Mariam S. Degani

Novel molecular hybrids of cinnamic acids and guanylhydrazones as potential antitubercular agents

In an attempt to identify potential new agents active against tuberculosis, 20 novel phenylacrylamide derivatives incorporating cinnamic acids and guanylhydrazones were synthesized using microwave assisted synthesis. Activity of the synthesized compounds was evaluated using resazurin microtitre plate assay (REMA) against Mycobacterium tuberculosis H37Rv. Based on empirical structure-activity relationship data it was observed that both steric and electronic parameters play major role in the activity of this series of compounds. Compound 7s (2E)-N-((-2-(3,4-dimethoxybenzylidene) hydrazinyl) (imino) methyl)-3-(4-methoxyphenyl) acrylamide showed MIC of 6.49microM along with good safety profile of >50-fold in VERO cell line. Thus, this compound could act as a potential lead for further antitubercular studies.

Pharmacophore mapping of a series of pyrrolopyrimidines, indolopyrimidines and their congeners as multidrug-resistance-associated protein (MRP1) modulators

AbstractPharmacophore mapping studies were undertaken for a series of molecules belonging to pyrrolopyrimidines, indolopyrimidines and their congeners as multidrug resistance-associated protein (MRP1) modulators. A five-point pharmacophore with two hydrogen bond acceptors (A), one lipophilic/hydrophobic group (H), one positive ionic feature (P) and one aromatic ring (R) as pharmacophoric features was developed. The pharmacophore hypothesis yielded a statistically significant 3D-QSAR model, with a correlation coefficient of r2u2009=u20090.799 for training set molecules. The model generated showed excellent predictive power, with a correlation coefficient Q2u2009=u20090.679 for an external test set of 20 molecules. The pharmacophore was further validated using four structurally diverse compounds with MRP1 modulatory activity. These compounds mapped well onto four of the five features of the pharmacophore. The pharmacophore proposed here was then utilised for the successful retrieval of active molecules with diverse chemotypes from database search. The geometry and features of pharmacophore are expected to be useful for the design of selective MRP1 inhibitors.n FigureAlignment of multidrug resistance-associated protein (MRP1) inhibitors with the developed pharmacophore.

Design, synthesis and antimycobacterial activity of cinnamide derivatives: a molecular hybridization approach.

A series of cinnamide derivatives was designed as potential antimycobacterial agents using molecular hybridization approach. The diamine moiety, a key feature of ethambutol and its other analogs, and certain structural features of cerulenin and cinnamic acid were hybridized to obtain cinnamide derivatives. The minimum inhibitory concentration (MIC) of all synthesized compounds was determined against M. tuberculosis H(37)R(v) using Resazurin Microtitre plate Assay (REMA) method. The synthesized molecules showed good to moderate activity with MIC in the range of 5-150 μM and good safety profile. Additionally, the most potent compound 1a, having MIC 5.1 μM exhibited synergy with rifampicin.

Pharmacophore mapping and electronic feature analysis for a series of nitroaromatic compounds with antitubercular activity

A five point pharmacophore was generated using PHASE for a series of nitroaromatic compounds and their congeners as antitubercular agents. The generated pharmacophore yielded significant 3D‐QSAR model with r2 of 0.890 for a training set of 92 molecules. The model also showed excellent predictive power with correlation coefficient Q2 of 0.857 for a test set of 31 compounds. The pharmacophore indicated that presence of a nitro group, a piperazine moiety, one aromatic ring feature and two acceptor features are necessary for potent antitubercular activity. The pharmacophore was supported by electronic property analysis using density functional theory (DFT) at B3LYP/3–21*G level. Molecular electrostatic profile of the compounds was consistent with the generated pharmacophore model, particularly appearance of localized negative potential regions near both the oxygen atoms of nitro group extending laterally to the isoxazole ring system/amide bond in the most active compounds. Calculated data further revealed that all active compounds have smaller LUMO energies located over the nitro group, furan ring, and isoxazole ring/amide bond attached to it. Higher negative values of LUMO energies concentrated over the nitro group are indicative of the electron acceptor capacity of the compounds, suggesting that these compounds are prodrugs and must be activated by TB‐nitroreductase. The results obtained from this study should aid in efficient design and development of nitroaromatic compounds as antitubercular agents.

Design, synthesis, and biological evaluation of 4-(5-nitrofuran-2-yl)prop-2-en-1-one derivatives as potent antitubercular agents.

Based on stereoelectronic feature analysis using density functional theory (DFT) at B3LYP/3-21∗G level, a series of 4-(5-nitrofuran-2-yl)prop-2-en-1-one derivatives with low LUMO energies (<-0.10eV); concentrated over the nitro group, furan moiety and α,β-unsaturated carbonyl bridge were envisaged as potential antitubercular agents. The target compounds were prepared by condensation of 5-nitro-2-furaldehyde with various ketones under acidic condition. The compounds were evaluated for antitubercular activity against Mycobacterium tuberculosis H37Rv and their cytotoxicity in VERO cell line. Several synthesized compounds showed good antitubercular activity of <5μM along with low cytotoxicity. In particular, compound ((E)-3-(5-nitrofuran-2-yl)-1-(4-(piperidin-1-yl)phenyl)prop-2-en-1-one) (3v) was found to be very potent (MIC: 0.19μM) with good selectivity index (MIC(90)/CC(50): >1800). Thus, this study shows the potential of stereoelectronic property analysis in developing improved nitroaromatics as antitubercular agents.

