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DL
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Plant Toxicity
« Thread started on: Dec 4th, 2006, 3:16pm » |
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http://naturalbird.com/mcwatters/plant_toxicology.htm
Know Your Poisonous and Non-Poisonous Plants
Alicia McWatters, PhD, CNC
(excerpt)
"....When a potentially harmful plant substance has been consumed in a small amount, the body normally eliminates it readily. Each bird is an individual in its level of tolerance to a particular toxic substance, so it is usually best to avoid the use of any plant, which is known to contain a high concentration of a toxic substance. However, due to the low body weight of birds, even a low concentration of a plant toxicant could pose a health risk, if it were consumed in a large enough quantity.
Wild birds may eat certain plant parts and experience no toxic effects, but this does not mean that these same plant parts are safe for our domestic birds.......
.....Often the toxic substance is only concentrated in specific parts of a plant. In some plants the toxin is located in the fruits or seeds; in others, the toxin may be contained in the leaves or roots. Many plants with edible parts also contain toxic parts. So we cannot assume that just because the fruits or leaves of a plant are safe that the roots, flowers, or seeds are safe. Therefore, knowing the edibility of the specific parts of a plant is very important when deciding whether to use a particular plant as a food source. ........It is important to acknowledge that even though plants are "natural" and "organic", this does not necessarily equate to "safe" and "healthful". Not only are common "safe" substances poisonous in increased doses ("The dose makes the poison"); but the toxic effects that plants produce vary with the species, health status, age of the individual(s), environmental conditions, such as the time of year, humidity, growth conditions, growth stage, and other factors also play a role in the hazards posed by toxic plants. ................
Certain plants or plant parts that are considered harmful, if eaten in the proper form, (i.e., cooked versus raw), may be rendered harmless and thus pose no danger. However, there are some plant toxins that are not reduced by cooking. ...........................................
Alkaloids and glycosides comprise two major classes of plant toxins, both highly complex and diverse. Some other toxic principals found in plants are oxalates, tannins, phenols, alcohols, ketones, protein substances, volatile oils, phototoxins and cancer-causing plant substances. What follows is a summary of these toxic compounds.................."
http://museum.gov.ns.ca/poison/pptoxin.htm
easy to understand summaries of major plant toxins with additional informational links
http://www.ansci.cornell.edu/plants/index.html
Poisonous Plants Informational Database (Cornell)-also provides a search by animal species
http://www.ivis.org/special_books/knight/chap1/ivis.pdf
Plants That Cause Sudden Death (Veterinary Toxicology Overview of this subject)
http://www.library.uiuc.edu/vex/toxic/comlist.htm
veterinary medicine library (choose from common names)
http://www.cfsan.fda.gov/~djw/plantox.html
FDA Poisonous Plants Database
http://www.merckvetmanual.com/mvm/htm/bc/ttox04.htm
from the MERCK Veterinary Manual (GREAT info listing habitat and distribution/main species affected and basic treatment measures)
http://www.ivis.org/special_books/Knight/Intro/IVIS.pdf
A Guide To Plant Poisoning of Animals
http://www.ivis.org/special_books/Knight/chap6b/ivis.pdf
Plants Afecting The Nervous System
http://www.ansci.cornell.edu/plants/toxicagents/saponin.html
SAPONINS (Alfalfa etc.)
http://dlhunicorn.conforums.com/index.cgi?board=toxicologydisease&action=display&num=1165263379&start=0#1165263379
Plants Affecting the Musculoskeletal System
(Veterinary Toxicology)
http://www.exoticanimal.net/Toxin/toxin-sequence.htm
This page provides a referenced listing of toxins and sources reported to be injurious to exotic animals (listed in animal sequence).
http://www.omafra.gov.on.ca/english/livestock/dairy/facts/87-016.htm
Great reference to general principles of toxicity from plants to livestock
http://southcampus.colostate.edu/poisonous_plants/index.cfm?countno=NO
Guide and search Database to poisonous plants (CSU)
http://www.cbif.gc.ca/pls/pp/poison?p_x=px
Canadian Poisonous Plants Information System
http://www.ivis.org/special_books/Knight/chap2/ivis.pdf
Plants Affecting The Cardiovascular System (Veterinary)
(cardiac) Glycosides. This article describes extensively the action and mechanism of toxicity and treatment measures. Specifc plants mentioned (see the Cornell database for a more complet list) are dogbane, lily of the valley, foxglove, oleander, milkweeds,yew, avocodo, death camas, hellebores, kalanchoe.
http://wildlife.tamu.edu/publications/TOXICPLA.PDF
Excellent guide to poisonous plants in TEXAS
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| « Last Edit: Aug 27th, 2007, 08:37am by DL » |
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DL
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Re: Plant Toxicity
« Reply #1 on: Apr 10th, 2007, 06:24am » |
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http://www.ansci.cornell.edu/plants/toxicagents/glucosin.html
GLUCOSINOLATES (GOITROGENIC GLYCOSIDES)
Introduction
Glucosinolates are thioethers. They generally consist of a sugar entity, b-D-thioglucose, with an ester bond to an organic aglycone that is an alkyl group yielding isothiocyanate, nitrile, thiocyanate or a similar compound upon hydrolysis. These compounds often contribute a bitter, "hot" taste to condiments (mustard, horseradish) and may exhibit goitrogenic or antithyroid activity.
