Biological activity of Juglans regia leaf extract and in silico evaluation of its phytochemicals against Plasmodium berghei target proteins

Parasitic infections remain a major global health challenge, with helminthiasis causing significant morbidity and economic losses. Limitations of synthetic anthelmintics, such as resistance and toxicity, have encouraged the search for natural plant-based alternatives. Juglans regia (walnut) leaves are rich in bioactive phytochemicals with potential antiparasitic effects. This study aimed to evaluate the anthelmintic efficacy of the methanolic leaf extract of J. regia (JRLE) against Eisenia fetida and to assess, through molecular docking, the potential interactions of its phytochemicals with selected Plasmodium berghei proteins. Fresh J. regia leaves were extracted with 70 % methanol using a maceration technique for 48 h at room temperature to obtain the crude extract. Adult E. fetida worms were treated with JRLE at concentrations of 50, 100, and 200 mg/ml, using mebendazole (10 mg/ml) as a reference and distilled water as a control. Paralysis and death times were recorded, and histological examinations were conducted to assess structural alterations in the worm cuticle. Phytochemicals identified in JRLE were docked against P berghei target proteins (Profilin, L-lactate dehydrogenase, Cytochrome c oxidase, Cytochrome b, and Pyridoxal 5’-phosphate synthase subunit) using Schrodinger Glide XP. JRLE exhibited significant dose-dependent anthelmintic activity, with the 200 mg/ml concentration inducing paralysis and death faster than mebendazole. Histological findings revealed cuticular erosion, epidermal vacuolization, and partial detachment of the cuticle from underlying tissues in treated worms. Molecular docking analysis revealed favorable binding interactions of compounds such as γ-sitosterol, stigmasterol, 3-O-methyl-D-glucose, and 4H-pyran-4-one derivatives with P. berghei target proteins, with docking scores ranging from approximately -4.494 to -9.799 kcal/mol, indicating stable ligand-protein complexes and suggesting potential antiplasmodial activity based on the in silico analysis. These findings demonstrate that JRLE exhibits promising anthelmintic activity and shows in silico evidence of potential antiplasmodial effects; however, further in vitro and in vivo investigations are necessary to validate the efficacy of its phytochemicals against Plasmodium species.