• WordNet 3.6
    • n alkaloid natural bases containing nitrogen found in plants
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Webster's Revised Unabridged Dictionary
    • n Alkaloid ăl"kȧ*loid (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.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.
    • Alkaloid of or pertaining to alkaloids.
    • Alkaloid Pertaining to, resembling, or containing, alkali.
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Century Dictionary and Cyclopedia
    • n alkaloid A body resembling an alkali in properties; one of a class of nitrogenous compounds which occur in plants in combination with organic acids, and are sometimes called the organic bases of plants, as morphine, nicotine, quinine, etc. They are intensely bitter, turn reddened litmus blue, are slightly soluble in water but readily soluble in alcohol, and have active medicinal or poisonous properties. Compounds having the general reactions and properties of alkaloids (ptomains) are found in decaying animal matters, being products of the decomposition of the tissues.
    • alkaloid Relating to or containing alkali.
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Chambers's Twentieth Century Dictionary
    • n Alkaloid al′ka-loid a vegetable principle possessing in some degree alkaline properties
    • adj Alkaloid pertaining to or resembling alkali
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Webster's Revised Unabridged Dictionary
Alkali, + -oid,: cf. F. alcaloïde,


In literature:

It is an exceedingly good solvent, especially for fats, alkaloids and iodine.
"Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 3" by Various
The alkaloids are therefore methyl truxillylecgonines.
"Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 5" by Various
Tea and coffee both contain the alkaloid caffeine, whilst cocoa contains theobromine.
"Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 6" by Various
He finds also in this mushroom muscarin and an atropin-like alkaloid.
"Student's Hand-book of Mushrooms of America, Edible and Poisonous" by Thomas Taylor
Another valuable artificial alkaloid, discovered in 1883 by Ludwig Knorr, claims aniline as a point of departure.
"Coal" by Raphael Meldola
As a rule, alkaloids are colorless, crystalline solids, although a few are liquids at ordinary temperatures.
"The Chemistry of Plant Life" by Roscoe Wilfred Thatcher
They are all, like atropine, mydriatic alkaloids, so-called from the effect on the eye.
"The Social Gangster" by Arthur B. Reeve
The poppy, on the other hand, produces nothing but opium and its alkaloids.
"Drugging a Nation" by Samuel Merwin
Although formed originally within the plant, it has been found possible to prepare several of these alkaloids by artificial means.
"The New Gresham Encyclopedia. Vol. 1 Part 1" by Various
This consists in the use of emetics or the stomach-pump, with lime-water, which decomposes the alkaloid.
"Encyclopaedia Britannica, 11th Edition, Volume 3, Slice 5" by Various

In news:

For centuries, people who live in the high Andes have chewed coca leaves, whose alkaloids act as a mild stimulant and help to ward off cold and hunger.
The company's challenge of the ban was specific to the sale of "a dietary supplement containing 10 mg or less of ephedrine alkaloids per daily dose.".
Goldenseal is a popular herbal product containing the alkaloids berberine and hydrastine.
Morphine is a molecule that can lay claim to being the original alkaloid and the first true drug, according to assistant professor Paul R Blakemore and professor emeritus James D White at Oregon State University, Corvallis ( Chem.
In the United States, ma huang and a variety of dietary supplements that contain ephedra alkaloids are widely promoted and used as a means of losing weight and increasing energy.
Alkaloids are responsible for the plants being poisonous and it's said eating rich fish or beef broth, grease, or butter may counteract the poison .
Native to Cuba, the tiny Mount Iberia frog packs a poison punch, thanks to its diet of alkaloid-laden mites.