Shashikant Vaidya

Biosynthesis of silver nanoparticles by Pseudomonas spp. isolated from effluent of an electroplating industry

The aim of this study was to isolate and screen bacteria from soil and effluent of electroplating industries for the synthesis of silver nanoparticles and characterize the potential isolate. Soil and effluent of electroplating industries from Mumbai were screened for bacteria capable of synthesizing silver nanoparticles. From two soils and eight effluent samples 20 bacterial isolates were obtained, of these, one was found to synthesize silver nanoparticles. Synthesis of silver nanoparticle by bacteria was confirmed by undertaking characterization studies of nanoparticles that involved spectroscopy and electron microscopic techniques. The potential bacteria was found to be Gram-negative short rods with its biochemical test indicating Pseudomonas spp. Molecular characterization of the isolate by 16S r DNA sequencing was carried out which confirmed its relation to Pseudomonas hibiscicola ATCC 19867. Stable nanoparticles synthesized were 50 nm in size and variable shapes as seen in SEM micrographs. The XRD and FTIR confirmed the crystalline structure of nanoparticles and presence of biomolecules mainly proteins as agents for reduction and capping of nanoparticles. The study demonstrates synthesis of nanoparticles by bacteria from effluent of electroplating industry. This can be used for large scale synthesis of nanoparticles by cost effective and environmentally benign mode of synthesis.

Novel Nanotechnology Based Delivery Systems for Chemotherapy and Prophylaxis of Tuberculosis

Abstract Tuberculosis (TB), a serious infectious disease caused by Mycobacterium tuberculosis , has resulted in more deaths than any other communicable disease, and has caused a lot of problems in the economy and social status of developing countries. Current chemotherapy for TB still relies on drugs discovered way back in the 1960s and is laborious, extensive, and remains extremely complicated to complete in many of the highest burdened regions. The various global strategies like DOTS therapy have not achieved much success, and the Third World is plagued with the development of drug-resistant strains. With difficulties in obtaining novel anti-TB drug candidates in the development pipeline, it is important to look into the existing drugs and develop novel and targeted delivery systems of these drugs, to overcome the drawbacks of current conventional formulations. Nanoparticle (NP) technology offers an attractive and promising approach to take the existing chemotherapies and deliver them more efficaciously, reducing the dosing frequency and duration of treatment, as well as increased bioavailability. In addition, it is possible to functionalize the NPs with specific ligands and achieve active targeting to the Mycobacterium -infested tissues, especially the alveolar macrophages. This advance can help achieve quicker cures, with lower doses, improved patient adherence, and overall reduce medication burden; all of which can help curb the development of drug resistance. Further, several nanotechnology-based vaccines as an alternative to the current bacilli Calmette–Guerin vaccine for prevention of TB are also promising approaches being investigated. This chapter will provide an insight into the nanotechnology approaches for chemotherapy and prophylaxis of TB, and highlight the challenges in implementation of these technologies.

Determination of the Efficacy of Isoxyl, A Mycolic Acid Inhibitor in Vitro against M. tuberculosis Strains in Comparison to Other Mycolic Acid Inhibitors

Multi drug resistant (MDR) tuberculosis (TB) has become more prevalent in recent years and second line drugs are not as effective as the standard therapy and are more toxic and expensive. There is an urgent need for new antitubercular drugs. The components of the cell envelope of Mycobacteria have been the subject of intense research for a number of years because of the fact that enzymes involved in their biosynthetic pathways including mycolic acids, offer attractive and selective targets for the developments of novel antimycobacterial agents. The mechanisms of action of various mycolic acid inhibitors like Isoniazide ( INH) and Ethionamide (ETH) have been studied intensively. Recently, mycolic acid inhibitors like Thiolactomycin (TLM), Triclosan (TRC) and Isoxyl (ISO) have been reported to have potent activity against MDR strains of M. tuberculosis. Present study was conducted with the objective of determining the efficacy of ISO in vitro against M. tuberculosis strains in comparison to other mycolic acid inhibitors. Minimum Inhibitory Concentration pattern of clinical isolates of M. tuberculosis to mycolic acid synthesis inhibitors namely TRC, TLM, ISO, INH And ETH were determined by agar dilution method. . Total 10 MDR strains and 10 susceptible strains of Mycobacterum tuberculosis (M. tuberculosis) along with standard strain of M. tuberculosis H37Rv were included in the study. This study shows promising activity of ISO against various strains of M.tuberculosis in comparison to other mycolic acid inhibitors. Hence more study on this compound will be beneficial in drug development process.

Determine Suitability of Isoxyl, A Mycolic Acid Inhibitor for Intermittent Chemotherapy of Tuberculosis

Intermittent chemotherapy is attractive. If drugs can be given less frequently than once a day, fully supervised treatment is much easier. In managing patients with tuberculosis (TB), administration of drugs at intermittent intervals would reduce cost and possibly toxicity of drugs, as well as enhance adherence through greater feasibility of directly observed therapy. There is an urgent need to develop new effective antitubercular compounds, compounds that increase the permeability of the mycobacterial cell wall by inhibiting the synthesis of cell wall components and enhance the activity of conventional drugs as a result of increased penetration of these latter agents to susceptible internal targets. As drug development is a long and expensive process, it becomes predominant to reexamine drugs that were formerly deemed effective against TB and increase the permeability of the Mycobacterial cell wall. One such drug is Isoxyl (ISO). ISO is an old drug, used for the clinical treatment of TB in 1960’s. Hence there was a thought to recheck its efficacy against Mycobacterium tuberculosis strains as it is an old drug which have proven its efficacy. Present study was conducted with the objective, to determine suitability of ISO for intermittent chemotherapy of TB.In vitro Pulsed exposure study of ISO against Test culture and Standard strain of M. tuberculosis H37 Rv after growth of test organisms in log phase was carried out. Viable counts were carried out before addition of drug, immediately after washing and at intervals thereafter.Sensitivity tests were set up on sterile LJM slants. The effect of exposure was estimated by noting the delay before the organisms began to grow. Pulsed exposure study of ISO in infected macrophages was also done. The rate of growth in the cultures after exposure to ISO was similar to the usual growth rate. ISO was not bactericidal during exposure and growth began immediately after the drug was removed by washing. There was significant difference, after applying un-paired t-test ,in the bacterial count observed by exposure in INH 1 mcg/ml (24 hrs exposure) and ISO 10 mcg/ ml (24 hrs exposure) and 10 mcg/ml (96 hrs exposure) concentrations. Same observations made in pulse exposure study of ISO in macrophage cell line. Summarizing, the assessment of suitability for intermittent chemotherapy, it seems likely that ISO would be least satisfactory. Some caution must be expressed about extrapolating the results of in vitro experiments and to the treatment of human TB. There is no adequate substitute for clinical studies of intermittent treatment of pulmonary tuberculosis with ISO.