Toxic Principle

Gelsemium species contain the neurotoxic alkaloids gelsemine, gelsemicine, gelsedine, gelseverine, and gelseminine. The indole, sempervirine, is also considered a significant toxic component. The alkaloids are found in all parts of the plant, especially in the flowers and roots. The alkaloids act on nerve endings causing paralysis, muscle weakness, and clonic convulsions. At high doses the alkaloids act centrally on the nervous system against gamma-amino butyric acid (GABA) causing convulsions and respiratory failure. Livestock are at greatest risk of eating the plants in winter as the plants are evergreen and the leaves are attractive when all other forage is not.

Description

There are two North American and one Asian species of Gelsemium. These evergreen, twining or trailing, perennials, have lanceolate to elliptic, shiny, green leaves with solitary, or 2-5 flowered cymes. The flowers are showy, fragrant, trumpet-shaped, bright yellow with five sepals, and 5 fused petals. Fruits are ovoid capsules with a short beak. The seeds are brown, flattened, and generally winged.

Musculoskeletal

Muscle weakness, muscle tremors

Treatment

Activated charcoal orally to help prevent further absorbtion of the toxic alkaloids. Convulsions may be controlled by the use of diazepam or pentobarbital.

Respiratory System

Decreased respirations and eventual respiratory paralysis and death.

Nervous System

In animals acutely poisoned by Gelsemium species, neurologic signs predominate, and are characterized by progressive weakness, convulsions, respiratory failure and death. Postmortem lesions are nonspecific. Histologically evidence of mild diffuse neuronal and cerebellar Purkinje cell loss with vacuolation of the brainstem and cerebral white matter may be present.

Special Notes

Carolina jessamine is commonly grown as a garden plant for the profusion of yellow flowers it produces in the summer. Cases of human poisoning are reported and in Asia the plant has been used for suicidal purposes. The risk of household pets being poisoned by eating the plant is minimal. Most cases of poisoning occur in livestock including geese that may graze on plant trimmings or the plant growing in or near their enclosure. References: 1. Saxton JE. Alkaloids of Gelsemium species. In The Alakaloids: Chemistry and Physiology. Vol 8. Manske RHF (ed). Academic Press, New York. 1965; 93-117. 2. Thompson LJ, Frazier K, Stiver S, Styer E. Multiple animal intoxications associated with Carolina jessamine (Gelsemium sempervirens) ingestions. Vet Hum Toxicol. 2002; 44:272-3. 3. Williamson JH,Craig FR,Barber CW, Cook FW. Some Effects of Feeding Gelsemium sempervirens (Yellow Jessamine) to Young Chickens and Turkeys Avian Diseases 1964, 8:183-190. 4. Blaw ME, Adkisson MA, Levin D, Garriott JC, Tindall RS. Poisoning with Carolina Jessamine(Gelsemium sempervirens [L.] Ait.). J Pediatr. 1979;94:998-1001.