Novel Dihydropyrimidinone Derivatives as Potential P-Glycoprotein Modulators.

P-glycoprotein (Pgp), an ATP binding cassette (ABC) transporter, is an ATP-dependent efflux pump responsible for cancer multidrug resistance. As part of efforts to identify human Pgp (hPgp) inhibitors, we prepared a series of novel triazole-conjugated dihydropyrimidinones using a synthetic approach that is well suited for obtaining compound libraries. Several of these dihydropyrimidinone derivatives modulate human P-glycoprotein (hPgp) activity with low micromolar EC50 values. Molecular docking studies suggest that these compounds bind to the M-site of the transporter.

Green Synthesis and Anticancer Potential of 1,4-Dihydropyridines-Based Triazole Derivatives: In Silico and In Vitro Study.

A library of 1,4-dihydropyridine-based 1,2,3-triazol derivatives has been designed, synthesized, and evaluated their cytotoxic potential on colorectal adenocarcinoma (Caco-2) cell lines. All compounds were characterized and identified based on their 1H and 13C NMR (Nuclear Magnetic Resonance) spectroscopic data. Furthermore, molecular docking of best anticancer hits with target proteins (protein kinase CK2α, tankyrase1, and tankyrase2) has been performed. Our results implicated that most of these compounds have significant antiproliferative activity with IC50 values between 0.63 ± 0.05 and 5.68 ± 0.14 µM. Moreover, the mechanism of action of most active compounds 13ab' and 13ad' suggested that they induce cell death through apoptosis in the late apoptotic phase as well as dead phase, and they could promote cell cycle arrest at the G2/M phase. Furthermore, the molecular docking study illustrated that 13ad' possesses better binding interaction with the catalytic residues of target proteins involved in cell proliferation and antiapoptotic pathways. Based on our in vitro and in silico study, 13ad' was found to be a highly effective anti-cancerous compound. The present data indicate that dihydropyridine-linked 1,2,3-triazole conjugates can be generated as potent anticancer agents.

Arylidene analogues as selective COX-2 inhibitors: synthesis, characterization, in silico and in vitro studies.

Pyrazole derivatives are known to be as non-steroidal anti-inflammatory drugs (NSAID). Celecoxib is the pioneer sulfonamide being pyrazole derivative COX-2 inhibitors, which used to treat pain and inflammation; they may also have a role in cancer prevention. In the present investigation, a series of arylidene analogues (NDP-4011 to NDP-4016) were synthesized by the condensation of 4-(3-methyl-5-oxo-4,5-dihydro-1H-pyrazol-1-yl) benzenesulfonamide (I) with various substituted aromatic aldehydes in ethanol using a catalytic amount of piperidine. All the synthesized compounds were well characterized by IR, 1H NMR, 13C NMR and mass spectrometry. The cytotoxicity of synthesized compounds was tested on the NRK-52E cell line. From which NDP-4011, NDP-4012, NDP-4013, NDP-1015 and NDP-4016 were found to have higher cytotoxicity whereas NDP-4014 showed less cytotoxicity compared to Celecoxib. The in silico pharmacokinetic parameters of compounds were evaluated to check their candidature as a drug. Molecular docking was carried out on COX-2 structures, which revealed that NDP-4011 to NDP-4016 targets allosteric binding site similar to the binding mode of the selective COX inhibitor Celecoxib. Furthermore, results of in vitro COX-2 inhibition assay supports arylidene analogues as COX-2 inhibitors.

Design, synthesis and antitumour evaluation of pyrrolo[1,2-f]-phenanthridine and dibenzo[f,h]pyrrolo[1,2-b]isoquinoline derivatives.

