Design,synthesis and biological evaluation of 2-(3,4-dimethoxyphenyl)-6 (1,2,3,6-tetrahydropyridin-4-yl)imidazo[1,2-a]pyridine analogues as antiproliferative agents

Two series of forty five novel 2-(3,4-dimethoxyphenyl)-6-(1,2,3,6-tetrahydropyridin-4-yl) imidazo[1,2-a]pyridine analogues (IPA 1–22, IPS 1–22 and IP-NH) have been designed, synthesized and structures confirmed by ¹H NMR, ¹³C NMR, mass spectrometry. Furthermore, single crystal was developed for IPS-13. All the final derived conjugates were evaluated for their in vitro antiproliferative activity against a panel of diverse cancer cell lines viz., A549 (lung cancer), HeLa (cervical cancer), B16F10 (melanoma) and found to show potent anticancer activity on the tested cell lines. Many of them showed the IC₅₀ values in the range 2.0–20.0 µM. The most active compounds (IPA 5,6,8,9,12,16,17,19 and IPS 7,8,9,22) from IPA and IPS series were screened to determine their cytotoxicity on HEK-293 (human embryonic kidney) normal cell line and were found to be nontoxic to normal human cells. The molecular interactions of the derivatised conjugates were also supported by molecular docking simulations. These derivatives may serve as lead structures for development of novel potential anticancer drug candidates.     

Aryl fluorosulfate analogues as potent antimicrobial agents: SAR,cytotoxicity and docking studies

A series of aryl fluorosulfate analogues (1–37) were synthesized and tested for in vitro antibacterial and antifungal studies, and validated by docking studies. The compounds 9, 12, 14, 19, 25, 26, 35, 36 and 37 exhibited superior antibacterial potency against tested bacterial strains, while compounds 2, 4, 5, 15, 35, 36 and 37 were found to have better antifungal activity against tested fungal strains, compared to standard antibiotic gentamicin and ketoconazole respectively. Among all the synthesized 37 analogs, compounds 25, 26, 35, 36 and 37 displayed excellent anti-biofilm property against Staphylococcus aureus. The structure–activity relationship (SAR) revealed that the antimicrobial activity depends upon the presence of –OSO₂F group and slender effect of different substituent’s on the phenyl rings. The electron donating (OCH₃) groups in analogs increase the antibacterial activity, and interestingly the electron withdrawing (Cl, NO₂, F and Br) groups increase the antifungal activity (except compound 35, 36 and 37). The mechanism of potent compounds showed membrane damage on bacteria confirmed by SEM. Compounds 35, 36 and 37 exhibited highest glide g-scores in molecular docking studies and validated the biocidal property.     

Structure-based design,synthesis and biological evaluation of a newer series of pyrazolo[1,5-a]pyrimidine analogues as potential anti-tubercular agents

In-depth study of structure-based drug designing can provide vital leads for the development of novel, clinically active molecules. In this present study, twenty six novel pyrazolo[1,5-a]pyrimidine analogues (6a-6z) were designed using molecular docking studies. The designed molecules were synthesized in good yields. Structural elucidation of the synthesized molecules was carried out using IR, MS, ¹H NMR and ¹³C NMR spectroscopy. All the synthesized compounds were evaluated for their in-vitro anti-tubercular activity against H37Rv strain by Alamar Blue assay method. Most of the synthesized compounds displayed potent anti-tubercular activities. Amongst all the tested compounds 6p, 6g, 6n and 6h exhibited promising anti-tubercular activity. Further, these potent compounds were gauged for MDR-TB, XDR-TB and cytotoxic study. None of these compounds exhibited potent cytotoxicity. Stability of protein ligand complex was further evaluated by molecular dynamics simulation for 10 ns. All these results indicate that the synthesized compounds could be potential leads for further development of new potent anti-tubercular agents.     

Synthesis of quinoline derivatives as diabetic II inhibitors and molecular docking studies

In searchof the potenttherapeutic agent as an α-glucosidase inhibitor, we have synthesized twenty-five analogs (1–25) of quinoline-based Schiff bases as an inhibitoragainst α-glucosidase enzyme under positive control acarbose (IC₅₀ = 38.45 ± 0.80 µM). From the activity profile it was foundthat analogs 1, 2, 3, 4, 11, 12 and 20with IC₅₀values 12.40 ± 0.40, 9.40 ± 0.30, 14.10 ± 0.40, 6.20 ± 0.30, 14.40 ± 0.40, 7.40 ± 0.20 and 13.20 ± 0.40 µMrespectively showed most potent inhibition among the series even than standard drug acarbose (IC₅₀ = 38.45 ± 0.80 µM). Here in the present study analog 4 (IC₅₀ = 6.20 ± 0.30 µM) was found with many folds better α-glucosidase inhibitory activity than the reference drug. Eight analogs like 5, 7, 8, 16, 17, 22, 24 and 25 among the whole series displayed less than 50% inhibition. The substituents effects on phenyl ring thereby superficially established through SAR study. Binding interactions of analogs and the active site of ligands proteins were confirmed through molecular docking study. Spectroscopic techniques like ¹H NMR, ¹³C NMR and ESIMS were used for characterization.     

