Design, synthesis and molecular docking study of novel triazole-quinazolinone hybrids as antimalarial and antitubercular agents.

In a quest to discover new antimalarial and antitubercular drugs, we have designed and synthesized a series of novel triazole-quinazolinone hybrids. The in vitro screening of the triazole-quinazolinone hybrid entities against the plasmodium species P. falciparum offered potent antimalarial molecules 6c, 6d, 6f, 6g, 6j & 6k owing comparable activity to the reference drugs. Furthermore, the target compounds were evaluated in vitro against Mycobacterium tuberculosis (MTB) H37Rv strain. Among the screened compounds, 6c, 6d and 6l were found to be the most active molecules with a MIC values of 19.57-40.68 µM. The cytotoxicity of the most active compounds was studied against RAW 264.7 cell line by MTT assay and no toxicity was observed. The computational study including drug likeness and ADMET profiling, DFT, and molecular docking study was done to explore the features of target molecules. The compounds 6a, 6g, and 6k exhibited highest binding affinity of -10.3 kcal/mol with docked molecular targets from M. tuberculosis. Molecular docking study indicates that all the molecules are binding to the falcipain 2 protease (PDB: 6SSZ) of the P. falciparum. Our findings indicated that these new triazole-quinazolinone hybrids may be considered hit molecules for further optimization studies.

Design, synthesis and antitubercular assessment of 1, 2, 3-triazole incorporated thiazolylcarboxylate derivatives.

A library of 1, 2, 3-triazole incorporated thiazolylcarboxylate derivatives (7a-q) and (8a-j) were synthesized and evaluated for their in-vitro antitubercular activity against Mycobacterium tuberculosis H37Rv. The two compounds 7h and 8h have displayed excellent antitubercular activity with MIC values of 3.12 and 1.56 µg/mL respectively (MIC values of standard drugs; Ciprofloxacin 1.56 µg/mL & Ethambutol 3.12 µg/mL). Whereas, the four compounds 7i, 7n, 7p and 8i displayed noticeable antitubercular activity with a MIC value of 6.25 µg/mL. The active compounds of the series were further studied for their cytotoxicity against RAW264.7 cell line using MTT assay. Furthermore, to study the probable mechanism of antitubercular action, physicochemical property profiling, DFT calculation and molecular docking study were executed on mycobacterial cell wall target Decaprenylphosphoryl-ß-d-ribose 2'-epimerase 1 (DprE1). Among all the compounds, 7h (-10 kcal/mol) and 8h (-10.1 kcal/mol) exerted the highest negative binding affinity against the targeted DprE1 (PDB: 4NCR) protein.

In vitro and in silico exploration of newly synthesized triazolyl- isonicotinohydrazides as potent antitubercular agents.

In the present study, we have reported the synthesis of novel isoniazid-triazole derivatives (4a-r), via the click chemistry approach. The synthesized isoniazid-triazole derivatives have potent in vitro antitubercular activity against the Mycobacterium tuberculosis (MTB) H37Rv strain. Among these compounds, 4b, 4f, 4g, 4j, 4k, 4m, 4o, 4p, and 4r were found to be the most active ones with a MIC value of 0.78 µg/mL. This activity is better than ciprofloxacin (MIC value = 1.56 µg/mL) and ethambutol (MIC value = 3.12 µg/mL). The compounds, 4a, 4c, 4d, 4e, 4h, 4i, 4l, and 4n have displayed activity equal to ciprofloxacin (MIC value = 1.56 µg/mL). The cytotoxicity of the active isoniazid-triazole derivatives was studied against RAW 264.7 cell line by MTT assay at 25 µg/mL concentration and no toxicity was observed. Moreover, in-vitro results were supported by in-silico studies with the known antitubercular target (PanK). The drug-likeness, density functional study, molecular docking, and molecular dynamics simulation studies of isoniazid-triazole derivatives validated the ability to form a stable complex with Pantothenate kinase (PanK), which will result in inhibiting the Pantothenate kinase (PanK). Therefore, the results obtained indicate that this class of compounds may offer candidates for future development, and positively provide drug alternatives for tuberculosis treatment.Communicated by Ramaswamy H. Sarma.

Syntheses, Molecular Docking and Biological Evaluation of 2-(2- hydrazinyl)thiazoles as Potential Antioxidant, Anti-Inflammatory and Significant Anticancer Agents.

