Red Aroeira (Schinus terebinthifolia)-based zinc oxide nanoparticles: A green approach to combat fish pathogens

Aquaculture production is often linked to improper use of chemotherapeutic agents for pathogen control, leading to adverse effects in organisms and environment. As an alternative over these toxicological agents, in this study we propose the development of zinc oxide (ZnO) nanoparticles using ethanolic extract of red Aroeira (Schinus terebinthifolia) (EERA) and tested them against fish pathogens. Green synthesized ZnO nanoparticles had a mean hydrodynamic diameter of ca. 150 nm, and showed a broad-spectrum antibacterial activity, as well as antifungal and antiparasitic activities against Saprolegnia parasitica and Ichthyophthirius multifiliis, at the highest tested concentrations (10 and 15 mg/mL). The extract alone showed antibacterial activity against Aeromonas hydrophila, but not against Streptococcus agalactiae, suggesting a synergistic effect between EERA and ZnO nanoparticles. These findings demonstrate that green ZnO nanoparticles hold significant potential as a multifunctional antimicrobial agent for managing various pathogens in aquaculture, offering an environmentally friendly alternative to conventional chemotherapeutics.