to indomethacin. Compounds 4e, 4f, and 4a were also found to significantly reduce the level of TNF-α, while compounds 4f, 4g, and 4d, showed a reduction in the level of IL-6 when compared to indomethacin. Compounds 4a, 4d, and 4f also reduces nitric oxide (NO) level, compared to indomethacin. Overall, the current study illustrates significant anti-inflammatory activities of these novel 7-(Trifluoromethyl) substituted indolizine derivatives.

Synthesis, characterization and larvicidal studies of ethyl 3-benzoyl-7-(piperidin-1-yl)indolizine-1-carboxylate analogues against Anopheles arabiensis and cheminformatics approaches

According to WHO, in 2021, there was an estimation of 247 million malaria cases from 84 malaria-endemic countries. Globally an estimated count of 2 billion malaria cases and 11.7 million deaths due to malaria were recorded in the past two decades. Further, the emergence of drug-resistant mosquitos threatens mankind. Therefore, the development of newer larvicidal agents is the need of the hour. This research identifies a new series of variably substituted indolizines for their effectiveness in controlling Anopheles arabiensis larvae through larvicidal activity. The series of Ethyl 3-benzoyl-7-(piperidin-1-yl)indolizine-1-carboxylate analogues (4a-j) were synthesized by reacting 4-(piperidin-1-yl)pyridine, phenacyl bromides with ethyl propiolate via 1, 3-dipolar cycloaddition and the green metrics of the process are reported. All the newly synthesized compounds were characterized by spectroscopic techniques such as 1H NMR,13C NMR, FT-IR, and HRMS. The larvicidal effectiveness of the newly synthesized compounds was assessed against Anopheles arabiensis. Among the compounds studied, namely 4c, 4d, 4e, and 4f, displayed the most notable larval mortality rates within the series, reaching 73%, 81%, 76%, and 71% respectively, in contrast with the negative control acetone. In comparison, the standard Temephos exhibited a mortality rate of 99% at the same concentration. Furthermore, computational approaches including molecular docking and molecular dynamics simulations identified the potential targets of the series compounds as the larval Acetylcholinesterase (AChE) enzyme and the Sterol Carrier Protein-2 (SCP-2) protein. However, it is essential for these computational predictions to undergo experimental validation.Communicated by Ramaswamy H. Sarma.

Nucleophilic sulfur controlled efficient ketothioamide synthesis from tribromomethyl carbinols

A mild, catalyst and oxidant-free efficient protocol for synthesizing α-ketothioamides is reported with a broad substrate scope. The presented protocol demonstrates the confined reactivity of amines. The polysulfide derived from elemental sulfur and amines in an aqueous medium drives the pathway toward diverse α-ketothioamides over thioamides. Substrates with different substituent groups were compatible with the presented protocol, and the respective ketothioamides were separated in good to excellent yields. The ketothioamides, known to exhibit anti-cancer properties, were synthesized by the proposed protocol. Furthermore, the synthetic utility was explored with the typical synthesis of ketoamides.

Development of Moringa oleifera as functional food targeting NRF2 signaling: antioxidant and anti-inflammatory activity in experimental model systems

Pharmacological activation of nuclear factor erythroid 2 related factor 2 (NRF2) provides protection against several environmental diseases by inhibiting oxidative and inflammatory injury. Besides high in protein and minerals, Moringa oleifera leaves contain several bioactive compounds, predominantly isothiocyanate moringin and polyphenols, which are potent inducers of NRF2. Hence, M. oleifera leaves represent a valuable food source that could be developed as a functional food for targeting NRF2 signaling. In the current study, we have developed a palatable M. oleifera leaf preparation (henceforth referred as ME-D) that showed reproducibly a high potential to activate NRF2. Treatment of BEAS-2B cells with ME-D significantly increased NRF2-regulated antioxidant genes (NQO1, HMOX1) and total GSH levels. In the presence of brusatol (a NRF2 inhibitor), ME-D-induced increase in NQO1 expression was significantly diminished. Pre-treatment of cells with ME-D mitigated reactive oxygen species, lipid peroxidation and cytotoxicity induced by pro-oxidants. Furthermore, ME-D pre-treatment markedly inhibited nitric oxide production, secretory IL-6 and TNF-α levels, and transcriptional expression of Nos2, Il-6, and Tnf-α in macrophages exposed to lipopolysaccharide. Biochemical profiling by LC-HRMS revealed glucomoringin, moringin, and several polyphenols in ME-D. Oral administration of ME-D significantly increased NRF2-regulated antioxidant genes in the small intestine, liver, and lungs. Lastly, prophylactic administration of ME-D significantly mitigated lung inflammation in mice exposed to particulate matter for 3-days or 3-months. In conclusion, we have developed a pharmacologically active standardized palatable preparation of M. oleifera leaves as a functional food to activate NRF2 signaling, which can be consumed as a beverage (hot soup) or freeze-dried powder for reducing the risk from environmental respiratory disease.

