Taxine A | |
Names | |
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IUPAC name 2α,13α-Diacetoxy-7β,10β-dihydroxy-9-oxo-2(3→20)-abeotaxa-4(20),11-dien-5α-yl (2R,3S)-3-(dimethylamino)-2-hydroxy-3-phenylpropanoate | |
Other names (1R,2S,3E,5S,7S,8S,10R,13S)-2,13-Diacetoxy-7,10-dihydroxy-8,12,15,15-tetramethyl-9-oxotricyclo[9.3.1.14,8]hexadeca-3,11-dien-5-yl (2R,3S)-3-(dimethylamino)-2-hydroxy-3-phenylpropanoate | |
Identifiers | |
3D model (JSmol) | |
ChEBI | |
ChemSpider | |
KEGG | |
PubChem CID | |
UNII | |
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Properties | |
C35H47NO10 | |
Molar mass | 641.751 g·mol−1 |
Melting point | 204-206 °C [1] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Taxine B | |
Names | |
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IUPAC name 10β-Acetoxy-1,2α,9α-trihydroxy-13-oxotaxa-4(20),11-dien-5α-yl (3R)-3-(dimethylamino)-3-phenylpropanoate | |
Identifiers | |
3D model (JSmol) | |
ChEBI | |
ChemSpider | |
KEGG | |
PubChem CID | |
| |
| |
Properties | |
C33H45NO8 | |
Molar mass | 583.722 g·mol−1 |
Melting point | 115 °C |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Taxine alkaloids, which are often named under the collective title of taxines, are the toxic chemicals that can be isolated from the yew tree. [2] [3] The amount of taxine alkaloids depends on the species of yew, with Taxus baccata and Taxus cuspidata containing the most. [4] The major taxine alkaloids are taxine A and taxine B although there are at least 10 different alkaloids. [5] Until 1956, it was believed that all the taxine alkaloids were one single compound named taxine. [4]
The taxine alkaloids are cardiotoxins with taxine B being the most active. [6] Taxine alkaloids have no medical uses but Paclitaxel and other taxanes that can be isolated from yews have been used as chemotherapy drugs. [7]
Taxine can be found in Taxus species: Taxus cuspidata, T. baccata (English yew), Taxus x media, Taxus canadensis, Taxus floridana, and Taxus brevifolia (Pacific or western yew). All of these species contain taxine in every part of the plant except in the aril, the fleshy covering of the seeds (berries). Concentrations vary between species, leading to varying toxicities within the genus. This is the case of Taxus brevifolia (Pacific yew) and Taxus baccata (English yew); T. baccata contains high taxine concentrations, which leads to a high toxicity, whereas T. brevifolia has a low toxicity. There are seasonal changes in the concentrations of taxine in yew plants, with the highest concentrations during the winter, and the lowest in the summer. [8] The poison remains dangerous in dead plant matter. [9]
These species have distinctive leaves, which are needle-like, small, spirally arranged but twisted so they are two-ranked, and linear-lanceolate. They are also characterized by their ability to regenerate from stumps and roots. [8]
Taxus species are found exclusively in temperate zones of the northern hemisphere. [10] In particular T. baccata is found all over Europe, as a dominant species or growing under partial canopies of deciduous trees. It grows well in steep rocky areas on calcareous substrates such as in the chalk downs of England, and in more continental climates it fares better in mixed forests. T. baccata is sensitive to frost, limiting its northern Scandinavian distribution. [11]
The toxic nature of yew trees has been known for millennia. [12] Greek and Roman writers have recorded examples of poisonings, including Julius Caesar's account of Cativolcus, king of Eburones, who committed suicide using the “juice of the yew”. [13] The first attempt to extract the poisonous substance in the yew tree was in 1828 by Piero Peretti, who isolated a bitter substance. [14] In 1856, H. Lucas, a pharmacist in Arnstadt, prepared a white alkaloid powder from the foliage of Taxus baccata L . which he named taxine. [15] The crystalline form of the substance was isolated in 1876 by W. Marmé, a French chemist. A. Hilger and F. Brande used elemental combustion analysis in 1890 to suggest the first molecular formula of . [4]