Design,synthesis, evaluation,and molecular docking of ursolic acid derivatives containing a nitrogen heterocycle as anti-inflammatory agents

Ursolic acid derivatives containing oxadiazole, triazolone, and piperazine moieties were synthesized in an attempt to develop potent anti-inflammatory agents. Structures of the synthesized compounds were elucidated by ¹H NMR, ¹³C NMR, and HRMS. Most of the synthesized compounds showed pronounced anti-inflammatory effects at 100?mg/kg. In particular, compound 11b, which displayed the most potent anti-inflammatory activity of all of the compounds prepared, with 69.76% inhibition after intraperitoneal administration, was more potent than the reference drugs indomethacin and ibuprofen. The cytotoxicity of the compounds was also assessed by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, and no compounds showed any appreciable cytotoxic activity (IC₅₀ >100?μmol/L). Furthermore, molecular docking studies of the synthesized compounds were performed to rationalize the obtained biological results. Overall, the results indicate that compound 11b could be a therapeutic candidate for the treatment of inflammation.     

Design,synthesis, anticancer evaluation,molecular docking and cell cycle analysis of 3-methyl-4,7-dihydropyrazolo[1,5-a]pyrimidine derivatives as potent histone lysine demethylases (KDM) inhibitors and apoptosis inducers

A novel series of pyrazolo[1,5-a]pyrimidines were synthesized and proved by their spectral and elemental analysis, some elected of the newly synthesized compounds were examined for their cytotoxic activity employing MTT assay on two cancer cell lines (Breast and Hela cancers). Compounds 5, 7e and 7i showed the higher cytotoxicity against two cancer cell lines with (IC₅₀ = 13.91 ± 1.4 and 22.37 ± 1.8 μM/L), (IC₅₀ = 6.56 ± 0.5 and 8.72 ± 0.9 μM/L) and (IC₅₀ = 4.17 ± 0.2 and 5.57 ± 0.4 μM/L) for two cancer cell lines breast and hela respectively, using doxorubicin as a reference drug. The most potent cytotoxic active compounds 5, 7e and 7i presented inhibitory activity against KDM (histone lysine demethylases) with IC₅₀ = 4.05, 1.91 and 2.31 μM, respectively. The most potent KDM inhibitor 7e (IC₅₀ = 1.91 μM) showed to cause cell cycle arrest at G2/M phase by 4 folds than control and induce total apoptotic effect by 10 folds more than control. In silico studies performed on the more potent cytotoxic active compounds 5, 7e and 7i included lipinisk's rule of five. Moreover, molecular docking study was utilized to explore the binding mode of the most active compounds to the target enzyme (PDB-ID: 5IVE). Also, some bioinformatics studies were carried out for compounds 7e and 7i using Swiss ADME (Swiss Institute of bioinformatics 2018).     

Studies on synthesis of novel pyrido[2,3-d]pyrimidine derivatives,evaluation of their antimicrobial activity and molecular docking

A series of novel pyrido[2,3-d]pyrimidine derivatives 6 were prepared starting from 2-amino-3-cyano-4-trifluoromethyl-6-phenyl pyridine 3 via Grignard’s reaction, cyclization followed by coupling with aliphatic and cyclic amines. All the compounds 6 were screened for antibacterial, minimum bactericidal concentration (MBC), biofilm inhibition activity as well as antifungal and minimum fungicidal concentration (MFC) activities. Among the screened compounds, the compounds 6e, 6f, and 6m which showed exhibiting promising activity have been identified. The results reveal that the compound pyrido[2,3-d]pyrimidine derivative 6e altered the sterol profile which may exert its antifungal activity through inhibition of ergosterol biosynthesis and could be an ideal candidate for antifungal therapy. The molecular docking results also validated the antifungal results.     

