Ritika Chauhan - Academia.edu (original) (raw)

Papers by Ritika Chauhan

Scientific Reports, 2020

Botulinum neurotoxins (BoNTs) represent a family of bacterial toxins responsible for neuroparalyt... more Botulinum neurotoxins (BoNTs) represent a family of bacterial toxins responsible for neuroparalytic disease ‘botulism’ in human and animals. Their potential use as biological weapon led to their classification in category ‘A’ biowarfare agent by Centers for Disease Control and Prevention (CDC), USA. In present study, gene encoding full length catalytic domain of BoNT/E-LC was cloned, expressed and protein was purified using Ni–NTA chromatography. Humoral immune response was confirmed by Ig isotyping and cell-mediated immunity by cytokine profiling and intracellular staining for enumeration of IFN-γ secreting CD4+ and CD8+ T cells. Increased antibody titer with the predominance of IgG subtype was observed. An interaction between antibodies produced against rBoNT/E-LC was established that showed the specificity against BoNT/E in SPR assay. Animal protection with rBoNT/E-LC was conferred through both humoral and cellular immune responses. These findings were supported by cytokine profi...

Mini-Reviews in Medicinal Chemistry, 2019

Botulinum neurotoxins (BoNTs) are the most toxic category A biological warfare agents. There is n... more Botulinum neurotoxins (BoNTs) are the most toxic category A biological warfare agents. There is no therapeutics available for BoNT intoxication yet, necessitating the development of a medical countermeasure against these neurotoxins. The discovery of small molecule-based drugs has revolutionized in the last two decades resulting in the identification of several small molecule inhibitors of BoNTs. However, none progressed to clinical trials. 8-Hydroxyquinolines scaffold-based molecules are important ‘privileged structures’ that can be exploited as inhibitors of a diverse range of targets. In this review, our study of recent reports suggests the development of 8-hydroxyquinoline derived molecules as a potential drug may be on the horizon.

Cancer Research, 2018

Despite showing clinical activity in BRAF-mutant melanoma, the MEK inhibitor (MEKi) trametinib fa... more Despite showing clinical activity in BRAF-mutant melanoma, the MEK inhibitor (MEKi) trametinib failed to show clinical benefit in KRAS-mutant colorectal cancer. To identify mechanisms of resistance to MEK inhibition we identified gene expression differences between MEKi-sensitive and MEKi-resistant colorectal cancer cell lines. Strikingly, inflammation-related gene sets were the most significantly enriched in cell lines exhibiting intrinsic or acquired resistance to MEK inhibition. The bromodomain inhibitor JQ1 suppressed inflammatory gene expression and in combination with MEK inhibitors displayed synergistic anti-proliferative activity, inhibited colony formation and induced apoptosis in colorectal cancer cell lines. NFkB activation was greater in cell lines resistant to MEK inhibition and JQ1 treatment suppressed TNF-induced translocation of NFkB to the nucleus. Resistance to MEK inhibition could be induced by inflammatory cytokines or by conditioned medium from macrophage cultur...

Protein & Peptide Letters, 2019

Background:Shiga toxins comprise a family of related proteins produced by bacteria Shigella dysen... more Background:Shiga toxins comprise a family of related proteins produced by bacteria Shigella dysenteriae and some strains of Escherichia coli that cause severe clinical manifestations. Severe Shiga toxin intoxication results in Haemolytic-Uremic Syndrome (HUS), up to 50% of HUS patients manifest some degree of renal failure and ~10% of such cases develop permanent renal failure or death. Objective: In present research work production of biologically active rStx from non-toxic rStxA and rStxB subunits were established that can be used in many biomedical applications.Methods:Purification of Shiga toxin from bacteria is a multistep time consuming process resulting in low yield. To overcome this problem, the rStxA and rStxB protein were separately cloned and expressed in E. coli host and purified through affinity chromatography. GST pull-down assay was performed for interaction study between rStxA and pentameric rStxB. The affinity between A and B subunits of reconstituted recombinant Sh...