BACKGROUND: Recently, researchers have worked on the development of new methods for the synthesis of bioactive heterocycles using polyethylene glycol as a green solvent. In this context, we report the synthesized 2-(2-hydrazinyl) thiazoles for their in vitro antioxidant, in vitro anti-inflammatory and in vitro anti-cancer activities. OBJECTIVE: The objective of the study was to develop novel antioxidant, anti-inflammatory and anti-cancer drugs. METHODS: At the outset, the condensation of substituted acetophenones 1, thiosemicarbazide 2, and α-haloketones 3 was carried out using PEG-400 (20 mL) in the presence of 5 mol% glacial acetic acid to afford thiosemicarbazones intermediate. Furthermore, these thiosemicarbazones were reacted with α-haloketones 3 to obtain appropriate 2-(2-hydrazinyl) thiazoles. The synthesized compounds were in vitro tested for their antioxidant, anti-inflammatory, and anti-cancer activity. RESULTS: In vitro evaluation report showed that nearly all molecules possessed potential antioxidant activity against 2,2-Diphenyl-1-picrylhydrazyl (DPPH), nitric oxide (NO), superoxide radical (SOR) and hydrogen peroxide (H2O2) radical scavenging activity. Most 2-(2-hydrazinyl) thiazoles derivatives have shown potential anti-inflammatory activity as compared to diclofenac sodium as a reference standard. 2-(2-Hydrazinyl) thiazoles derivatives showed significant anticancer activity for human leukemia cell line K-562 compared to adriamycin as a reference standard. CONCLUSION: All tested compounds showed potential 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide (NO) radical scavenging activity. Among the tested series, 4b, 4d and 4e exhibited good hydrogen peroxide and 4b, 4e, 4f and 4g showed excellent superoxide radical scavenging activity. In addition, the 4b, 4e and 4g compounds revealed potent in vitro anti-inflammatory activity against standard diclofenac sodium drug. 2-(2-Hydrazinyl) thiazole derivatives, such as 4c and 4d, showed significant anticancer activity against human leukemia cell line K-562. Thus, these molecules provide an interesting template for the design and development of new antioxidant, anti-inflammatory, and anti-cancer agents.

Design and in silico investigation of novel Maraviroc analogues as dual inhibition of CCR-5/SARS-CoV-2 Mpro.

A sudden increase in life-threatening COVID-19 infections around the world inflicts global crisis and emotional trauma. In current study two druggable targets, namely SARS-COV-2 Mpro and CCR-5 were selected due to their significant nature in the viral life cycle and cytokine molecular storm respectively. The systematic drug repurposing strategy has been utilized to recognize inhibitory mechanism through extensive in silico investigation of novel Maraviroc analogues as promising inhibitors against SARS-CoV-2 Mpro and CCR-5. The dual inhibition specificity approach implemented in present study using molecular docking, molecular dynamics (MD), principal component analysis (PCA), free energy landscape (FEL) and MM/PBSA binding energy studies. The proposed Maraviroc analogues obtained from in silico investigation could be easily synthesized and constructive in developing significant drug against COVID-19 pandemic, with essentiality of their in vivo/in vitro evaluation to affirm the conclusions of this study. This will further fortify the concept of single drug targeting dual inhibition mechanism for treatment of COVID-19 infection and complications.

Potential of NO donor furoxan as SARS-CoV-2 main protease (Mpro) inhibitors: in silico analysis.

The sharp spurt in positive cases of novel coronavirus-19 (SARS-CoV-2) worldwide has created a big threat to human. In view to expedite new drug leads for COVID-19, Main Proteases (Mpro) of novel Coronavirus (SARS-CoV-2) has emerged as a crucial target for this virus. Nitric oxide (NO) inhibits the replication cycle of SARS-CoV. Inhalation of nitric oxide is used in the treatment of severe acute respiratory syndrome. Herein, we evaluated the phenyl furoxan, a well-known exogenous NO donor to identify the possible potent inhibitors through in silico studies such as molecular docking as per target analysis for candidates bound to substrate binding pocket of SARS-COV-2 Mpro. Molecular dynamics (MD) simulations of most stable docked complexes (Mpro-22 and Mpro-26) helped to confirm the notable conformational stability of these docked complexes under dynamic state. Furthermore, Molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) calculations revealed energetic contributions of key residues of Mpro in binding with potent furoxan derivatives 22, 26. In the present study to validate the molecular docking, MD simulation and MM-PBSA results, crystal structure of Mpro bound to experimentally known inhibitor X77 was used as control and the obtained results are presented herein. We envisaged that spiro-isoquinolino-piperidine-furoxan moieties can be used as effective ligand for SARS-CoV-2 Mpro inhibition due to the presence of key isoquinolino-piperidine skeleton with additional NO effect.Communicated by Ramaswamy H. Sarma.

