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In chemistry, a glycoside is a
molecule A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioche ...
in which a sugar is bound to another
functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the re ...
via a
glycosidic bond A glycosidic bond or glycosidic linkage is a type of covalent bond that joins a carbohydrate (sugar) molecule to another group, which may or may not be another carbohydrate. A glycosidic bond is formed between the hemiacetal or hemiketal group ...
. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. These can be activated by
enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolys ...
, which causes the sugar part to be broken off, making the chemical available for use. Many such plant glycosides are used as
medication A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the medical field and ...
s. Several species of ''
Heliconius ''Heliconius'' comprises a colorful and widespread genus of brush-footed butterflies commonly known as the longwings or heliconians. This genus is distributed throughout the tropical and subtropical regions of the New World, from South America ...
'' butterfly are capable of incorporating these plant compounds as a form of chemical defense against predators. 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 A glycosidic bond or glycosidic linkage is a type of covalent bond that joins a carbohydrate (sugar) molecule to another group, which may or may not be another carbohydrate. A glycosidic bond is formed between the hemiacetal or hemiketal group ...
. Glycosides can be linked by an O- (an '' O-glycoside''), N- (a '' glycosylamine''), S-(a ''
thioglycoside In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides ...
''), or C- (a '' C-glycoside'') glycosidic bond. According to the
IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...
, the name "''C''-glycoside" is a misnomer; the preferred term is "''C''-glycosyl compound". The given definition is the one used by
IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...
, which recommends the
Haworth projection In chemistry, a Haworth projection is a common way of writing a structural formula to represent the cyclic structure of monosaccharides with a simple three-dimensional perspective. Haworth projection approximate the shapes of the actual mole ...
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 polysaccharides. The sugar group is then known as the ''glycone'' and the non-sugar group as the ''
aglycone An aglycone (aglycon or genin) is the compound remaining after the glycosyl group on a glycoside is replaced by a hydrogen atom. For example, the aglycone of a cardiac glycoside would be a steroid molecule. Detection A way to identify aglycone ...
'' or ''genin'' part of the glycoside. The glycone can consist of a single sugar group ( monosaccharide), two sugar groups (
disaccharide A disaccharide (also called a double sugar or ''biose'') is the sugar formed when two monosaccharides are joined by glycosidic linkage. Like monosaccharides, disaccharides are simple sugars soluble in water. Three common examples are sucrose, la ...
), or several sugar groups (
oligosaccharide An oligosaccharide (/ˌɑlɪgoʊˈsækəˌɹaɪd/; from the Greek ὀλίγος ''olígos'', "a few", and σάκχαρ ''sácchar'', "sugar") is a saccharide polymer containing a small number (typically two to ten) of monosaccharides (simple sug ...
). The first glycoside ever identified was
amygdalin Amygdalin (from Ancient Greek: ' "almond") is a naturally occurring chemical compound found in many plants, most notably in the seeds (kernels) of apricots, bitter almonds, apples, peaches, cherries, and plums. Amygdalin is classified as a cy ...
, by the French chemists Pierre Robiquet and Antoine Boutron-Charlard, in 1830.


Related compounds

Molecules containing an N-glycosidic bond are known as glycosylamines. Many authors in
biochemistry Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and ...
call these compounds ''N-glycosides'' and group them with the glycosides; this is considered a misnomer and is discouraged by the
International Union of Pure and Applied Chemistry The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...
. Glycosylamines and glycosides are grouped together as
glycoconjugates Glycoconjugates are the classification family for carbohydrates – referred to as glycans – which are covalently linked with chemical species such as proteins, peptides, lipids, and other compounds. Glycoconjugates are formed in processes term ...
; other glycoconjugates include
glycoproteins Glycoproteins are proteins which contain oligosaccharide chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosy ...
, glycopeptides, peptidoglycans,
glycolipids Glycolipids are lipids with a carbohydrate attached by a glycosidic (covalent) bond. Their role is to maintain the stability of the cell membrane and to facilitate cellular recognition, which is crucial to the immune response and in the conne ...
, and
lipopolysaccharides Lipopolysaccharides (LPS) are large molecules consisting of a lipid and a polysaccharide that are bacterial toxins. They are composed of an O-antigen, an outer core, and an inner core all joined by a covalent bond, and are found in the outer m ...
.


