One of the mysteries of the English language finally explained.
Any of a class of nitrogenous organic compounds of plant origin which have pronounced physiological actions on humans. They include many drugs (morphine, quinine) and poisons (atropine, strychnine).
- ‘Caffeine is a bitter alkaloid found especially in coffee, tea, and kola nuts and used medicinally as a stimulant and diuretic.’
- ‘Many multicellular trichomes are glandular, developing a terminal gland which may secrete a variety of compounds, such as alkaloids to deter or poison predators.’
- ‘The isolation of morphine from opium takes advantage of the amphoteric nature of the alkaloid, since morphine is a phenolic amine.’
- ‘The cinchona tree contains more than 20 alkaloids of which quinine and quinidine are the most important.’
- ‘Morphine is an alkaloid, meaning that it is an organic compound that contains carbon, hydrogen and nitrogen, and forms a water-soluble salt.’
- ‘The alkaloids in poppy include morphine, narcotine and codeine - the reasons why opium is used most frequently as a sedative.’
- ‘Plant or vinca alkaloids are derived from plants and block cell division during mitosis.’
- ‘Barbiturates are derived from barbituric acid, an alkaloid with nitrogen-containing rings.’
- ‘They are precursors of benzoic phenanthridine alkaloids, active ingredients of many medicinal plant extracts.’
- ‘Prominent examples are quinolizidine alkaloids, gossypol, glucosinolates, nonproteinogenic amino acids and furanocoumarins.’
- ‘Other important alkaloids are caffeine, ricinine, and quinine.’
- ‘Terpenoid indole alkaloids absorb UV radiation and are implicated as having a UV-protective role in plants.’
- ‘Berberine is an alkaloid occurring in the plant genera Berberis and Coptis.’
- ‘Caffeine is a naturally occurring drug belonging to a group of compounds called alkaloids.’
- ‘Key alkaloids present in goldenseal include berberine, hydrastine, and canadine.’
- ‘CE analysis of plant secondary metabolites such as flavonoids, alkaloids, and phenolic acids is now common.’
- ‘Second, the alkaloid is refluxed with acetic anhydride for about five hours.’
- ‘At present, the chemical components of this water extract are thought to include only alkaloids, terpenes and pigments.’
- ‘This material is a complex mixture of about 20 different alkaloids or nitrogen containing organic bases.’
- ‘Diuretics can be found in terpenes, phenolics and alkaloids.’
Early 19th century: coined in German from alkali.
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