Antiparasitic Activity of Silver Nanoparticles Synthesized from <i>Artemisia cina</i> Aqueous Extract Against <i>Haemonchus contortus</i>.

Abstract

Parasitic infections, particularly those caused by <i>Haemonchus contortus</i> (<i>H. contortus</i>), severely impact livestock production, with growing resistance to commercial anthelmintics posing a major challenge. Green-synthesized metallic nanoparticles using <i>Artemisia cina</i> (<i>A. cina</i>), a plant with known anthelmintic and antioxidant properties, represent a promising sustainable alternative for parasite control. In this study, silver nanoparticles (AgNPs) were synthesized using an aqueous extract of <i>A. cina</i> to evaluate their anthelmintic activity against infective larvae (L3) of <i>H. contortus</i> and their effect on the expression of oxidative stress-related genes. The larval mortality bioassay was conducted in 96-well microtiter plates by incubating L3 larvae with increasing AgNP concentrations for 24 h. To investigate oxidative stress responses, larvae were exposed to sublethal concentrations of AgNPs, <i>A. cina</i> aqueous extract, AgNO₃, and H₂O₂. Expression levels of SOD, GPx, and CAT genes were then quantified by RT-qPCR at multiple post-exposure time intervals. The synthesis was optimized by varying parameters such as pH, temperature, and extract volume. The nanoparticles were characterized using UV-Vis spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), and Electrophoretic Light Scattering (ELS). Overall, synthesis at pH 8 yielded small, spherical, stable, and abundant AgNPs. In vitro assays on L3 larvae showed a mortality rate of 91.33% at the highest AgNP concentration (500 μg/mL), with lethal concentration (LC50 and LC90) values of 4.128 ppm (μg/mL) and 17.993 μg/mL, respectively. Relative expression analyses revealed that AgNPs induced the overexpression of the <i>SOD</i> gene, highlighting its role in the oxidative stress response. In contrast, the expression levels of <i>GPx</i> and <i>CAT</i> genes were markedly downregulated. These results suggest that <i>SOD</i> could serve as a potential biomarker of oxidative stress induced by AgNPs in combination with <i>A. cina</i> metabolites, influencing the infective stages of <i>H. contortus</i>.