Chemistry

Much of the chemistry of glycosides is explained in the article on
glycosidic bond A glycosidic bond or glycosidic linkage is a type of covalent bond that joins a carbohydrate (sugar) molecule to another group, which may or may not be another carbohydrate. A glycosidic bond is formed between the hemiacetal or hemiketal group ...
s. For example, the glycone and aglycone portions can be chemically separated by
hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolys ...
in the presence of acid and can be hydrolyzed by alkali. There are also numerous
enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
s that can form and break glycosidic bonds. The most important cleavage enzymes are the
glycoside hydrolase Glycoside hydrolases (also called glycosidases or glycosyl hydrolases) catalyze the hydrolysis of glycosidic bonds in complex sugars. They are extremely common enzymes with roles in nature including degradation of biomass such as cellulose (ce ...
s, and the most important synthetic enzymes in nature are
glycosyltransferase Glycosyltransferases (GTFs, Gtfs) are enzymes (EC 2.4) that establish natural glycosidic linkages. They catalyze the transfer of saccharide moieties from an activated nucleotide sugar (also known as the "glycosyl donor") to a nucleophilic glyco ...
s. Genetically altered enzymes termed glycosynthases have been developed that can form glycosidic bonds in excellent yield. There are many ways to chemically synthesize glycosidic bonds. Fischer glycosidation 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 is the condensation of glycosyl halides and alcohols in the presence of metal salts such as
silver carbonate Silver carbonate is the chemical compound with the formula Ag2CO3. This salt is yellow but typical samples are grayish due to the presence of elemental silver. It is poorly soluble in water, like most transition metal carbonates. Preparation and ...
or
mercuric oxide Mercury(II) oxide, also called mercuric oxide or simply mercury oxide, is the inorganic compound with the formula Hg O. It has a red or orange color. Mercury(II) oxide is a solid at room temperature and pressure. The mineral form montroydite is v ...
.


Classification

Glycosides can be classified 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 is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...
, then the molecule is a glucoside; if it is fructose, then the molecule is a fructoside; if it is glucuronic acid, then the molecule is a
glucuronide A glucuronide, also known as glucuronoside, is any substance produced by linking glucuronic acid to another substance via a glycosidic bond. The glucuronides belong to the glycosides. Glucuronidation, the conversion of chemical compounds to glucu ...
; etc. In the body, toxic substances are often bonded to glucuronic acid to increase their water solubility; the resulting glucuronides are then excreted. Compounds can also be generally defined based on the class of glycone; for example, biosides are glycosides with a disaccharide (biose) glycone.


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 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: :Endohyd ...
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 alcoholic glycoside is salicin, which is found in the genus ''
Salix Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist s ...
''. Salicin is converted in the body into salicylic acid, which is closely related to
aspirin Aspirin, also known as acetylsalicylic acid (ASA), is a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and/or inflammation, and as an antithrombotic. Specific inflammatory conditions which aspirin is used to treat inc ...
and has analgesic,
antipyretic An antipyretic (, from ''anti-'' 'against' and ' 'feverish') is a substance that reduces fever. Antipyretics cause the hypothalamus to override a prostaglandin-induced increase in temperature. The body then works to lower the temperature, which r ...
, and
anti-inflammatory Anti-inflammatory is the property of a substance or treatment that reduces inflammation or swelling. Anti-inflammatory drugs, also called anti-inflammatories, make up about half of analgesics. These drugs remedy pain by reducing inflammation as o ...
effects.


Anthraquinone glycosides

These glycosides contain an aglycone group that is a derivative of
anthraquinone Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic organic compound with formula . Isomers include various quinone derivatives. The term anthraquinone however refers to the isomer, 9,10-anthraquinone (IUPAC: 9,10-dioxoan ...
. They have a
laxative Laxatives, purgatives, or aperients are substances that loosen stools and increase bowel movements. They are used to treat and prevent constipation. Laxatives vary as to how they work and the side effects they may have. Certain stimulant, lubri ...
effect. They are mainly found in
dicot The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, t ...
plants except the family
Liliaceae The lily family, Liliaceae, consists of about 15 genera and 610 species of flowering plants within the order Liliales. They are monocotyledonous, perennial, herbaceous, often bulbous geophytes. Plants in this family have evolved with a fair a ...
which are
monocot Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one Embryo#Plant embryos, embryonic leaf, or cotyledon. Th ...
s. They are present in senna, rhubarb and '' Aloe'' species. Anthron and anthranol are reduced forms of anthraquinone.


