Metabolic Enzyme Inhibitory and Larvicidal Activity of Biosynthesized and Heat Stabilized Silver Nanoparticles Using Annona muricata Leaf Extract

Abstract

The synthesis of silver nanoparticles (AgNPs) using Annona muricata (A. muricata) leaf extract and its larvicidal, metabolic enzyme inhibitory properties was demonstrated here. The AgNPs were synthesized and analyzed by using UV-visible spectroscopy and observed a maximum absorbance peak at 420 nm which corresponds to the AgNPs. The XRD analysis showed the 2θ intense values (111, 200, 220, and 311) within the ranges of Bragg’s reflection; Fourier transform infrared spectroscopy (FTIR) showed that AgNPs were capped with alkanes, amides, and alkenes functional groups which act as a reducing, capping, and stabilizing agent; and field emission scanning electron microscope (FESEM) and high-resolution transmission electron microscopy (HRTEM) results indicated that synthesized AgNPs were spherical in shape with the size of 20–34 nm and energy-dispersive X-ray (EDX) spectroscopy exhibited a strong signal of silver. Various concentrations of AgNPs (6, 12, 18, 24, 30 μg mL−1) and aqueous leaf extract (ALE) (30, 60, 90, 120, 150 μg mL−1) were evaluated, and in all the concentrations, AgNPs showed significant larvicidal properties against three different second instar larvae, when compared to ALE. ALE exhibited LC50 and LC90 values of (LC50 45.521 μg/mL; LC90 456.406 μg/mL) against Ae. aegypti followed by An. stephensi (LC50 61.878 μg/mL; LC90 565.309 μg/mL) and Cx. quinquefasciatus (LC50 68.952 μg/mL; LC90 444.512 μg/mL), and AgNPs were exhibited LC50 and LC90 values (LC50 3.089 μg/mL; LC90 18.467 μg/mL) against Ae. aegypti followed by An. stephensi (LC50 3.155 μg/mL; LC90 39.888 μg/mL) and Cx. quinquefasciatus (LC50 5.188 μg/mL; LC90 31.660 μg/mL), respectively. The A. muricata leaf extract-mediated AgNPs were also evaluated for the first time to identify their metabolic enzyme inhibitory activity which also showed significant results.