Glycoside
Overview
 
In chemistry
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

, a glycoside (ˈɡlaɪkəsaɪd) is a molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

 in which a sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...

 is bound to a non-carbohydrate moiety, usually a small organic molecule. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. These can be activated by enzyme hydrolysis
Hydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...

, which causes the sugar part to be broken off, making the chemical available for use. Many such plant glycosides are used as medication
Medication
A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...

s.
Encyclopedia
In chemistry
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

, a glycoside (ˈɡlaɪkəsaɪd) is a molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

 in which a sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...

 is bound to a non-carbohydrate moiety, usually a small organic molecule. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. These can be activated by enzyme hydrolysis
Hydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...

, which causes the sugar part to be broken off, making the chemical available for use. Many such plant glycosides are used as medication
Medication
A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...

s. In animals and humans, poisons are often bound to sugar molecules as part of their elimination from the body.

In formal terms, a glycoside is any molecule in which a sugar group is bonded through its anomeric carbon to another group via a glycosidic bond
Glycosidic bond
In chemistry, a glycosidic bond is a type of covalent bond that joins a carbohydrate molecule to another group, which may or may not be another carbohydrate....

. Glycosides can be linked by an O- (an O-glycoside), N- (a glycosylamine
Glycosylamine
Glycosylamine is a class of biochemical compounds consisting of an amine with a β-N-glycosidic bond to a carbohydrate, thus forming a cyclic hemiaminal ether bond .Examples include nucleosides such as adenosine....

), S-(a thioglycoside), or C- (a C-glycoside) glycosidic bond. The given definition is the one used by IUPAC, which recommends the Haworth projection
Haworth projection
A Haworth projection is a common way of representing the cyclic structure of monosaccharides with a simple three-dimensional perspective.The Haworth projection was named after the English chemist Sir Norman Haworth....

 to correctly assign stereochemical configurations. Many authors require in addition that the sugar be bonded to a non-sugar for the molecule to qualify as a glycoside, thus excluding polysaccharide
Polysaccharide
Polysaccharides are long carbohydrate molecules, of repeated monomer units joined together by glycosidic bonds. They range in structure from linear to highly branched. Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit. Depending on the structure,...

s. The sugar group is then known as the glycone and the non-sugar group as the aglycone
Aglycone
An aglycone is the non-sugar compound remaining after replacement of the glycosyl group from a glycoside by a hydrogen atom. The spelling aglycon is sometimes encountered .Classes of phytochemicals found in the aglycone and glycosides forms :...

or genin part of the glycoside. The glycone can consist of a single sugar group (monosaccharide
Monosaccharide
Monosaccharides are the most basic units of biologically important carbohydrates. They are the simplest form of sugar and are usually colorless, water-soluble, crystalline solids. Some monosaccharides have a sweet taste. Examples of monosaccharides include glucose , fructose , galactose, xylose...

) or several sugar groups (oligosaccharide
Oligosaccharide
An oligosaccharide is a saccharide polymer containing a small number of component sugars, also known as simple sugars...

).

The first glycoside ever identified was amygdalin
Amygdalin
Amygdalin , C20H27NO11, is a glycoside initially isolated from the seeds of the tree Prunus dulcis, also known as bitter almonds, by Pierre-Jean Robiquet...

, by the French chemists Pierre Robiquet and Antoine Boutron-Charlard, in 1830.

Related compounds

Molecules containing an N-glycosidic bond are known as glycosylamines and are not discussed in this article. (Many authors in biochemistry
Biochemistry
Biochemistry, sometimes called biological chemistry, is the study of chemical processes in living organisms, including, but not limited to, living matter. Biochemistry governs all living organisms and living processes...

 call these compounds N-glycosides and group them with the glycosides; this is considered a misnomer and discouraged by IUPAC.)

Chemistry

Much of the chemistry of glycosides is explained in the article on glycosidic bond
Glycosidic bond
In chemistry, a glycosidic bond is a type of covalent bond that joins a carbohydrate molecule to another group, which may or may not be another carbohydrate....

s. For example, the glycone and aglycone portions can be chemically separated by hydrolysis
Hydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...

 in the presence of acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...

. There are also numerous enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

s that can form and break glycosidic bonds. The most important cleavage enzymes are the glycoside hydrolases, and the most important synthetic enzymes in nature are glycosyltransferases. Genetically altered enzymes termed glycosynthases have been developed that can form glycosidic bonds in excellent yield.

