Originally, any one of hundreds of plant and fungal products distinguished by alkaline (basic) reactions, but now restricted to heterocyclic nitrogen-containing and often complex structures possessing pharmacologic activity; their trivial name s usually end in -ine ( e.g., morphine, atropine, colchicine). Alkaloids are synthesized by plants and are found in the leaf, bark, seed, or other parts, usually constituting the active principle of the crude drug; they are a loosely defined group, but may be classified according to the chemical structure of their main nucleus. For medicinal purposes, due to improved water solubility, the salts of alkaloids ( e.g., morphine sulfate, codeine phosphate) are usually used. see also individual a. or a. class. SYN: vegetable base.
- ergot alkaloids (er′got) any of a large number of alkaloids obtained from the ergot fungus Claviceps purpurea or semisynthetically derived; examples include ergotamine, ergonovine, dihydroergotamine, lysergic acid diethylamide (LSD), methysergide.
- fixed a. a nonvolatile a..
- Vinca alkaloids alkaloids such as vincristine and vinblastine (antitumor agents) extracted from the periwinkle plant. SYN: Catharanthus alkaloids.

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al·ka·loid 'al-kə-.lȯid n any of numerous usu. colorless, complex, and bitter organic bases (as morphine or caffeine) containing nitrogen and usu. oxygen that occur esp. in seed plants and are typically physiologically active
al·ka·loi·dal .al-kə-'lȯid-əl adj

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one of a diverse group of nitrogen-containing substances that are produced by plants and have potent effects on body function. Many alkaloids are important drugs, including morphine, quinine, atropine, and codeine.

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al·ka·loid (alґkə-loid″) [alkali + -oid] one of a large group of nitrogenous basic substances found in plants. They are usually very bitter and many are pharmacologically active. Examples are atropine, caffeine, coniine, morphine, nicotine, quinine, and strychnine. The term is also applied to synthetic substances (artificial a's) which have structures similar to plant alkaloids, such as procaine.

Medical dictionary. 2011.

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  • Alkaloid — Al ka*loid ([a^]l k[.a]*loid), Alkaloidal Al ka*loid al ([a^]l k[.a]*loid al), a. [Alkali + oid: cf. F. alcalo[ i]de.] 1. Pertaining to, resembling, or containing, alkali. [1913 Webster] 2. of or pertaining to alkaloids. [WordNet 1.5] …   The Collaborative International Dictionary of English

  • Alkaloid — Al ka*loid ([a^]l k[.a]*loid), n. (Chem.) An organic base, especially one of a class of nitrogen containing substances occurring ready formed in the tissues of plants and the bodies of animals. [1913 Webster] Note: Alkaloids all contain nitrogen …   The Collaborative International Dictionary of English

  • alkaloid — (n.) 1831, from ALKALI (Cf. alkali) (q.v.) + OID (Cf. oid). A general term applied to basic compounds of vegetable origin, bitter in taste, and having powerful effects on the animal system [Flood]. As an adjective by 1859 …   Etymology dictionary

  • alkaloid — {{/stl 13}}{{stl 8}}rz. mnż I, D. u, Mc. alkaloididzie, zwykle w lm {{/stl 8}}{{stl 7}} zasadowy związek organiczny pochodzenia roślinnego zawierający azot, zwykle nierozpuszczalny w wodzie, np. morfina, strychnina, chinina, nikotyna; odznacza… …   Langenscheidt Polski wyjaśnień

  • alkaloid — [al′kə loid΄] n. [ ALKAL(I) + OID] any of a number of heterocyclic, colorless, crystalline, bitter organic substances, such as caffeine, morphine, quinine, and strychnine, having alkaline properties and containing nitrogen: they are found in… …   English World dictionary

  • alkaloid — /al keuh loyd /, Biochem., Chem., Pharm. n. 1. any of a large class of organic, nitrogen containing ring compounds of vegetable origin and sometimes synthesized, some of which are liquid but most of which are solid, that have a bitter taste, that …   Universalium

  • Alkaloid — Strukturformel des Alkaloids Morphin Alkaloide (Wortbildung aus arabisch al qualja: „Pflanzenasche“ und griechisch oides: „ähnlich“) sind natürlich vorkommende, chemisch heterogene, meist basische, stickstoffhaltige organische Verbindungen des… …   Deutsch Wikipedia

  • Alkaloid — This article is about the chemical compounds alkaloids. For the pharmaceutical company in the Republic of Macedonia see Alkaloid (company).Alkaloids are naturally occurring chemical compounds containing basic nitrogen atoms.… …   Wikipedia

  • alkaloid — UK [ˈælkəˌlɔɪd] / US noun [countable/uncountable] Word forms alkaloid : singular alkaloid plural alkaloids chemistry a substance found in plants that is used in drugs and poisons. Morphine, nicotine, and strychnine are all alkaloids …   English dictionary

  • alkaloid — al|ka|loid1 [ ælkə,lɔıd ] noun count or uncount SCIENCE a substance found in plants that is used in drugs or as a poison alkaloid al|ka|loid 2 [ ælkə,lɔıd ] adjective AMERICAN TECHNICAL another word for ALKALINE …   Usage of the words and phrases in modern English

  • alkaloid — alkaloidas statusas T sritis chemija apibrėžtis Fiziologiškai aktyvi azoto turinti bazė, randama augaluose. atitikmenys: angl. alkaloid rus. алкалоид …   Chemijos terminų aiškinamasis žodynas

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