Computer Assisted Models for Blood Brain Barrier Permeation of 1, 5-Benzodiazepines.

AIM: To generate and validate predictive models for blood-brain permeation (BBB) of CNS molecules using the QSPR approach. BACKGROUND: Prediction of molecules crossing BBB remains a challenge in drug delivery. Predictive models are designed for the evaluation of a set of preclinical drugs which may serve as alternatives for determining BBB permeation by experimentation. OBJECTIVE: The objective of the present study was to generate QSPR models for the permeation of CNS molecules across BBB and its validation using existing in-house leads. METHODS: The present study envisaged the determination of the set of molecular descriptors which are considered significant correlative factors for BBB permeation property. Quantitative Structure- Property Relationship (QSPR) approach was followed to describe the correlation between identified descriptors for 45 molecules and highest, moderate and least BBB permeation data. The molecular descriptors were selected based on drug-likeness, hydrophilicity, hydrophobicity, polar surface area, etc. of molecules that served the highest correlation with BBB permeation. The experimental data in terms of log BB were collected from available literature, subjected to 2D-QSPR model generation using a regression analysis method like Multiple Linear Regression (MLR). RESULTS: The best QSPR model was Model 3, which exhibited regression coefficient as R2= 0.89, F = 36; Q2= 0.7805 and properties such as polar surface area, hydrophobic hydrophilic distance, electronegativity, etc., which were considered key parameters in the determination of the BBB permeability. The developed QSPR models were validated with in-house 1,5-benzodiazepines molecules and correlation studies were conducted between experimental and predicted BBB permeability. CONCLUSION: The QSPR model 3 showed predictive results that were in good agreements with experimental results for blood-brain permeation. Thus, this model was found to be satisfactory in achieving a good correlation between selected descriptors and BBB permeation for benzodiazepines and tricyclic compounds.

Capsaicin Loaded Solid SNEDDS for Enhanced Bioavailability and Anticancer Activity: In-Vitro, In-Silico, and In-Vivo Characterization.

In this investigation, the fabrication of capsaicin loaded self nano emulsifying drug delivery system (SNEDDS) was attempted to improve the effectiveness of capsaicin through the oral route. A pseudo-ternary phase diagram was constructed at different km values (1:1, 2:1, & 3:1). Nine liquid formulations (L-CAP-1 to L-CAP-9) were prepared at km = 3, evaluated & converted to solid free-flowing granules using neusilin® US2. L-CAP-3 comprising of 15% isopropyl myristate, 33.75% Labrafil, & 11.25% ethanol exhibited higher % transmittance (98.90 ± 1.24%) & lower self-emulsification time (18.19 ± 0.46 s). FT-IR spectra showed no incompatibility whereas virtual analysis confirmed hydrogen bond interaction between amino hydrogen in the capsaicin & oxygen of the neusilin. DSC & XRD study revealed the amorphization & molecular dispersion of capsaicin in S-SNEDDS. TEM analysis confirmed the nano-sized spherical globules. Within 15 min, L-SNEDDS, S-SNEDDS, & pure capsaicin showed 87.36 ± 3.25%, 85.19 ± 4.87%, & 16.61 ± 3.64% drug release respectively. S-CAP-3 significantly (P < 0.001) inhibited the proliferation of HT-29 colorectal cancer cells than capsaicin. Apoptosis assay involving Annexin V/PI staining for S-CAP-3 treated cells demonstrated a significant (P < 0.001) apoptotic rate. Remarkably, 3.6 fold increase in bioavailability was observed after oral administration of capsaicin-SNEDDS than plain capsaicin.

Synthesis and Modeling Studies of Furoxan Coupled Spiro-Isoquinolino Piperidine Derivatives as NO Releasing PDE 5 Inhibitors.

