Crossword clues for glucoside
The Collaborative International Dictionary
Glucoside \Glu"co*side\, n. [See Glucose.] (Chem.) One of a large series of amorphous or crystalline substances, occurring very widely distributed in plants, rarely in animals, and regarded as influental agents in the formation and disposition of the sugars. They are frequently of a bitter taste, but, by the action of ferments, or of dilute acids and alkalies, always break down into some characteristic substance (acid, aldehyde, alcohol, phenole, or alkaloid) and glucose (or some other sugar); hence the name. They are of the nature of complex and compound ethers, and ethereal salts of the sugar carbohydrates.
n. (context biochemistry English) A glycoside that yields glucose after hydrolysis.
n. a glycoside derived from glucose
A glucoside is a glycoside that is derived from glucose. Glucosides are common in plants, but rare in animals. Glucose is produced when a glucoside is hydrolysed by purely chemical means, or decomposed by fermentation or enzymes.
The name was originally given to plant products of this nature, in which the other part of the molecule was, in the greater number of cases, an aromatic aldehydic or phenolic compound (exceptions are sinigrin and jalapin or scammonin). It has now been extended to include synthetic ethers, such as those obtained by acting on alcoholic glucose solutions with hydrochloric acid, and also the polysaccharoses, e.g. cane sugar, which appear to be ethers also. Although glucose is the most common sugar present in glucosides, many are known which yield rhamnose or iso-dulcite; these may be termed pentosides. Much attention has been given to the non-sugar parts (aglyca) of the molecules; the constitutions of many have been determined, and the compounds synthesized; and in some cases the preparation of the synthetic glucoside effected.
The simplest glucosides are the alkyl ethers which have been obtained by reacting hydrochloric acid on alcoholic glucose solutions. A better method of preparation is to dissolve solid anhydrous glucose in methanol containing hydrochloric acid. A mixture of alpha- and beta-methylglucoside results.
Classification of the glucosides is a matter of some intricacy. One method based on the chemical constitution of the non-glucose part of the molecules has been proposed that posits four groups: (I) alkyl derivatives, (2) benzene derivatives, (3) styrolene derivatives, and (4) anthracene derivatives. A group may also be constructed to include the cyanogenic glucosides, i.e. those containing prussic acid. Alternate classifications follow a botanical classification, which has several advantages; in particular, plants of allied genera contain similar compounds. In this article the chemical classification will be followed, and only the more important compounds will be discussed herein.
Usage examples of "glucoside".
From the bark of the stem and root of the apple, pear and plum trees, a glucoside is to be obtained in small crystals, which possesses the peculiar property of producing artificial diabetes in animals to whom it is given.
The seeds contain abundantly a demulcent oil, whilst the petals furnish a glucoside which is colourless unless treated with alkalies, when it becomes of a golden yellow.
The seeds themselves contain in the cotyledons and endosperm from 30 to 40 per cent of a fixed oil, of a light yellow colour, and about 25 per cent proteids, together with wax, resin, sugar, phosphates, acetic acid, and a small quantity of the glucoside Linamarin.
It has properties very similar to Black Mustard seeds, containing Sinigrin, a crystalline glucoside, which is decomposed in the presence of water by Myrosin, an enzyme found also in the root, the chief produce being the volatile oil Allyl, isothiocyanate, which is identical with that of Black Mustard seed.
Other constituents are a crystalline saponin- like glucoside, an amorphous, bitter glucoside, which is a modification of tannin, and is known as Ipecacuanhic acid, choline, resin, pectin, starch, sugar, calcium oxalate, odorous, fatty matter and a disagreeable-smelling volatile oil.
The assertion has been made that the bark contains glucosides which yield on hydrolysis Chrysophanic acid, but the evidence on this point is conflicting.
The seeds also contain the crystalline glucoside Sinalbin and the enzyme Myrosin, which unite to form a volatile oil, called Sinalbin Mustard Oil, used for various purposes, though not so pungent as that of Black Mustard.
The Bitter Almond seed also contains a ferment Emulsin, which in presence of water acts on the soluble glucoside Amygdalin yielding glucose, prussic acid and the essential oil of Bitter Almonds, or Benzaldehyde, which is not used in medicine.
Arum leaves give off prussic acid when injured, being a product of certain glucosides contained, called cyanophoric glucosides.