Nematicidal effect of plumbagin on Caenorhabditis elegans: a model for testing a nematicidal drug.

Plumbagin, (5-hydroxy-2-methyl-1,4-naphthoquinone), a natural substance found in the roots of plant species in the genus Plumbago, has been used as a traditional medicine against many diseases. In this study, Caenorhabditis elegans was used as a model for testing the anthelmintic effect of plumbagin. The compound exhibited a nematicidal effect against all stages of C. elegans: L4 was least susceptible, while L1 was most susceptible to plumbagin with an LC50 of 220 and 156 mu M, respectively. Plumbagin inhibited C. elegans development from L1 to adult stages with an IC50 of 235 mu M, and body length was also reduced at concentrations of 25 and 50 mu g/ml. Brood sizes decreased from 203 +/- 6 to 43 +/- 6 and 18 +/- 3 eggs per hatch in plumbagin-treated worms at 10, 25, 50 mu g/ ml, respectively. Furthermore, plumbagin was lethal to strains resistant to the nematicides levamisole, albendazole, and ivermectin, indicating that it possesses a strong and unique nematicidal action. Plumbagin decreased the number of mitochondria in hypodermal and intestinal cells and body wall muscles and damaged the ultrastructure of these tissues. Taken together, plumbagin may be a new drug against parasitic nematodes.