Biosynthesized silver nanoparticles using floral extract of Chrysanthemum indicum L.--potential for malaria vector control.

Mosquitoes transmit serious human diseases, causing millions of deaths every year. The use of synthetic insecticides to control vector mosquitoes has caused physiological resistance and adverse environmental effects in addition to high operational cost. Insecticides synthesized of natural products for vector control have been a priority in this area. In the present study, silver nanoparticles (Ag NPs) were green-synthesized using a floral extract of Chrysanthemum indicum screened for larvicidal and pupicidal activity against the first to fourth instar larvae and pupae of the malaria vector Anopheles stephensi mosquitoes. The synthesized Ag NPs were characterized by using UV-vis absorption, X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray spectroscopy techniques. The textures of the yielded Ag NPs were found to be spherical and polydispersed with a mean size in the range of 25-59 nm. Larvae and pupae were exposed to various concentrations of aqueous extract of C. indicum and synthesized Ag NPs for 24 h, and the maximum mortality was observed from the synthesized Ag NPs against the vector A. stephensi (LC50 = 5.07, 10.35, 14.19, 22.81, and 35.05 ppm; LC90 = 29.18, 47.15, 65.53, 87.96, and 115.05 ppm). These results suggest that the synthesized Ag NPs have the potential to be used as an ideal eco-friendly approach for the control of A. stephensi. Additionally, this study provides the larvicidal and pupicidal properties of green-synthesized Ag NPs with the floral extract of C. indicum against vector mosquito species from the geographical location of India.

Characterization of ambrette seed oil and its mode of action in bacteria.

In the present study, chemical composition and the antibacterial mechanism of ambrette seed oil are investigated. Chemical composition of the oil was analysed by gas chromatography-mass spectrometry (GC-MS). Thirty-five compounds were identified and the major compounds were found to be farnesol acetate (51.45%) and ambrettolide (12.96%). The antibacterial activity was performed by well diffusion assay and the mechanisms were studied by measuring the alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and protein leakage assays. The antibacterial effect of the ambrette seed oil showed inhibitory effect against Bacillus subtilis, Staphylococcus aureus and Enterococcus faecalis. The LDH activity was high in all tested bacteria compared with control, whereas the ALP and protein concentrations were also increased in E. faecalis. Molecular docking revealed the ligands farnesol acetate and ambrettolide had satisfactory binding energy towards the beta lactamase TEM-72 and dihydrofolate reductase (DHFR) protein. Due to its better antibacterial properties, the ambrette seed oil could be used as a source of antibacterial agents.