Chemical composition and in vitro activity of Calotropis procera (Ait.) latex on Haemonchus contortus

- A new compound, 1-(2′,5′-dimethoxyphenyl)-glycerol, was isolated in ethyl acetate extract of Calotropis procera latex (EAECPL).
- EAECPL efficiently inhibited egg hatching, larval development and motility of the adult worms of Haemonchus contortus.
- Structural changes were not detected in the worm's cuticle treated with EAECPL.

Calotropis procera is among the species of medicinal plants that have traditionally been used for the treatment of parasites in small ruminants, stimulating the scientific validation of anthelmintic effects. This study aimed to investigate the chemical composition of ethyl acetate extract of Calotropis procera latex (EAECPL), assess the in vitro effect against Haemonchus contortus and the structural changes caused in the adult worm. The latex was collected, lyophilized and subjected to washing with the ethyl acetate solvent to obtain EAECPL. The constituents of the extract were isolated by column chromatography and identified by 13C and 1H nuclear magnetic resonance spectroscopy. The egg hatching test (EHT), larval development test (LDT) and adult worms motility test (WMT) were conducted to evaluate the effectiveness of EAECPL on eggs, larvae and adult of H. contortus, respectively. The worms obtained from the WMT, after 24 h exposure to EAECPL or controls were observed on a scanning electron microscope (SEM). The results were analysed by variance analysis and compared with Tukey's test (P < 0.05). Three compounds were isolated from EAECPL and identified as urs-19(29)-en-3-yl acetate, (3β)-Urs-19(29)-en-3-ol, and 1-(2′,5′-dimethoxyphenyl)-glycerol. In the EHT, EAECPL inhibited larval hatching by 91.8% at dose of 4 mg/ml. In the LDT 1 mg/ml inhibited 99.8% larval development. In the WMT, EAECPL in the concentration of 100 μg/ml inhibited 100% motility of worms, 12 h post-exposition. In the SEM, obvious differences were not detected between the negative control worms and the worms treated with EAECPL. In this study, EAECPL showed an effect on inhibition egg hatching, larval development and motility of the adult worms of H. contortus. This should be related both to the identified compounds, as well as the other compounds present in the EAECPL, acting alone or synergistically.