Ergot

From Freepedia

Ergot refers to the Claviceps ascomycete fungus. Claviceps is parasitic on certain grains and grasses. The form the fungus takes to over-winter is called a sclerotium, and this small structure is what is usually referred to as 'ergot', although referring to the members of the Claviceps genus as 'ergot' is also correct. There are about 50 known species of Claviceps, most of them in the tropical regions. Economically important species are Claviceps purpurea (grasses and cereals), Claviceps fusiformis (pearl millet, buffel grass), Claviceps paspali (dallis grass), and Claviceps africana[1](sorghum). C. purpurea can affect a number of cereals including rye (its most common host), triticale, wheat and barley. It affects oats only rarely. There are three races or varieties of C. purpurea, differing in their host specifity [2]: G1 - land grasses of open meadows and fields; G2 - grasses from moist, forest and mountain habitats; G3 (C. purpurea var. spartinae) - salt marsh grasses (Spartina, Distichlis).

Contents

Life cycle of the fungus

An ergot kernel called sclerotium develops when a floret of flowering grass or cereal is infected by a spore of Claviceps fungus. The infection process mimicks a pollen grain growing into an ovary during fertilization. The fungus then destroys the plant ovary and attaches itself on a vascular bundle originally intended for seed nutrition. The first stage of ergot infection manifests itself like a white soft tissue producing sugary honeydew, that often drops out of florets. Honeydew contains millions of asexual spores (conidia) which are dispersed to other florets by insects. Later, sphacelia converts into a hard dry sclerotium inside the husk. At this stage, alkaloids and lipids are accumulating in the sclerotium. When mature sclerotium drops to the ground, the fungus remains dormant until proper conditions trigger its fruiting phase (onset of spring, rain period, etc.). It germinates forming one or several structures with head and stipe, variously colored (resembling tiny mushroom). In the head, sexual threadlike spores are formed, which are ejected at the same time, when suitable grass hosts are flowering. Ergot infection causes a reduction in the yield and quality of grain and hay produced, and if infected grain or hay is fed to livestock it causes a disease called ergotism.

Black and protruding sclerotia of C. purpurea are well known. However, many tropical ergots have brown or greyish sclerotia, mimicking the shape of the host seed, therefore the infection is often overlooked.

Effects on humans and animals

Ergot contains alkaloids of the ergoline group, which have a wide range of activities including effects on circulation and neurotransmission. Ergotism is the name for the collection of symptoms a human or animal has when it has ingested (too much of) this fungus. Ergotism went also under the name "St. Anthony's fire" hinting at burning sensations in the limbs[3]. Another of ergot alkaloid effects is vasoconstriction, therefore, ergotism may lead to gangrene and loss of the limbs due to limited blood circulation. This may also cause insanity, convulsions, or death, due to limited circulation to the brain. Other symptoms include strong uterine contractions, nausea, seizures, and unconsciousness. Monks of the order of St. Anthony_the_Great specialized in treating ergotism victims with balms containing tranquilizing and blood circulation stimulating plants; they were also skilled in amputations. Entire villages have been known to suffer ergotism after the village bakery used infected grain.

In addition to ergot alkaloids, Claviceps paspali produce also tremorgens (paspalitrem) causing "paspalum staggers" in cattle.

Historically, controlled doses of ergot were used to induce abortions and to stop maternal bleeding after childbirth, but simple ergot extract is no longer used as a pharmaceutical.

Among those who studied ergot and its derivatives was Albert Hofmann, whose experiments led to the discovery of LSD, a powerfully hallucinogenic ergot derivative that affects the serotonin system. Contrary to some rumors, ergot contains no LSD, but there are links between the two substances:

  • LSD was first synthesised during research on the active ingredients of ergot.
  • Lysergic acid, a raw material used in the synthesis of LSD, was and is still prepared from ergot.

History

The disease cycle of the ergot fungus was first described in the 1800s, but the connection with ergot and epidemics among people and animals was known several hundred years before that.

Human poisoning due to the consumption of rye bread made from ergot-infected grain was common in Europe in the Middle Ages. The phenomenon known as Dancing mania has been blamed on accidental consumption of the fungus.

It has also been posited — though speculatively — that the Salem Witch Trials were initiated by young women who had consumed ergot-tainted rye.

Kykeon, the beverage consumed by participants in the ancient Greek mystery of Eleusinian Mysteries, might have been based on hallucinogens from ergot.

Nowadays, rye grain is infected repeatedly to produce ergot.

External links

Psychedelic lysergamides edit

LSD | Ergine | Ergoline | Ergonovine

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