Expansion of a novel lead targeting M. tuberculosis DHFR as antitubercular agents

A series of 1-(1-benzyl-2-methyl-5-((1-phenyl-1H-1,2,3-triazol-4-yl)methoxy)-1H-indol-3-yl)ethanone and ethyl 1-benzyl-2-methyl-5-((1-phenyl-1H-1,2,3-triazol-4-yl)methoxy)-1H-indole-3-carboxylate derivatives were designed based on bioisosteric replacement of previously reported antitubercular agent (IND-07). Twenty ligands were successfully synthesized and some of them were found to have good in vitro activity (MIC?<?10?μM) against the H₃₇Rv strain of Mycobacterium tuberculosis. Among these compounds, KC-08 and KC-11 inhibited Mtb-DHFR with 4- and 18-fold selectivity for Mtb-DHFR over h-DHFR, respectively. Compound KC-11 display acceptable ADME, and better pharmacokinetic profiles than IND-07. Docking studies were performed to predict the binding mode of the compounds within the active site of Mtb-DHFR and h-DHFR. The results of our study suggest that compound KC-11 may serve as a valuable lead for the design and development of selective inhibitors of Mtb-DHFR with potential therapeutic application in tuberculosis.     

Identification and synthesis of novel inhibitors of mycobacterium ATP synthase

A non-diaryl quinoline scaffold 6,7-dihydropyrazolo[1,5-a]pyrazin-4-one was identified by screening of diverse set of compounds against M. smegmatis ATP synthase. Herein, we disclose our efforts to develop the structure activity relationship against Mycobacterium tuberculosis (Mtb.H37Rv strain) around the identified hit 1. A scaffold hopping approach was used to identify compounds 14a, 14b and 24a with improved activity against MTb.H37Rv.     

Molecular dynamics simulations of the chemokine CCL2 in complex with pull down-derived heparan sulfate hexasaccharides

Background

Binding of chemokines to glycosaminoglycans (GAGs) is a crucial step in leukocyte recruitment to inflamed tissues.

Design,synthesis and biological evaluation of novel desloratadine derivatives with anti-inflammatory and H1 antagonize activities

To improve the anti-inflammatory activity of desloratadine, we designed and synthesized a series of novel desloratadine derivatives. All compounds were evaluated for their anti-inflammatory and H₁ antagonistic activities. Among them, compound 2c showed the strongest H₁ antagonistic and anti-inflammatory activity. It also exhibited promising pharmacokinetic profiles and low toxicity. All these results suggest that compound 2c as a novel anti-allergic agent is worthy of further investigation.     

The Plasmodium knowlesi MAHRP2 ortholog localizes to structures connecting Sinton Mulligan's clefts in the infected erythrocyte

During development within the host erythrocyte malaria parasites generate nascent membranous structures which serve as a pathway for parasite protein transport to modify the host cell. The molecular basis of such membranous structures is not well understood, particularly for malaria parasites other than Plasmodium falciparum. To characterize the structural basis of protein trafficking in the Plasmodium knowlesi-infected erythrocyte, we identified a P. knowlesi ortholog of MAHRP2, a marker of the tether structure that connects membranous structures in the P. falciparum-infected erythrocyte. We show that PkMAHRP2 localizes on amorphous structures that connect Sinton Mulligan's clefts (SMC) to each other and to the erythrocyte membrane. Three dimensional reconstruction of the P. knowlesi-infected erythrocyte revealed that the SMC is a plate-like structure with swollen ends, reminiscent of the morphology of the Golgi apparatus. The PkMAHRP2-localized amorphous structures are possibly functionally equivalent to P. falciparum tether structure. These findings suggest a conservation in the ultrastructure of protein trafficking between P. falciparum and P. knowlesi.     

Correlation of pacing site in right ventricle with paced QRS complex duration

Background

Pacing from RV mid septum and outflow tract septum has been proposed as a more physiological site of pacing and narrower paced QRS complex duration. The paced QRS morphology and duration in different RV pacing sites is under continued discussion. Hence, this study was designed to address the correlation of pacing sites in right ventricle with paced QRS complex duration.

Transcriptional analysis of Pieris rapae in response to P. rapae granulovirus

Pieris rapae granulovirus (PrGV) is an important pathogen that has been exploited as a microbial insecticide to control agriculture pests. They can specifically infect cabbage butterfly (Pieris rapae), causing a series of pathological symptoms. In this infected P. rapae at 6?h and 72?h. As a result, a series of host genes were significantly modulated following PrGV infection, including those correlated with exoskeleton, ribosome, heat shock protein (HSP), proteasome, oxidation-reduction and apoptosis. Taken together, our study unveiled the P. rapae response to PrGV at different time point and provided a potential strategy for pest management.     

