Antiparasitic efficacy of chalepensin from Ruta chalepensis L. Against Trichinella spiralis: In Vitro, In Vivo, and...

Ruta chalepensis L. is a medicinal species widely used in ethnomedicine for gastrointestinal disorders and parasitic diseases. Among its bioactive compounds, the furanocoumarins chalepensin and graveoline have shown antiparasitic activity. This study aimed to evaluate the nematocidal potential of graveoline and chalepensin, isolated from R. chalepensis, against Trichinella spiralis in both in vitro cultures and an experimental in vivo model. The compounds were obtained from leaves and stems and first tested against first-stage larvae (L1) in culture. Selectivity indices (SI) were calculated based on cytotoxicity in Vero cells. Based on in vitro efficacy, chalepensin was selected for evaluation in a murine model of trichinellosis at 50 mg/kg/day administered over three consecutive days against three different infection stages: intestinal (days 0-2), migrating (days 13-15), and encysted (days 34-36). Larvae per gram of muscle were quantified on day 43. Histological sections were analyzed for capsule morphology and inflammation. Additionally, molecular docking was performed to explore potential parasite targets. Both compounds exhibited superior activity compared to the R. chalepensis extract (LC₅₀ = 28.2 µg/mL; SI = 22.4). Chalepensin exhibited strong in vitro activity (LC₅₀ = 0.1 µg/mL; SI = 8561), superior to graveoline (LC₅₀ = 1.1 µg/mL; SI = 162). In vivo, chalepensin reduced larval burden by 90.7 % (intestinal), 37.5 % (migrating), and 37.0 % (encysted). Histology revealed reduced capsule thickness and pericystic inflammation. Docking predicted high affinity for thymidylate synthase (ΔG = -7.175 kcal/mol), suggesting interference with DNA synthesis. Chalepensin demonstrates potent nematocidal activity against T. spiralis, supporting its potential utility as a phytochemical-based therapeutic candidate for the management of trichinellosis.