There are a great many ways to chemically synthesize glycosidic bonds. Fischer glycosidation
Fischer glycosidation
Fischer glycosidation refers to the formation of a glycoside by the reaction of an aldose or ketose with an alcohol in the presence of an acid catalyst...

 refers to the synthesis of glycosides by the reaction of unprotected monosaccharides with alcohols (usually as solvent) in the presence of a strong acid catalyst. The Koenigs-Knorr reaction
Koenigs-Knorr reaction
The Koenigs–Knorr reaction in organic chemistry is the substitution reaction of a glycosyl halide with an alcohol to give a glycoside. It is one of the oldest and simplest glycosylation reactions...

 is the condensation of glycosyl halides and alcohols in the presence of metal salts such as silver carbonate or mercuric oxide.

Classification

We can classify glycosides by the glycone, by the type of glycosidic bond, and by the aglycone.

By glycone/presence of sugar

If the glycone group of a glycoside is glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

, then the molecule is a glucoside
Glucoside
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....

; if it is fructose
Fructose
Fructose, or fruit sugar, is a simple monosaccharide found in many plants. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed directly into the bloodstream during digestion. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847...

, then the molecule is a fructoside
Fructoside
Fructosides are glycosides where the glycone group is fructose....

; if it is glucuronic acid
Glucuronic acid
Glucuronic acid is a carboxylic acid. Its structure is similar to that of glucose. However, glucuronic acid's sixth carbon is oxidized to a carboxylic acid...

, then the molecule is a glucuronide
Glucuronide
A glucuronide, also known as glucuronoside, is any substance produced by linking glucuronic acid to another substance via a glycosidic bond...

; etc. In the body, toxic substances are often bonded to glucuronic acid to increase their water solubility; the resulting glucuronides are then excreted.

By type of glycosidic bond

Depending on whether the glycosidic bond lies "below" or "above" the plane of the cyclic sugar molecule, glycosides are classified as α-glycosides or β-glycosides. Some enzymes such as α-amylase
Amylase
Amylase is an enzyme that catalyses the breakdown of starch into sugars. Amylase is present in human saliva, where it begins the chemical process of digestion. Food that contains much starch but little sugar, such as rice and potato, taste slightly sweet as they are chewed because amylase turns...

 can only hydrolyze α-linkages; others, such as emulsin, can only affect β-linkages.

There are four type of linkages present between glycone and aglycone:
  • C-linkage/glycosidic bond, "nonhydrolysable by acids or enzymes"
  • O-linkage/glycosidic bond
  • N-linkage/glycosidic bond
  • S-linkage/glycosidic bond

By aglycone

Glycosides are also classified according to the chemical nature of the aglycone. For purposes of biochemistry and pharmacology, this is the most useful classification.

Alcoholic glycosides

An example of an alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....

ic glycoside is salicin, which is found in the genus salix. Salicin is converted in the body into salicylic acid
Salicylic acid
Salicylic acid is a monohydroxybenzoic acid, a type of phenolic acid and a beta hydroxy acid. This colorless crystalline organic acid is widely used in organic synthesis and functions as a plant hormone. It is derived from the metabolism of salicin...

, which is closely related to aspirin
Aspirin
Aspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. It was discovered by Arthur Eichengrun, a chemist with the German company Bayer...

 and has analgesic
Analgesic
An analgesic is any member of the group of drugs used to relieve pain . The word analgesic derives from Greek an- and algos ....

, antipyretic
Antipyretic
Antipyretics ; an-tee-pahy-ret-iks; from the Greek anti, against, and pyreticus, are drugs or herbs that reduce fever. Normally, they will not lower body temperature if one does not have a fever. Antipyretics cause the hypothalamus to override an interleukin-induced increase in temperature...

, and antiinflammatory
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...

 effects.

Anthraquinone glycosides

These glycosides contain an aglycone group that is a derivative of anthraquinone
Anthraquinone
Anthraquinone, also called anthracenedione or dioxoanthracene is an aromatic organic compound with formula . Several isomers are possible, each of which can be viewed as a quinone derivative...

