Purpose: Terpenoid compounds found in natural plant products have been shown to have biocidal activity against agricultural, human health and veterinary pests. Specific neurological activity has been found to be highly variable between different terpenoids acting on different organisms and receptors. This research effects of plant terpenoids on the nematode neuro-receptor, ACR-16, from Ascaris suum. We tested multiple plant derived terpenoids against the ACR-16 receptor. Methods: Receptors were expressed in oocytes from Xenopus lavis. We used two electrode voltage clamp to test the receptor response when exposed to a mix of the natural agonist, acetylcholine, and a test terpenoid. Concentration response characterizations were performed at 100 µM and 10 µM concentrations of the terpenoid compounds. Results: No terpenoid tested showed agonist activity on the ACR-16 receptor. Most compounds tested showed a significant inhibition of the acetylcholine response. EC50 values of the acetylcholine response were not changed, however, the maximal current was significantly lower than the acetylcholine control for many terpenoids even at the lower concentration. Isomer terpenoids, geraniol and nerol, showed differential antagonism of the maximal current. Conclusions: Many terpenoids were shown to have antagonistic neuro-modulatory activity at the ACR-16 receptor. The differential response to isomeric terpenoids suggests that there is a specific binding site tied to this activity.

Plant terpenoids as a source of novel nematicides

2019 Fall National Meeting

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