Synthesis and preliminary biological evaluation of novel N-(3-aryl-1,2,4-triazol-5-yl) cinnamamide derivatives as potential antimycobacterial agents: an operational Topliss Tree approach.

A series of novel N-(3-aryl-1,2,4-triazol-5-yl) cinnamamide derivatives were designed on basis of structural similarity to the known FAS II inhibitors. Topliss operational method was used to optimize the potency of molecules. The minimum inhibitory concentration (MIC) of all synthesized compounds was determined against Mycobacterium tuberculosis H(37)R(v) using resazurin microtitre assay (REMA) plate method. The synthesized compounds exhibit antimycobacterial activity in the range of 5-95μM with a good safety profile.

Rational drug design based synthesis of novel arylquinolines as anti-tuberculosis agents.

A series of novel arylquinoline derivatives was designed retaining significant pharmacophoric features and three dimensional geometry of bedaquiline. In silico ADME study was performed to assess drug likeness and toxicity profiles of the designed molecules. The compounds were evaluated for activity against Mycobacterium tuberculosis H37Rv using Resazurin Microtitre Assay (REMA) plate method and cytotoxicity in VERO C1008 cell line. Several of the synthesized compounds exhibited good antituberculosis activity and selectivity, especially compounds, 12i (MIC: 5.18 μM and MIC/CC50: 152.86) and 12l (MIC: 5.59 μM and MIC/CC50: 160.57). The study opens up a new platform for the development of arylquinoline based drugs for treating tuberculosis.

Microwave assisted benzoin condensation using thiamine as catalyst

α-Hydroxyketones were prepared in appreciable yields at a very high speed, (by the benzoin condensation) under microwave irradiation using a catalytic amount of thiamine hydrochloride, from various aromatic as well as heteroaromatic aldehydes. They can be used as intermediates in NCE synthesis.

Microwave-Assisted Development of Orally Disintegrating Tablets by Direct Compression

ABSTRACTOrally disintegrating tablets (ODTs) are challenged by the need for simple technology to ensure good mechanical strength coupled with rapid disintegration. The objective of this work was to evaluate microwave-assisted development of ODTs based on simple direct compression tableting technology. Placebo ODTs comprising directly compressible mannitol and lactose as diluents, super disintegrants, and lubricants were prepared by direct compression followed by exposure to >97% relative humidity and then microwave irradiation for 5xa0min at 490xa0W. Placebo ODTs with hardness (>5xa0kg/cm2) and disintegration time (<60xa0s) were optimized. Palatable ODTs of Lamotrigine (LMG), which exhibited rapid dissolution of LMG, were then developed. The stability of LMG to microwave irradiation (MWI) was confirmed. Solubilization was achieved by complexation with beta-cyclodextrin (β-CD). LMG ODTs with optimal hardness and disintegration time (DT) were optimized by a 23 factorial design using Design Expert software. Taste masking using sweeteners and flavors was confirmed using a potentiometric multisensor-based electronic tongue, coupled with principal component analysis. Placebo ODTs with crospovidone as a superdisintegrant revealed a significant increase in hardness from ∼3 to ∼5xa0kg/cm2 and a decrease in disintegration time (<60xa0s) following microwave irradiation. LMG ODTs had hardness >5xa0kg/cm2, DTu2009<u200930s, and rapid dissolution of LMG, and good stability was optimized by DOE and the design space derived. While β-CD complexation enabled rapid dissolution and moderate taste masking, palatability, which was achieved including flavors, was confirmed using an electronic tongue. A simple step of humidification enabled MWI-facilitated development of ODTs by direct compression presenting a practical and scalable advancement in ODT technology.

E84G mutation in dihydrofolate reductase from drug resistant strains of Mycobacterium tuberculosis (Mumbai, India) leads to increased interaction with Trimethoprim

BACKGROUNDnDihydrofolate reductase (DHFR) (dfrA gene) is an essential enzyme for cell survival and an unexplored target in Mycobacterium tuberculosis (Mtb). This study was carried out to analyze mutations in the dfrA gene amongst 20 clinical DNA samples from Mtb isolates obtained from Mumbai, India.nnnMETHODSnSequencing of the PCR amplified dfrA gene from these DNA isolates revealed a point mutation in one strain, leading to a glutamic acid to glycine change. In silico simulation studies revealed a surface alteration in the enzyme due to this E84G mutation. The amplified mutant gene was cloned and expressed. The mutant protein was assessed against known DHFR inhibitors: Methotrexate and Trimethoprim.nnnRESULTSnAn increased affinity for inhibitor Trimethoprim and native substrate dihydrofolate was observed with the mutant. Methotrexate did not vary in its activity with both the enzyme forms.nnnCONCLUSIONSnThe Glu84Gly point mutation may lead to a variation in the strain which may cause resistance in the future.