. They have a laxative
Laxative
Laxatives are foods, compounds, or drugs taken to induce bowel movements or to loosen the stool, most often taken to treat constipation. Certain stimulant, lubricant, and saline laxatives are used to evacuate the colon for rectal and/or bowel examinations, and may be supplemented by enemas under...

 effect. They are mainly found in dicot plants except the Liliaceae
Liliaceae
The Liliaceae, or the lily family, is a family of monocotyledons in the order Liliales. Plants in this family have linear leaves, mostly with parallel veins but with several having net venation , and flower arranged in threes. Several have bulbs, while others have rhizomes...

 family which are monocots. They are present in senna, rhubarb
Rhubarb
Rhubarb is a group of plants that belong to the genus Rheum in the family Polygonaceae. They are herbaceous perennial plants growing from short, thick rhizomes. They have large leaves that are somewhat triangular-shaped with long fleshy petioles...

 and Aloe
Aloe
Aloe , also Aloë, is a genus containing about 500 species of flowering succulent plants. The most common and well known of these is Aloe vera, or "true aloe"....

species. Antron and anthranol are reduced forms of anthraquinone

Coumarin glycosides

Here the aglycone is coumarin
Coumarin
Coumarin is a fragrant chemical compound in the benzopyrone chemical class, found in many plants, notably in high concentration in the tonka bean , vanilla grass , sweet woodruff , mullein , sweet grass , cassia cinnamon and sweet clover...

 or a derivative. An example is apterin
Apterin
Apterin is a furanocoumarin glucoside reported to dilate coronary arteries as well as block calcium channels. It can be found plants of the Apiaceae family. It has been isolated from the root of plants in the genus Angelica, including Garden Angelica and in Zizia aptera....

 which is reported to dilate the coronary arteries as well as block calcium channel
Calcium channel
A Calcium channel is an ion channel which displays selective permeability to calcium ions. It is sometimes synonymous as voltage-dependent calcium channel, although there are also ligand-gated calcium channels.-Comparison tables:...

s. Other coumarin glycosides are obtained from dried leaves of Psoralea corylifolia
Psoralea corylifolia
Psoralea corylifolia is an important plant in the Indian Ayurveda and Tamil Siddha systems of medicine, and also Chinese medicine. The seeds of this plant contain a variety of coumarins including psoralen. The seeds have a variety of medicinal uses, but the specific role of psoralen in these uses...

.

Cyanogenic glycosides

In this case, the aglycone contains a cyanide
Cyanide
A cyanide is a chemical compound that contains the cyano group, -C≡N, which consists of a carbon atom triple-bonded to a nitrogen atom. Cyanides most commonly refer to salts of the anion CN−. Most cyanides are highly toxic....

 group. In many plants, these glycosides are stored in the vacuole
Vacuole
A vacuole is a membrane-bound organelle which is present in all plant and fungal cells and some protist, animal and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic molecules including enzymes in solution, though in certain...

, but, if the plant is attacked, they are released and become activated by enzymes in the cytoplasm
Cytoplasm
The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...

. These remove the sugar part of the molecule and release toxic hydrogen cyanide. Storing them in inactive forms in the cytoplasm prevents them from damaging the plant under normal conditions.

An example of these is amygdalin
Amygdalin
Amygdalin , C20H27NO11, is a glycoside initially isolated from the seeds of the tree Prunus dulcis, also known as bitter almonds, by Pierre-Jean Robiquet...

 from almond
Almond
The almond , is a species of tree native to the Middle East and South Asia. Almond is also the name of the edible and widely cultivated seed of this tree...

s. They can also be found in the fruits (and wilting leaves) of the rose family
Rosaceae
Rosaceae are a medium-sized family of flowering plants, including about 2830 species in 95 genera. The name is derived from the type genus Rosa. Among the largest genera are Alchemilla , Sorbus , Crataegus , Cotoneaster , and Rubus...

 (including cherries
Cherry
The cherry is the fruit of many plants of the genus Prunus, and is a fleshy stone fruit. The cherry fruits of commerce are usually obtained from a limited number of species, including especially cultivars of the wild cherry, Prunus avium....

, apple
Apple
The apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...

s, plum
Plum
A plum or gage is a stone fruit tree in the genus Prunus, subgenus Prunus. The subgenus is distinguished from other subgenera in the shoots having a terminal bud and solitary side buds , the flowers in groups of one to five together on short stems, and the fruit having a groove running down one...

s, almonds, peach
Peach
The peach tree is a deciduous tree growing to tall and 6 in. in diameter, belonging to the subfamily Prunoideae of the family Rosaceae. It bears an edible juicy fruit called a peach...

es, apricot
Apricot
The apricot, Prunus armeniaca, is a species of Prunus, classified with the plum in the subgenus Prunus. The native range is somewhat uncertain due to its extensive prehistoric cultivation.- Description :...

s, raspberries
Raspberry
The raspberry or hindberry is the edible fruit of a multitude of plant species in the genus Rubus, most of which are in the subgenus Idaeobatus; the name also applies to these plants themselves...

