@article { ISI:000293993600017, title = {Method to extract intact and pure RNA from mycobacteria}, journal = {Analytical Biochemistry}, volume = {417}, number = {2}, year = {2011}, month = {OCT}, pages = {286-288}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, address = {525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA}, abstract = {

We describe a high-yielding, simple, and aerosol-free protocol for the isolation of RNA from mycobacteria that does not require sophisticated instruments. The method yielded 50 mu g of RNA from 10(7) cells, 50 times more than a recently reported method. Our method can extract total RNA from aerobically grown bacteria and from in vitro hypoxia-induced dormant bacilli and mycobacteria residing within infected macrophages. (C) 2011 Elsevier Inc. All rights reserved.

}, keywords = {Dormant, Hypoxia, Mycobacteria, RNA isolation, Spheroplast, Trizol}, issn = {0003-2697}, doi = {10.1016/j.ab.2011.06.028}, author = {Akhtar, Shamim and Sarkar, Sampa and Mishra, Abhishek and Sarkar, Dhiman} } @article { ISI:000360705500008, title = {Chemical and biological metal nanoparticles as antimycobacterial agents: a comparative study}, journal = {International Journal of Antimicrobial Agents}, volume = {46}, number = {2}, year = {2015}, month = {AUG}, pages = {183-188}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Resistance among mycobacteria leading to multidrug-resistant and extensively drug-resistant tuberculosis is a major threat. However, nanotechnology has provided new insights in drug delivery and medicine development. This is the first comparative report to determine the activity of chemically and biologically synthesised silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) against mycobacteria. Screening data revealed the high mycobactericidal efficiency of AgNPs, with minimum inhibitory concentrations (MICs) of \<3 mu g/mL, whereas no such activity was exhibited by AuNPs at concentrations up to 100 mu g/mL. Moreover, in vitro and ex vivo THP-1 infection model assays showed greater efficacy of chemical AgNPs compared with biogenic AgNPs to inhibit active and dormant stage mycobacterial growth. Up to 40\% cytotoxicity against human cell lines was observed at a AgNP concentration of 10 x MIC (30 mu g/mL) after 48 h. AgNPs were shown to have more specificity towards mycobacteria than towards other Gram-negative and Gram-positive pathogenic bacteria. The selectivity index was found to be in the range of 11-23, indicating the potential of these nanoparticles for use in developing new therapeutics for tuberculosis. (C) 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

}, keywords = {Antibiotic resistance, Antimycobacterial agent, Cytotoxicity, Mycobacteria, Nanoparticles, tuberculosis}, issn = {0924-8579}, doi = {10.1016/j.ijantimicag.2015.03.014}, author = {Singh, Richa and Nawale, Laxman U. and Arkile, Manisha A. and Shedbalkar, Utkarsha U. and Wadhwani, Sweety A. and Sarkar, Dhiman and Chopade, Balu Ananda} } @article { ISI:000375559600001, title = {Phytogenic silver, gold, and bimetallic nanoparticles as novel antitubercular agents}, journal = {International Journal of Nanomedicine}, volume = {11}, year = {2016}, month = {MAY}, pages = {1889{\textemdash}1897}, publisher = {DOVE MEDICAL PRESS LTD}, address = {PO BOX 300-008, ALBANY, AUCKLAND 0752, NEW ZEALAND}, abstract = {

