Docking studies on novel analogues of 8 methoxy fluoroquinolones against GyrA mutants of Mycobacterium tuberculosis

Contemporary and emerging pharmacotherapeutic agents for the treatment of Lassa viral haemorrhagic fever disease

This review was designed to discuss the emerging and current pharmacotherapeutic agents for the treatment of Lassa viral haemorrhagic fever disease (LVHFD), also known as Lassa fever (LF). Original peer-reviewed articles that investigated LF were identified using the Medline Entrez-PubMed search. Information was also sourced from printed textbooks and reports by recognized health professional bodies such as the WHO, CDC, the Nigerian Federal Ministry of Health and the United Nations Children's Fund (UNICEF). A total of 103 articles were reviewed and 78 were found to contain information relevant to the study. LF remains an endemic disease of public health concern in the West Africa region, and in the rest of the world as cases have been imported into non-endemic regions as well. Currently, there are no approved vaccines or therapeutics for the treatment of Lassa mammarenavirus (LASV) infection. There are, however, off-label therapeutics being used (ribavirin and convalescent plasma) whose efficacy is suboptimal. Research is still ongoing on possible therapeutic options and drug repurposing of therapeutic agents currently in use for other clinical conditions. Considered therapeutic options include favipiravir, taribavirin, Arevirumab-3 and experimental drugs such as losmapimod, adamantyl diphenyl piperazine 3.3, Arbidol (umifenovir) and decanoyl-RRLL-chloromethyl ketone (dec-RRLL-CMK). Current treatments for LF are limited, hence the institution of mitigating measures to prevent infection is of utmost importance and should be prioritized, especially in endemic regions. Heightened searches for other therapeutic options with greater efficacy and lower toxicity are still ongoing, as well as for vaccines as the absence of these classifies the disease as a priority disease of high public health impact.

Topoisomerase II as a target for repurposed antibiotics in Candida albicans: an in silico study

Fluoroquinolines, the widely used antibacterial antibiotics, have been shown to interact with human DNA topoisomerases supporting their use as repurposed cancer drugs in humans. In this communication molecular docking of eleven Fluoroquinolines against predicted structure of Candida albicans DNA Topoisomerase II is reported for the first time. C. albicans topoisomerase II structure prediction was done by using homology modeling tool. Ligand preparation and molecular docking with C. albicans topoisomerase II were done by using Autodock tool. These antibiotics formed hydrogen bond with good binding affinity at ARG 841, GLN803, ALA840 amino acid residues in the active site of C. albicans Topoisomerase II. We hypothesize that DNA toposiomerases may be the targets of Fluroquinoline group of antibiotics in C. albicans causing inhibition of growth.

The antibacterial agent, moxifloxacin inhibits virulence factors of Candida albicans through multitargeting

Fluoroquinolines are broad spectrum fourth generation antibiotics. Some of the Fluoroquinolines exhibit antifungal activity. We are reporting the potential mechanism of action of a fluoroquinoline antibiotic, moxifloxacin on the growth, morphogenesis and biofilm formation of the human pathogen Candida albicans. Moxifloxacin was found to be Candidacidal in nature. Moxifloxacin seems to inhibit the yeast to Hyphal morphogenesis by affecting signaling pathways. It arrested the cell cycle of C. albicans at S phase. Docking of moxifloxacin with predicted structure of C. albicans DNA Topoisomerase II suggests that moxifloxacin may bind and inhibit the activity of DNA Topoisomerase II in C. albicans. Moxifloxacin could be used as a dual purpose antibiotic for treating mixed infections caused by bacteria as well as C. albicans. In addition chances of developing moxifloxacin resistance in C. albicans are less considering the fact that moxifloxacin may target multiple steps in yeast to hyphal transition in C. albicans.

Computer-Aided Drug Discovery Approaches against the Tropical Infectious Diseases Malaria, Tuberculosis, Trypanosomiasis, and Leishmaniasis

Despite the tremendous improvement in overall global health heralded by the adoption of the Millennium Declaration in the year 2000, tropical infections remain a major health problem in the developing world. Recent estimates indicate that the major tropical infectious diseases, namely, malaria, tuberculosis, trypanosomiasis, and leishmaniasis, account for more than 2.2 million deaths and a loss of approximately 85 million disability-adjusted life years annually. The crucial role of chemotherapy in curtailing the deleterious health and economic impacts of these infections has invigorated the search for new drugs against tropical infectious diseases. The research efforts have involved increased application of computational technologies in mainstream drug discovery programs at the hit identification, hit-to-lead, and lead optimization stages. This review highlights various computer-aided drug discovery approaches that have been utilized in efforts to identify novel antimalarial, antitubercular, antitrypanosomal, and antileishmanial agents. The focus is largely on developments over the past 5 years (2010-2014).

Frequency and geographic distribution of gyrA and gyrB mutations associated with fluoroquinolone resistance in clinical Mycobacterium tuberculosis isolates: a systematic review

BACKGROUND

The detection of mutations in the gyrA and gyrB genes in the Mycobacterium tuberculosis genome that have been demonstrated to confer phenotypic resistance to fluoroquinolones is the most promising technology for rapid diagnosis of fluoroquinolone resistance.

METHODS

In order to characterize the diversity and frequency of gyrA and gyrB mutations and to describe the global distribution of these mutations, we conducted a systematic review, from May 1996 to April 2013, of all published studies evaluating Mycobacterium tuberculosis mutations associated with resistance to fluoroquinolones. The overall goal of the study was to determine the potential utility and reliability of these mutations as diagnostic markers to detect phenotypic fluoroquinolone resistance in Mycobacterium tuberculosis and to describe their geographic distribution.

RESULTS

Forty-six studies, covering four continents and 18 countries, provided mutation data for 3,846 unique clinical isolates with phenotypic resistance profiles to fluoroquinolones. The gyrA mutations occurring most frequently in fluoroquinolone-resistant isolates, ranged from 21-32% for D94G and 13-20% for A90V, by drug. Eighty seven percent of all strains that were phenotypically resistant to moxifloxacin and 83% of ofloxacin resistant isolates contained mutations in gyrA. Additionally we found that 83% and 80% of moxifloxacin and ofloxacin resistant strains respectively, were observed to have mutations in the gyrA codons interrogated by the existing MTBDRsl line probe assay. In China and Russia, 83% and 84% of fluoroquinolone resistant strains respectively, were observed to have gyrA mutations in the gene regions covered by the MTBDRsl assay.

CONCLUSIONS

Molecular diagnostics, specifically the Genotype MTBDRsl assay, focusing on codons 88-94 should have moderate to high sensitivity in most countries. While we did observe geographic differences in the frequencies of single gyrA mutations across countries, molecular diagnostics based on detection of all gyrA mutations demonstrated to confer resistance should have broad and global utility.

Computational models for tuberculosis drug discovery

The search for small molecules with activity against Mycobacterium tuberculosis increasingly uses -high-throughput screening and computational methods. Previously, we have analyzed recent studies in which computational tools were used for cheminformatics. We have now updated this analysis to illustrate how they may assist in finding desirable leads for tuberculosis drug discovery. We provide our thoughts on strategies for drug discovery efforts for neglected diseases.