4-Aryl-1,4-Dihydropyridines as Potential Enoyl-Acyl Carrier Protein Reductase Inhibitors: Antitubercular Activity and Molecular Docking Study

BACKGROUND

Tuberculosis remains one of the most deadly infectious diseases worldwide due to the emergence of multi-drug resistance (MDR) and extensively drug resistance (XDR) strains of Mycobacterium tuberculosis (MTB).

AIMS

Currently, available drugs are getting resistant and toxic. Hence, there is an urgent need for the development of potent molecules to treat tuberculosis.

MATERIALS AND METHODS

Herein, the screening of a total of eight symmetrical 1,4-dihydropyridine (1,4- DHP) derivatives (4a-4h) was carried out for whole-cell anti-TB activity against the susceptible H37Rv and MDR strains of MTB.

RESULTS AND DISCUSSION

Most of the compounds exhibited moderate to excellent activity against the susceptible H37Rv. Moreover, the most promising compound 4f (against H37Rv) having paratrifluoromethyl phenyl group at 4-position and bis para-methoxy benzyl ester group at 3- and 5- positions of 1,4-dihydropyridine pharmacophore, exhibited no toxicity, but demonstrated weak activity against MTB strains resistant to isoniazid and rifampicin. In light of the inhibitory profile of the title compounds, enoyl-acyl carrier protein reductase (InhA) appeared to be the appropriate molecular target. A docking study of these derivatives against InhA receptor revealed favorable binding interactions. Further, in silico predicted ADME properties of these compounds 4a-4h were found to be in the acceptable ranges, including satisfactory Lipinski's rule of five, thereby indicating their potential as drug-like molecules.

CONCLUSION

In particular, the 1,4-DHP derivative 4f can be considered an attractive lead molecule for further exploration and development of more potent anti-TB agents as InhA inhibitors.

Anti-tubercular activity and molecular docking studies of indolizine derivatives targeting mycobacterial InhA enzyme

A series of 1,2,3-trisubstituted indolizines (2a-2f, 3a-3d, and 4a-4c) were screened for in vitro whole-cell anti-tubercular activity against the susceptible H37Rv and multidrug-resistant (MDR) Mycobacterium tuberculosis (MTB) strains. Compounds 2b-2d, 3a-3d, and 4a-4c were active against the H37Rv-MTB strain with minimum inhibitory concentration (MIC) ranging from 4 to 32 µg/mL, whereas the indolizines 4a-4c, with ethyl ester group at the 4-position of the benzoyl ring also exhibited anti-MDR-MTB activity (MIC = 16-64 µg/mL). In silico docking study revealed the enoyl-acyl carrier protein reductase (InhA) and anthranilate phosphoribosyltransferase as potential molecular targets for the indolizines. The X-ray diffraction analysis of the compound 4b was also carried out. Further, a safety study (in silico and in vitro) demonstrated no toxicity for these compounds. Thus, the indolizines warrant further development and may represent a novel promising class of InhA inhibitors and multi-targeting agents to combat drug-sensitive and drug-resistant MTB strains.

