Ergot and ergotism

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Ergot and ergotism

Ergot is the seedlike body of fungi (molds) of the genus Claviceps; ergotism is a complex disease of humans and certain domestic animals caused by ingestion of grains and cereals infested with ergot. Ingestion of these long, hard, purplish-black structures called sclerotia may lead to convulsions, abortion, hallucinations, or death. During the Middle Ages, hundreds of thousands of people are believed to have died from this disease, often referred to as holy fire, St. Anthony's fire, or St. Vitus' dance. Epidemics in humans, although less prevalent in modern times, last occurred in 1951, and the potential danger is always present, as shown by annual livestock losses due to ergot poisoning. There are 32 recognized species of Claviceps, most of which infect members of the grass family. Only three species are parasitic on the rushes and sedges. See Plant pathology

Sclerotia have an unusual chemical makeup. They carry only 10% water by weight, and 50% of the dry weight is composed of fatty acids, sugars, and sugar alcohols, which make the ergot a storehouse of energy. Unfortunately, they also contain the poisonous alkaloids, ranging from 0 to 1.2% of the dry weight.

There are three types of ergotism (gangrenous, convulsive, and hallucinogenic). Their symptoms often overlap; the hallucinogenic form is usually observed in combination with one of the other two. The unusual combination of gangrenous and convulsive symptoms is sometimes observed in the Balkans and areas near the Rhine River.

The hallucinogenic form often includes symptoms of one of the other types. In its more pure form, it is referred to as choreomania, St. Vitus' dance, or St. John's dance. Vivid hallucinations are accompanied by psychic intoxication reminiscent of the effects of many of the modern psychedelic drugs. Early reports state that the disease usually manifested itself in the form of strange public dances that might last for days or weeks on end. Dancers made stiff jerky movements accompanied by wild hopping, leaping, screaming, and shouting. They were often heard conversing with devils or gods, and danced compulsively, as if possessed, until exhaustion caused them to fall unconscious or to lie twitching on the ground. High mortality rates were associated with severe epidemics involving any of the three forms of ergotism. The success with which the disease is controlled in humans has been brought about by (1) agricultural inspection, (2) use of wheat, potatoes, and maize instead of rye, (3) limited control of ergot, (4) reserves of sound grain, and (5) forecasting severe ergot years. The most recent and best-recorded epidemic was in southern France in 1951 when an unscrupulous miller used moldy grain to make flour.

In the early twentieth century two ergot alkaloids (ergotoxine and ergotamine) were isolated. Unfortunately, they caused significant side effects and were not as specific or active as some of the crude aqueous preparations. Shortly after its discovery, ergotamine was found to be effective in the treatment of migraines. Both ergotoxine and ergotamine cause vasoconstriction that can lead to gangrene with chronic use.

In 1935 a new water-soluble ergot alkaloid, ergonovine, was synthesized. Ergonovine is used to facilitate childbirth by stimulating uterine contractions. Many other important lysergic acid derivatives have been produced by means of semisynthesis. Of these derivatives, LSD-25 (d-lysergic acid diethylamide) is the most famous. LSD has been used experimentally, mainly in psychiatry and neurophysiology. See Psychotomimetic drug

Through extensive research, many other uses for ergot alkaloids has been found. Ergotamine and dihydroergotamine are used to treat migraines, and methysergine is used in migraine prophylaxis. Dihydroergotoxine is prescribed for hypertension, cerebral diffuse sclerosis, and peripheral vascular disorders. Ergocorine and the less toxic agroclavine have been reported as unusual experimental birth-control agents. The drugs appear to inhibit implantation of the ovum. Several semisynthetic alkaloids are also active implantation inhibitors.

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.