Oncogene, Jan 23, 2018

Despite showing clinical activity in BRAF-mutant melanoma, the MEK inhibitor (MEKi) trametinib ha... more Despite showing clinical activity in BRAF-mutant melanoma, the MEK inhibitor (MEKi) trametinib has failed to show clinical benefit in KRAS-mutant colorectal cancer. To identify mechanisms of resistance to MEKi, we employed a pharmacogenomic analysis of MEKi-sensitive versus MEKi-resistant colorectal cancer cell lines. Strikingly, interferon- and inflammatory-related gene sets were enriched in cell lines exhibiting intrinsic and acquired resistance to MEK inhibition. The bromodomain inhibitor JQ1 suppressed interferon-stimulated gene (ISG) expression and in combination with MEK inhibitors displayed synergistic effects and induced apoptosis in MEKi-resistant colorectal cancer cell lines. ISG expression was confirmed in patient-derived organoid models, which displayed resistance to trametinib and were resensitized by JQ1 co-treatment. In in vivo models of colorectal cancer, combination treatment significantly suppressed tumor growth. Our findings provide a novel explanation for the lim...

Protein expression and purification, 2018

Botulinum neurotoxins (BoNTs) are the most toxic biological substances known. Their potential use... more Botulinum neurotoxins (BoNTs) are the most toxic biological substances known. Their potential use as biological warfare agent results in their classification as category A biowarfare agent by Centers for Disease Control and Prevention (CDC), USA. Presently, there are no approved detection system and pharmacological treatments for BoNT intoxication. Although a toxoid vaccine is available for immuno-prophylaxis, vaccines cannot reverse the effect of pre-translocated toxin. Direct handling of the live BoNTs for developing detection and therapeutics may pose fatal danger. This concern was addressed by purifying the recombinant catalytically active light chain of BoNT/F. BoNT/F-LC gene was amplified from the genomic DNA using specifically designed primers and expressed in Escherichia coli. Expression and purification profile were optimized under different conditions for biologically active light chain production. Specific polyclonal antibodies generated against type F illustrates in vivo...

Asian Journal of Pharmaceutical and Clinical Research, 2017

Objective: Prodigiosin is a red tripyrrole pigment which is synthesized as a secondary metaboli... more Objective: Prodigiosin is a red tripyrrole pigment which is synthesized as a secondary metabolite by biotypes A1, A2, and A6 of Serretia marcescens. This study was aimed to optimize production parameters for prodigiosin pigment produced by S. marcescens strain JAR8 and to determine its antimicrobial, cytotoxicity, and dyeing properties.Methods: The effect of various media components, process parameters (temperature, pH, incubation period), and other supplements was investigated, and the maximum production of prodigiosin was found to be at temperature 28°C, pH 7.0, incubation period of 5 day with peptone in the media. Antibacterial, cytotoxicity, and dyeing properties of prodigiosin were studied in depth.Results: The antimicrobial study of prodigiosin revealed that it is a potent inhibitor of Gram-positive bacteria as well as Gram-negative bacteria. The prodigiosin exhibited commendable dose-dependent cytotoxicity effect against human bone cancer cells with the IC50 of 108 μg/ml. P...

In silico approach towards finding inhibitory effect of phytochemicals on Trypanothione reductase... more In silico approach towards finding inhibitory effect of phytochemicals on Trypanothione reductase in Leishmania donovani A Thesis submitted in partial fulfilment of the requirements for the degree of