Coumarin glycosides

Here, the aglycone is
coumarin Coumarin () or 2''H''-chromen-2-one is an aromatic organic chemical compound with formula . Its molecule can be described as a benzene molecule with two adjacent hydrogen atoms replaced by a lactone-like chain , forming a second six-membered h ...
or a derivative. An example is
apterin Apterin is a furanocoumarin and the glucoside of vaginol. It has been isolated from the root of plants in the family Apiaceae such as members of the genus '' Angelica'', including the garden angelica and ''Zizia aptera ''Zizia aptera'' is a fl ...
which is reported to dilate the
coronary arteries The coronary arteries are the arterial blood vessels of coronary circulation, which transport oxygenated blood to the heart muscle. The heart requires a continuous supply of oxygen to function and survive, much like any other tissue or organ o ...
as well as block calcium channels. Other coumarin glycosides are obtained from dried leaves of '' Psoralea corylifolia''.


Chromone glycosides

In this case, the aglycone is called benzo-gamma-pyrone.


Cyanogenic glycosides

In this case, the aglycone contains a
cyanohydrin In organic chemistry, a cyanohydrin or hydroxynitrile is a functional group found in organic compounds in which a cyano and a hydroxy group are attached to the same carbon atom. The general formula is , where R is H, alkyl, or aryl. Cyanohydr ...
group. Plants that make cyanogenic glycosides store them in the
vacuole A vacuole () is a membrane-bound organelle which is present in 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 m ...
, but, if the plant is attacked, they are released and become activated by enzymes in the
cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. ...
. These remove the sugar part of the molecule, allowing the cyanohydrin structure to collapse and release toxic hydrogen cyanide. Storing them in inactive forms in the vacuole prevents them from damaging the plant under normal conditions. Along with playing a role in deterring herbivores, in some plants they control germination,
bud In botany, a bud is an undeveloped or embryonic shoot and normally occurs in the axil of a leaf or at the tip of a stem. Once formed, a bud may remain for some time in a dormant condition, or it may form a shoot immediately. Buds may be spec ...
formation, carbon and nitrogen transport, and possibly act as antioxidants. The production of cyanogenic glycosides is an evolutionarily conserved function, appearing in species as old as
ferns A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes except th ...
and as recent as angiosperms. These compounds are made by around 3,000 species. in screens they are found in about 11% of cultivated plants but only 5% of plants overall; humans seem to have selected for them. Examples include
amygdalin Amygdalin (from Ancient Greek: ' "almond") is a naturally occurring chemical compound found in many plants, most notably in the seeds (kernels) of apricots, bitter almonds, apples, peaches, cherries, and plums. Amygdalin is classified as a cy ...
and
prunasin (''R'')-prunasin is a cyanogenic glycoside related to amygdalin. Chemically, it is the glucoside of (''R'')- mandelonitrile. Natural occurrences Prunasin is found in species in the genus ''Prunus'' such as '' Prunus japonica'' or '' P. maximow ...
which are made by the
bitter almond The almond (''Prunus amygdalus'', syn. ''Prunus dulcis'') is a species of tree native to Iran and surrounding countries, including the Levant. The almond is also the name of the edible and widely cultivated seed of this tree. Within the genus ...
tree; other species that produce cyanogenic glycosides are sorghum (from which
dhurrin Dhurrin is a cyanogenic glycoside produced in many plants. Discovered in multiple sorghum varieties in 1906 as the culprit of cattle poisoning by hydrogen cyanide, dhurrin is most typically associated with '' Sorghum bicolor'', the organism use ...
, the first cyanogenic glycoside to be identified, was first isolated),
barley Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley p ...
, flax,
white clover ''Trifolium repens'', the white clover, is a herbaceous perennial plant in the bean family Fabaceae (otherwise known as Leguminosae). It is native to Europe, including the British Isles,Clapham, A.R., Tutin, T.G. and Warburg., E.F. 1968. ''Excursio ...
, and
cassava ''Manihot esculenta'', commonly called cassava (), manioc, or yuca (among numerous regional names), is a woody shrub of the spurge family, Euphorbiaceae, native to South America. Although a perennial plant, cassava is extensively cultivated ...
, which produces
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. Upon exposure to enzymes and gut flora in the human intestine, linamarin and its methylat ...
and lotaustralin. Amygdalin and a synthetic derivative,
laetrile Amygdalin (from Ancient Greek: ' "almond") is a naturally occurring chemical compound found in many plants, most notably in the seeds (kernels) of apricots, bitter almonds, apples, peaches, cherries, and plums. Amygdalin is classified as a ...
, were investigated as potential drugs to treat cancer and were heavily promoted as alternative medicine; they are ineffective and dangerous. Some butterfly species, such as the ''
Dryas iulia ''Dryas iulia'' (often incorrectly spelled ''julia''),Lamas, G. (editor) (2004). Atlas of Neotropical Lepidoptera. Checklist: Part 4A. Hesperioidea – Papilionoidea. commonly called the Julia butterfly, Julia heliconian, the flame, or flambeau ...
'' and '' Parnassius smintheus'', have evolved to use the cyanogenic glycosides found in their host plants as a form of protection against predators through their unpalatability.