A series of 1,2-bis(hydroxymethyl)pyrrolo[1,2-f]phenanthridine derivatives and their alkyl (ethyl and isopropyl) carbamates and 12,13-bis(hydroxymethyl)-9,14-dihydro-dibenzo[f,h]pyrrolo[1,2-b]isoquinoline derivatives were synthesized for antiproliferative evaluation. The preliminary antitumour studies revealed that these two types of bis(hydroxymethyl) derivatives showed significant antitumour activities and were able to inhibit the growth of various human tumour cell lines in vitro. Several of the derivatives were demonstrated to cause DNA interstrand cross-links by an alkaline agarose gel shifting assay. These conjugates were cytotoxic to a variety of cancer cell lines by inducing DNA damage, delaying cell cycle progression in the G2/M phase and triggering apoptosis. Compound 21a, dissolved in a vehicle suitable for intravenous administration, was selected for antitumour studies in animal models. We demonstrated that at a dose that did not cause body weight loss in mice, compound 21a could significantly suppress the growth of tumour xenografts of human lung cancer H460 and colorectal cancer HCT-116 cells in nude mice. Our present results confirm the antitumour activities of these conjugates.

Scale Effect of a Fluorescent Waveguide in Organic Micromaterials: A Case Study Based on Coumarin Microfibers.

The classical method for evaluating the waveguide ability only focuses on the optical loss coefficient. However, for the micro- or submicroscale, an organic waveguide is demonstrated by the present study whose scale effect should not be neglected. We found that the optical loss coefficient increased remarkably when decreasing the sectional size of the microfibers. Furthermore, simulations based on Finite-Difference Time-Domain also demonstrated the size-dependent effect of the waveguide. Both the experimental and simulating results showed that the optical loss coefficient converges to a certain value, which means that the scale effect can be neglected as the sectional size is large enough. On the basis of the present study, we suggest that the scale-dependent effect on the sectional size of the waveguide should be investigated by evaluating the waveguide ability by the optical loss coefficient.

Evaluation and in vivo efficacy study of pyrano[3,2-c]quinoline analogues as TNF-α inhibitors.

A series of pyrano[3,2 c]quinoline was evaluated for its in vivo efficacy as TNF-α inhibitor using LPS, phosphodiesterase (PDE)-4, and CIA assays in different mice/rat models. The synthesis was performed using one-pot multicomponent condensation between 2,4-dihydroxy-1-methylquinoline, malononitrile, and diverse un(substituted) aromatic aldehydes. In vivo efficacy of the title compounds was evaluated using LPS assay in BALB/c mice, PDE4 inhibition in ketamine-xylazine-induced anesthetize SD rats, and CIA assay was performed in DBA/1J mice as per the standard literature protocols. The outcome of the study revealed that compound 4v was found to be most promising candidate of the series. It was efficacious with 48.8 ± 13.0% inhibition of TNF-α release at 100 mg/kg p.o., in the LPS assay in Balb/c mice model. It was effective in PDE4 assay in ketamine-xylazine-induced anesthetize SD rats with duration of 38.3 ± 4.5 min for reversal of anesthetic effect and also showed significant inhibition of PDE4 in salbutamol treated U937 cell assay. It was also abolished TNF-α induced phosphorylation and degradation of IκBα. Ultimately, its effect on CIA-related bone and cartilage damage was found statistically similar to Enbrel.

Evaluation of Pyrano[3,2 C] Quinoline Analogues as Anticancer Agents.

BACKGROUND: Quinoline analogues exhibited diversified biological activities depending on the structure type. A number of natural products with pyrano[3,2-c]quinolone structural motifs and patented chromenes were reported as promising cytotoxic agents. OBJECTIVE: The present study is aimed to evaluate a new series of pyrano[3,2-c]quinoline scaffolds derived from the fusion of bioactive quinolone pharmacophore with structurally diverse aryl substituted chromene for its cytotoxicity. METHODS: A library of pyrano[3,2-c]quinoline analogues was prepared from one-pot multi component synthesis using various aromatic aldehydes, malononitrile and 2,4-dihydroxy-1-methylquinoline. The new synthetics were primarily screened for its cytotoxicity (IC50) against different human cancer cell lines in vitro. The promising synthetics were further evaluated in vitro for their potency against different kinase activity. The promising compounds were finally tested for their in vivo efficacy in SCID type mice HCT-116 tumor model. RESULTS: The screening results revealed that compounds 4c, 4f, 4i and 4j showed promising activity in in vitro study. However, compound 4c was found to be the most potent candidate with 23% tumor growth inhibition in HCT-116 tumor mice model. CONCLUSION: The structure activity relationship suggested that 3-substitution on the aryl ring at C4 position of the pyrano[3,2 c]quinolone moiety seems to have an important position for cytotoxicity activity. However, 3- chloro substitution at C4 aryl ring showed a significant alteration of the bioactive conformer of the parent scaffold and outcome with compound 4c as the most potent candidate of the series.