Isoxazolo[3,4-d]pyridazinones positively modulate the metabotropic glutamate subtypes 2 and 4

Isoxazolo[3,4-d] pyridazinones ([3,4-d]s) are selective positive modulators of the metabotropic glutamate receptors (mGluRs) subtypes 2 and 4, with no functional cross reactivity at mGluR_1a, mGLuR₅ or mGluR₈. Modest binding for two of the [3,4-d]s is observed at the allosteric fenobam mGluR₅ site, but not sufficient to translate into a functional effect. The structure activity relationship (SAR) for mGluR₂ and mGluR₄ are distinct: the compounds which select for mGluR₂ all contain fluorine on the N-6 aryl group. Furthermore, the [3,4-d]s in this study showed no significant binding at inhibitory GABA_A, nor excitatory NMDA receptors, and previously we had disclosed that they lack significant activity at the System Xc-Antiporter. A homology model based on Conn’s mGluR₁ crystal structure was examined, and suggested explanations for a preference for allosteric over orthosteric binding, subtype selectivity, and suggested avenues for optimization of efficacy as a reasonable working hypothesis.     

Fipronil enhanced natural occurrence of Fusarium solani (Hypocreales: Nectriaceae) on building infesting termite Heterotermes indicola Wasmann (Blattodea: Rhinotermitidae)

The Southeast Asian subterranean termite, Heterotermes indicola Wasmann (Blattodea; Rhinotermitidae), is recognized as a building infesting lower termite species in urban environment. The extensive use of chemical termiticides against aerial mud tubes and underground nests of H. indicola beneath the buildings could not suppress its infestation; however, it enhanced the environmental contamination and insecticide resistance. In the present study, we tried to control termites using naturally occurring entomopathogenic fungi Fusarium solani (Mart.) Sacc., along with sublethal concentrations of termiticide fipronil in no-choice feeding pathogenecity bioassay for 20?days. Termite mortality after 20?days of continuous exposure to highest fungal treatment 1?×?10⁹?conidia/mL was 10% exclusively, whereas 100% mortality was calculated just after 16?days of concurrently exposure to 5?ppm of fipronil and highest rate of fungus 1?×?10⁹?conidia/mL. These results indicated that insecticidal stress declined the immune response of termites and reduced the repellency of termites against fungal conidia by breaching the primary defense mechanism (allogrooming). This co-application of F. solani at suitable sublethal concentrations of fipronil showed the promising potential against termites that may reduce the selection pressure of pesticides and resistance risk by targeted pests, but further investigations are necessary for developing field trials.     

Combination therapies with HSP90 inhibitors against colorectal cancer

Oncogene stability and homeostasis mediated by the HSP90 chaperone is a crucial protection trait of cancer cells. Therefore, HSP90 represents an attractive therapeutic target for many cancers, including colorectal cancer. Although monotherapy has limited clinical efficacy, preclinical and early-phase clinical studies indicate improved antitumor activity when HSP90 inhibitors are combined with chemotherapies or targeted agents. This may be further improved with a biomarker-guided approach based on oncogenic HSP90 clients, or stratification based on the consensus molecular subtypes of colorectal cancer, suggesting a synergistic activity with 5-fluorouracil in preclinical models of the chemorefractory mesenchymal subtype. Furthermore, HSP90 inhibition may activate mechanisms to turn non-immunogenic tumors hot and improve their recognition by the immune system, suggesting synergy with immune checkpoint blockade.     

Synthesis and urease inhibitory potential of benzophenone sulfonamide hybrid in vitro and in silico

This study deals with the synthesis of benzophenone sulfonamides hybrids (1–31) and screening against urease enzyme in vitro. Studies showed that several synthetic compounds were found to have good urease enzyme inhibitory activity. Compounds 1 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-4′′-nitrobenzenesulfonohydrazide), 2 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-3′′-nitrobenzenesulfonohydrazide), 3 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-4′′-methoxybenzenesulfonohydrazide), 4 (3′′,5′′-dichloro-2′′-hydroxy-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 6 (2′′,4′′-dichloro-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 8 (5-(dimethylamino)-N′-((4-hydroxyphenyl)(phenyl)methylene)naphthalene-1-sulfono hydrazide), 10 (2′′-chloro-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 12 (N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide) have found to be potently active having an IC₅₀ value in the range of 3.90–17.99?µM. These compounds showed superior activity than standard acetohydroxamic acid (IC₅₀?=?29.20?±?1.01?µM). Moreover, in silico studies on most active compounds were also performed to understand the binding interaction of most active compounds with active sites of urease enzyme. Structures of all the synthetic compounds were elucidated by ¹H NMR, ¹³C NMR, EI-MS and FAB-MS spectroscopic techniques.     

Rational modification of Mannich base-type derivatives as novel antichagasic compounds: Synthesis,in vitro and in vivo evaluation

The current chemotherapy against Chagas disease is inadequate and insufficient. A series of ten Mannich base-type derivatives have been synthesized to evaluate their in vitro antichagasic activity. After a preliminary screening, compounds 7 and 9 were subjected to in vivo assays in a murine model. Both compounds caused a substantial decrease in parasitemia in the chronic phase, which was an even better result than that of the reference drug benznidazole. In addition, compound 9 also showed better antichagasic activity during the acute phase. Moreover, metabolite excretion, effect on mitochondrial membrane potential and the inhibition of superoxide dismutase (SOD) studies were also performed to identify their possible mechanism of action. Finally, docking studies proposed a binding mode of the Fe-SOD enzyme similar to our previous series, which validated our design strategy. Therefore, the results suggest that these compounds should be considered for further preclinical evaluation as antichagasic agents.     

