Biosynthesis of Cholinesterase-inhibitory Substances from Non-inhibitory Dialkyl Thiophosphates by Plant Tissues

Aqueous solutions of the potassium salts of diethyl thiophosphate and diethyl dithiophosphate were applied to intact leaves of the following 10 plant species: alfalfa (Medicago saliva L.), carrot (Daucus carota L.), strawberry (Fragaria chiloensis, Duchesne), American elderberry (Sambucus canadensis L.), velvetleaf (Abutilon theophrasti Medic.), dandelion (Taraxacum officinale Weber), soybean (Glycine max, Merr.), lima bean (Phaseolus limensis Macf.), catnip (Nepeta cataria L.), and Virginia creeper (Hedera quinquefolia L.). After 24 to 72 hours, aqueous homogenates of all species, excepting carrot, inhibited the action of human plasma cholinesterase in vitro. Neither the plant homogenates nor the thiophosphate salts either separately or mixed brought about inhibition. It is postulated that dialkyl thio- or dithiophosphates are incorporated by intact living plant tissue into cholinesterase-inhibitory esters

A Preliminary Survey of Some Midwestern Plants for Substances Inhibiting Human Plasma Cholinesterase in Vitro

Substances which inhibit the action of human plasma cholinesterase in vitro have been found in aqueous extracts of various members of the plant family Solanaceae. A preliminary survey of some weedy and cultivated midwestern representatives of this family revealed eleven active species in six genera: Datura, Lycopersicon, Nicotiana, Petunia, Physalis, and Solanum. A member each of the genera Capsicum and Lycium were inactive. Inhibitory substances were not found in thirty-one species representing nineteen plant families other than Solanaceae