Design,synthesis and molecular modeling studies of new series of s-triazine derivatives as antimicrobial agents against multi-drug resistant clinical isolates

Three novel series of s-triazine derivatives, including thirty-five new compounds 2a-d, 3a-3p, 4b-d, 5b-d, 6d-6d, and 7a-7f were synthesized comprising a diversity of substituents based on the structure of Astrazeneca arylaminotriazine DNA gyrase B inhibitor. The antimicrobial activity was determined for all compounds against Staphylococcus aureus, Escherichia coli and Candida albicans using the two-fold serial dilution technique and against reference standards Ampicillin for the antibacterial screening and Clotrimazole regarding the antifungal evaluation. The tested compounds showed strong to moderate antibacterial inhibitory action and weak antifungal activity. Compounds 3j and 6b were the most potent antibacterial agents against the tested strains and multi-drug resistant (MDR) clinical isolates of Klebsiella pneumoniae and methicillin resistant Staphylococcus aureus (MRSA1) with minimal toxicity in comparison to the reference drugs. In silico molecular properties calculations and molecular docking study for 3j and 6b revealed that both compounds could be considered as promising antibacterial DNA gyrase B inhibitors.     

Identification of some novel pyrazolo[1,5-a]pyrimidine derivatives as InhA inhibitors through pharmacophore-based virtual screening and molecular docking

The InhA inhibitors play key role in mycolic acid synthesis by preventing the fatty acid biosynthesis pathway. In this present article, Pharmacophore modelling and molecular docking study followed by in silico virtual screening could be considered as effective strategy to identify newer enoyl-ACP reductase inhibitors. Pyrrolidine carboxamide derivatives were opted to generate pharmacophore models using HypoGen algorithm in Discovery studio 2.1. Further it was employed to screen Zinc and Minimaybridge databases to identify and design newer potent hit molecules. The retrieved newer hits were further evaluated for their drug likeliness and docked against enoyl acyl carrier protein reductase. Here, novel pyrazolo[1,5-a]pyrimidine analogues were designed and synthesized with good yields. Structural elucidation of synthesized final molecules was perform through IR, MASS, ¹H-NMR, ¹³C-NMR spectroscopy and further tested for its in vitro anti-tubercular activity against H37Rv strain using Microplate Alamar blue assay (MABA) method. Most of the synthesized compounds displayed strong anti-tubercular activities. Further, these potent compounds were gauged for MDR-TB, XDR-TB and cytotoxic study.     

Structure-based design,synthesis, and evaluation of imidazo[1,2-b]pyridazine and imidazo[1,2-a]pyridine derivatives as novel dual c-Met and VEGFR2 kinase inhibitors

To identify compounds with potent antitumor efficacy for various human cancers, we aimed to synthesize compounds that could inhibit c-mesenchymal epithelial transition factor (c-Met) and vascular endothelial growth factor receptor 2 (VEGFR2) kinases. We designed para-substituted inhibitors by using co-crystal structural information from c-Met and VEGFR2 in complex with known inhibitors. This led to the identification of compounds 3a and 3b, which were capable of suppressing both c-Met and VEGFR2 kinase activities. Further optimization resulted in pyrazolone and pyridone derivatives, which could form intramolecular hydrogen bonds to enforce a rigid conformation, thereby producing potent inhibition. One compound of particular note was the imidazo[1,2-a]pyridine derivative (26) bearing a 6-methylpyridone ring, which strongly inhibited both c-Met and VEGFR2 enzyme activities (IC₅₀ = 1.9, 2.2 nM), as well as proliferation of c-Met-addicted MKN45 cells and VEGF-stimulated human umbilical vein endothelial cells (IC₅₀ = 5.0, 1.8 nM). Compound 26 exhibited dose-dependent antitumor efficacy in vivo in MKN45 (treated/control ratio [T/C] = 4%, po, 5 mg/kg, once-daily) and COLO205 (T/C = 13%, po, 15 mg/kg, once-daily) mouse xenograft models.     

Synthesis,cytotoxicity, antimicrobial and anti-biofilm activities of novel pyrazolo[3,4-b]pyridine and pyrimidine functionalized 1,2,3-triazole derivatives

