Synthesis of novel spiro[pyrazolo[4,3-d]pyrimidinones and spiro[benzo[4,5]thieno[2,3-d]pyrimidine-2,3'-indoline]-2',4(3H)-diones and their evaluation for anticancer activity.

An efficient and novel method for the preparation of spiro[pyrazolo[4,3-d]pyrimidin]-7'(1'H)-ones by the condensation of 4-amino-1-methyl-3-propylpyrazole-5-carboxamide with ketones under mild conditions using catalytic InCl3 was reported. This method has been extended for the synthesis of novel spiro[benzo[4,5]thieno[2,3-d]pyrimidine-2,3'-indoline]-2',4(3H)-dione which are having potential applications in medicinal chemistry. All the synthesized compounds were evaluated for their anti-proliferative properties in vitro against cancer cell lines and several compounds were found to be active. Further in vitro studies revealed that inhibition of sirtuins could be the possible mechanism of action of these molecules.

A transcriptional repressive role for epithelial-specific ETS factor ELF3 on oestrogen receptor alpha in breast cancer cells.

Oestrogen receptor-α (ERα) is a ligand-dependent transcription factor that primarily mediates oestrogen (E2)-dependent gene transcription required for mammary gland development. Coregulators critically regulate ERα transcription functions by directly interacting with it. In the present study, we report that ELF3, an epithelial-specific ETS transcription factor, acts as a transcriptional repressor of ERα. Co-immunoprecipitation (Co-IP) analysis demonstrated that ELF3 strongly binds to ERα in the absence of E2, but ELF3 dissociation occurs upon E2 treatment in a dose- and time-dependent manner suggesting that E2 negatively influences such interaction. Domain mapping studies further revealed that the ETS (E-twenty six) domain of ELF3 interacts with the DNA binding domain of ERα. Accordingly, ELF3 inhibited ERα's DNA binding activity by preventing receptor dimerization, partly explaining the mechanism by which ELF3 represses ERα transcriptional activity. Ectopic expression of ELF3 decreases ERα transcriptional activity as demonstrated by oestrogen response elements (ERE)-luciferase reporter assay or by endogenous ERα target genes. Conversely ELF3 knockdown increases ERα transcriptional activity. Consistent with these results, ELF3 ectopic expression decreases E2-dependent MCF7 cell proliferation whereas ELF3 knockdown increases it. We also found that E2 induces ELF3 expression in MCF7 cells suggesting a negative feedback regulation of ERα signalling in breast cancer cells. A small peptide sequence of ELF3 derived through functional interaction between ERα and ELF3 could inhibit DNA binding activity of ERα and breast cancer cell growth. These findings demonstrate that ELF3 is a novel transcriptional repressor of ERα in breast cancer cells. Peptide interaction studies further represent a novel therapeutic option in breast cancer therapy.

Experimental and molecular docking investigation on DNA interaction of N-substituted phthalimides: antibacterial, antioxidant and hemolytic activities.

A series of Schiff base molecules derived from a phthalimide scaffold was investigated as efficient antibacterial, antioxidant and DNA-interacting agents. The spectroscopic characterization of these derivatives was studied in detail using elemental analysis and spectroscopic techniques. The DNA-binding profile of title molecules against Ct-DNA (calf thymus) was investigated by absorbance, fluorescence, hydrodynamics and thermal denaturation investigations. The bacterial inhibition potential of these molecules was investigated against Escherichia coli and Staphylococcus aureus. Molecule 3c emerged as the most active against S. aureus (IC50 : 14.8 µg/mL), whereas compounds 3a and 3b displayed potential antibacterial activities against E. coli (IC50 : 49.7 and 67.6 µg/mL). Molecular docking studies of these compounds against GlcN-6-P synthase were carried out to rationalize antibacterial efficiency of these molecules. These newly synthesized molecules were screened for their scavenging capacity against 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and H2 O2 free radicals and the results were compared with ascorbic acid as synthetic antioxidant. The title molecules 3a, 3b and 3e showed less than 20% hemolysis, which indicated their significant non-toxic behavior.

A New Isoindoline Based Schiff Base Derivative as Cu(II) Chemosensor: Synthesis, Photophysical, DNA Binding and Molecular Docking Studies.