For the next 60 years, it was generally accepted that taxine was made of a single compound and it was well known enough for Agatha Christie to use it as a poison in A Pocket Full of Rye (1953). However, in 1956, Graf and Boeddeker discovered that taxine was actually a complex mixture of alkaloids rather than a single alkaloid. [16] Using electrophoresis, they were able to isolate the two major components, taxine A and taxine B. taxine A was the fastest moving band and accounted for 1.3% of the alkaloid mixture, while taxine B was the slowest moving band and accounted for 30% of the mixture. [17] The full structure of taxine A was reported in 1982, [1] taxine B in 1991. [18]
Almost all parts of Taxus baccata, perhaps the best-known Taxus species, contain taxines. [19]
Taxines are cardiotoxic calcium and sodium channel antagonists. [20] If any leaves or seeds of the plant are ingested, urgent medical attention is recommended as well as observation for at least 6 hours after the point of ingestion. [21] [22] There are currently no known antidotes for yew poisoning, but drugs such as atropine have been used to treat the symptoms. [23] Taxine B, the most common alkaloid in Taxus species, is also the most cardiotoxic taxine, followed by taxine A. [6] [24] [4]
Taxine alkaloids are absorbed quickly from the intestine and in high enough quantities can cause death due to general cardiac failure, cardiac arrest or respiratory failure. [25] Taxines are also absorbed efficiently via the skin and Taxus species should thus be handled with care and preferably with gloves. [26] Taxus Baccata leaves contain approximately 5 mg of Taxines per 1g of leaves. [24] The estimated lethal dose (LDmin) of taxine alkaloids is approximately 3.0 mg/kg body weight for humans. [27] [28] Different studies show different toxicities; a major reason is the difficulty of measuring taxine alkaloids. [29]
Minimum lethal doses (oral LDmin) for many different animals have been tested: [29]
Several studies [30] have found taxine LD50 values under 20 mg/kg in mice and rats.
Cardiac and cardiovascular effects:
Both these effects lead to hypotension, which gives many symptoms including:
and many other typical signs of low blood pressure.
Intestinal effects:
Respiratory effects:
If the poisoning is severe and not treated:
Diagnosis of yew poisoning is very important if the patient is not already aware of having ingested parts of the yew tree. The method of diagnosis is the determination of 3,5-dimethoxyphenol, a product of the hydrolysis of the glycosidic bond in taxine, in the blood, the gastric contents, the urine, and the tissues of the patient. This analysis can be done by gas or liquid chromatography and also by mass spectroscopy.
There are no specific antidotes for taxine, so patients can only receive treatment for their symptoms.
It is also important to control blood pressure and heart rate to treat the heart problems. Atropine has been used successfully in humans to treat bradycardias and arrhythmias caused by taxine. It is more effective if administered early, but it is also necessary to be cautious with administration because it can produce an increase in myocardial oxygen demand and potentiate myocardial hypoxia and dysfunction. An artificial cardiac pacemaker can also be installed to control the heartbeat.
Other treatments are useful to treat the other symptoms of poisoning: positive pressure ventilation if respiratory distress is present, fluid therapy to support blood pressure and maintain hydration and renal function, and gastrointestinal protectants. It may also be necessary to control aggressive behaviour and convulsions with tranquilizers. [34]
The toxic effects of T. baccata have been known since ancient times. In most cases, poisoning is accidental, especially in cases involving children or animals. However, there are cases in which the poison is used as a suicide method. [35]
Because taxine poisoning is often only diagnosed after the death of the patient due to its rapid effect, preventing exposure is very important. Even dried parts of the plant are toxic because they still contain taxine molecules. Pet owners must ensure that yew branches or leaves are not used as toys for dogs or as perches for domestic birds.