Design and Synthesis of 1,2-Bis(hydroxymethyl)pyrrolo[2,1- a]phthalazine Hybrids as Potent Anticancer Agents that Inhibit Angiogenesis and Induce DNA Interstrand Cross-links.

Hybrid molecules are composed of two pharmacophores with different biological activities. Here, we conjugated phthalazine moieties (antiangiogenetic pharmacophore) and bis(hydroxymethyl)pyrrole moieties (DNA cross-linking agent) to form a series of bis(hydroxymethyl)pyrrolo[2,1- a]phthalazine hybrids. These conjugates were cytotoxic to a variety of cancer cell lines by inducing DNA damage, arresting cell cycle progression at the G2/M phase, triggering apoptosis, and inhibiting vascular endothelial growth factor receptor 2 (VEGFR-2) in endothelial cells. Among them, compound 29d encapsulated in a liposomal formulation (e.g., 29dL) significantly suppressed the growth of small-cell lung cancer cell (H526) xenografts in mice. Based on immunohistochemical staining, the tumor xenografts in mice treated with 29dL showed time-dependent decreases in the intensity of CD31, a marker of blood vessels, whereas the intensity of γ-H2AX, a marker of DNA damage, increased. The present data revealed that the conjugation of antiangiogenic and DNA-damaging agents can generate potential hybrid agents for cancer treatment.

Synthesis and Biological Screening of Pyrano[3,2-c]quinoline Analogues as Anti-inflammatory and Anticancer Agents.

A series of pyrano[3,2-c]quinoline based structural analogues was synthesized using one-pot multicomponent condensation between 2,4-dihydroxy-1-methylquinoline, malononitrile, and diverse un(substituted) aromatic aldehydes. The synthesized compounds were evaluated for their anti-inflammatory and cytotoxicity activity. Initially, all the compounds were evaluated for the percent inhibition of cytokine release, and cytotoxicity activity and 50% inhibitory concentrations (IC50) were also determined. Based on the primary results, it was further studied for their ability to inhibit TNF-α production in the human peripheral blood mononuclear cells (hPBMC) assay. The screening results revealed that compound 4c, 4f, 4i, and 4j were found most active candidates of the series against both anti-inflammatory and anticancer activity. The structure-activity relationship is discussed and suggested that 3-substitution on the aryl ring at C4 position of the pyrano[3,2-c]quinolone structural motif seems to be an important position for both TNF-α and IL-6 inhibition and anticancer activity as well. However, structural diversity with electron withdrawing, electron donating, sterically hindered, and heteroaryl substitution sincerely affected both the inflammation and anticancer activities.

Ruthenium-catalysed one-pot regio- and diastereoselective synthesis of pyrrolo[1,2-a]indoles via cascade C-H functionalization/annulation.

A cascade approach has been developed towards dual C-C bond formation via consecutive C-H functionalization/cyclization giving access to pyrrolo[1,2-a]indoles in a highly regio- and diastereoselective manner using catalytic [Ru(p-cymene)Cl2]2. The methodology was further expanded to attain pentacyclic structures involving manifold C-C bond creation.

Structural Investigation of Vinca Domain Tubulin Binders by Pharmacophore, Atom based QSAR, Docking and Molecular Dynamics Simulations.