A series of novel pyrazolo[3,4-b]pyridine and pyrimidine functionalized 1,2,3-triazole derivatives 8a–g and 9a–g were prepared starting from 6-trifluoromethylpyridine-2(1H)one 2 via selective O-alkylation, followed by cyclisation using hydrazine hydrate to obtain 6-(trifluoromethyl)-1H-pyrazolo[3,4-b]pyridin-3-amine 4. Compound 4 was diazotized followed by reaction with sodium azide, resulted in 3-azido-6-(trifluoromethyl)-1H-pyrazolo[3,4-b]pyridine 5. Compound 5 was further cyclized with N-/O-propargylated pyrimidine derivatives under Sharpless conditions and obtained compounds 6 and 7, respectively. Each set of compounds 6 and 7 were alkylated with different alkyl halides and obtained respective products 8 and 9. All the products were screened for cytotoxicity against four human cancer cell lines such as A549-Lung (CCL-185), MCF7-Breast (HTB-22), DU145-Prostate (HTB-81) and HeLa-Cervical (CCL-2), compounds 9d, 9e and 9f which showed promising activity have been identified. The products were also screened for antimicrobial, anti bio-film and MBC activities. Promising compounds in each case have been identified.     

Azoalkyl ether imidazo[2,1-b]benzothiazoles as potentially antimicrobial agents with novel structural skeleton

A series of new azoalkyl ether imidazo[2,1-b]benzothiazoles were developed via a convenient synthetic procedure. The antimicrobial assays showed that a good number of the prepared derivatives exhibited significant inhibitory properties against most of the tested strains. Especially 2-methyl-5-nitroimidazole derivative 5a presented superior inhibit activity against MRSA and B. typhi with MIC?=?4?μg/mL and MIC?=?1?μg/mL, respectively. The highly active compound 5a showed low toxicity against mammalian cells without obvious triggering of the development of bacterial resistance, and it also possessed rapid bactericidal efficacy. Molecular docking study exposed that the active molecule 5a could interact with the active site of S. aureus gyrase through hydrogen bond. Quantum chemical studies were also performed to explain the high antibacterial activity. Further investigation revealed that compound 5a could significantly associate with gyrase–DNA complex by mean of hydrogen bonds and could efficiently intercalate into MRSA DNA to form 5a–DNA supramolecular complex, which impart potent bioactivity.     

Design,synthesis, molecular docking of new lipophilic acetamide derivatives affording potential anticancer and antimicrobial agents

Fifteen new substituted N-2-(2-oxo-3-phenylquinoxalin-1(2H)-yl) acetamides 5a-f, 6a-f, and 8a-c were synthesized by reacting ethyl 2-(2-oxo-3-phenylquinoxalin-1(2H)-yl)acetate with various primary amines including benzylamines, sulfonamides, and amino acids. The in vitro antimicrobial screening of the target compounds was screened to assess their antibacterial and antifungal activity. As a result, seven compounds namely; 5a, 5c, 5d, 6a, 6c, 8b and 8c showed a promising broad spectrum antibacterial activity against both Gram-positive and Gram-negative strains. Among these, the analogs 5c and 6d were nearly as equiactive as ciprofloxacin drug. Meanwhile, four compounds namely; 5c, 6a, 6f and 8c exhibited appreciable antifungal activity with MIC values range 33–40 mg/mL comparable with clotrimazole (MIC 25 mg/mL). In addition, the anticancer effects of the synthesized compounds were evaluated against three cancer lines. The data obtained revealed the benzylamines and sulpha derivatives were the most active compounds especially 5f and 6f ones. Further EGFR enzymatic investigation was carried out for these most active compounds 5f and 6f resulting in inhibitory activity by 1.89 and 2.05 µM respectively. Docking simulation was performed as a trial to study the mechanisms and binding modes of these compounds toward the enzyme target, EGFR protein kinase enzyme. The results revealed good compounds placement in the active sites and stable interactions similar to the co-crystallized reference ligand. Collectively, the analogs 5f and 6f could be further utilized and optimized as good cytotoxic agents.     

Synthesis and biological evaluation of novel 4,7-dihydroxycoumarin derivatives as anticancer agents

A series of novel 4,7-dihydroxycoumarin based acryloylcyanohydrazone derivatives were synthesized and evaluated for antiproliferative activity against four different cancer cell lines (A549, HeLa, SKNSH, and MCF7). Most of the compounds displayed potent cytotoxicity with IC₅₀ values ranging from 3.42 to 31.28 µM against all the tested cancer cell lines. The most active compound, 8h was evaluated for pharmacological mechanistic studies on cell cycle progression and tubulin polymerization inhibition assay. The results revealed that the compound 8h induced the cell cycle arrest at G2/M phase and inhibited tubulin polymerization with IC₅₀ = 6.19 µM. Experimental data of the tubulin polymerization inhibition assay was validated by molecular docking technique and the results exhibited strong hydrogen bonding interactions with amino acids (ASN-101, TYR-224, ASN-228, LYS-254) of tubulin.     