The effects of Taxine in humans are very similar to the effects on other animals. It has the same mechanisms of action, and most of the times the ingestion of yew material is diagnosed with the death of the animal. Moreover, clinical signs, diagnosis, treatment, and prevention are mostly the same as in humans. This was seen due to the many experiments realized on rats, pigs, and other animals. [8]
Poisoning is typically caused by ingestion of decorative yew shrubs or trimmings thereof. In animals the only sign is often sudden death. Diagnosis is based on knowledge of exposure and foliage found in the digestive tract. With smaller doses, animals display uneasiness, trembling, dyspnea, staggering, weakness, and diarrhea. Cardiac arrhythmias worsen over time, eventually causing death. "Necropsy findings are unremarkable and nonspecific", generally including pulmonary, hepatic, and splenic congestion. With lower doses, mild inflammation may be seen in the upper gastrointestinal tract. [19]
Some animals are immune to the effects of taxine, particularly deer. [19]
The toxicity of the yew plant is due to a number of substances, the principal ones being toxic alkaloids (taxine B, paclitaxel, isotaxine B, taxine A), glycosides (taxicatine) and taxane derivates (taxol A, taxol B). [36]
There have been many studies about the toxicity of the taxine alkaloids, [37] [38] and they have shown that their mechanism of action is interference with the sodium and calcium channels of myocardial cells, increasing the cytoplasmic calcium concentrations. Their mechanism is similar to drugs such as verapamil, although taxines are more cardioselective. [39] They also reduce the rate of the depolarization of the action potential in a dose-dependent manner. This produces bradycardia, hypotension, depressed myocardial contractility, conduction delay, arrhythmias, and other complications. [40]
Some taxine alkaloids have been isolated to study their effects and characteristics. This has allowed the discovery of some of the particular effects of each substance of the plant. For example, taxine A does not influence blood pressure, taxol causes cardiac disturbances in some people, that taxine B is the most toxic of these substances. [41]
Because a derivative from the yew, paclitaxel, functions as an anticancer drug, there have been investigations to show whether taxine B could also be used as a pharmaceutical. [42]
Paclitaxel (PTX), sold under the brand name Taxol among others, is a chemotherapy medication used to treat ovarian cancer, esophageal cancer, breast cancer, lung cancer, Kaposi's sarcoma, cervical cancer, and pancreatic cancer. It is administered by intravenous injection. There is also an albumin-bound formulation.
Aconitine is an alkaloid toxin produced by various plant species belonging to the genus Aconitum, known also commonly by the names wolfsbane and monkshood. Monkshood is notorious for its toxic properties.
Strychnine is a highly toxic, colorless, bitter, crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents. Strychnine, when inhaled, swallowed, or absorbed through the eyes or mouth, causes poisoning which results in muscular convulsions and eventually death through asphyxia. While it is no longer used medicinally, it was used historically in small doses to strengthen muscle contractions, such as a heart and bowel stimulant and performance-enhancing drug. The most common source is from the seeds of the Strychnos nux-vomica tree.
Taxus is a genus of coniferous trees or shrubs known as yews in the family Taxaceae. Yews occur around the globe in temperate zones of the northern hemisphere, northernmost in Norway and southernmost in the South Celebes. Some populations exist in tropical highlands.
Ethion (C9H22O4P2S4) is an organophosphate insecticide. Ethion is known to affect a neural enzyme called acetylcholinesterase and prevent it from working.
Solanine is a glycoalkaloid poison found in species of the nightshade family within the genus Solanum, such as the potato, the tomato, and the eggplant. It can occur naturally in any part of the plant, including the leaves, fruit, and tubers. Solanine has pesticidal properties, and it is one of the plant's natural defenses. Solanine was first isolated in 1820 from the berries of the European black nightshade, after which it was named. It belongs to the chemical family of saponins.
Nicotine poisoning describes the symptoms of the toxic effects of nicotine following ingestion, inhalation, or skin contact. Nicotine poisoning can potentially be deadly, though serious or fatal overdoses are rare. Historically, most cases of nicotine poisoning have been the result of use of nicotine as an insecticide. More recent cases of poisoning typically appear to be in the form of Green Tobacco Sickness, or due to unintended ingestion of tobacco or tobacco products or consumption of nicotine-containing plants.
Samandarin or Samandarine is the main steroidal alkaloid secreted by the fire salamander (Salamandra salamandra). The compound is extremely toxic (LD50 = 70 µg/kg in mice). Poisoning can cause convulsions, respiratory paralysis, and eventual death. Samandarin is also believed to be the active ingredient in Salamander brandy, a Slovenian drink with purported hallucinogenic and aphrodisiac effects.