Crystallography, Molecular Modeling, and COX-2 Inhibition Studies on Indolizine Derivatives

The cyclooxygenase-2 (COX-2) enzyme is an important target for drug discovery and development of novel anti-inflammatory agents. Selective COX-2 inhibitors have the advantage of reduced side-effects, which result from COX-1 inhibition that is usually observed with nonselective COX inhibitors. In this study, the design and synthesis of a new series of 7-methoxy indolizines as bioisostere indomethacin analogues (5a-e) were carried out and evaluated for COX-2 enzyme inhibition. All the compounds showed activity in micromolar ranges, and the compound diethyl 3-(4-cyanobenzoyl)-7-methoxyindolizine-1,2-dicarboxylate (5a) emerged as a promising COX-2 inhibitor with an IC₅₀ of 5.84 µM, as compared to indomethacin (IC₅₀ = 6.84 µM). The molecular modeling study of indolizines indicated that hydrophobic interactions were the major contribution to COX-2 inhibition. The title compound diethyl 3-(4-bromobenzoyl)-7-methoxyindolizine-1,2-dicarboxylate (5c) was subjected for single-crystal X-ray studies, Hirshfeld surface analysis, and energy framework calculations. The X-ray diffraction analysis showed that the molecule (5c) crystallizes in the monoclinic crystal system with space group P 2₁/n with a = 12.0497(6)Å, b = 17.8324(10)Å, c = 19.6052(11)Å, α = 90.000°, β = 100.372(1)°, γ = 90.000°, and V = 4143.8(4)ų. In addition, with the help of Crystal Explorer software program using the B3LYP/6-31G(d, p) basis set, the theoretical calculation of the interaction and graphical representation of energy value was measured in the form of the energy framework in terms of coulombic, dispersion, and total energy.

Investigation of Antifungal Properties of Synthetic Dimethyl-4-Bromo-1-(Substituted Benzoyl) Pyrrolo[1,2-a] Quinoline-2,3-Dicarboxylates Analogues: Molecular Docking Studies and Conceptual DFT-Based Chemical Reactivity Descriptors and Pharmacokinetics Evaluation

Candida albicans, an opportunistic fungal pathogen, frequently colonizes immune-compromised patients and causes mild to severe systemic reactions. Only few antifungal drugs are currently in use for therapeutic treatment. However, evolution of a drug-resistant C. albicans fungal pathogen is of major concern in the treatment of patients, hence the clinical need for novel drug design and development. In this study, in vitro screening of novel putative pyrrolo[1,2-a]quinoline derivatives as the lead drug targets and in silico prediction of the binding potential of these lead molecules against C. albicans pathogenic proteins, such as secreted aspartic protease 3 (SAP3; 2H6T), surface protein β-glucanase (3N9K) and sterol 14-alpha demethylase (5TZ1), were carried out by molecular docking analyses. Further, biological activity-based QSAR and theoretical pharmacokinetic analysis were analyzed. Here, in vitro screening of novel analogue derivatives as drug targets against C. albicans showed inhibitory potential in the concentration of 0.4 µg for BQ-06, 07 and 08, 0.8 µg for BQ-01, 03, and 05, 1.6 µg for BQ-04 and 12.5 µg for BQ-02 in comparison to the standard antifungal drug fluconazole in the concentration of 30 µg. Further, in silico analysis of BQ-01, 03, 05 and 07 analogues docked on chimeric 2H6T, 3N9K and 5TZ1 revealed that these analogues show potential binding affinity, which is different from the therapeutic antifungal drug fluconazole. In addition, these molecules possess good drug-like properties based on the determination of conceptual Density Functional Theory (DFT)-based descriptors, QSAR and pharmacokinetics. Thus, the study offers significant insight into employing pyrrolo[1,2-a]quinoline analogues as novel antifungal agents against C. albicans that warrants further investigation.

