Bioactivity-guided isolation and identification of Sclareol as a potent anthelmintic compound from Salvia sclarea L against Haemonchus contortus.

Salvia sclarea has been traditionally valued in herbal medicine for its antimicrobial and therapeutic properties; however, its potential as an anthelmintic agent remains largely unexplored. Considering the growing problem of resistance to synthetic drugs such as Albendazole, there is an urgent need to validate the traditional anthelmintic claim of plants and plant-based derivatives. The aim of the study was to isolate bioactive anthelmintic compounds (against Haemonchus contortus) through bioactivity-guided fractionation from ethyl acetate extract of Salvia sclarea. Ethyl acetate extract of S. sclarea was subjected to silica gel column chromatography, and fractions were screened using egg hatch test (EHT) and adult mortality test (AMT) with Haemonchus contortus parasite. The most active fraction was further purified, and the isolated compound was structurally characterized using Fourier Transform Infrared (FTIR), Nuclear Magnetic Resonance (¹H NMR and ¹³C NMR), and Time-of-Flight Mass Spectrometry (TOF-MS). Ultrastructural alterations in parasites were examined using scanning and transmission electron microscopy. Bioassay-guided fractionation led to the isolation of a labdane-type diterpenoid identified as sclareol. The compound exhibited significant dose-dependent egg hatch inhibition (74.33 ± 1.45% at 400 µg/mL) and induced 100% adult mortality within 90 min at the same concentration. Microscopic analyses revealed severe tegumental disruption, hypodermal damage, mitochondrial degeneration, and cytoplasmic vacuolization in treated parasites, indicating both surface and intracellular modes of action as revealed by SEM & TEM studies. The findings provide pharmacological evidence supporting the potential of Salvia sclarea as a source of plant-based anthelmintic agent and can emerges as a promising bioactive compound, reinforcing the relevance of ethnomedicinal plants as sustainable alternatives to conventional anthelmintics.