Larvicidal efficacy of silver nanoparticles synthesized biologically using Swietenia mahagoni (L.) Jacq. leaf extract against Anopheles stephensi, Culex quinquefasciatus and Cx. vishnui group

Mosquito borne diseases are a global crisis, particularly in developing countries. Non-availability of apposite vaccines against these diseases has lead to sole dependence on the vector managerial steps for dropping the incidences. In the present study, we tried to evaluate the larvicidal potential of biologically synthesized silver nanoparticles (Ag NP) using aqueous leaf extracts of Swietenia mahagoni (L.) Jacq. against third instar larvae of Anopheles stephensi, Culex quinquefasciatus and Culex vishnui group. Aqueous extract of leaves reduced the aqueous silver ions to produce stable Ag NP. The characterization of synthesized nanoparticles was done through UV-Vis spectrum, Transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscope. Third instar larvae of three mosquito species namely An. stephensi, Cx. quinquefasciatus and Cx. vishnui group were exposed to different concentrations of synthesized nanoparticles for 24, 48and 72 h. TEM measured the range of nanoparticle size as 8-9 nm whereas XRD measured as 6 nm. Cent percent mortality of larvae of An. stephensi was recorded at 80 ppm at 48 h. About 96 and 80% mortality of Cx. vishnui group and Cx. quinquefasciatus larvae respectively were noted at 80 ppm after 72 h of exposure. The result of regression analysis proved that the mortality rate (Y) was positively correlated with the period of exposure (X) and regression coefficients were close to one. Toxicity study on non-target species showed no injurious activity during experimental period. Results indicate, possibly a first report on mosquito larvicidal effect of Ag NP synthesized using S. mahagoni leaf extract which may be used to effectively control the larval forms of three important vector mosquitoes

Drug discovery in Tuberculosis: A molecular approach.

Summary: Despite unquestionable success of the combination drug therapy, tuberculosis (TB) very recently has drawn major attention because of the global upsurge of MDR-TB, XDR –TB and HIV-TB co-infection cases. In the last four decades, only one compound is added to the treatment regimen leaving ample opportunities to find out a new generation of TB drugs. The modern concept of drug discovery utilizes the integrated knowledge of genomics, proteomics, molecular biology and systems biology to identify more specific targets. The purpose of this review is to revisit the field of tuberculosis drug discovery based on those new concepts to identify novel targets.