Gut microbial metabolites as therapeutics to treat of alcoholic liver disease

Alcoholic liver disease (ALD) is resultant of excessive consumption of alcohol. ALD is the world’s third largest risk factor for diseases and disabilities and accounting for 5.9% of all deaths worldwide. ALD patients exhibit increased gut permeability, gut microbial dysbiosis, endotoxemia and hepatic steatosis. Recent studies, unequivocally demonstrated the importance of gut microbiota and their metabolites in regulating host pathophysiology. Urolithin A (UroA) is a gut microbial metabolite derived from dietary ellagic acid and ellagitannins containing foods. Previously, we showed that UroA act as an AhR agonist and activate AhR-Nrf2 pathways to induce tight junction proteins and enhance gut barrier function. In the current study, we tested the hypothesis that correcting gut barrier dysfunction, blocking inflammation and reducing hepatic steatosis simultaneously by UroA would provide better therapeutic options to treat ALD. Our studies suggested that UroA significantly induced expression of tight junction (TJ) proteins (Occludin, Cldn4 and ZO1) in AhR-Nrf2 dependent manner and protected from alcohol-induced downregulation of TJ proteins and reduced gut barrier leakage. Further, UroA attenuated ALD pathogenesis in both acute and chronic experimental mouse models by reducing alcohol induced barrier permeability, systemic endotoxin levels and inflammatory mediators. In these models, UroA treatment also significantly reduced alcohol induced liver ALT/AST levels, inflammatory mediators (TNF-α, IL-6, IL-1β) and triglyceride levels as well as prevented liver damage. In summary, these studies highlight that the mechanisms of microbial metabolite, UroA and its multi-pronged beneficial effects in attenuating ALD.

Structural investigation of methyl 3-(4-fluoro-benzo-yl)-7-methyl-2-phenyl-indolizine-1-carboxyl-ate, an inhibitory drug towards Mycobacterium tuberculosis

The title compound, C24H18FNO3, crystallizes in the monoclinic centrosymmetric space group P21/n and its mol-ecular conformation is stabilized via C-H⋯O intra-molecular inter-actions. The supra-molecular network mainly comprises C-H⋯O, C-H⋯F and C-H⋯π inter-actions, which contribute towards the formation of the crystal structure. The different inter-molecular inter-actions have been further analysed via Hirshfeld surface analysis and fingerprint plots.

Larvicidal Activities of 2-Aryl-2,3-Dihydroquinazolin -4-ones against Malaria Vector Anopheles arabiensis, In Silico ADMET Prediction and Molecular Target Investigation

Malaria, affecting all continents, remains one of the life-threatening diseases introduced by parasites that are transmitted to humans through the bites of infected Anopheles mosquitoes. Although insecticides are currently used to reduce malaria transmission, their safety concern for living systems, as well as the environment, is a growing problem. Therefore, the discovery of novel, less toxic, and environmentally safe molecules to effectively combat the control of these vectors is in high demand. In order to identify new potential larvicidal agents, a series of 2-aryl-1,2-dihydroquinazolin-4-one derivatives were synthesized and evaluated for their larvicidal activity against Anopheles arabiensis. The in silico absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties of the compounds were also investigated and most of the derivatives possessed a favorable ADMET profile. Computational modeling studies of the title compounds demonstrated a favorable binding interaction against the acetylcholinesterase enzyme molecular target. Thus, 2-aryl-1,2-dihydroquinazolin-4-ones were identified as a novel class of Anopheles arabiensis insecticides which can be used as lead molecules for the further development of more potent and safer larvicidal agents for treating malaria.

In silico Design and Synthesis of Tetrahydropyrimidinones and Tetrahydropyrimidinethiones as Potential Thymidylate Kinase Inhibitors Exerting Anti-TB Activity Against Mycobacterium tuberculosis

Background and Purpose

Tuberculosis has been reported to be the worldwide leading cause of death resulting from a sole infectious agent. The emergence of multidrug-resistant tuberculosis and extensively drug-resistant tuberculosis has made the battle against the infection more difficult since most currently available therapeutic options are ineffective against these resistant strains. Therefore, novel molecules need to be developed to effectively treat tuberculosis disease. Preliminary docking studies revealed that tetrahydropyrimidinone derivatives have favorable interactions with the thymidylate kinase receptor. In the present investigation, we report the synthesis and the mycobacterial activity of several pyrimidinones and pyrimidinethiones as potential thymidylate kinase inhibitors.

