Simarouba berteroana Krug & Urb. Extracts and Fractions Possess Anthelmintic Activity Against Eggs and Larvae of Multidrug-Resistant Haemonchus contortus

Gastrointestinal nematode infections significantly impact small ruminant production, causing substantial economic losses worldwide. The rising resistance to anthelmintics has led to the search for alternative treatments, including phytotherapeutic approaches. This study investigates the chemical composition and anthelmintic activity of crude extracts and fractions from Simarouba berteroana, an endemic plant from Hispaniola, against a multidrug-resistant isolate of Haemonchus contortus. Chemical analyses revealed high contents of phenolic compounds, tannins, and flavonoids and confirmed the presence of 22 quassinoids, 5 phytosterol lipids, 3 terpenoid quinones, 3 alkaloids, and 1 naphthoquinone. The hydroalcoholic and iso-butanol fractions showed the strongest egg hatching inhibition (IC50 = 0.93 and 1.21 mg/mL, respectively), while hexane fractions were less effective (p < 0.05). Fluorescence microscopy showed that the extracts and fractions adhered to eggshells, causing evisceration and cuticle detachment in hatched larvae. All extracts, except for hexane fractions, inhibited larval exsheathment at 0.3 mg/mL, with phenolic compounds being responsible for this effect. These results provide the first evidence of the ovicidal and larval exsheathment inhibition activities of S. berteroana extracts and fractions against H. contortus, highlighting their potential in managing gastrointestinal nematodes in small ruminants. Further in vivo studies are needed to confirm these findings.