AIM AND OBJECTIVE: Vinca domain of tubulin protein is the potential target for different microtubule targeting drugs (MTD). However, its binding mechanism and structure-activityrelationship (SAR) is not well understood in terms of ligand-receptor interactions and structure functionality requirements. This limits the exploitation of vinca domain for developing novel clinical leads. Herein, as a progressive step towards the exploration of this target, we rendered the in-silico insight through the development of a robust pharmacophore model followed by the QSAR, Molecular Docking and Molecular Dynamics (MD) simulations. Furthermore, the study was undertaken to identify potent inhibitors that can inhibit vinca domain of tubulin. MATERIALS AND METHODS: Utilizing the well-defined tubulin polymerization inhibition activities, common pharmacophore hypotheses were constructed and scored for their rankings. The hypotheses were validated by 3D-Atom based QSAR and tested for various statistically relevant metrices. Thereafter, virtual screening was performed with ZINC natural product database and the screened hits were evaluated for structure-based studies via molecular docking and molecular dynamics simulations. RESULTS: The predictive 3D-QSAR based pharmacophore model consists of two hydrogen bond acceptors (A), two hydrogen bond donors (D) and one hydrophobic (H) group. Significance of the model was reflected from the statistical parameters viz. r2 = 0.98, q2 = 0.72, F = 562.9, RMSE = 0.11 and Pearson-R = 0.87. Further, the docking scores of the retrieved hits deciphered that the ligands were adequately bound in the pocket. Moreover, RMSD fluctuations of protein (1.0 to 1.75A) and ligand (0.3 to 2.3 Å) in molecular dynamics simulations insinuate towards the conformational and interactions stability of the complexes. CONCLUSION: The quantitative pharmacophore model was developed from range of natural product scaffolds in order to incorporate all the complimentary features accountable for inhibition. The obtained hits were found to occupy similar binding region and superimpose well over the reference ligand. Therefore, it can be concluded that hierarchical combination of methods exploited in this study can steer the identification of novel scaffolds. Moreover, the rendered hit molecules could serve as potential inhibitory leads for the development of improved inhibitors targeting Vinca domain.

Novel N-mustard-benzimidazoles/benzothiazoles Hybrids, Synthesis and Anticancer Evaluation.

BACKGROUND: Bendamustine, an N-mustard-benzoimidazole hybrid conjugate, was recently approved for the treatment of chronic lymphocytic leukemia. However, the short half-life of bendamustine may limit its clinical applications. OBJECTIVE: The purpose of this study is to design and synthesize compounds with a more favorable pharmacokinetic profile. METHODS: We synthesized a series of hybrid molecules comprising a phenyl N-mustard moiety and benzothiazole or benzimidazole scaffold linked via a urea linker and evaluated their antitumor activity and plasma stability. RESULTS: We revealed that these agents exhibited significant cytotoxicity against a panel of human lymphoblastic leukemia and human solid tumor cells in culture. Human lymphoblastic leukemia CCRM-CEM cells were the most sensitive to the tested compounds. In general, the new hybrids were as potent as cisplatin, but significantly more cytotoxic than bendamustine. Phenyl N-mustard-benzothiazole compound 27d and phenyl N-mustardbenzimidaloe compound 32b possessed significant cytotoxicity and led to apoptotic death in the treated tumor cells. These two agents were able to induce DNA interstrand cross-linking and arrested cell cycle progression at the G2/M phase. Furthermore, we showed that these new hybrids were more chemically stable than bendamustine in rat plasma. CONCLUSION: Our results suggest that conjugation of phenyl N-mustard pharmacophore at C6 of benzimidazole or at C8 of the benzothiazole ring via a urea linker is likely an approach to increase the chemical stability and bioavailability. Highlights ⇒ Series of benzimidazoles and benzothiazoles linked to N-mustard were synthesized. ⇒ The newly synthesized derivatives induced DNA interstrand cross-links. ⇒ These derivatives induced cell cycle arrest in the G2/M phase and triggered apoptosis in H460 cells. ⇒ The new compounds are more cytotoxic than bendamustine. ⇒ The new compounds were chemically more stable than bendamustine in rat plasma.

Novel indolizino[8,7-b]indole hybrids as anti-small cell lung cancer agents: Regioselective modulation of topoisomerase II inhibitory and DNA crosslinking activities.