Methods

The title compounds (1a-d) and (2a-b) were synthesized by a one-pot three-component Biginelli reaction. They were subsequently characterized and used for whole-cell anti-TB screening against H37Rv and multidrug-resistant (MDR) strains of Mycobacterium tuberculosis (MTB) by the resazurin microplate assay (REMA) plate method. Molecular modeling was conducted using the Accelry's Discovery Studio 4.0 client program to explain the observed bioactivity of the compounds. The pharmacokinetic properties of the synthesized compounds were predicted and analyzed.

Results

Of the compounds tested for anti-TB activity, pyrimidinone 1a and pyrimidinethione 2a displayed moderate activity against susceptible MTB H37Rv strains at 16 and 32 µg/mL, respectively. Only compound 2a was observed to exert modest activity at 128 µg/mL against MTB strains with cross-resistance to rifampicin and isoniazid. The presence of the trifluoromethyl group was essential to retain the inhibitory activity of compounds 1a and 2a. Molecular modeling studies of these compounds against thymidylate kinase targets demonstrated a positive correlation between the bioactivity and structure of the compounds. The in-silico ADME (absorption, distribution, metabolism, and excretion) prediction indicated favorable pharmacokinetic and drug-like properties for most compounds.

Conclusion

Pyrimidinone 1a and pyrimidinethione 2a were identified as the leading compounds and can serve as a starting point to develop novel anti-TB therapeutic agents.

Novel Series of Methyl 3-(Substituted Benzoyl)-7-Substituted-2-Phenylindolizine-1-Carboxylates as Promising Anti-Inflammatory Agents: Molecular Modeling Studies

The cyclooxygenase-2 (COX-2) enzyme is considered to be an important target for developing novel anti-inflammatory agents. Selective COX-2 inhibitors offer the advantage of lower adverse effects that are commonly associated with non-selective COX inhibitors. In this work, a novel series of methyl 3-(substituted benzoyl)-7-substituted-2-phenylindolizine-1-carboxylates was synthesized and evaluated for COX-2 inhibitory activity. Compound 4e was identified as the most active compound of the series with an IC50 of 6.71 M, which is comparable to the IC50 of indomethacin, a marketed non-steroidal anti-inflammatory drug (NSAID). Molecular modeling and crystallographic studies were conducted to further characterize the compounds and gain better understanding of the binding interactions between the compounds and the residues at the active site of the COX-2 enzyme. The pharmacokinetic properties and potential toxic effects were predicted for all the synthesized compounds, which indicated good drug-like properties. Thus, these synthesized compounds can be considered as potential lead compounds for developing effective anti-inflammatory therapeutic agents.

Design, synthesis, and structural elucidation of novel NmeNANAS inhibitors for the treatment of meningococcal infection

Neisseria meningitidis is the primary cause of bacterial meningitis in many parts of the world, with considerable mortality rates among neonates and adults. In Saudi Arabia, serious outbreaks of N. meningitidis affecting several hundreds of pilgrims attending Hajj in Makkah were recorded in the 2000–2001 season. Evidence shows increased rates of bacterial resistance to penicillin and other antimicrobial agents that are used in the treatment of the meningococcal disease. The host’s immune system becomes unable to recognize the polysialic acid capsule of the resistant N. meningitidis that mimics the mammalian cell surface. The biosynthetic pathways of sialic acid (i.e., N-acetylneuraminic acid [NANA]) in bacteria, however, are somewhat different from those in mammals. The largest obstacle facing previously identified inhibitors of NANA synthase (NANAS) in N. meningitidis is that these inhibitors feature undesired chemical and pharmacological characteristics. To better comprehend the binding mechanism underlying these inhibitors at the catalytic site of NANAS, we performed molecular modeling studies to uncover essential structural aspects for the ultimate recognition at the catalytic site required for optimal inhibitory activity. Applying two virtual screening candidate molecules and one designed molecule showed promising structural scaffolds. Here, we report ethyl 3-benzoyl-2,7-dimethyl indolizine-1-carboxylate (INLZ) as a novel molecule with high energetic fitness scores at the catalytic site of the NmeNANAS enzyme. INLZ represents a promising scaffold for NmeNANAS enzyme inhibitors, with new prospects for further structural development and activity optimization.

