Cholinesterase inhibitors

Acetylcholine is a neurotransmitter (a chemical which transmits nerve impulses or signals) in the brain and the peripheral nervous system. The enzyme cholinesterase functions to break down acetylcholine. When cholinesterase is inhibited, the continued presence of acetylcholine over-stimulates the post-synaptic nerve cell, causing the symptoms of poisoning that characterize the anti-cholinesterases. Synthetic insecticides in the organophosphate and carbamate group have the same mechanism of action.

Glycoalkaloids are naturally-occurring anti-cholinesterases, the most common of which are solanine and chaconine. These occur in plants of the genus Solanum, which includes potatoes, tomatoes, and eggplants. The total glycoalkaloid content in potato tubers varies with the variety, with the greatest concentration occurring in the sprouts, peelings, and sun-greened areas. Poisoning has resulted from ingestion of potato sprouts, sprouted potatoes, and greened potatoes. Symptoms of green potato poisoning include stomach pain, nausea, and vomiting, rapid and difficult respiration, and death. Glycoalkaloid levels of over 20 mg per 100 gram of fresh tissue are considered unsafe.¹ Cooked potatoes with elevated glycoalkaloid levels have been associated with a bitter flavor, and in controlled experiments levels higher than 11 mg per 100 g could be perceived by some individuals as a bitter flavor.² However, the flavor is not necessarily an indicator of toxicity, nor is the absence of a flavor an indication of a lack of glycoalkaloids.

References
Back to List of Endogenous Plant Toxins

Prepared Summer 1997 by Bernadene Magnuson, Ph.D.
University of Idaho, Dept. of Food Science and Toxicology - EXTOXNET FAQ Team.