A new chemo sensor 2-(4-methylbenzylideneamino)-isoindoline-1,3-dione (PDB) was synthesized and characterized by UV-Vis., IR, (1)H NMR, (13)C NMR spectral and elemental analysis. Its photophysical properties in organic solvents with different polarity were studied. The sensitivity of the PDB in different pH solutions was investigated and the results indicated that PDB would be able to act as an efficient "off-on-off" switch for pH. This chemosensor displayed high selectivity towards Cu(2+) in the presence of metal ions Ba(2+), Cd(2+), Co(2+), Hg(2+), Ni(2+), Pb(2+), K(+) and Zn(2+) in DMF/H2O solution. Furthermore DNA binding and molecular docking studies were also carried out to investigate the biological potential of the test compound. The interaction of compound (PDB) with Ct-DNA was examined by absorption, CD spectroscopy, cyclic voltammetry and viscosity measurements. In silico studies revealed that the test compound (PDB) showed good affinity towards the target receptor d (CGCGAATTCGCG)2 with the binding energy of -7.70 kcal/mol.

Evaluation of DNA Binding, Radicals Scavenging and Antimicrobial Studies of Newly Synthesized N-Substituted Naphthalimides: Spectroscopic and Molecular Docking Investigations.

In this study, we investigated a new series of naphthalimide based Schiff base compounds as potential DNA binding, antioxidant and antimicrobial agents. The structural characterization of synthesized compounds was carried out with the aid of elemental analysis and spectroscopic techniques (UV-vis., IR, (1)H and (13)C NMR). The DNA binding properties of target compounds against Ct-DNA (calf thymus) have been investigated in detail by numerous biophysical techniques (UV-vis, fluorescence, ethidium bromide displacement assay, Time resolved fluorescence, viscosity, cyclic voltammetry and circular dichorism) and the evidences have suggested that the test compounds could interact with DNA via intercalative binding. The extent of DNA binding (Kb) of these compounds follow the order of 3b (3.33 × 10(4) M(-1)) > 3a (2.25 × 10(4) M(-1)) > 3c (2 × 10(4) M(-1)), suggesting that compound 3b binds more strongly to Ct- DNA than the compounds 3a and 3c. Molecular docking results further support intercalative binding of test compounds with DNA. The binding energies of docked compounds (3a-3c) were found to be -8.20 to -8.69 kcal/ mol, suggesting greater binding affinity to Ct-DNA. The synthesized compounds displayed potential antimicrobial activities against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Salmonella typhimurium. Compound 3c has emerged as most active against all the four tested bacterial strains with MIC value in the range of 0.031-0.062 mg/mL. In the mutagenicity studies, all the test compounds were found to be non-mutagenic both in the presence and absence of metabolic activation. Furthermore, the antioxidant activity experiments show that these compounds exhibited potential scavenging activities against DPPH and H2O2 radicals.

A new insight into identification of in silico analysis of natural compounds targeting GPR120.

G-protein coupled receptor (GPR120) is an omega-3 fatty acid receptor that inhibits macrophage-induced tissue inflammation. Recent studies revealed GPR120 promotes colorectal carcinoma through modulation of VEGF, IL-8, PGE2, and NF-kB expression. However, three-dimensional structure of GPR120 is not yet available in Protein Data Bank (PDB). In the present study, we focused on a 3-D structural model of GPR120 has been constructed using homology modeling techniques. The structural quality of the predicted GPR120 model was verified using Procheck, Whatif, ProSA, and Verify 3D. After this chemical database of natural compounds have been constructed and screened for its druggability using molinspiration server. Molecular docking studies of natural compounds on GPR120 model revealed that silibinin (- 6.87 kcal/mol), withanolide (- 6.19 kcal/mol), limonene (- 6.17 kcal/mol), and cervical (- 6.15 kcal/mol) have shown good docking interactions with active site residues of the target. Active site residues of Arg280, Asp275, and Gly122 showed hydrogen-bonding interactions with predicted compounds. Based on these in silico findings, we proposed that virtual screening of natural compounds against of GPR120 is a novel approach to find potential anti-colorectal cancer therapeutics.

Design and screening of syringic acid analogues as BAX activators-An in silico approach to discover "BH3 mimetics".

Although BAX, which is a molecular hit squad that incentive apoptosis was found to be an attractive emerging target for anticancer agents. The molecular mechanism of small molecules/peptides involved in the BAX activation was remain unknown. The present focus of the study is to identification and development of novel molecules which are precisely activates BAX mediated apoptosis. In this process we identified some syringic acid analogues associated with the BAX hydrophobic groove by a virtual-screen approach. Results from the docking studies revealed that, SA1, SA9, SA10, SA14 and SA21 analogues have shown good interaction with BAX trigger site, of which SA10 and SA14 bound specifically with Lys21 at α1 helix of BAX, a critical residue involved in BAX activation. All docking calculations of SA analogues were compared with clinically tested BH3 mimetics. In this entire in silico study, SA analogous have performed an ideal binding interactions with BAX compared to BH3 mimetics. Further, in silico point mutation of BAX-Lys21 to Glu21 resulted in structural change in BAX and showed reduced binding energy and hydrogen bond interactions of the selected ligands. Based on these findings, we propose that virtual screening and mutation analysis of BAX is found to be the critical advance method towards the discovery of novel anticancer therapeutics.