Synthesis and Structural Elucidation of Novel Benzothiazole Derivatives as Anti-tubercular Agents: In-silico Screening for Possible Target Identification

BACKGROUND

Benzothiazole derivatives are known for anti-TB properties. Based on the known anti-TB benzothiazole pharmacophore, in the present study, we described the synthesis, structural elucidation, and anti-tubercular screening of a series of novel benzothiazole (BNTZ) derivatives (BNTZ 1-7 and BNTZ 8-13).

OBJECTIVE

The study aims to carry out the development of benzothiazole based anti-TB compounds.

METHODS

Title compounds are synthesized by microwave method and purified by column chromatography. Characterization of the compounds is achieved by FT-IR, NMR (1H and 13C), LCMS and elemental analysis. Screening of test compounds for anti-TB activity is achieved by Resazurin Microplate Assay (REMA) Plate method.

RESULTS

It was noted that the BNTZ compound with an isoquinoline nucleus (BNTZ 9) exhibited remarkable anti-tubercular activity at 8 µg/mL against both the susceptible strain H37Rv and the multi-drug resistant tuberculosis strains of Mycobacterium tuberculosis. On the other hand, the BNTZ compound with a naphthalene nucleus (BNTZ 2) revealed anti-tubercular activity at 6 µg/mL and 11 µg/mL against both the susceptible strain H37Rv and the multi-drug resistant tuberculosis strains of M. tuberculosis, respectively. One of the selected BNTZ derivatives BNTZ 13 was used for single crystal X-ray studies.

CONCLUSION

To identify the appropriate target for potent BNTZ compounds from the series, molecular modeling studies revealed the multiple strong binding of several BNTZs with mycobacterium lysine-ɛ-aminotransferase and decaprenyl-phosphoryl-β-D-ribose 2'-oxidase. The interaction is derived by forming favorable hydrogen bonds and stacking interactions. This new class of BNTZ compounds gave promising anti-tubercular actions in the low micromolar range, and can be further optimized on a structural basis to develop promising, novel, BNTZ pharmacophore-based anti-tubercular drugs.

Computational, crystallographic studies, cytotoxicity and anti-tubercular activity of substituted 7-methoxy-indolizine analogues

Indolizines are heteroaromatic compounds, and their synthetic analogues have reportedly showed promising pharmacological properties. In this study, a series of synthetic 7-methoxy-indolizine derivatives were synthesised, characterised and evaluated for in vitro whole-cell anti-tuberculosis (TB) screening against susceptible (H37Rv) and multi-drug-resistant (MDR) strains of Mycobacterium tuberculosis (MTB) using the resazurin microplate assay method. The cytotoxicity was evaluated using the MTT assay. In silico molecular-docking study was conducted for compounds 5a-j against enoyl-[acyl-carrier] protein reductase, a key enzyme of the type II fatty acid synthesis that has attracted much interest for the development of novel anti-TB compounds. Thereafter, molecular dynamic (MD) simulation was undertaken for the most active inhibitors. Compounds 5i and 5j with the methoxy functional group at the meta position of the benzoyl group, which was at the third position of the indolizine nucleus, demonstrated encouraging anti-TB activity against MDR strains of MTB at 16 μg/mL. In silico studies showed binding affinity within the range of 7.07-8.57 kcal/mol, with 5i showing the highest binding affinity. Hydrogen bonding, π-π- interactions, and electrostatic interactions were common with the active site. Most of these interactions occurred with the catalytic amino acids (Pro193, Tyr158, Phe149, and Lys165). MD simulation showed that 5j possessed the highest binding affinity toward the enzyme, according to the two calculation methods (MM/PBSA and MM/GBSA). The single-crystal X-ray studies of compounds 5c and 5d revealed that the molecular arrangements in these two structures were mostly guided by C-H···O hydrogen-bonded dimeric motifs and C-H···N hydrogen bonds, while various secondary interactions (such as π···π and C-H···F) also contributed to crystal formation. Compounds 5a, 5c, 5i, and 5j exhibited no toxicity up to 500 μg/mL. In conclusion, 5i and 5j are promising anti-TB compounds that have shown high affinity based on docking and MD simulation results.