, and crabapple
Crabapple
Crabapple is a term used for several species of Malus in the family Rosaceae, which are characterized by small sour fruit resembling familiar table apples . They are usually small trees or shrubs....

s). Cassava
Cassava
Cassava , also called yuca or manioc, a woody shrub of the Euphorbiaceae native to South America, is extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy tuberous root, a major source of carbohydrates...

, an important food plant in Africa and South America, contains cyanogenic glycosides and, therefore, has to be washed and ground under running water prior to consumption. Sorghum
Sorghum
Sorghum is a genus of numerous species of grasses, one of which is raised for grain and many of which are used as fodder plants either cultivated or as part of pasture. The plants are cultivated in warmer climates worldwide. Species are native to tropical and subtropical regions of all continents...

 (Sorghum bicolor) expresses cyanogenic glycosides in its roots and, thus, is resistant to pests such as rootworms (Diabrotica
Diabrotica
Diabrotica is a widespread genus of beetles, sometimes referred to as cucumber beetles or corn rootworms, in the family Chrysomelidae. Members of this genus include several destructive agricultural pest species.-Range:...

 spp.) that plague its cousin maize
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...

 (Zea mays L.). It was once thought that cyanogenic glycosides might have anti-cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

 properties, but this idea was disproven (see Amygdalin). A recent study may also show that increasing levels may result in much higher levels of cyanogenic glycoside production in sorghum
Sorghum
Sorghum is a genus of numerous species of grasses, one of which is raised for grain and many of which are used as fodder plants either cultivated or as part of pasture. The plants are cultivated in warmer climates worldwide. Species are native to tropical and subtropical regions of all continents...

 and cassava
Cassava
Cassava , also called yuca or manioc, a woody shrub of the Euphorbiaceae native to South America, is extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy tuberous root, a major source of carbohydrates...

 plants, making them highly toxic and inconsumable. A doubling of concentration was found to double the concentration of cyanogenic glycosides in the leaves.

Dhurrin
Dhurrin
Dhurrin is a cyanogenic glycoside occurring in plants. Its biosynthesis has been elucidated. Dhurrin is hydrolyzed in the stomach of an insect into a carbohydrate and aglycone. The aglycone is unstable and releases hydrogen cyanide....

, linamarin
Linamarin
Linamarin is a cyanogenic glucoside found in the leaves and roots of plants such as cassava, lima beans, and flax. It is a glucoside of acetone cyanohydrin...

, lotaustralin
Lotaustralin
Lotaustralin is a cyanogenic glucoside found in small amounts in Fabaceae Austral Trefoil , cassava , lima bean , roseroot and white clover , among other plants...

, and prunasin are also classified as cyanogenic glycosides.

Flavonoid glycosides

Here the aglycone is a flavonoid
Flavonoid
Flavonoids , are a class of plant secondary metabolites....

. Examples of this large group of glycosides include:
  • Hesperidin
    Hesperidin
    Hesperidin is a flavanone glycoside found abundantly in citrus fruits. Its aglycone form is called hesperetin. Its name is derived from the Hesperides nymphs of Greek mythology. Hesperidin is believed to play a role in plant defense. It acts as an antioxidant according to in vitro studies...

     (aglycone: Hesperetin
    Hesperetin
    Hesperetin is a bioflavonoid and, to be more specific, a flavanone. Hesperidin is water-soluble due to the presence of the sugar part in its structure, so on ingestion it releases its aglycone, i.e, hesperetin....

    , glycone: Rutinose
    Rutinose
    Rutinose is the disaccharide also known as 6-O-L-rhamnosyl-D-glucose that is present in some flavonoid glycosides. It is prepared from rutin by hydrolysis with the enzyme rhamnodiastase....

    )
  • Naringin
    Naringin
    Naringin is a flavanone glycoside. It is a major flavonoid in grapefruit and gives the grapefruit juice its bitter taste. It is metabolized to the flavanone naringenin in humans...