Nitric oxide (NO) is considered to be one of the most important intracellular messengers that play an active role as neurotransmitter in regulation of various cardiovascular physiological and pathological processes. Nitric oxide (NO) is a major factor in penile erectile function. NO exerts a relaxing action on corpus cavernosum and penile arteries by activating smooth muscle soluble guanylate cyclase and increasing the intracellular concentration of cyclic guanosine monophosphate (cGMP). Phophodiesterase (PDE) inhibitors have potential therapeutic applications. NO hybridization has been found to improve and extend the pharmacological properties of the parental compound. The present study describes the synthesis of novel furoxan coupled spiro-isoquinolino-piperidine derivatives and their smooth muscle relaxant activity. The study reveals that, particularly 10d (1.50 ± 0.6) and 10g (1.65 ± 0.7) are moderate PDE 5 inhibitors as compared to Sidenafil (1.43 ± 0.5). The observed effect was explained by molecular modelling studies on phosphodiesterase.

Acrylamide grafted neem (Azadirachta indica) gum polymer: Screening and exploration as a drug release retardant for tablet formulation.

The study was initiated with the intent to synthesize acrylamide grafted neem gum polymer (AAm-g-NG), and screen its drug release retardation ability both in vitro and in vivo. Different batches (NGP-1 to NGP-9) of tablet formulation were prepared by varying polymer concentration using propranolol HCl and compared with HPMC K100 M and marketed SR tablets. FTIR study proved the grafting phenomenon and showed no incompatibility between AAm-g-NG and propranolol HCl. AAm-g-NG showed significant swelling and water retention capacity than NG. AAm-g-NG was found to be biodegradable and exhibited no toxicity to Artemia salina. After 12 h, NGP-6 showed non-significant (p > 0.05; f2= ∼ 90) percent drug release (80.52 ±â€¯3.41%) compare to marketed formulation (79.65 ±â€¯4.08%). Significant swelling of the matrix caused slower diffusion of the drug. NGP-6 and marketed formulation in rabbits showed the non-significant difference between Cmax and Tmax, hence NGP-6 meets the requirement of sustained-release tablets.

Multi-Targeted Design and Development of Dihydroisoquinolines as Potent Antimalarials.

BACKGROUND: Malaria is a serious parasitic infection with greater morbidity and motility in recent decades. Cysteine protease and DHODH enzyme serve as a potential target for antimalarial agents which inhibit parasite multiplication in the erythrocyte stage. Development of new leads which specifically target cysteine protease and DHODH enzyme can reduce the side effects and overcome multidrug resistance. OBJECTIVES: Representing the design and development of antimalarial agents by targeting cysteine protease and DHODH (Dihydroorotate dehydrogenase) enzyme by structure-based drug design. METHODS: In present work, the rational development of antimalarial agents by targeting cysteine protease and DHODH has been made by integrating binding confirmation from virtual analysis and synthetic procedures. RESULTS: A novel series of dihydroisoquinolines was designed by structure-based drug design. Compounds from the dataset were screened for interaction at the target site by performing molecular docking study and subsequently, all molecules were screened for drug-like properties and toxicity, prior to synthesis molecules subjected to virtual filters. Designed molecules which exceed these virtual filters were synthesized, characterized and finally screened for antimalarial activity. CONCLUSION: In this work, it has been observed that compound A1, A5, A6 and A9 showed desirable biological activity towards targets and also specific hydrogen bonding interaction with the targets. Further optimization in leads yields a drug-like candidate and may overcome multidrug resistance.

Development of 'S', 'N' Heterocycles as Antimycobacterials Targeting Fatty Acid Biosynthesis.

BACKGROUND: Mycobacterium tuberculosis is a causative organism of tuberculosis, which is the most deadly disease after cancer in the current decade. The development of multidrug and broadly drug- resistant strains makes the tuberculosis problem more and more critical. In the last 40 years, only one molecule is added to the treatment regimen. Generally, drug design and development programs are targeted proteins whose function is known to be essential to the bacterial cell. OBJECTIVES: Here are the development of 'S', 'N' heterocycles as antimycobacterials targeting fatty acid biosynthesis are reported. MATERIALS AND METHODS: In the present communication, rational development of anti-mycobacterial agent's targeting fatty acid biosynthesis has been done by integrating the pocket modeling and virtual analysis. RESULTS: The identified potential 33 lead compounds were synthesized, characterized by physicochemical and spectroscopic methods like IR, NMR spectroscopy and further screened for antimycobacterial activity using isoniazid as standard. All the designed compounds have shown profound antimycobacterial activity. CONCLUSION: In this present communication, we found that 3c, 3f, 3l and 4k molecules had expressive desirable biological activity and specific interactions with fatty acids. Further optimization of these leads is necessary for the development of potential antimycobacterial drug candidates having fewer side effects.

