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Poisonous Plants in GB

56 57 Plants Due to the large and constantly growing number of toxic compounds that have been isolated from plants, it is most convenient to sort them by their chemical groupings. The main ones are alkaloids These are nitrogenous alkaline carbon compounds. They often make the plant taste bitter and are biologically very active, exhibiting a wide range of pharmacological effects depending upon the specific alkaloids present. Examples are nicotine tobacco, morphine opium poppies, atropine deadly nightshade, and caffeine coffee. Most alkaloids are considered toxic. Glycosides These organic compounds result from the combination of a sugar, such as glucose or fructose known as the glycone, with another mollecule known as the aglycone via a glycosidic bond. Glycosides become active in the body when enzymes break the glyconeaglycone bond, releasing both concentrated sugars and the aglycone part to freely react within the biochemical systems of the body. An example is digoxin from foxglove that has a powerful muscular and electrical effect upon the heart and is very toxic. amygdalin is a glycoside found in many members of the rose family, for example the cherry laurel, and in many rosefamily foods such as cherry, plum, peach, almond and apricot kernels, and apple pips. When acted upon by enzymes within the body, hydrogen cyanide is liberated from its aglycone and this can cause cyanide poisoning, however in the tiny quantities found in many foodstuffs it is more likely to behave as an antioxidant, which might be beneficial to health. saPonins These compounds cause a frothing effect when mixed with water, and they act as mild detergents. In fact, they are often the raw ingredients for vegetable soaps. Small quantities of saponins bind to cholesterol in the body, facilitating its excretion. However larger concentrations may damage cells and can be haemolytic see haemolytic poisons below. Examples of plants considered toxic due to saponins include horse chestnut, and soapwort. Beneficial saponin containing foods include red peppers and chilli peppers, tomatoes and grape skins. MushrooMs To date there has been far less research on the constituents of mushrooms compared to the vascular plants above. Eating wild mushrooms is becoming very popular in the UK, and it is most useful to group the fungal toxins according to their physiological actions neurotoxins Many of these are alkaloids see description above. 1. muscarine poisoning from inocybes, clitocybes, mycenae and others affects the peripheral nervous system and is normally noticeable from 15 to 45 minutes after mushroom ingestion. It produces sweating, stomach cramps, increased urination and tear flow, lowered heart beat, blood pressure and respiration, and convulsions. In sufficient dose it occasionally leads to death by cardiac or respiratory failure, but poisoning usually subsides within 2 hours. 2. muscimol and ibotenic acid are found in a number of mushrooms, typically the panther cap Amanita pantherina and fly agaric Amanita muscaria. Symptoms typically occur around an hour after ingestion, and include twitching, euphoria, illusions, hallucinations, increased blood pressure and pulse, and hyperactivity interspersed with periods of deep sleep. Gastro intestinal upset may also be present. Symptoms may last for up to 12 hours. Death from this type of poisoning is rare but it has occurred, and the panther cap is particularly dangerous. 3. psilocybin and psilocin are found in numerous mushroom species, in particular among members of paneolus, psilocybe and stropharia, These neurotoxins act directly upon the brain and central nervous system producing profound feelings of excitation, euphoria, and hallucinations which can be either joyful or perplexing. Religious or spiritual experiences are frequently reported. Symptoms occur approximately 40 minutes after ingestion, and may last for 6 or more hours, after which time the patient normally makes a complete recovery. Rarely and possibly owing to existing psychological issues ingesting these toxins can lead to longerterm psychological illness. ProtoPlasMic Poisons 1. cyclopeptides These compounds vary in toxicity, and are even associated with a variety of beneficial medical effects where they occur in some families of green plants. However, they can be cytotoxic, immunosuppressive and are often enzyme inhibitors. Some of them are deadly poisons. The most deadly examples of these compounds are found among fungi, including the deathcap Amanita phalloides, destroying angel Amanita virosa, some omphalotus, conocybe and galerina species, and some small parasol species lepiota. These deadly cyclopeptides for example amatoxin halt cell replication and are recycled in the body rather than being broken down and excreted, leading to multiple organ failure and death over a period of days or weeks. Without very early medical intervention there is no known antidote. Symptoms of poisoning are initially violent gastrointestinal disturbance, occurring at least 6 and usually 12 or more hours after ingestion, followed by apparent recovery and then death from organ failure. 2. hydrazines are alkaloids found in some species of false morels, gyromitra and verpa, that cause superficially similar symptoms to those of amatoxin poisoning from the death cap or destroying angel detailed above. Though similar, poisoning is typically less severe. 3. orellanine is found in Cortinarius orellanus and a number of other cortinarius species. Symptoms occur 2 3 days and up to 3 weeks after consumption, resulting in many cases of misdiagnosis. Initially symptoms are flulike, but are followed by renal failure and may lead to death without further treatment. Gastrointestinal irritants Fungi may contain a wide variety of gastrointestinal irritants of chemically different types, for example the yellowstaining mushroom Agaricus xanthodermus, and Satans boletus Boletus satanas, which both produce severe gastrointestinal poisoning. Symptoms include violent stomach cramps, vomiting and diarrhoea 2 to 4 hours after ingestion, passing in 24 to 48 hours and rarely life threatening. haeMolytic Poisons Haemolytic substances from various chemical groups cause the breaking open of read blood cells and the release of haemoglobin into the blood plasma, resulting in some cases in severe anaemia which can be very dangerous. An example of a good edible mushroom that contains a haemolytic poison is the blusher, Amanita rubescens, which is poisonous when raw but the toxicity is destroyed by heat. The mushroom is first parboiled the water being discarded and then cooked. Additionally, recent studies of the edible Jews ear Auricularia auriculajudae show that it can significantly lower blood platelet count, particularly when eaten raw. note These lists are not exhaustive. Many more types of active substances are found in plants and fungi. Appendix i types oF poison
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