Purpose: Multi- and extensively drug-resistant tuberculosis (TB) is a global threat to human health. It requires immediate action to seek new antitubercular compounds and devise alternate strategies. Nanomaterials, in the present scenario, have opened new avenues in medicine, diagnosis, and therapeutics. In view of this, the current study aims to determine the efficacy of phytogenic metal nanoparticles to inhibit mycobacteria. Methods: Silver (AgNPs), gold (AuNPs), and gold-silver bimetallic (Au-AgNPs) nanoparticles synthesized from medicinal plants, such as Barleria prionitis, Plumbago zeylanica, and Syzygium cumini, were tested against Mycobacterium tuberculosis and M. bovis BCG. In vitro and ex vivo macrophage infection model assays were designed to determine minimum inhibitory concentration (MIC) and half maximal inhibitory concentration of nanoparticles. Microscopic analyses were carried out to demonstrate intracellular uptake of nanoparticles in macrophages. Besides this, biocompatibility, specificity, and selectivity of nanoparticles were also established with respect to human cell lines. Results: Au-AgNPs exhibited highest antitubercular activity, with MIC of \<2.56 mu g/mL, followed by AgNPs. AuNPs did not show such activity at concentrations of up to 100 mu g/mL. In vitro and ex vivo macrophage infection model assays revealed the inhibition of both active and dormant stage mycobacteria on exposure to Au-AgNPs. These nanoparticles were capable of entering macrophage cells and exhibited up to 45\% cytotoxicity at 30 mu g/mL (ten times MIC concentration) after 48 hours. Among these, Au-AgNPs synthesized from S. cumini were found to be more specific toward mycobacteria, with their selectivity index in the range of 94-108. Conclusion: This is the first study to report the antimycobacterial activity of AuNPs, AgNPs, and Au-AgNPs synthesized from medicinal plants. Among these, Au-AgNPs from S. cumini showed profound efficiency, specificity, and selectivity to kill mycobacteria. These should be investigated further to develop novel TB nanoantibiotics.

}, keywords = {Antimycobacterial agent, Cytotoxicity, drug resistance, Mycobacteria, Nanoparticles, tuberculosis}, issn = {1178-2013}, doi = {10.2147/IJN.S102488}, author = {Singh, Richa and Nawale, Laxman and Arkile, Manisha A. and Wadhwani, Sweety and Shedbalkar, Utkarsha and Chopade, Snehal and Sarkar, Dhiman and Chopade, Balu Ananda} } @article {47088, title = {PNA-mediated efflux inhibition as a therapeutic strategy towards overcoming drug resistance in Mycobacterium smegmatis}, journal = {Microbial Pathogenesis}, volume = {151}, year = {2021}, month = {FEB}, pages = {104737}, type = {Article}, abstract = {

The emergence of antibiotic-resistant strains of Mycobacterium tuberculosis and the decelerating development of new and effective antibiotics has impaired the treatment of tuberculosis (TB). Efflux pump inhibitors (EPIs) have the potential to improve the efficacy of existing anti-TB drugs although with toxicity limitations. Peptide nucleic acids (PNAs), oligonucleotide mimics, by virtue of their high nucleic acid binding specificity have the capability to overcome this drawback. We, therefore, investigated the efflux pump inhibitory properties of a PNA designed against an efflux pump of Mycobacterium smegmatis. LfrA, an efflux pump found in M. smegmatis, is majorly involved in conferring innate drug resistance to this strain and, therefore, was selected as a target for gene silencing via PNA. qRT-PCR and EtBr assays confirmed the EPI activity of the anti-lfrA PNA. On testing the effect of the anti-lfrA PNA on the bactericidal activity of a fluoroquinolone, norfloxacin, we observed that 5 mu M of anti-lfrA PNA in combination with norfloxacin led to an enhanced killing of up to 2.5 log-fold against wild-type and a lab-generated multidrug resistant strain, exemplifying its potential in countering resistance. Improved efficacy was also observed against intra-macrophage mycobacteria, where the drug-PNA combination enhanced bacterial clearance by 1.3 log-fold. Further, no toxicity was observed with PNA concentrations up to 4 times higher than the efficacious anti-lfrA PNA concentration. Thus, PNA, as an adjuvant, presents a novel and viable approach to rejuvenate anti-TB therapeutics.

}, keywords = {Adjuvant, Antibiotic resistance, Antisense, Efflux pump, Gene silencing, Mycobacteria, Peptide nucleic acid (PNA)}, issn = {0882-4010}, doi = {10.1016/j.micpath.2021.104737}, author = {Ghosh, Saptarshi and Cotta, Karishma Berta and Hande, Aniket A. and Fernandes, Moneesha and Mehra, Sarika} }