Submitted to: Grassland International Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/30/2000
Publication Date: 2/1/2001
Citation: Gustine, D.L., Sanderson, M.A., Gueldner, R.C. 2001. A strategy for detecting natural anthelmintic constituents of the grassland species plantago lanceolata. Grassland International Congress Proceedings. 19:464-465. Interpretive Summary: Farmers and researchers have observed that cattle feeding on the weed plantain (Plantago lanceolata) have fewer health problems caused by internal parasites such as the brown stomach worm (Ostertagia ostertagi). Scientists have suggested that this unproven observation is due to a natural medicinal called aucubin, which is made by the plantain plant. Research was conducted in Pennsylvania to determine whether plantain extracts and aucubin are toxic to the brown stomach worm in laboratory tests. Researchers found that extracts from plantain are toxic to the worms, but aucubin and pasture clippings were not. This proved that plantain contains extractable components that can kill the brown stomach worm, but that aucubin was not one of the components. Further research to identify the active components in plantain may lead to new treatments to control internal parasites in cattle and to improved plantain through plant tbreeding.
Technical Abstract: A strategy to detect anthelmintic constituents in plants using a bioassay-driven purification approach was tested in narrow leaf plantain (Plantago lanceolata), a palatable and nutritious plant species commonly found in grasslands. Reports in the literature suggest that plantain ingested by cattle can control or reduce internal parasite levels, possibly ydue to the iridoid glucoside aucubin. Lyophilized, ground leaves of wild P. lanceolata plants were extracted with 95% ethanol or boiling water containing calcium carbonate. Initial extracts or partially purified extracts recovered from charcoal treatment (0 to 250 mg ml-1), 5 Ug ml-1 of the anthelmintic levamisole, or 5 mg ml-1 of aucubin were bioassayed. Sheathed bovine parasites (Ostertagia ostertagi) were placed in wells of tissue culture plates containing 1 ml of test solution and incubated at room temperature in the dark for three days. The percent of moving worms was unchanged for water controls and reduced to 0% for levamisole. Initia extracts (about 150 mg), reduced the number of O. ostertagi to < 30% of control by day 3. Initial extracts from tall fescue and white clover foliage did not show anthelmintic effects. Partially purified plantain extracts had anthelmintic activity at concentrations of 150 to 250 mg ml-1, as did levamisole. Authentic aucubin significantly reduced the number of swimming worms at day 2, which returned to starting values at day 3. Partially purified extract (78 mg ml-1) in the presence or absence of B-glucosidase had activity < 30% of control in the bioassay. Thin-layer chromatography confirmed that aucubin was converted to its aglycone during the bioassay. If plantain fed to cattle has beneficial anthelmintic action, it is due to something other than aucubin.