MTA1 expression in human cancers - Clinical and pharmacological significance.

Remarkably, majority of the cancer deaths are due to metastasis, not because of primary tumors. Metastasis is one of the important hallmarks of cancer. During metastasis invasion of primary tumor cells from the site of origin to a new organ occurs. Metastasis associated proteins (MTAs) are a small family of transcriptional coregulators that are closely associated with tumor metastasis. These proteins are integral components of nuclear remodeling and deacetylation complex (NuRD). By virtue of being integral components of NuRD, these proteins regulate the gene expression by altering the epigenetic changes such as acetylation and methylation on the target gene chromatin. Among the MTA proteins, MTA1 expression is very closely correlated with the aggressiveness of several cancers that includes breast, liver, colon, pancreas, prostate, blood, esophageal, gastro-intestinal etc. Considering its close association with aggressiveness in human cancers, MTA1 may be considered as a potential therapeutic target for cancer treatment. The recent developments in its crystal structure further strengthened the idea of developing small molecule inhibitors for MTA1. In this review, we discuss the recent trends on the diverse functions of MTA1 and its role in various cancers, with the focus to consider MTA1 as a 'druggable' target in the control of human cancers.

Oestrogen receptor negativity in breast cancer: a cause or consequence?

Endocrine resistance, which occurs either by de novo or acquired route, is posing a major challenge in treating hormone-dependent breast cancers by endocrine therapies. The loss of oestrogen receptor α (ERα) expression is the vital cause of establishing endocrine resistance in this subtype. Understanding the mechanisms that determine the causes of this phenomenon are therefore essential to reduce the disease efficacy. But how we negate oestrogen receptor (ER) negativity and endocrine resistance in breast cancer is questionable. To answer that, two important approaches are considered: (1) understanding the cellular origin of heterogeneity and ER negativity in breast cancers and (2) characterization of molecular regulators of endocrine resistance. Breast tumours are heterogeneous in nature, having distinct molecular, cellular, histological and clinical behaviour. Recent advancements in perception of the heterogeneity of breast cancer revealed that the origin of a particular mammary tumour phenotype depends on the interactions between the cell of origin and driver genetic hits. On the other hand, histone deacetylases (HDACs), DNA methyltransferases (DNMTs), miRNAs and ubiquitin ligases emerged as vital molecular regulators of ER negativity in breast cancers. Restoring response to endocrine therapy through re-expression of ERα by modulating the expression of these molecular regulators is therefore considered as a relevant concept that can be implemented in treating ER-negative breast cancers. In this review, we will thoroughly discuss the underlying mechanisms for the loss of ERα expression and provide the future prospects for implementing the strategies to negate ER negativity in breast cancers.

Molecular modeling and docking studies of O-succinylbenzoate synthase of M. tuberculosis--a potential target for antituberculosis drug design.

Menaquinone is a lipid-soluble naphthoquinone that is essential for various pivotal functions of bacteria. Naphthoquinone is synthesized from chorismate of the shikimate pathway in microorganisms. Due to its absence in humans and animals, menaquinone biosynthesis has been an attractive target for development of antibiotics against a number of important microbial pathogens, such as Mycobacterium tuberculosis (Mtb). In shikimate pathway, O-succinylbenzoate synthase (OSBS) plays a major role and is one of the major potential drug targets. For Mtb-OSBS, a systematic study was conducted to get an insight about Mtb-OSBS enzyme and the corresponding inhibitors using in silico methods. The 3-D model of Mtb-OSBS was built using structure coordinates of Thermobifida fusca. O-succinylbenzoate synthase, the model, was further refined. The active site amino acids have been identified by comparing the template sequence with the Mtb-OSBS sequence. We identified that Lys(108), Asn(140), Asp(138), Lys(110), Glu(189), Ser(236), Asp(188), Arg(27), Tyr(52), and Ser(237) are highly conserved, and these may play a vital role as active residues, similar to that in template protein. As per the competitive binding of substrate (2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate (SHCHC)), we screened the SHCHC through AutoDock 4.0. The SHCHC molecule was further modified structurally and optimized through PRODRG server. Docking of the 12 lead molecules for best interactions with Mtb-OSBS has given an insight that all the lead molecules have shown interactions with active site amino acids of Mtb-OSBS. MD simulation analysis report has shown the stable conformation annotations of Mtb-OSBS. These hypothetical studies create another way to develop more potential drugs against the deadly mycobacterium.

Design and evaluation of new chemotherapeutics of aloe-emodin (AE) against the deadly cancer disease: an in silico study.