How poisoning occurs
Glycosinolates are hydrolyzed by either the enzyme glucosinolase or thioglucosidase into glucose, HSO4- , and one of the following aglycone derivatives: isothiocynates, thiocyanates, nitriles, or related compounds such as oxazolidine-2-thiones. The enzymes for hydrolysis are produced by plants and by rumen organisms. They react with the glucosinolates when plant tissue is crushed, for example by mastication, or when the plant is consumed into the rumen of a ruminant animal.
Isothiocyanates - are irritating to mucous membranes and not readily consumed in sufficient quantities to be toxic. However, if they are consumed as glycosinolates and then hydrolyzed to isothiocyanates in the gut, they can have powerful antithyroid effects and interfere with the synthesis of necessary thyroid hormones.
Oxazolidine-2- thiones - are closely related to isothiocyanates. One way they are produced is by the conversion of the glucosinolate progoitrin in rapeseed meal to goitrin which in turn is hydolyzed to these compounds. Oxazolidine-2-thiones depress growth and increase the incidence of goiters. They inhibit thyroid function by blocking the incorporation of iodine into thyroxine precursors and by suppressing thyroxine secretion from the thyroid.
Nitriles - depress growth, cause liver and kidney lesions, and in severe cases --> liver necrosis, bile duct hyperplasia, and megalocytosis of tubular epithelium in the kidney.
Thiocyanates - inhibit iodine uptake by the thyroid --> leading to reduced iodination of tyrosine --> resulting in decreased production of the important thyroid hormone thyroxine.
Plants involved
Some common plants that contain glucosinolates include
Amoracia lapathifolia, Horseradish
Brassica campestris, Turnips, yellow-hulled rape
Brassica chinensis, Pak-choi
Brassica napus, Rutabaga, brown-hulled rape
Brassica nigra, Black mustard
Brassica oleracea, Cabbage, brusselssprouts, brocolli, cauliflower, kale, kohlrabi
Crambe abyssinica, Crambe
Limnanthes alba, Meadowfoam
Nasturtium officinalis, Watercress
Raphanus sativus, Radish
Thiaspi arvense, Stinkweed
Symptoms of poisoning:
Glucosinolates are found in several oil meals that have been used traditionally in the northern states, Canada, and Europe as protein supplements for livestock. Some examples include crambe, mustard, and meadowfoam meal, and most importantly, rapeseed meal. Rapeseed meal contains several glucosinolates and produces not only oxazolidine-2-thiones but also isothiocyanates, nitriles and thiocyanates.
Poultry and swine and other nonruminants can tolerate 5-10% rapeseed meal in their diets. Symptoms of poisoning in poultry may include depressed growth , goiters, perosis, poor egg production, off-flavored eggs, enlarged thyroid in chick embryos, and liver damage. Symptoms of poisoning in swine include growth depression, goiters, and enlarged livers.
Although rumen enzymes break down glucosinolate aglucones to their toxic derivatives, other rumen enzymes are able to metabolize these toxicants into less toxic compounds. Hence, ruminants can generally tolerate diets of 10% rapeseed meal. More than this canl cause antithyroid symptoms.
Glucosinolates and their derivatives can be transferred through milk and placenta to the young of female animals.
Prevention of poisoning:
Addition of extra iodine to diets can help to counteract the antithyroid effects of thiocyanates but not of oxazolidine-2-thiones.
Canadian plant breeders have developed low-glucosinolate cultivars of rapeweed. These cultivars are referred to as canola rather than rapeweed. Meal from them can be used in high enough quantities to provide all the protein supplementation demanded in livestock diets that require high levels of protein.
Benefits of glucosinolates:
Glucosinolates are responsilble for the unique taste of many of the condiments that make our foods more interesting to taste.
Research indicates that glucosinolates and their derivatives may have potential in fighting human cancers. Inclusion of Brassica vegetables appear to help protect against rectal and colon cancer. These vegetables aid in the detoxification of carcinogens such as aflatoxins and polybromobiphenyl. They enhance the activity of several hepatic enzymes used in detoxification processes. Benzyl isothiocyanate and thiocyanate have been shown in the lab to inhibit tumor development in animals exposed to carcinogens. Indole-3- carbinol, a product of glucosinolates, is a compound with promise in anticancer research.
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