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).
Uses
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.