A novel series of bis(hydroxymethyl)indolizino[8,7-b]indole hybrids composed of ß-carboline (topoisomerase I/II inhibition) and bis(hydroxymethyl)pyrrole (DNA cross-linking) are synthesized for antitumor evaluation. Of tumor cell lines tested, small cell lung cancer (SCLC) cell lines are the most sensitive to the newly synthesized compounds. These hybrids induce cell cycle arrest at the G2/M phase, trigger tumor cell apoptotic death, and display diverse mechanisms of action involving topoisomerase II (Topo II) inhibition and induction of DNA cross-linking. Intriguingly, the substituent at N11 (H or Me) plays a critical role in modulating Topo II inhibition and DNA cross-linking activities. N11-Me derivatives predispose to induce DNA crosslinks, whereas N11-H derivatives potently inhibit Topo II. Computational analysis implicates that N11-Me restrict the torsion angles of the two adjacent OH on pyrrole resulting in a favorable of DNA cross-linking. Among these hybrids, compound 17a with N11-H is more effective than cisplatin and etoposide, but as potent as irinotecan, against the growth of SCLC H526 cells in xenograft model.

Insights into the structural perturbations of spliced variants of CD44: a modeling and simulation approach.

Transient interactions between cancer stem cells and components of the tumor microenvironment initiate various signaling pathways crucial for carcinogenesis. Predominant hyaluronan (HA) receptor, CD44 is structurally and functionally one of the most variable cell surface receptors having the potential to generate a diverse repertory of CD44 isoforms by alternative splicing of variant exons and post-translational modifications. A structurally distinctive variant of CD44, CD44v10, has an inevitable role in malignant progression, invasion, and metastasis. This can be attributed to the binding of HA with CD44v10, which demonstrates a completely different behavioral pattern as compared to the other spliced variants of CD44 molecule. Absence of a comprehensively predicted crystal structure of human CD44s and CD44v10 is an impediment in understanding the resultant structural alterations caused by the binding of HA. Thus, in this study, we aim to predict the CD44s and CD44v10 structures to their closest native confirmation and study the HA binding-induced structural perturbations using homology modeling, molecular docking, and MD simulation approach. The results depicted that modeled 3D structures of CD44s and CD44v10 isoforms were found to be stable throughout MD simulations; however, a substantial decrease was observed in the binding affinity of HA with CD44v10 (-5.355 kcal/mol) as compared to CD44s. Furthermore, loss and gain of several H-bonds and hydrophobic interactions in CD44v10-HA complex during the simulation process not only elucidated the reason for decreased binding affinity for HA but also prompted toward the plausible role of HA-induced structural perturbations in occurrence and progression of carcinogenesis.

Method development and validation: quantitation of telmisartan bulk drug and its tablet formulation by 1 H NMR spectroscopy.

The quantitative NMR (qNMR) spectroscopy is nowadays a new tool for the determination of pharmaceutical potent biologically active molecules in bulk drug and its tablet formulation than the other analytical techniques. Herein, qNMR method was developed for an anti-hypertensive drug, telmisartan in bulk drug and its tablet formulation. The precise method was developed by using malononitrile as an internal standard. The methylene signal of telmisartan appeared at δ = 5.46 ppm (singlet) relative to the signal of malononitrile at δ = 3.59 ppm (singlet) in CDCl3 , as an NMR solvent. The development and validation of the method were carried out as per International Conference on Harmonization guidelines. The method was found to be linear (r2  = 0.9999) for 0.5 to 3.5 mg/ml in the drug concentration range. The relative standard deviation for accuracy and precession was not more than 2.0%. The sensitivity of the method was carried out by limit of detection and a limit of quantification, at 0.05 and 0.2 mg/ml, respectively, concentration. The robustness of the method was studied by changing parameters as well as different solvent manufacturer company. The result shows that method was accurately developed for quantification of telmisartan in pharmaceutical dosage form. The developed method by 1 H NMR spectroscopy is comparatively easy and more precise with respect to the other analytical tools. Copyright © 2016 John Wiley & Sons, Ltd.

Dihedral angle study in Hesperidin using NMR Spectroscopy.