Differentially expressed genes: OCT-4, SOX2, STAT3, CDH1 and CDH2, in cultured mesenchymal stem cells challenged with serum of women with endometriosis

Endometriosis is a common chronic gynecological disorder defined as the presence of ectopic functional endometrial tissues, outside uterine cavity, primarily on the pelvic peritoneum and the ovaries. Several studies revealed a correlation between aberrant stem-cell activity in the endometrium and endometriosis. Yet the molecular and cellular behaviors of mesnchymal stem cells in development of endometriosis are hampered by lack of invitro experiments. Our aim was to explore morphological and molecular changes associated with mesenchymal stem cells (MSCs) exposition to serum derived from women with severe endometriosis. Two cell cultures of MSCs isolated from endometrial tissues of two endometriosis-free women. Each cell culture was treated individually with the serum of women with endometriosis (experimental group/n =?7), and serum of women without endometriosis (control group/ n = 4) for 14?days. Quantitative Real-Time PCR was performed later to reveal expression of OCT-4, CDH1 and CDH2, STAT3 and SOX2 genes. Morphologically, cells showed no significant changes. However from molecular point of view, we found increased expression in OCT-4, CDH1 and CDH2. For STAT3 and SOX2 we did not find a significant difference. This study shows that endometriosis serum induced molecular changes in human endometrial MSCs (EnMSCs) that might be related to altered cell behavior which may be a step in differentiation that may be completed invivo by other factors to complete the process of transition. Further researches are needed for optimization to reach differentiation.     

Caspase-3 mediated programmed cell death by a gold-stabilised peptide carbene

The synthesis of novel N-heterocyclic carbene complexes derived from a tripeptide ligand (L), containing non-natural amino acid, thiazolylalanine is described here. The peptide ligand was reacted with suitable precursors to generate gold and mercury carbene complexes. The plausible structures of both complexes were predicted by spectroscopic data and DFT calculations. The binding energy data was also analyzed to predict their stability. The gold carbene complex (1A), showed activity against MCF7 breast cancer cell line due to mitochondrial triggered caspase-3 mediated programmed cell death. Its internalization inside cells could be observed due to autofluorescence. This study affords a methodology for successful generation of peptide carbene complexes for their therapeutic potential.     

Synthesis and evaluation of a novel quinoline-triazole analogs for antitubercular properties via molecular hybridization approach

Towards a quest for establishing new antitubercular agents, we have designed new quinoline–triazole hybrid analogs in a six-step reaction sequence involving versatile reactions like Vilsmeier–Haack and click reaction protocol. The design is based on the structural modification of bedaquiline moiety and involves molecular hybridization approach. The structure of the synthesized product was elucidated by single crystal X-ray diffraction study. The synthesized target compounds were screened for their antitubercular activity against Mycobacterium bovis. Interestingly, two compounds of the series (8d and 8m) showed significant inhibition with MIC of 31.5 and 34.8 μM. Compounds bearing 3-fluoro phenyl and n-octyl groups on the 1,2,3-triazole ring emerged as the most potent leads among the compounds tested. Further these hit compounds were also screened for their cytotoxic effect on human embryonic kindey 293 (HEK293) cells and other cancer cell lines such as HeLa (Cervical), PC3 (Prostate), Panc-1 (Pancreatic) and SKOV3 (Ovarian) indicating to be safer with the minimal cytotoxicity.     

Expression of Leptospira membrane proteins Signal Peptidase (SP) and Leptospira Endostatin like A (Len A) in BL-21(DE3) is toxic to the host cells

Heterologous expression of Integral Membrane Proteins (IMPs) is reported to be toxic to the host system in many studies. Even though there are reports on various concerns like transformation efficiency, growth properties, protein toxicity, inefficient expression and protein degradation in IMP overexpression, no studies so far addressed these issues in a comprehensive way. In the present study, two transmembrane proteins of the pathogen Leptospira interrogans, namely Signal peptidase (SP), and Leptospira Endostatin like A (Len-A) were taken along with a cytosolic protein Hydrolase (HYD) to assess the differences in transformation efficiency, protein toxicity, and protein stability when over expressed in Escherichia coli (E. coli). Bioinformatics analysis to predict the transmembrane localization indicated that both SP and Len are targeted to the membrane. The three proteins were expressed in full length in the E. coli expression strain, BL 21 (DE3). Significant changes were observed for the strains transformed with IMP genes under the parameters analysed such as, the transformation efficiency, survival of colonies on IPTG-plate, culture growth kinetics and protein expression compared to the strain harbouring the cytosolic protein gene.