     (aglycone: Naringenin
    Naringenin
    Naringenin is a flavanone, a type of flavonoid, that is considered to have a bioactive effect on human health as antioxidant, free radical scavenger, anti-inflammatory, carbohydrate metabolism promoter, and immune system modulator. It is the predominant flavanone in grapefruit.-Biological...

    , glycone: Rutinose
    Rutinose
    Rutinose is the disaccharide also known as 6-O-L-rhamnosyl-D-glucose that is present in some flavonoid glycosides. It is prepared from rutin by hydrolysis with the enzyme rhamnodiastase....

    )
  • Rutin
    Rutin
    Rutin, also called rutoside, quercetin-3-O-rutinoside and sophorin, is a citrus flavonoid glycoside found in buckwheat, the leaves and petioles of Rheum species, and asparagus...

     (aglycone: Quercetin
    Quercetin
    Quercetin , a flavonol, is a plant-derived flavonoid found in fruits, vegetables, leaves and grains. It also may be used as an ingredient in supplements, beverages or foods.-Occurrence:...

    , glycone: Rutinose
    Rutinose
    Rutinose is the disaccharide also known as 6-O-L-rhamnosyl-D-glucose that is present in some flavonoid glycosides. It is prepared from rutin by hydrolysis with the enzyme rhamnodiastase....

    )
  • Quercitrin
    Quercitrin
    Quercitrin is a glycoside formed from the flavonoid quercetin and the deoxy sugar rhamnose. It is a constituent of the dye quercitron. It can be found in Tartary buckwheat ....

     (aglycone: Quercetin
    Quercetin
    Quercetin , a flavonol, is a plant-derived flavonoid found in fruits, vegetables, leaves and grains. It also may be used as an ingredient in supplements, beverages or foods.-Occurrence:...

    , glycone: Rhamnose
    Rhamnose
    Rhamnose is a naturally occurring deoxy sugar. It can be classified as either a methyl-pentose or a 6-deoxy-hexose. Rhamnose occurs in nature in its L-form as L-rhamnose . This is unusual, since most of the naturally occurring sugars are in D-form...

    )


Among the important effects of flavonoids are their antioxidant
Antioxidant
An antioxidant is a molecule capable of inhibiting the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When...

 effect. They are also known to decrease capillary
Capillary
Capillaries are the smallest of a body's blood vessels and are parts of the microcirculation. They are only 1 cell thick. These microvessels, measuring 5-10 μm in diameter, connect arterioles and venules, and enable the exchange of water, oxygen, carbon dioxide, and many other nutrient and waste...

 fragility.

Phenolic glycosides (simple)

Here the aglycone is a simple phenol
Phenol
Phenol, also known as carbolic acid, phenic acid, is an organic compound with the chemical formula C6H5OH. It is a white crystalline solid. The molecule consists of a phenyl , bonded to a hydroxyl group. It is produced on a large scale as a precursor to many materials and useful compounds...

ic structure. An example is arbutin
Arbutin
Arbutin is both an ether and a glycoside; a glycosylated hydroquinone extracted from bearberry plant in the genus Arctostaphylos. It inhibits tyrosinase and thus prevents the formation of melanin. Arbutin is therefore used as a skin-lightening agent. Arbutin is found in wheat, and is concentrated...

 found in the Common Bearberry
Bearberry
Bearberries are three species of dwarf shrubs in the genus Arctostaphylos. Unlike the other species of Arctostaphylos , they are adapted to Arctic and sub-Arctic climates, and have a circumpolar distribution in northern North America, Asia and Europe, one with a small highly disjunctive population...

 Arctostaphylos uva-ursi. It has a urinary antiseptic effect.

Saponins

These compounds give a permanent froth when shaken with water. They also cause hemolysis
Hemolysis
Hemolysis —from the Greek meaning "blood" and meaning a "loosing", "setting free" or "releasing"—is the rupturing of erythrocytes and the release of their contents into surrounding fluid...

 of red blood cell
Red blood cell
Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...

s. Saponin glycosides are found in liquorice. Their medicinal value is due to their expectorant, and corticoid and anti-inflammatory
Anti-inflammatory
Anti-inflammatory refers to the property of a substance or treatment that reduces inflammation. Anti-inflammatory drugs make up about half of analgesics, remedying pain by reducing inflammation as opposed to opioids, which affect the central nervous system....

