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 Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food ...

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 Jinigrin and

Jalapin Scammonin (also known as jalapin or scammonium) is a glycoside that has been isolated from the stems of ''Ipomoea purga'' (jalap plant) and from ''Convolvulus scammonia ''Convolvulus scammonia'', known commonly as scammony, is a bindweed native ...

Scammonin Scammonin (also known as jalapin or scammonium) is a glycoside that has been isolated from the stems of ''Ipomoea purga'' (jalap plant) and from ''Convolvulus scammonia'' (scammony). References External links

Glycosides Glycolipids ...

). It has now been extended to include synthetic ethers, such as those obtained by acting on

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...

ic 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 Rhamnose (Rha, Rham) is a naturally occurring deoxy sugar. It can be classified as either a methyl-pentose or a 6-deoxy-hexose. Rhamnose predominantly occurs in nature in its L-form as L-rhamnose (6-deoxy-L-mannose). This is unusual, since most o ...

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 Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...

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 Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

contain similar compounds. In this article the chemical classification will be followed, and only the more important compounds will be discussed herein.

Ethylene derivatives

These are generally mustard oils, which are characterized by a burning taste; their principal occurrence is in mustard and ''Tropaeolum'' seeds. Sinigrin, or the potassium salt of inyronic acid not only occurs in mustard seed, but also in black pepper and in horseradish root. Hydrolysis with barium hydroxide, or decomposition by the ferment myrosin, gives glucose, allyl mustard oil and potassium hydroxide. Sinalbin occurs in white pepper; it decomposes to the mustard oil, glucose and

sinapin Sinapine is an alkaloidal amine found in some seeds, particularly oil seeds of plants in the family Brassicaceae. It is the choline ester of sinapic acid. Sinapine was discovered by Etienne Ossian Henry in 1825. Occurrence Sinapine typically oc ...

, a compound of choline and sinapic acid.

Glycosides Glycolipids ...

occurs in

scammony ''Convolvulus scammonia'', known commonly as scammony, is a bindweed native to the countries of the eastern part of the Mediterranean basin; it grows in bushy waste places, from Syria in the south to the Crimea in the north, its range extending w ...

; it hydrolyses to glucose and jalapinolic acid.

Benzene derivatives

These are generally oxy and oxyaldehydic compounds. ; Benzoic acid derivatives The benzoyl derivative cellotropin has been used for tuberculosis.

Populin Populin is a glucoside occurring in the bark, buds and leaves of certain species of poplar. The alkaline cleavage of populin produces benzoate and the glucoside salicin Salicin is an alcoholic β-glucoside. Salicin is produced in (and named a ...

, which occurs in the leaves and bark of ''Populus tremula'', is benzoyl salicin. Benzoyl-beta-D-glucoside is a compound found in ''Pteris ensiformis''. ;Phenol derivatives There are a number of glucosides found in

natural phenol In biochemistry, naturally occurring phenols are natural products containing at least one phenol functional group. Phenolic compounds are produced by plants and microorganisms. Organisms sometimes synthesize phenolic compounds in response to eco ...

s and polyphenols, as, for example, in the

flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

s chemical family. Arbutin, which occurs in bearberry along with

methyl arbutin In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula . In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in many ...

, hydrolyses to hydroquinone and Glucose. Pharmacologically it acts as a urinary antiseptic and diuretic; Salicin, also termed

Saligenin Salicyl alcohol (saligenin) is an organic compound with the formula C6H4(OH)(CH2OH). It is a white solid that is used as a precursor in organic synthesis. Chemical synthesis Salicyl alcohol can be prepared through the reduction of salicylal ...

and glucose occurs in the willow. The enzymes

ptyalin α-Amylase is an enzyme (EC 3.2.1.1; systematic name 4-α-D-glucan glucanohydrolase) that hydrolyses α bonds of large, α-linked polysaccharides, such as starch and glycogen, yielding shorter chains thereof, dextrins, and maltose: :Endo ...

and emulsin convert it into glucose and saligenin, ortho-oxybenzylalcohol. Oxidation gives the aldehyde

helicin Helicin is the ''O''-glucoside of salicylaldehyde Salicylic aldehyde (2-hydroxybenzaldehyde) is the organic compound with the formula (C7 H6 O2) C6H4CHO-2-OH. Along with 3-hydroxybenzaldehyde and 4-hydroxybenzaldehyde, it is one of the three ...

Styrolene derivatives

This group contains a benzene and also an

ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene i ...

group, being derived from

styrolene Styrene () is an organic compound with the chemical formula C6H5CH=CH2. This derivative of benzene is a colorless oily liquid, although aged samples can appear yellowish. The compound evaporates easily and has a sweet smell, although high concen ...

. Coniferin, C₁₆H₂₂O₈, occurs in the cambium of

conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...

wood. Emulsin converts it into glucose and coniferyl alcohol, while oxidation gives glycovanillin, which yields with emulsin, glucose and vanillin.

Syringin Syringin is a natural chemical compound first isolated from the bark of lilac (''Syringa vulgaris'') by Meillet in 1841. It has since been found to be distributed widely throughout many types of plants. It is also called eleutheroside B, and is fo ...