Crystal structure and Hirshfeld surface analysis of diethyl 2-[4-(4-fluoro-phen-yl)-2-methyl-4-oxobutan-2-yl]malonate

The title compound, C18H23FO5, was synthesized by reacting diethyl malonate with 1-(4-fluoro-phen-yl)-3-methyl-but-2-en-1-one. The mol-ecule adopts a loose conformation stabilized by weak C-H⋯O and C-H⋯π inter-actions. In the crystal, the mol-ecules are joined by C-H⋯O contacts into infinite chains along the b-axis direction with a C(6) graph-set motif. Hirshfeld surface analysis and fingerprint plots demonstrate the predominance of H⋯H, O⋯H and F⋯H inter-molecular inter-actions in the crystal structure.

Prevention of pesticide-induced neuronal dysfunction and mortality with nucleophilic poly-Oxime topical gel

Organophosphate-based pesticides inhibit acetylcholinesterase (AChE), which plays a pivotal role in neuromuscular function. While spraying in the field, farmworkers get exposed to pesticides through the dermal route. Internalized pesticide inhibits AChE, which leads to neurotoxicity, cardiotoxicity, cognitive dysfunction, loss of endurance, and death in severe cases. Here, we present a nucleophilic pyridine-2-aldoxime-functionalized chitosan-based topical gel (poly-Oxime gel) that rapidly deactivates organophosphates, methyl parathion (MPT), on the skin of rats, which leads to reduced AChE inhibition in the blood and tissues. Testing the robustness of poly-Oxime gel, we report reduction in AChE inhibition following repeated dermal administration of MPT in the presence of poly-Oxime gel. Furthermore, poly-Oxime gel prevented MPT-induced neuromuscular dysfunction, loss of endurance, and locomotor coordination. We observe a 100% survival in rats following topical MPT administration in the presence of poly-Oxime gel. This prophylactic gel may therefore help farmworkers by limiting pesticide-induced toxicity and mortality.

Crystal structure of 1-[3,5-bis-(tri-fluoro-meth-yl)phen-yl]-2-bromo-ethan-1-one

The title compound, C10H5BrF6O, synthesized via continuous stirring of 3,5-bis-(tri-fluoro-meth-yl) aceto-phenone with bromine in an acidic medium and concentrated under reduced pressure, crystallizes with four mol-ecules in the unit cell (Z = 4) and one formula unit in the asymmetric unit. In the crystal, mol-ecules are linked in a head-to-tail fashion into dimers along the b-axis direction through weak C-H⋯Br and C-O⋯Csp2 inter-actions. C-H⋯O, C-F⋯π and F⋯F inter-actions are also observed.

Benzothiazole analogs as potential anti-TB agents: computational input and molecular dynamics

Biotin is very important for the survival of Mycobacterium tuberculosis. 7,8-Diamino pelargonic acid aminotransaminase (DAPA) is a transaminase enzyme involved in the biosynthesis of biotin. The benzothiazole title compounds were investigated for their in vitro anti-tubercular activity against two tubercular strains: H37Rv (ATCC 25,177) and MDR-MTB (multidrug-resistant M. tuberculosis, resistant to isoniazid, rifampicin, and ethambutol) by an agar incorporation method. The possible binding mode and predicted affinity were computed using a molecular docking study. Among the synthesized compounds in the series, the title compound {2-(benzo[d]thiazol-2-yl-methoxy)-5-fluorophenyl}-(4-chlorophenyl)-methanone was found to exhibit significant activity with minimum inhibitory concentrations of 1 μg/mL and 2 μg/mL against H37Rv and MDR-MTB, respectively; this compound showed the highest binding affinity (-24.75 kcal/mol) as well.

Efficient Synthesis and Characterization of Novel Substituted 3-Benzoylindolizine Analogues via the Cyclization of Aromatic Cycloimmoniumylides with Electrondeficient Alkenes

Background:

Indolizine pharmacophore is known to exhibit various promising pharmacological properties such as analgesic, anticancer, antihistaminic, antidiabetic, anti-inflammatory, antileishmanic, antimicrobial, antimutagenic, antioxidant, antitubercular, antiviral, larvicidal and herbicidal activities.

