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The Collaborative International Dictionary

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.

  2. of or pertaining to alkaloids.


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.

Note: Alkaloids all contain nitrogen, carbon, and hydrogen, and many of them also contain oxygen. They include many of the active principles in plants; thus, morphine and narcotine are alkaloids found in opium.

Douglas Harper's Etymology Dictionary

1831, from alkali (q.v.) + -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.


a. Relating to, resembling, or containing alkali. n. (context organic chemistry English) Any of many organic heterocyclic bases, that occur in nature and often have medicinal properties.


n. natural nitrogen-containing bases found in plants


Alkaloids are a group of naturally occurring chemical compounds that mostly contain basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar structure are also 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.

Alkaloids are produced by a large variety of organisms including bacteria, fungi, plants, and animals. They can be purified from crude extracts of these organisms by acid-base extraction. Alkaloids have a wide range of pharmacological activities including antimalarial (e.g. quinine), antiasthma (e.g. ephedrine), anticancer (e.g. homoharringtonine), cholinomimetic (e.g. galantamine), vasodilatory (e.g. vincamine), antiarrhythmic (e.g. quinidine), analgesic (e.g. morphine), antibacterial (e.g. chelerythrine), and antihyperglycemic activities (e.g. piperine). Many have found use in traditional or modern medicine, or as starting points for drug discovery. Other alkaloids possess psychotropic (e.g. psilocin) and stimulant activities (e.g. cocaine, caffeine, nicotine, theobromine), and have been used in entheogenic rituals or as recreational drugs. Alkaloids can be toxic too (e.g. atropine, tubocurarine). Although alkaloids act on a diversity of metabolic systems in humans and other animals, they almost uniformly evoke a bitter taste.

The boundary between alkaloids and other nitrogen-containing natural compounds is not clear-cut. Compounds like amino acid peptides, proteins, nucleotides, nucleic acid, amines, and antibiotics are usually not called alkaloids. Natural compounds containing nitrogen in the exocyclic position ( mescaline, serotonin, dopamine, etc.) are usually classified as amines rather than as alkaloids. Some authors, however, consider alkaloids a special case of amines.

Alkaloid (company)

Alkaloid is a company from the Republic of Macedonia working on manufacturing drugs, processing botanical raw material and manufacturing cosmetics and chemical products for more than seven decades. “Alkaloid” is a joint-stock company which incorporates two profit centers: Pharmacy and Chemistry; Cosmetics and Botanicals; it has a subsidiary: “Alkaloid CONS”, as well as 13 affiliates outside of the Republic of Macedonia (in Serbia, Montenegro, Kosovo, Albania, Bosnia and Herzegovina, Croatia, Slovenia, Switzerland, Bulgaria, Romania, Ukraine, Russia and the United States). The company has around 1.300 employees with a dominant capital owned by private shareholders, 5,05% of which are foreign investors.

Usage examples of "alkaloid".

Ironically, coca, the one that had first piqued his imagination, was the last to have its alkaloid isolated.

Of course, he was writing about coca, not cocaine, but the moment the alkaloid was isolated from the leaf they were assumed to be one and the same.

Because he was German, he was familiar with the work of Wohler and Niemann atGottingenand knew all about their escapades in alkaloid isolation.

A side interest, though it was a deep one, had led me in 1884 to obtain from Merck what was then a little known alkaloid, cocaine, and to study its physiological action.

Chapare leaf meanwhile - large, high in alkaloid and no good for chewing at all - was excellent for processing into cocaine paste.

Because the alkaloid was more soluble in acid than it was in petrol, once the mixture was stirred, it moved into the water.

Absolute alcohol will then dissolve out the alkaloid, and leave it on evaporation in a crystalline form.

When the alkaloid is heated in a watchglass with a drop of strong sulphuric acid until the acid begins to fume, and is then allowed to get quite cold, a drop of nitric acid produces a brilliant red colour.

A cadaveric alkaloid or ptomaine has been found in the body, possessing many of the actions of aconitine.

They are probably allied to neurine, an alkaloid obtained from the brain and also from the bile.

His night vision had returned and he could see clearly the squat silhouette of the alkaloid factory on the horizon.

When his last sandwich was eaten, Sumner was parked again outside the alkaloid factory.

A crystalline alkaloid which is fatal to frogs in a dose of one centigramme, has been isolated from the common Stinging Nettle.

This is a volatile alkaloid which is not poisonous, and is thought to be almost identical with ammonia.

I told you: some crude flavorings, an alcohol vehicle, and an alkaloid from an Indian grass.