, which occurs in the bark of '' Syringa vulgaris'', is a methoxyconiferin. Phloridzus occurs in the root-bark of various fruit trees; it hydrolyses to glucose and phloretin, which is the phloroglucin ester of paraoxyhydratropic acid. It is related to the

pentosides In chemistry, a pentose is a monosaccharide (simple sugar) with five carbon atoms. The chemical formula of many pentoses is , and their molecular weight is 150.13 g/mol.naringin, C₂₇H₃₂O₁₄, which hydrolyses to rhamnose and naringenin, the phioroglucin ester of para-oxycinnamic acid, and hesperidin, which hydrolyses to

and hesperetin, the

phloroglucin Phloroglucinol is an organic compound with the formula C6H3(OH)3. It is a colorless solid. It is used in the synthesis of pharmaceuticals and explosives. Phloroglucinol is one of three isomeric benzenetriols. The other two isomers are hydroxyquin ...

ester of meta-oxy-para-methoxycinnamic acid or isoferulic acid, C₁₀H₁₀O₄. * Aesculin (C₂₁H₂₄O₁₃), occurring in horse-chestnut and California buckeye, and daphnin, occurring in ''

Daphne alpina ''Daphne alpina'' is a shrub, of the family Thymelaeaceae. It is deciduous, and is found in southern and central Europe. Description The shrub has an erect habit, and grows to a height of 40 to 60 cm. It grows leaves that are 1 to 4 ...

'', are

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

ic; the former hydrolyses to glucose and aesculetin (C₉H₆O₄ — 6,7-dihydroxycoumarin), the latter to glucose and daphnetin (7,8-dihydroxycoumarin). *

Fraxin Fraxin is a glucoside of fraxetin. Bibliography

Coumarins Phenol glucosides {{aromatic-stub ...

, occurring in '' Fraxinus excelsior'', and with aesculin, hydrolyses to glucose and

fraxetin Fraxetin is an ''O''-methylated coumarin. It can be found in ''Fraxinus rhynchophylla'' and seeds of ''Datura stramonium''. Fraxin is a glucoside of fraxetin. References

O-methylated coumarins Catechols {{phenol-stub ...

( also known as 7,8-dihydroxy-6-methoxycoumarin) *

Flavone Flavone is an organic compound with the formula . A white solid, flavone is a derivative of chromone with a phenyl (Ph) substituent adjacent to the ether group. The compound is of little direct practical importance, but susbstituted derivatives, t ...

or benzo-7-pyrone derivatives are numerous; in many cases they (or the non-sugar part of the molecule) are vegetable dyes. * Quercitrin is a yellow dyestuff found in '' Quercus velutina''; it hydrolyses to

and quercetin, a dioxy-~3-phenyl-trioxybenzoy-pyrone.a * Rhamnetin, a splitting product of the glucosides of '' Rhamnus'', is monomethyl quercetin; fisetin, from '' Rhus cotinus'', is monoxyquercetin;

chrysin Chrysin, also called 5,7-dihydroxyflavone, is a flavone found in honey, propolis, the passion flowers, ''Passiflora caerulea'' and ''Passiflora incarnata'', and in ''Oroxylum indicum''. It is extracted from various plants, such as the blue passion ...

is phenyl-dioxybenzo-y-pyrone. * Saponarin, a glucoside found in '' Saponaria officinalis'', is a related compound. * Strophanthin is the name given to two different compounds, g-strophanthin (

ouabain Ouabain or (from Somali ''waabaayo'', "arrow poison" through French ''ouabaïo'') also known as g-strophanthin, is a plant derived toxic substance that was traditionally used as an arrow poison in eastern Africa for both hunting and warfare. ...

) obtained from ''

Strophanthus gratus ''Strophanthus gratus'' is a plant in the dogbane family Apocynaceae. Description ''Strophanthus gratus'' is a woody liana that can grow up to , with a trunk diameter of up to . Its fragrant flowers feature a white corolla, topped by red or pur ...

'' and k-strophanthin from ''Stroph. kombé''.

Anthracene derivatives

These are generally substituted anthraquinones; many have medicinal applications, being used as purgatives, while one, ruberythric acid, yields the valuable dyestuff madder, the base of which is alizarin. Chrysophanic acid, a dioxymethylanthraquinone, occurs in rhubarb, which also contains emodin, a trioxymethylanthraquinone; this substance occurs in combination with rhamnose in ''Frangula'' bark. Arguably the most important cyanogenic glucoside is amygdalin, which occurs in bitter almonds. The enzyme maltase decomposes it into glucose and mandelic nitrile glucoside; the latter is broken down by emulsin into glucose,

benzaldehyde Benzaldehyde (C6H5CHO) is an organic compound consisting of a benzene ring with a formyl substituent. It is the simplest aromatic aldehyde and one of the most industrially useful. It is a colorless liquid with a characteristic almond-like odor. ...

and prussic acid. Emulsin also decomposes amygdalin directly into these compounds without the intermediate formation of mandelic nitrile glucoside. Several other glucosides of this nature have been isolated. The

saponin Saponins (Latin "sapon", soap + "-in", one of), also selectively referred to as triterpene glycosides, are bitter-tasting usually toxic plant-derived organic chemicals that have a foamy quality when agitated in water. They are widely distributed ...

s are a group of substances characterized by forming a lather with water; they occur in soap-bark. Mention may also be made of indican, the glucoside of the indigo plant; this is hydrolysed by the indigo ferment, indimulsiri, to indoxyl and indiglucin.

Ethylene derivatives

Benzene derivatives

Styrolene derivatives

Anthracene derivatives

References

Further reading