Inorganic Chemistry Communications, 2016

Tetra coordinated copper(II) complex of formula [Cu(L 1)(imid)] is synthesized using imidazole an... more Tetra coordinated copper(II) complex of formula [Cu(L 1)(imid)] is synthesized using imidazole and a tridentate O,N,O hydrazone ligand L 1 prepared by condensation of 1,1,1-trifluoropentanedione and 4-chlorobenzhydrazide. The ligand and complex are characterized by UV-Visible, FTIR, NMR, mass and single crystal XRD techniques. DNA binding mode is assessed by UV absorption, fluorescence spectral and circular dichroism studies. Based on the results, it is observed that complex has preferred intercalative mode of binding with DNA. The binding constant, K b , was found to be 4.02 ± 0.09 × 10 4 M −1. Thermodynamic parameters such as ΔH, ΔS and ΔG obtained from acridine orange fluorescence displacement assay revealed that the hydrophobic and hydrogen bonding interactions are playing a major role in the binding pattern. In addition, cytotoxicity of the complex towards MCF-7 breast cancer cell line has also been assessed.

Journal of Pure and Applied Microbiology

International Journal of Pharmacy and Pharmaceutical Sciences

ABSTRACT

International Journal of Pharmaceutical Sciences and Research

ABSTRACT: In the present study, Vigna mungo (blackgram) have been used to investigate bioactive c... more ABSTRACT: In the present study, Vigna mungo (blackgram) have been used to investigate bioactive compounds through soxhlet extraction. The obtained methanol extract was evaluated for antimicrobial activity by Kirby- Bauer method against bacterial strains (Enterococci sp., Pseudomonas aeruginosa, Klebsiella sp., Bacillus sp., Staphylococcus aueres) and fungal strains (Aspergillus niger, Candida albicans) on Muller Hinton agar medium and potato dextrose agar medium respectively. The blackgram was analyzed for the presence of proteins through SDS-PAGE and compared with the BSA (66KDa) and Lysine (18KDa) protein markers. The sensitivity of the obtained methanol extract against pathogenic microorganisms was studied with the combined effect of commercially available antibiotics which resulted in good and enhanced antimicrobial effect. The methanol extract of blackgram was also analyzed for bioactive compounds through gaschromatography mass spectrometry (GC-MS). The GC-MS spectrum revealed ...

Research Journal of Pharmacy and Technology, 2015

The present investigation was aimed to explore in vitro and in silico antimicrobial potential of ... more The present investigation was aimed to explore in vitro and in silico antimicrobial potential of secondary metabolites produced by terrestrial actinomycetes, S. xanthochromogenes JAR5 isolated from deep forest of Kodaikanal, Tamil Nadu, India and was confirmed by 16S rRNA gene sequencing analysis. The bioactive metabolites produced by the strain JAR5 were obtained from the optimized culture medium through solvent extraction method. The crude extract obtained was purified using silica gel column chromatography and partially purified active elute was characterized using UV, FTIR and GC-MS spectroscopic analysis. The partially purified bioactive metabolites produced by strain JAR5 showed 23.333±0.471 diameter zone of inhibition and minimum inhibitory concentration of 80 μg/ml against Enterococcus sp. In silico molecular docking studies revealed binding into crystal structure of topoisomerase II using Autodock vina 4.2 program. The molecular docking of biological active compounds is in good agreement with in vitro antimicrobial screening where the bioactive metabolites showed effective inhibitory effect against Enterococcus sp.

Scientia Pharmaceutica, 2013

The biological approach to synthesize metal nanoparticles is an important aspect of current nanot... more The biological approach to synthesize metal nanoparticles is an important aspect of current nanotechnology research. Silver nanoparticles have been well-known for their inhibitory and antimicrobial effects. The ever-increasing antibiotic resistance in pathogenic and opportunistic microorganisms is a major threat to the health care industry. In the present investigation, silver nanoparticles have been successfully biosynthesized by Streptomyces sp JAR1. Biosynthesized silver nanoparticles were characterized by means of several analytical techniques including a UV-Visible spectrophotometer, Fourier transform infrared spectroscopy, X-ray diffraction pattern analysis, and atomic force microscopy. An evaluation of the antimicrobial activity of silver nanoparticles (AgNPs) was carried out against clinically important pathogenic microorganisms. The metal nanoparticles were also evaluated for their combined effects with antibiotics against the clinical pathogens. The antibacterial activities of the antibiotics increased in the presence of the biologically synthesized AgNPs against the clinically important pathogens. The highest enhancing effect was observed for erythromycin against the test pathogens.