 effects. Steroid saponins, for example, in Dioscorea
Dioscorea
Dioscorea is a genus of over 600 species of flowering plants in the family Dioscoreaceae, native throughout the tropical and warm temperate regions of the world. The vast majority of the species are tropical, with only a few species extending into temperate climates...

 wild yam
Wild yam
Dioscorea villosa is a species of a twining tuberous vine that is native to and found growing wild in North America. Its fame is based on its steroid-like saponins which can be chemically converted to progesterone ; and cortisone....

 the sapogenin
Sapogenin
Sapogenins are the aglycones, or non-saccharide, portions of the family of natural products known as saponins. Sapogenins contain steroid or other triterpene frameworks as their key organic feature. For example, steroidal sapogenins like tiggenin, neogitogenin, and tokorogenin have been isolated...

 diosgenin
Diosgenin
Diosgenin, a steroid sapogenin, is the product of hydrolysis by acids, strong bases, or enzymes of saponins, extracted from the tubers of Dioscorea wild yam, such as the Kokoro...

 - in form of its glycoside dioscin - is an important starting material for production of semi-synthetic glucocorticoids and other steroid hormones such as progesterone
Progesterone
Progesterone also known as P4 is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species...

. The ginsenosides are triterpene
Triterpene
Triterpenes are terpenes consisting of six isoprene units and have the molecular formula C30H48.The pentacyclic triterpenes can be classified into lupane, oleanane or ursane groups.Animal- and plant-derived triterpenes exist, such as:*squalene...

 glycosides and Ginseng saponins from Panax Ginseng C. A. Meyer, (Chinese ginseng
Ginseng
Ginseng is any one of eleven species of slow-growing perennial plants with fleshy roots, belonging to the genus Panax of the family Araliaceae....

) and Panax quinquefolius (American Ginseng
American Ginseng
American ginseng, Panax quinquefolius, is a herbaceous perennial plant in the ivy family, commonly used as Chinese or herbal medicine.It is native to eastern North America, though it is also cultivated in places such as China....

).
In general, the use of the term saponin in organic chemistry is discouraged, because many plant constituents can produce foam
Foam
-Definition:A foam is a substance that is formed by trapping gas in a liquid or solid in a divided form, i.e. by forming gas regions inside liquid regions, leading to different kinds of dispersed media...

, and many triterpene
Triterpene
Triterpenes are terpenes consisting of six isoprene units and have the molecular formula C30H48.The pentacyclic triterpenes can be classified into lupane, oleanane or ursane groups.Animal- and plant-derived triterpenes exist, such as:*squalene...

-glycosides are amphipolar under certain conditions acting as a tenside.
More modern uses of saponins in biotechnology are as adjuvants in vaccines: Quil A and its derivative QS-21, isolated from the bark of Quillaja saponaria Molina, to stimulate both the Th1 immune response and the production of cytotoxic T-lymphocytes (CTLs) against exogenous antigens make them ideal for use in subunit vaccines and vaccines directed against intracellular pathogens as well as for therapeutic cancer vaccines but with the aforementioned side-effects of hemolysis
Hemolysis
Hemolysis —from the Greek meaning "blood" and meaning a "loosing", "setting free" or "releasing"—is the rupturing of erythrocytes and the release of their contents into surrounding fluid...

.

Steroidal glycosides or cardiac glycosides

Here the aglycone part is a steroid
Steroid
A steroid is a type of organic compound that contains a characteristic arrangement of four cycloalkane rings that are joined to each other. Examples of steroids include the dietary fat cholesterol, the sex hormones estradiol and testosterone, and the anti-inflammatory drug dexamethasone.The core...

al nucleus. These glycosides are found in the plant genera Digitalis
Digitalis
Digitalis is a genus of about 20 species of herbaceous perennials, shrubs, and biennials that are commonly called foxgloves. This genus was traditionally placed in the figwort family Scrophulariaceae, but recent reviews of phylogenetic research have placed it in the much enlarged family...

, Scilla
Scilla
Scilla is a genus of about 50 bulb-forming perennial herbs in the family Asparagaceae, subfamily Scilloideae, native to woodlands, subalpine meadows, and seashores throughout Europe and Asia...

, and Strophanthus
Strophanthus
Strophanthus is a genus of 35-40 species of flowering plants in the family Apocynaceae, native mainly to tropical Africa, extending to South Africa, with a few species in Asia, from southern India to the Philippines and southern China. The name derives from the long twisted threadlike segments of...

