Nematicidal activity of menthol and its dithiophosphoric derivatives

The effects of (–)-(1R,2S,5R)-menthol and its dithiophosphoric derivatives - O,O-di-(–)-menthyldithiophosphoric acid, its sodium, 8S,9R-quinine, (S)-(–)-nicotinic and pyridoxonium salts on the organism of the free-living soil nematode Caenorhabditis elegans were investigated. (–)-(1R,2S,5R)-menthol had no toxic effect on nematodes. O,O-di-(–)-menthyldithiophosphoric acid and its sodium salt caused dose-dependent death of nematodes. The toxic effect of these substances on the C. elegans organism developed with a lag-phase and reached its maximum value after 24 hours at concentrations of O,O-di-(–)-menthyldithiophosphoric acid and its sodium salt of 500 and 400 μg/mL, respectively. The LC50 values were 191.5 μg/mL for O,O-di-(–)-menthyldithiophosphoric acid, and 181.6 μg/mL for its sodium salt. 8S,9R-quinine, (S)-(–)-nicotinium and pyridoxonium salts of O,O-di-(–)-menthyldithiophosphoric acid were less toxic against C. elegans, causing 89.5–98.5% death of nematodes upon 24 hour exposure at a concentration of 2000 μg/mL. The study of the antihelmintic properties of (–)-(1R,2S,5R)-menthyl dithiophosphoric derivatives is promising for the creation of drugs both for the treatment of helminthiasis in domestic animals and humans, and as well as nematicides to control phytonematodes parasitizing in plants