Objective:

In the present investigation, it was envisaged to synthesize a series of novel ethyl-7-substituted-3-(4- substituted benzoyl)-2-substituted indolizine-1-carboxylates by employing chromium(IV)oxide as dehydrogenating agent with triethylamine combination.

Method:

Synthesis of a series of proposed polysubstituted indolizines by employing chromium(IV)oxide as dehydrogenating agent with triethylamine combination. Final compounds were characterized by spectroscopic techniques viz fourier-transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, liquid chromatography- mass spectrometry, elemental analysis and selected title compound diethyl-3-(4- cyanobenzoyl)indolizine-1,2-dicarboxylate by single crystal X-ray method.

Results:

Aromatic cycloimmoniumylides undergo smooth cyclization with electron-deficient alkenes in the presence of triethylamine and DMF at room temperature to afford intermediates ethyl 7-substituted-2- substituted-3-(4-substituted benzoyl)-1,2,3,8a-tetrahydroindolizine-1-carboxylates, which on dehydrogenation with chromium(IV)oxide to obtain the title compounds ethyl-7-substituted-3-(4-substituted benzoyl)-2- substituted indolizine-1-carboxylates.

Conclusion:

The research was focused on developing an efficient protocol for the synthesis of a novel series of ethyl 3-substituted benzoyl-7-substituted-2-substituted indolizine-1-carboxylates with suitable pharmacological properties in good to excellent yields.

Efficient synthesis and characterization of novel indolizines: exploration of in vitro COX-2 inhibitory activity and molecular modelling studies

Novel indolizine scaffolds as COX-2 inhibiting agents.

Molecular modeling studies and anti-TB activity of trisubstituted indolizine analogues; molecular docking and dynamic inputs

A series of trisubstituted indolizine analogues has been designed as a result of a fragment-based approach to target the inhibition of mycobacterial enoyl-acyl carrier protein reductase. Anti-tuberculosis (TB) screening of the characterized compounds by a resazurin microplate assay method revealed that ethyl group at second position of indolizine nucleus exhibited activity against susceptible and multidrug-resistant strains of Mycobacterium tuberculosis at concentration of 5.5 and 11.3 μg/mL, respectively. A molecular docking study was also conducted to evaluate the stability of the active compounds, and compound with ethyl substitution at second position of indolizine nucleus showed the highest free binding energy of ΔG -24.11 (kcal/mol), a low clash score of 3.04, and high lipo score of -13.33. Indolizine analog with ethyl substitution at second position demonstrated Molecular Mechanics/Generalized Born Surface Area (-23.85 kcal/mol). Two molecular dynamics studies were computed (100 ps and 50 ns) to calculate the relationship between the potential and kinetic energies of the active anti-TB compound with time and temperature. The discovery of this lead may have a positive impact on anti-TB drug discovery.

Deletion and translocation of chromosome 11q13 sequences in cervical carcinoma cell lines

Molecular genetic studies on HeLa cell-derived nontumorigenic and tumorigenic hybrids have previously localized the HeLa cell tumor-suppressor gene to the long arm of chromosome 11. Extensive molecular and cytogenetic studies on HeLa cells have shown chromosome band 11q13 to be rearranged in this cell line. To determine whether q13 rearrangement is a nonrandom event in cervical carcinomas, six different human papilloma virus (HPV)-positive (HeLa, SiHa, Caski, C4-I, Me180, and Ms751) and two different HPV-negative (C33A and HT3) cell lines were studied. Long-range restriction mapping using a number of q13-specific probes showed molecular rearrangements within 75 kb of INT2 probe in three HPV-positive cell lines (HeLa, SiHa, and Caski) and in an HPV-negative cell line (HT3). FISH using an INT2 YAC identified a breakpoint within the sequences spanned by this YAC in two of the cell lines, HeLa and Caski. INT2 cosmid derived from this YAC showed deletion of cosmid sequences in two other cell lines, SiHa and C33A. These two cell lines, however, retained cosmid sequences of Cyclin D1, a probe localized 100 kb proximal to INT2. Deletions being the hallmark of a tumor-suppressor gene, we conclude that the 100-kb interval between the two cosmids might contain sequences of the cervical carcinoma tumor-suppressor gene.