. They are used in the treatment of heart disease
Heart disease
Heart disease, cardiac disease or cardiopathy is an umbrella term for a variety of diseases affecting the heart. , it is the leading cause of death in the United States, England, Canada and Wales, accounting for 25.4% of the total deaths in the United States.-Types:-Coronary heart disease:Coronary...

s, e.g., congestive heart failure
Congestive heart failure
Heart failure often called congestive heart failure is generally defined as the inability of the heart to supply sufficient blood flow to meet the needs of the body. Heart failure can cause a number of symptoms including shortness of breath, leg swelling, and exercise intolerance. The condition...

 (historically as now recognised does not improve survivability; other agents are now preferred) and arrhythmia.

Steviol glycosides

These sweet glycosides found in the stevia
Stevia
Stevia is a genus of about 240 species of herbs and shrubs in the sunflower family , native to subtropical and tropical regions from western North America to South America. The species Stevia rebaudiana, commonly known as sweetleaf, sweet leaf, sugarleaf, or simply stevia, is widely grown for its...

 plant Stevia rebaudiana Bertoni have 40-300 times the sweetness of sucrose
Sucrose
Sucrose is the organic compound commonly known as table sugar and sometimes called saccharose. A white, odorless, crystalline powder with a sweet taste, it is best known for its role in human nutrition. The molecule is a disaccharide composed of glucose and fructose with the molecular formula...

. The two primary glycosides, stevioside and rebaudioside A, are used as natural sweeteners
Sugar substitute
A sugar substitute is a food additive that duplicates the effect of sugar in taste, usually with less food energy. Some sugar substitutes are natural and some are synthetic. Those that are not natural are, in general, called artificial sweeteners....

 in many countries. These glycosides have steviol
Steviol
Steviol is a diterpene first isolated from Stevia rebaudiana in 1931. Its chemical structure was not fully elucidated until 1960.Steviol is found in the form of glycosides including the sweet chemical compound stevioside....

 as the aglycone part. Glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

 or rhamnose
Rhamnose
Rhamnose is a naturally occurring deoxy sugar. It can be classified as either a methyl-pentose or a 6-deoxy-hexose. Rhamnose occurs in nature in its L-form as L-rhamnose . This is unusual, since most of the naturally occurring sugars are in D-form...

-glucose combinations are bound to the ends of the aglycone to form the different compounds.

Thioglycosides

As the name implies (q.v. thio-), these compounds contain sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

. Examples include sinigrin
Sinigrin
Sinigrin is a glucosinolate that belongs to the family of glucosides found in some plants of the Brassicaceae family such as Brussels sprouts, broccoli, and the seeds of black mustard to name but a few...

, found in black mustard, and sinalbin
Sinalbin
Sinalbin is a glucosinolate found in the seeds of white mustard, Sinapis alba, and in many wild plant species. In contrast to mustard from black mustard seeds which contain sinigrin, mustard from white mustard seeds has only a weakly pungent taste.The less sharp taste is because the mustard oil...

, found in white mustard
White Mustard
White mustard is an annual plant of the family Brassicaceae. It is sometimes also referred to as Brassica alba or B. hirta...

.

See also

  • Carbohydrate
    Carbohydrate
    A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...

  • Carbohydrate chemistry
    Carbohydrate chemistry
    Carbohydrate chemistry is a subdiscipline of chemistry primarily concerned with the synthesis, structure, and function of carbohydrate structures. Due to the general structure of carbohydrates, their synthesis is often preoccupied with the selective formation of glycosidic linkages and the...

  • Natural products
  • Glycosylation
    Glycosylation
    Glycosylation is the reaction in which a carbohydrate, i.e. a glycosyl donor, is attached to a hydroxyl or other functional group of another molecule . In biology glycosylation refers to the enzymatic process that attaches glycans to proteins, lipids, or other organic molecules...

  • Chemical glycosylation
    Chemical glycosylation
    A chemical glycosylation reaction involves the coupling of a sugar to a glycosyl acceptor forming a glycoside. If the acceptor is another sugar, the product is an oligosaccharide. The reaction involves coupling a glycosyl donor to a glycosyl acceptor via activation utilizing a suitable activator...

  • Glycorandomization
    Glycorandomization
    Glycorandomization, which literally means “diversification of sugar-containing compounds”, is a tool currently used in the pharmaceutical industry to modify the sugar residues of the glycosylated natural products by using unique glycosylation strategies...


External links

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