Direct anthelmintic effects of a purified chicory extract against free-living stages of Cooperia oncophora: preliminary results

Direct anthelmintic effects of a purified extract from chicory (Cichorium intybus L.) were assessed on eggs and first-stage larvae (L1) of C. oncophora. Chicory leaves (cv. Spadona) were collected from an organic dairy farm in Denmark. Dried leaf tissue was extracted in a Soxhlet apparatus with methanol as the extraction medium. The resulting extract was dried and fractionated using solid-phase extraction (SPE) cartridges to enhance isolation of secondary metabolites such as sesquiterpene lactones. The obtained elutate was dried, dissolved in 100 % DMSO and serially diluted to obtain concentrations ranging from 5 to 0.12 mg dry matter (DM)/mL. Two Jersey calves (4 months old) mono-infected with C. oncophora were used for collection of nematode eggs. Isolated eggs were used in an egg hatch assay (EHA) with 6 concentrations of the chicory extract (tested in duplicates, final DMSO concentration of 2%). Thiabendazole (1000 μg/ml) and 2 % DMSO in water were used as positive and negative controls, respectively. After 48 hours of incubation (25oC), the percentage of hatched L1 in negative controls was > 90%. Hatching percentages were dramatically decreased in the presence of the chicory extract, with more than 95% inhibition at concentrations ≥ 2.5 mg DM/mL, and an EC50 value of 0.64 mg DM/mL. After 48 hours of incubation, 11% of the hatched L1 in the negative controls were dead, while 95 % and 65% of hatched L1 were dead in the presence of chicory extract at 0.31 and 0.12 mg DM/mL, respectively. All hatched L1 were found dead in the presence of the chicory extract at concentrations > 0.31 mg DM/mL. These results show that chicory can have a significant anthelmintic effect against cattle nematodes. Further studies are ongoing to characterize the active compounds in the extract, and determine the mechanism of nematocidal action.