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

Overview

• This study investigates the anti-Theileria equi activity of methanolic extract derived from Artemisia scoparia, assessing its effectiveness in laboratory conditions, safety in live models, and identifying key active compounds.

Background

• Equine piroplasmosis is a disease transmitted by ticks that mainly affects horses.
• The disease is caused by two parasites: Theileria equi and Babesia caballi.
• Current primary treatment for T. equi infections involves imidocarb dipropionate, which carries risks of systemic toxicity, limiting its use.
• Artemisia annua is widely known for antimalarial properties; however, the medicinal potential of a related plant, Artemisia scoparia, especially against theileriosis, is less explored.

Research Objectives

• To evaluate the in vitro efficacy of methanolic extracts of Artemisia scoparia against Theileria equi.
• To assess the in vivo safety of the most active fraction of the methanolic extract in an animal model (mice).
• To identify the bioactive molecules responsible for antiparasitic activity using chromatographic and mass spectrometric methods.

Methodology and Key Findings

• Extraction and Fractionation:
  • Methanolic extract of Artemisia scoparia (ASME) was prepared, followed by activity-guided fractionation to isolate the methanolic fraction (MF-ASME) showing highest activity.
• In vitro efficacy:
  • MF-ASME demonstrated the ability to inhibit growth of Theileria equi with an IC₅₀ value of 52.67 µg/mL (concentration that inhibits 50% of parasite growth).
  • Low cytotoxicity was observed against horse peripheral blood mononuclear cells (PBMCs) with a CC₅₀ (concentration toxic to 50% of cells) of 238.2 µg/mL.
  • The selectivity index, indicating safety margin between toxicity to host cells and parasite inhibition, was calculated as 4.52, suggesting favorable selectivity.
• In vivo safety assessment:
  • MF-ASME was administered to mice at a safety dose of 250 mg/kg.
  • No significant organ toxicity or adverse effects on organ function biomarkers were detected, indicating a good safety profile.
• Compound identification:
  • High Performance Liquid Chromatography (HPLC) and Liquid Chromatography–Mass Spectrometry/Mass Spectrometry (LC-MS/MS) analyses revealed 17 bioactive compounds in MF-ASME.
  • Primary antimalarial-related compounds identified included artemisinin, artemether, and dihydroartemisinin, known for their antiparasitic properties.

Significance and Potential Applications

• The study validates Artemisia scoparia, particularly its methanolic fraction, as a promising natural source for developing new treatments against equine theileriosis.
• MF-ASME shows both effective anti-parasitic activity and safety in preclinical models, advantages over existing treatments limited by toxicity.
• The identification of well-known antimalarial compounds suggests potential mechanisms of action and supports further pharmacological investigation.
• This work lays the foundation for future in vivo efficacy studies in horses and possible clinical development of botanical therapies for tick-borne equine diseases.

Conclusion

• Methanolic fraction of Artemisia scoparia demonstrates notable in vitro inhibition of Theileria equi and shows safety in animal models.
• The presence of established antimalarial agents within this fraction highlights its therapeutic potential.
• Further research is warranted to develop MF-ASME as a novel, safer treatment option for equine theileriosis.