Taxus baccata is a species of evergreen tree in the family Taxaceae, native to Western Europe, Central Europe and Southern Europe, Northwest Africa, northern Iran, and Southwest Asia. It is the tree originally known as yew, though with other related trees becoming known, it may now be known as common yew, English yew, or European yew. It is primarily grown as an ornamental. Most parts of the plant are poisonous, with toxins that can be absorbed through inhalation and through the skin; consumption of even a small amount of the foliage can result in death.
Cicutoxin is a naturally-occurring poisonous chemical compound produced by several plants from the family Apiaceae including water hemlock (Cicuta species) and water dropwort (Oenanthe crocata). The compound contains polyene, polyyne, and alcohol functional groups and is a structural isomer of oenanthotoxin, also found in water dropwort. Both of these belong to the C17-polyacetylenes chemical class.
Taxus cuspidata, the Japanese yew or spreading yew, is a member of the genus Taxus, native to Japan, Korea, northeast China and the extreme southeast of Russia.
Theobromine poisoning, also informally called chocolate poisoning or cocoa poisoning, is an overdosage reaction to the xanthine alkaloid theobromine, found in chocolate, tea, cola beverages, and some other foods.
Taxanes are a class of diterpenes. They were originally identified from plants of the genus Taxus (yews), and feature a taxadiene core. Paclitaxel (Taxol) and docetaxel (Taxotere) are widely used as chemotherapy agents. Cabazitaxel was FDA approved to treat hormone-refractory prostate cancer.
Taxus canadensis, the Canada yew or Canadian yew, is a conifer native to central and eastern North America, thriving in swampy woods, ravines, riverbanks and on lake shores. Locally called simply "yew", this species is also referred to as American yew or ground-hemlock.
Oleandrin is a cardiac glycoside found in the poisonous plant oleander. As a main phytochemical of oleander, oleandrin is associated with the toxicity of oleander sap, and has similar properties to digoxin.
Tricyclic antidepressant overdose is poisoning caused by excessive medication of the tricyclic antidepressant (TCA) type. Symptoms may include elevated body temperature, blurred vision, dilated pupils, sleepiness, confusion, seizures, rapid heart rate, and cardiac arrest. If symptoms have not occurred within six hours of exposure they are unlikely to occur.
Conium maculatum, colloquially known as hemlock, poison hemlock or wild hemlock, is a highly poisonous biennial herbaceous flowering plant in the carrot family Apiaceae, native to Europe and North Africa. A hardy plant capable of living in a variety of environments, hemlock is widely naturalized in locations outside its native range, such as parts of Australia, West Asia, and North and South America, to which it has been introduced. It is capable of spreading and thereby becoming an invasive weed.
Zygacine is a steroidal alkaloid of the genera Toxicoscordion, Zigadenus, Stenanthium and Anticlea of the family Melanthiaceae. These plants are commonly known and generally referred to as death camas. Death camas is prevalent throughout North America and is frequently the source of poisoning for outdoor enthusiasts and livestock due to its resemblance to other edible plants such as the wild onion. Despite this resemblance, the death camas plant lacks the distinct onion odor and is bitter to taste.
Anagyrine is a teratogenic alkaloid first isolated from Anagyris foetida in the year 1885 by French biologists Hardy and Gallois. A. foetida, the Stinking Bean Trefoil, is a highly toxic shrub native to the Mediterranean region, with a long history of use in folk medicine. In the year 1939 Anagyrine was found by James Fitton Couch to be identical to an alkaloid present in many species belonging to the plant genus Lupinus (lupins). The toxin can cause crooked calf disease if a cow ingests the plant during certain periods of pregnancy.
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: CS1 maint: multiple names: authors list (link)Archived 2014-05-09 at the Wayback Machine Asheesh K. Tiwary, Birgit Puschner, Hailu Kinde, Elizabeth R. Tor (2005). "Diagnosis of Taxus (Yew) poisoning in a horse". Journal of Veterinary Diagnostic Investigation.
Andrea Persico, Giuseppe Bacis, Francesca Uberti, Claudia Panzeri, Chiara Di Lorenzo, Enzo Moro, and Patrizia Restani (2011). "Identification of Taxine Derivatives in Biological Fluids from a Patient after Attempted Suicide by Ingestion of Yew (Taxus baccata) Leaves". Journal of Analytical Toxicology. Vol. 35