Journal of King Saud University - Science, 2013

Antimicrobial secondary metabolites from extremophiles play a significant role in the pharmacolog... more Antimicrobial secondary metabolites from extremophiles play a significant role in the pharmacological industry due to their stable and strong activity and it is used in the treatment of microbial infections. In the present work, Halomonas salifodinae MPM-TC (M. Peter Marian-T. Citarasu) was isolated from the solar salt works in India and identified by 16S rRNA sequencing. The secondary metabolites were extracted from H. salifodinae MPM-TC and tested for antibacterial activity against aquatic bacterial pathogens such as Vibrio harveyi, Vibrio parahaemolyticus, Pseudomonas aeruginosa and Aeromonas hydrophila isolated from infected fish/shrimp, and it effectively controlled them with more than 10 mm of zone of inhibition. The metabolites were purified through silica column chromatography and in vitro antiviral activity was performed against White Spot Syndrome Virus (WSSV) using different fractions. Among the different tested fractions, fraction-III (F-III) was able to suppress WSSV replication. Shrimps challenged with a WSSV inoculum incubated with F-III and treated Fenneropenaeus indicus survived around twice as many as the controls. Gas chromatography-mass spectroscopic (GC-MS) analysis revealed that the antiviral active fraction contains around eight compounds including Perfluorotributylamine, Cyclopentane, 1-butyl-2-ethyl and 1,1 0-Biphenyl]-3-amine. Further the active fraction F-III was incorporated in the artificial diets at the concentration of 200 (HS1), 400 (HS2) and 800 (HS3) lg kg À1 and fed to F. indicus for

The Journal of Organic Chemistry, 1980

Engineering Geology, 2001

Chinese Chemical Letters, 2011

Aromatic aldehydes undergo crossed-aldol condensation with ketones in the presence of catalytic a... more Aromatic aldehydes undergo crossed-aldol condensation with ketones in the presence of catalytic amount of sulfamic acid (SA) to afford the corresponding a, b-unsaturated aldol products under solvent-free conditions in good to high yields at 45-80 8C.

BMC Genomics, 2011

Background: The whitefly Trialeurodes vaporariorum is an economically important crop pest in temp... more Background: The whitefly Trialeurodes vaporariorum is an economically important crop pest in temperate regions that has developed resistance to most classes of insecticides. However, the molecular mechanisms underlying resistance have not been characterised and, to date, progress has been hampered by a lack of nucleotide sequence data for this species. Here, we use pyrosequencing on the Roche 454-FLX platform to produce a substantial and annotated EST dataset. This 'unigene set' will form a critical reference point for quantitation of over-expressed messages via digital transcriptomics. Results: Pyrosequencing produced around a million sequencing reads that assembled into 54,748 contigs, with an average length of 965 bp, representing a dramatic expansion of existing cDNA sequences available for T. vaporariorum (only 43 entries in GenBank at the time of this publication). BLAST searching of non-redundant databases returned 20,333 significant matches and those gene families potentially encoding gene products involved in insecticide resistance were manually curated and annotated. These include, enzymes potentially involved in the detoxification of xenobiotics and those encoding the targets of the major chemical classes of insecticides. A total of 57 P450s, 17 GSTs and 27 CCEs were identified along with 30 contigs encoding the target proteins of six different insecticide classes. Conclusion: Here, we have developed new transcriptomic resources for T. vaporariorum. These include a substantial and annotated EST dataset that will serve the community studying this important crop pest and will elucidate further the molecular mechanisms underlying insecticide resistance.