Antiparasitic Activity of Silver Nanoparticles Synthesized from Artemisia cina Aqueous Extract Against Haemonchus contortus

Abstract

Parasitic infections, particularly those caused by Haemonchus contortus (H. contortus), severely impact livestock production, with growing resistance to commercial anthelmintics posing a major challenge. Green-synthesized metallic nanoparticles using Artemisia cina (A. cina), 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 A. cina to evaluate their anthelmintic activity against infective larvae (L3) of H. contortus 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, A. cina 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 SOD gene, highlighting its role in the oxidative stress response. In contrast, the expression levels of GPx and CAT genes were markedly downregulated. These results suggest that SOD could serve as a potential biomarker of oxidative stress induced by AgNPs in combination with A. cina metabolites, influencing the infective stages of H. contortus.