The Bcl-2 family proteins include pro- and antiapoptotic factors acting as critical arbiters of apoptotic cell death decisions in most circumstances. Evasion of apoptosis is one of the hallmarks of cancer, relevant to tumorigenesis as well as resistance to cytotoxic drugs, and deregulation of Bcl-2 proteins was observed in many cancers. Since Bax-mediated induction of apoptosis is a crucial mechanism in cancerous cells, we aimed at conducting in silico analysis on Bax in order to predict the possible interactions for anticancer agents. The present report depicts the binding mode of aloe-emodin and its structurally modified derivatives onto Bax. The structural information about the binding site of Bax for docked compounds obtained from this study could aid in screening and designing new anticancer agents or selective inhibitors for chemotherapy against Bax.

Synthesis and biological activity of new resveratrol derivative and molecular docking: dynamics studies on NFkB.

Resveratrol (RVS) is a naturally occurring antioxidant, able to display an array of biological activities. In the present investigation, a new derivative of RVS, RVS(a), was synthesized, and its biological activity was determined on U937 cells. It was observed that RVS(a) showed pronounced activity on U937 cells than RVS. RVS(a) is able to induce apoptosis in tumor cell lines through subsequent DNA fragmentation. From the EMSA results, it was evident that RVS(a) was able to suppress the activity of NFkB by interfering its DNA binding ability. Furthermore, the molecular interaction analysis (docking and dynamics) stated that RVS(a) has strong association with the IkB-alpha site of NFkB compared with RVS; this binding nature of RVS(a) might be prevent the NFkB binding ability with DNA. The present findings represent the potential activity of propynyl RVS on U937 cells and signifying it as a one of putative chemotherapeutic drugs against cancer.

Comprehensive structural and functional characterization of Mycobacterium tuberculosis UDP-NAG enolpyruvyl transferase (Mtb-MurA) and prediction of its accurate binding affinities with inhibitors.

Tuberculosis (TB) remains the most frequent and important infectious disease causing morbidity and death in the world. One third of the world's population is infected with Mycobacterium tuberculosis (Mtb), the etiologic agent of TB. The bacterial enzyme MurA catalyzes the transfer of enolpyruvate from phosphoenolpyruvate (PEP) to uridine diphospho-N-acetylglucosamine (UNAG), which is the first committed step of bacterial cell wall biosynthesis. In this work, 3D structure model of Mtb-MurA enzyme has been developed for the first time by homology modeling and molecular dynamics simulation techniques. Multiple sequence alignment and 3D structure model provided the putative substrate binding pocket of Mtb-MurA with respect to E. coli MurA. This analysis was helpful in identifying the binding sites and molecular function of the MurA homologue. Molecular docking study was performed on this 3D structure model, using different classes of inhibitors like fosfomycin, cyclic disulfide analog RWJ-3981, pyrazolopyrimidine analog RWJ-110192, purine analog RWJ-140998, 5-sulfonoxy-anthranilic acid derivatives T6361, T6362 and the results showed that the 5-sulfonoxyanthranilic acid derivatives showed the best interaction compared to other inhibitors. We also designed new efficient analogs of T6361 and T6362 which showed even better interaction with Mtb-MurA than the parental 5-sulfonoxy-anthranilic acid derivatives. Further the comparative molecular electrostatic potential and cavity depth analysis of Mtb-MurA suggested several important differences in its substrate and inhibitor binding pocket. Such differences could be exploited in the future for designing a more specific inhibitor for Mtb-MurA enzyme.

Insights from Streptococcus pneumoniae glucose kinase structural model.

Streptococcus pneumonia is the common cause of sepsis and meningitis. Emergence of multiple antibiotic resistant strains in the community-acquired bacterium is catastrophic. Glucose kinase (GLK) is a regulatory enzyme capable of adding phosphate group to glucose in the first step of streptomycin biosynthesis. The activity of glucose kinase was regulated by the Carbon Catabolite Repression (CCR) system. Therefore, it is important to establish the structure-function relation of GLK in S. pneumoniae. However, a solved structure for S. pneumoniae GLK is not available at the protein data bank (PDB). Therefore, we created a model of GLK from S. pnemoniae using the X-ray structure of Glk from E. faecalis as template with MODELLER (a comparative modeling program). The model was validated using protein structure checking tools such as PROCHECK, WHAT IF and ProSA for reliability. The active site amino acid Asp114 in the template is retained in S. pneumoniae GLK model (Asp115). Solvent accessible surface area (ASA) analysis of the GLK model showed that known key residues playing important role in active site for ligand binding and metal ion binding are buried and hence not accessible to solvent. The information thus discussed provides insight to the molecular understanding of glucose kinase in S. pneumoniae.