Alkaloids, ergot

Description

The ergot alkaloids are found within the sclerotium of the fungus Claviceps purpurea. The sclerotium is the hard tuberlike resting stage of this fungus and is a dark gray, purple, or black cylindrical structure measuring 1.5 cm in length and 0.5 cm in width. Claviceps purpurea may be found on a number of different grains, with rye contamination most often reported. A cold winter followed by a wet spring favors germination. If the sclerotia are not removed from contaminated grain by beating or sieving, humans or animals may accidentally ingest them.
The earliest documented case of ergotism occurred in AD 857 in the Rhine Valley. The symptoms were called ‘Holy Fire’ because of the burning sensation in the extremities and the belief that it was a punishment from God. It later became known in the Middle Ages as St. Anthony’s Fire after the monks of St. Anthony’s order began providing treatment with some success. The cause remained unknown and widespread epidemic of ergotism continued to erupt every 5 to 10 years for several millennia. However, in 1670, a French physician proposed that the symptoms of St. Anthony’s Fire were due to the consumption of ergot-infected rye. With this discovery, harvesting methods became more adept at removing the sclerotia of C. purpurea. While ergotism has since become rare, recent outbreaks have occurred in Germany (1879–81), Russia (1926–27), and Ethiopia (1977–78).

The Uses of Alkaloids, ergot

Ergot was used as early as the sixteenth century to strengthen uterine contractions. Currently, ergotamine tartrate is combined with caffeine and administered to relieve migraine headaches. Ergonovine has been used to treat postpartum hemorrhage. Derivatives of ergots are used to manage amenorrhea and as an adjunct in the treatment of Parkinson’s disease. Hydrogenated ergot alkaloids have been used for symptoms of idiopathic mental decline in elderly patients, but have also been linked to an increased risk of leaky heart valves.

Environmental Fate

Certain ergot alkaloids are not heat stable and exposure to high temperatures such as in baking bread will reduce concentrations significantly. Inactive ergot alkaloids are more resistant to heat and may survive processing. Prior to preparation, milling of the grain will remove the sclerotia as well so that most prepared foods have very low levels of ergot alkaloids.

Toxicity evaluation

The pharmacological mechanisms associated with ergot toxicity are complex and have not been fully delineated. Ergotamine interacts with serotonergic, dopaminergic, and a-adrenergic receptors. In the central nervous system, ergots have a sympatholytic effect. They also stimulate serotonergic receptors, which contributes to its hallucinogenic activity. Peripherally, ergots act as a-adrenergic agonists resulting in peripheral vasospasm. The vasoconstrictive action of ergots can produce widespread arterial spasm. Endothelial injury associated with arterial spasm may cause local thrombosis and subsequent gangrene.