Nematocidal activity of some anthelmintics, traditional medicines, and spices by new assay method using larvae of toxocara canis

A new assay method for the screening of nematocidal drugs using the larva of dog roundworm, Toxocara canis, and the usefulness of this method are described. By using this method, the nematocidal activities of more than 40 commercially available spices were compared with the activities of known anthelmintic drugs and traditional medicines used for the anthelmintic purpose. Most of the anthelmintic drugs, which are used for matured parasites, were found to be only slightly or not at all active by this method, while, most spices, particularly their methanol extracts, were appreciably effective against the larva. The structures of nematocidal principles occurring in some of these spices were quite different from those of known anthelmintics, implying that this new assay method will lead to the discovery of a new type of anthelmintic drugs which directly kill the nematodes.