Anti-Theileria equi activity of methanolic extract of Artemisia scoparia: In vitro efficacy, in vivo safety, and identification of lead molecules.

Equine piroplasmosis is a tick-borne disease that affects horses and is caused by Theileria equi and Babesia caballi. Currently, imidocarb dipropionate is the primary treatment for T. equi infections; however, its application is limited by its potential systemic toxicity. Artemisia annua is widely recognised for its antimalarial properties, whereas Artemisia scoparia has traditionally been used for various medicinal purposes. However, the therapeutic potential of A. scoparia against theileriosis in animals remains largely unknown. Activity-guided fractionation of a methanolic extract of A. scoparia (ASME) identified the methanolic fraction (MF-ASME) as the most active against T. equi in vitro (IC₅₀: 52.67 µg/mL). MF-ASME exhibited low cytotoxicity in horse PBMCs (CC₅₀: 238.2 µg/mL), resulting in a favourable selectivity index of 4.52. Organ toxicity assessment in a mouse model confirmed the safety of MF-ASME at the safety dose (SD: 250 mg/kg). Biomarker analysis confirmed its safety, with no significant adverse effects on organ function. HPLC and LC-MS/MS analyses identified 17 bioactive compounds in MF-ASME, with artemisinin, artemether, and dihydroartemisinin as the primary antimalarial agents. These results support the potential of MF-ASME for further therapeutic development against equine theileriosis.