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Dioscorine
Dioscorine is an alkaloid toxin isolated from the tubers of tropical yam on several continents. It has been used as a monkey poison in some African countries, and as an arrow poison to aid in hunting in several parts of Asia. It was first isolated from '' Dioscorea hirsute'' (synonymous with ''Dioscorea hirsuta'') by Boorsma in 1894 and obtained in a crystalline form by Schutte in 1897, and has since been found in other ''Dioscorea'' species. Dioscorine is a neurotoxin that acts by blocking the nicotinic acetylcholine receptor. Dioscorine is generally isolated in tandem with other alkaloids such as dioscin but is usually the most potent toxin in the mixture. It is a convulsant, producing symptoms similar to picrotoxin, with which it shares a similar mechanism of action. (Dioscorine is not to be confused with dioscorin, the yam storage protein.) Origin and uses Dioscorine was first isolated from the tubers of ''Dioscorea hirsuta'' by Boorsma in 1894, and the tubers of ''Dioscor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yam (vegetable)
Yam is the common name for some plant species in the genus '' Dioscorea'' (family Dioscoreaceae) that form edible tubers. Yams are perennial herbaceous vines cultivated for the consumption of their starchy tubers in many temperate and tropical regions, especially in West Africa, South America and the Caribbean, Asia, and Oceania. The tubers themselves, also called "yams", come in a variety of forms owing to numerous cultivars and related species. Yams were independently domesticated on three different continents: Africa (''Dioscorea rotundata''), Asia (''Dioscorea alata''), and the Americas (''Dioscorea trifida''). Etymology The name "yam" appears to derive from Portuguese ''inhame'' or Canarian (Spain) ''ñame'', which derived from West African languages during trade. However in both languages, this name commonly refers to the taro plant (''Colocasia esculenta'') from the genus ''Colocasia'', as opposed to '' Dioscorea''. The main derivations borrow from verbs me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkaloid
Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar structure may also be termed alkaloids. In addition to carbon, hydrogen and nitrogen, alkaloids may also contain oxygen, sulfur and, more rarely, other elements such as chlorine, bromine, and phosphorus.Chemical Encyclopedia: alkaloids xumuk.ru Alkaloids are produced by a large variety of organisms including , , Medicinal plant, plants, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antagonist
An antagonist is a character in a story who is presented as the chief foe of the protagonist. Etymology The English word antagonist comes from the Greek ἀνταγωνιστής – ''antagonistēs'', "opponent, competitor, villain, enemy, rival," which is derived from ''anti-'' ("against") and ''agonizesthai'' ("to contend for a prize"). Types Heroes and villains The antagonist is commonly positioned against the protagonist and their world order. While most narratives will often portray the protagonist as a hero and the antagonist as a villain, like Harry Potter and Lord Voldemort in '' Harry Potter'', the antagonist does not always appear as the villain. In some narratives, like Light Yagami and L in '' Death Note'', the protagonist is a villain and the antagonist is an opposing hero. Antagonists are conventionally presented as making moral choices less savory than those of protagonists. This condition is often used by an author to create conflict within a story. This is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Toxins
A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849–1919) and is derived from the word toxic. Toxins can be small molecules, peptides, or proteins that are capable of causing disease on contact with or absorption by body tissues interacting with biological macromolecules such as enzymes or cellular receptors. Toxins vary greatly in their toxicity, ranging from usually minor (such as a bee sting) to potentially fatal even at extremely low doses (such as botulinum toxin). Toxins are largely secondary metabolites, which are organic compounds that are not directly involved in an organism's growth, development, or reproduction, instead often aiding it in matters of defense. Terminology Toxins are often distinguished from other chemical agents strictly based on their biological origin. Less s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nicotinic Antagonists
A nicotinic antagonist is a type of anticholinergic drug that inhibits the action of acetylcholine (ACh) at nicotinic acetylcholine receptors. These compounds are mainly used for peripheral muscle paralysis in surgery, the classical agent of this type being tubocurarine,P. Taylor (1990). In ''Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th Ed.'', (A. G. Gilman et al., Eds.), pp. 166-186, New York: Pergamon Press. but some centrally acting compounds such as bupropion, mecamylamine, and 18-methoxycoronaridine block nicotinic acetylcholine receptors in the brain and have been proposed for treating nicotine addiction. *Note: Succinylcholine is a nicotinic agonist. See neuromuscular blocking agents page for details on the mechanism of action. See also * Nicotinic acetylcholine receptor * Nicotinic agonist * Muscarinic acetylcholine receptor * Muscarinic agonist * Muscarinic antagonist A muscarinic receptor antagonist (MRA) is a type of anticholinergic agent t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkaloids
Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar structure may also be termed alkaloids. In addition to carbon, hydrogen and nitrogen, alkaloids may also contain oxygen, sulfur and, more rarely, other elements such as chlorine, bromine, and phosphorus.Chemical Encyclopedia: alkaloids xumuk.ru Alkaloids are produced by a large variety of organisms including , , |
Pentobarbital
Pentobarbital (previously known as pentobarbitone in Britain and Australia) is a short-acting barbiturate typically used as a sedative, a preanesthetic, and to control convulsions in emergencies. It can also be used for short-term treatment of insomnia but has been largely replaced by the benzodiazepine family of drugs. In high doses, pentobarbital causes death by respiratory arrest. It is used for veterinary euthanasia and is used by some U.S. states and the U.S. federal government for executions of convicted criminals by lethal injection. In some countries and states, it is also used for physician-assisted suicide. Pentobarbital was widely abused and sometimes known as "yellow jackets" due to the yellow capsule of the Nembutal brand. Pentobarbital in oral (pill) form is no longer commercially available. Uses Medical Typical applications for pentobarbital are sedative, short term hypnotic, preanesthetic, insomnia treatment, and control of convulsions in emergencies. Abbott P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cardiac Glycosides
Cardiac glycosides are a class of organic compounds that increase the output force of the heart and decrease its rate of contractions by inhibiting the cellular sodium-potassium ATPase pump. Their beneficial medical uses are as treatments for congestive heart failure and cardiac arrhythmias; however, their relative toxicity prevents them from being widely used. Most commonly found as secondary metabolites in several plants such as foxglove plants, these compounds nevertheless have a diverse range of biochemical effects regarding cardiac cell function and have also been suggested for use in cancer treatment. Classification General structure The general structure of a cardiac glycoside consists of a steroid molecule attached to a sugar (glycoside) and an R group. The steroid nucleus consists of four fused rings to which other functional groups such as methyl, hydroxyl, and aldehyde groups can be attached to influence the overall molecule's biological activity. Cardiac glycosi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NMDA
''N''-methyl--aspartic acid or ''N''-methyl--aspartate (NMDA) is an amino acid derivative that acts as a specific agonist at the NMDA receptor mimicking the action of glutamate, the neurotransmitter which normally acts at that receptor. Unlike glutamate, NMDA only binds to and regulates the NMDA receptor and has no effect on other glutamate receptors (such as those for AMPA and kainate). NMDA receptors are particularly important when they become overactive during, for example, withdrawal from alcohol as this causes symptoms such as agitation and, sometimes, epileptiform seizures. Biological function In 1962, J.C. Watkins reported synthesizing NMDA, an isomer of the previously know''N''-Methyl--aspartic-acid (PubChem ID 4376) NMDA is a water-soluble -alpha-amino acid — an aspartic acid derivative with an ''N''-methyl substituent and - configuration — found across Animalia from lancelets to mammals. At homeostatic levels NMDA plays an essential role as a neurotransmitter and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inverse Agonist
In pharmacology, an inverse agonist is a drug that binds to the same receptor as an agonist but induces a pharmacological response opposite to that of the agonist. A neutral antagonist has no activity in the absence of an agonist or inverse agonist but can block the activity of either. Inverse agonists have opposite actions to those of agonists but the effects of both of these can be blocked by antagonists. A prerequisite for an inverse agonist response is that the receptor must have a constitutive (also known as intrinsic or basal) level of activity in the absence of any ligand. An agonist increases the activity of a receptor above its basal level, whereas an inverse agonist decreases the activity below the basal level. The efficacy of a full agonist is by definition 100%, a neutral antagonist has 0% efficacy, and an inverse agonist has < 0% (i.e., negative) efficacy. Examples Receptors for which inverse agonists have been identified include the[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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