Utilization of herbivore defensive latex from the weed Calotropis procera L in the green synthesis of silver nanoparticles and its potential application in the control of dengue vector Aedes aegypti

Abstract

Milky latex produced by few and not all the plants are the treasure chest of various bioactive compounds with defensive potential against herbivores, insects and pathogens. Mankind have utilized latices in the preparation of novel plant-based therapies for centuries. Therefore, an attempt has been made to synthesis silver nanoparticles (AgNPs) using AgNO₃ as a precursor and latex from C. procera as a reducing agent. The surface plasmon absorption peak at 430 nm confirmed AgNPs formation. The sharp peak with narrow width illustrated the homogenous nature. The face centre cubic structure of AgNPs was confirmed by the XRD pattern. FT-IR analysis deduced that the bio-molecules in the latex of C. procera are responsible for the reduction of AgNO₃ to AgNPs. Biosynthesised L-AgNPs possessed well pronounced antibacterial activity against P. aeruginosa and K. pneumoniae. Anti-inflammatory activity of the nanoparticle determined by membrane stabilization and proteinase inhibitory assay was found to be in dose-dependent. LC₅₀ value of L-AgNPs was found to be 63.09 µg/mL against IV instar larvae of A. aegypti. Distinct morphological changes were observed in the mosquito larva on exposure to various concentrations of L-AgNPs.