In vitro studies were carried out to investigate anthelmintic activities of two commercial tannin preparations, quebracho (QT) and wattle (WT), against a freshly isolated mouse nematode (Heligmosomoides polygyrus) and goat nematodes (Haemonchus contortus and Oesophagostomum columbianum). The worms were incubated at 38 – 39 °C in culture media containing varying concentrations of the tannins. Worm activity was monitored for 48 h and the time taken for individual worms to die was recorded. Survival of the nematodes was significantly reduced by the addition of the tannin preparations to the culture media. Addition of polyethylene glycol (PEG), which binds and inactivates tannins, to media containing tannins significantly increased the survival time of the worms, suggesting that the toxicity of the extracts was at least partially due to the tannins. Worms dying in cultures containing QT or WT had darkly stained guts, an indication that death was due to ingestion of the tannins in the media. These results support the hypothesis that tannins in commercial extracts could have direct toxic effects on parasitic nematodes.
"Experientia docet" - Experience is the best teacher