Hesperidin is flavonoid molecule found in citrus fruits (Citrus reticulata), especially difficult to extract, classify and characterize. Present work is to study the unresolved relative configuration of Hesperidin through the dihedral angle, coupling constant and different NMR techniques. The Karplus equation and its modifications have been originated from the valence bond theory and associated with dihedral angle and coupling constant. The result data set of calculated dihedral angle can probe significant method to assign the virtual configuration of natural products and also resolved stereochemistry of Hesperidin at C-2 position in. Copyright © 2016 John Wiley & Sons, Ltd.

Design and Synthesis of 1,4-dihydropyridine Derivatives as Anti-cancer Agent.

AIMS: A series of 1,4-dihydropyridine based compounds bearing benzylpyridinium moiety have been designed and evaluated for in vitro anticancer activity against glioblastoma U87MG, lung cancer A549 and colorectal adenocarcinoma Caco-2 cell lines using the MTT assay. METHOD: Among these compounds, 7b, 7d, 7e, and 7f exhibited potent anticancer activity against the cell lines tested. The cytotoxicity of the synthesized derivatives was compared to standard drugs (carboplatin, gemcitabine, and daunorubicin). RESULT: Thus, synthesized 1,4-dihydropyridines can be considered as the encouraging molecules for further drug development as anticancer agents.

Insights on the structural perturbations in human MTHFR Ala222Val mutant by protein modeling and molecular dynamics.

Methylenetetrahydrofolate reductase (MTHFR) protein catalyzes the only biochemical reaction which produces methyltetrahydrofolate, the active form of folic acid essential for several molecular functions. The Ala222Val polymorphism of human MTHFR encodes a thermolabile protein associated with increased risk of neural tube defects and cardiovascular disease. Experimental studies have shown that the mutation does not affect the kinetic properties of MTHFR, but inactivates the protein by increasing flavin adenine dinucleotide (FAD) loss. The lack of completely solved crystal structure of MTHFR is an impediment in understanding the structural perturbations caused by the Ala222Val mutation; computational modeling provides a suitable alternative. The three-dimensional structure of human MTHFR protein was obtained through homology modeling, by taking the MTHFR structures from Escherichia coli and Thermus thermophilus as templates. Subsequently, the modeled structure was docked with FAD using Glide, which revealed a very good binding affinity, authenticated by a Glide XP score of -10.3983 (kcal mol(-1)). The MTHFR was mutated by changing Alanine 222 to Valine. The wild-type MTHFR-FAD complex and the Ala222Val mutant MTHFR-FAD complex were subjected to molecular dynamics simulation over 50 ns period. The average difference in backbone root mean square deviation (RMSD) between wild and mutant variant was found to be ~.11 Å. The greater degree of fluctuations in the mutant protein translates to increased conformational stability as a result of mutation. The FAD-binding ability of the mutant MTHFR was also found to be significantly lowered as a result of decreased protein grip caused by increased conformational flexibility. The study provides insights into the Ala222Val mutation of human MTHFR that induces major conformational changes in the tertiary structure, causing a significant reduction in the FAD-binding affinity.

Synthesis of Novel Pyrimidin-4-One Bearing Piperazine Ring-Based Amides as Glycogen Synthase Kinase-3ß Inhibitors with Antidepressant Activity.

Novel pyrimidin-4-one derivatives have been synthesized using EDC coupling and evaluated as glycogen synthase kinase-3ß (GSK-3ß) inhibitors. Among all the synthesized compounds, compound 5 (3-methyl-6-phenyl-2-(piperazin-1-yl)-3,4-dihydropyrimidin-4-one) exhibited the most potent inhibitory activity against GSK-3ß with IC50 value of 74 nm. The molecular docking studies were performed to elucidate the binding modes of the compounds with the target, and a crucial interaction involving hydrogen bond formation with Val-135 to the active site of GSK-3ß was observed. Furthermore, the synthesized compounds were subjected to in vivo evaluation of their antidepressant activity, and compound 5 showing highest inhibition of GSK-3ß was also found to significantly reduce the duration of immobility at 50 mg/kg, when compared with fluoxetine, a known antidepressant drug. The results of our study suggest that compound 5 may serve as a valuable template for the design and development of inhibitors of GSK-3ß with antidepressant activity.