Discovery of novel potent GPR40 agonists containing imidazo[1,2-a]pyridine core as antidiabetic agents

Free fatty acid receptor 1 (FFA1 or GPR40) has been studied for many years as a target for the treatment of type 2 diabetes mellitus. In order to increase potency and reduce hepatotoxicity, a series of novel compounds containing imidazo[1,2-a]pyridine scaffold as GPR40 agonist were synthesized. Compound I-14 was identified as an effective agonist as shown by the conspicuous drop in blood glucose in normal and diabetic mice. It had no risk of hepatotoxicity compared with TAK-875. Moreover, good pharmacokinetic (PK) properties of I-14 were observed (CL = 27.26 ml/h/kg, t_1/2 = 5.93 h). The results indicate that I-14 could serve as a possible candidate to treat diabetes.     

Design,synthesis and biological evaluation of imidazo[1,5-a]pyrazin-8(7H)-one derivatives as BRD9 inhibitors

BRD9 is the subunit of mammalian SWI/SNF chromatin remodeling complex (BAF). SWI/SNF complex mutations were found in nearly 20% of human cancers. The biological role played by BRD9 bromodomain remains poorly understood, and it is therefore imperative to identify potent and highly selective inhibitors to effectively explore the biology of individual bromodomain proteins. In this paper, we synthesized a series of imidazo[1,5-a]pyrazin-8(7H)-one derivatives as potent BRD9 inhibitors and evaluated their BRD9 inhibitory activity in vitro and anti-proliferation effects against tumor cells. Gratifyingly, compound 27 and 29 exhibited robust potency of BRD9 inhibition with IC₅₀ values of 35 and 103?nM respectively. Docking studies were performed to explain the structure-activity relationship. Furthermore, compound 27 potently inhibited cell proliferation in cell lines A549 and EOL-1 with an IC₅₀ value of 6.12?μM and 1.76?μM respectively. The chemical probe, compound 27, was identified that should prove to be useful in further exploring BRD9 bromodomain biology in both in vitro and in vivo settings.     

Design,synthesis and biological evaluation of 8-substituted-6-hydrazonoindolo[2,1-b]quinazolin-12(6H)-one scaffolds as potential cytotoxic agents: IDO-1 targeting molecular docking studies

Herein, we have reported the synthesis of 18 novel 8-substituted tryptanthrin analogues based on our earlier work. All these tryptanthrin analogues were well characterized by ¹H & ¹³C NMR, FT-IR, Mass Spectrometry and Elemental Analysis. All these 8-substituted analogues were screened for their anti-oxidant activity by DPPH radical scavenging assay. Out of all the tested compounds, T¹¹, T¹², T¹⁷ and T¹⁸ showed potent anti-oxidant activity. The anti-cancer activity have been performed by using MTT assay protocol and their results depicts that compounds having the 4-pyridyl or 4-carboxyphenyl substituents at the 8th position of the tryptanthrin framework are found to be the most promising cytotoxic agent against A549, MCF-7 and HeLa human cancer cell lines compared to others as well as with the standard drug cisplatin. Moreover, the comparative molecular docking studies against the three protein receptors IDO1, EGFR and HER2 strongly suggested that IDO1 is the best target protein, which exhibits lowest binding energies of ?11.73 and ?11.61 kcal mol^?1 for T¹¹ and T¹² scaffolds, respectively towards the in vitro anti-cancer activity.     

Synthesis,biological evaluation and molecular modeling of novel thienopyrimidinone and triazolothienopyrimidinone derivatives as dual anti-inflammatory antimicrobial agents

New thienopyrimidinone and triazolothienopyrimidinone derivatives have been synthesized. These compounds were subjected to anti-inflammatory and antimicrobial activity screening aiming to identify new candidates that have dual anti-inflammatory and antimicrobial activities.Compounds 5, 7 and 10a showed minimal ulcerogenic effect and high selectivity towards human recombinant COX-2 over COX-1 enzyme. Their docking outcome correlated with their biological activity and assured the high selectivity binding towards COX-2. In addition, they could act safely up to 80 mg/kg orally or 40 mg/kg parentrally. The antimicrobial screening showed that compound 10a displayed distinctive inhibitory effect on the growth of Escherichia coli comparable to that of ampicillin. Moreover, compounds 5, 7, 9 and 12a possessed 50% of the inhibitory activity of ampicillin against E. coli. Thus, compounds 5, 7 and 10a represent promising dual acting anti-inflammatory and antimicrobial agents. This work provides rewarding template enriching the chemical space for dual anti-inflammatory anti-microbial activities.