Optimization of Thiazolidone Scaffolds Using Pocket Modeling for Development of Potential Secretory System Inhibitors of Mycobacterium tuberculosis.

OBJECTIVES: Mycobacterium tuberculosis is the causative organism of tuberculosis, which is the most lethal disease after cancer in the current decade. The development of multidrug and broadly drug-resistant strains is making the problem of tuberculosis more and more critical. In the last 40 years, only one molecule has been added to the treatment regimen. Generally, drug design and development programs target proteins whose function is known to be essential to the bacterial cell. M. tuberculosis possesses specialized protein export systems like the SecA2 export pathway and ESX pathways. MATERIALS AND METHODS: In the present communication, rational development of an antimycobacterial agent's targeting protein export system was carried out by integrating pocket modeling and virtual analysis. RESULTS: The 23 identified potential lead compounds were synthesized, characterized by physicochemical and spectroscopic methods like infrared and nuclear magnetic resonance spectroscopy, and further screened for antimycobacterial activity using isoniazid as standard. All the designed compounds showed profound antimycobacterial activity. CONCLUSION: We found that Q30, M9, M26, U8, and R26 molecules had significant desirable biological activity and specific interactions with Sec of mycobacteria. Further optimization of these leads is necessary for the development of potential antimycobacterial drug candidates with fewer side effects.

Pharmacophore Identification and QSAR Studies on Substituted Benzoxazinone as Antiplatelet Agents: kNN-MFA Approach.

The three-dimensional quantitative structure-activity relationship (3D-QSAR) and pharmacophore identification studies on 28 substituted benzoxazinone derivatives as antiplatelet agents have been carried out. Multiple linear regression (MLR) method was applied for QSAR model development considering training and test set approaches with various feature selection methods. Stepwise (SW), simulated annealing (SA) and genetic algorithm (GA) were applied to derive QSAR models which were further validated for statistical significance and predictive ability by internal and external validation. The results of pharmacophore identification studies showed that hydrogen bond accepters, aromatic and hydrophobic, are the important features for antiplatelet activity. The selected best 3D kNN-MFA model A has a training set of 23 molecules and test set of 5 molecules with validation (q(2)) and cross validation (pred_r(2)) values 0.9739 and 0.8217, respectively. Additionally, the selected best 3D QSAR (MLR) model B has a training set of 23 molecules and test set of 5 molecules with validation (r(2)) and cross validation (pred_r(2)) values of 0.9435 and 0.7663, respectively, and four descriptors at the grid points S_123, E_407, E_311 and H_605. The information rendered by 3D-QSAR models may lead to a better understanding and designing of novel potent antiplatelet molecules.

Synthesis, characterization and quantification of simvastatin metabolites and impurities.

Simvastatin is used in treatment of hypercholesterolemia because it regulates cholesterol synthesis as a result of its ß-hydroxy acid acting as an inhibitor of 3-hydroxy-methylglutaryl coenzyme A (HMG-CoA). The present communication deals with synthesis, characterization and development of accurate, precise and sensitive Reverse Phase High Performance Liquid Chromatography (RP-HPLC) method for simultaneous estimation of simvastatin and its synthetic impurities. The impurities methyl ether and ß-hydroxy acid of simvastatin were synthesized in the laboratory and characterized by MS, NMR and FT-IR spectroscopy. The separation of simvastatin and its impurities was carried out on an isocratic JASCO RP-HPLC system using KYA TECH HIQ SIL C(18) column (150 × 4.6 mm internal diameter, particle size 5 µm) operating at ambient temperature using acetonitrile:water (80:20 v/v) with 0.1% orthophosphoric acid as mobile phase. The method developed for HPLC analysis of three impurities along with simvastatin was validated using ICH Q2B (R1) guidelines and it complied with these guidelines. The results of analysis were found to be in the range of 98.14% to 101.89% for all analytes with acceptable accuracy and precision. The method can be used for detection and quantification of synthetic impurities in bulk or formulations of simvastatin.