Flavonoid glycosides

Here, the aglycone is a flavonoid. Examples of this large group of glycosides include: * Hesperidin (aglycone:
hesperetin Hesperetin is the 4'-methoxy derivative of eriodictyol, a flavanone. Hesperetin's 7-O-glycoside, hesperidin, is a naturally occurring flavanon-glycoside, the main flavonoid in lemons and sweet oranges. Hesperetin (and naringenin, the parent flav ...
, glycone:
rutinose Rutinose is the disaccharide also known as 6-''O''-α-L- rhamnosyl-D-glucose (C12H22O10) that is present in some flavonoid glycosides. It is prepared from rutin by hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of wat ...
) *
Naringin Naringin is a flavanone-7-''O''- glycoside between the flavanone naringenin and the disaccharide neohesperidose. The flavonoid naringin occurs naturally in citrus fruits, especially in grapefruit, where naringin is responsible for the fruit' ...
(aglycone:
naringenin Naringenin is a flavorless, colorless flavanone, a type of flavonoid. It is the predominant flavanone in grapefruit, and is found in a variety of fruits and herbs. Structure Naringenin has the skeleton structure of a flavanone with three hydro ...
, glycone: rutinose) *
Rutin Rutin, also called rutoside, quercetin-3-O-rutinoside and sophorin, is the glycoside combining the flavonol quercetin and the disaccharide rutinose (α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranose). It is a flavonoid found in a wide variety of pl ...
(aglycone:
quercetin Quercetin is a plant flavonol from the flavonoid group of polyphenols. It is found in many fruits, vegetables, leaves, seeds, and grains; capers, red onions, and kale are common foods containing appreciable amounts of it. It has a bitter flavor ...
, glycone: rutinose) *
Quercitrin Quercitrin is a glycoside formed from the flavonoid quercetin and the deoxy sugar rhamnose. Austrian chemist Heinrich Hlasiwetz (1825-1875) is remembered for his chemical analysis of quercitrin. Occurrence Quercitrin is a constituent of the ...
(aglycone: quercetin, glycone: rhamnose) Among the important effects of flavonoids are their antioxidant effect. They are also known to decrease
capillary A capillary is a small blood vessel from 5 to 10 micrometres (μm) in diameter. Capillaries are composed of only the tunica intima, consisting of a thin wall of simple squamous endothelial cells. They are the smallest blood vessels in the bod ...
fragility.


Phenolic glycosides

Here, the aglycone is a simple
phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it ...
ic structure. An example is
arbutin Arbutin is a glycoside; a glycosylated hydroquinone extracted from the bearberry plant in the genus ''Arctostaphylos'' among many other medicinal plants, primarily in the family Ericaceae. Applied topically, it inhibits tyrosinase and thus prev ...
found in the Common Bearberry ''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 or haemolysis (), also known by several other names, is the rupturing ( lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may occur in vivo ...
of
red blood cell Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...
s. Saponin glycosides are found in liquorice. Their medicinal value is due to their
expectorant Mucoactive agents are a class of chemical agents that aid in the clearance of mucus or sputum from the upper and lower airways, including the lungs, bronchi, and trachea. Mucoactive drugs include expectorants, mucolytics, mucoregulators, and muco ...
,
corticoid Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are invol ...
and anti-inflammatory effects. Steroid saponins are important starting material for the production of semi-synthetic
glucocorticoids Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebr ...
and other
steroid hormones A steroid hormone is a steroid that acts as a hormone. Steroid hormones can be grouped into two classes: corticosteroids (typically made in the adrenal cortex, hence ''cortico-'') and sex steroids (typically made in the gonads or placenta). Withi ...
such as progesterone; for example in Dioscorea
wild yam Wild yam is a common name for several plants and may refer to: * '' Dioscorea dregeana'', native to southern Africa * ''Dioscorea villosa ''Dioscorea villosa'' is a species of twining tuberous vine which is native to eastern North America. It is ...
the
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 such as tigge ...
diosgenin, in the form of its glycoside dioscin. The
ginsenosides Ginsenosides or panaxosides are a class of natural product steroid glycosides and triterpene saponins. Compounds in this family are found almost exclusively in the plant genus ''Panax'' (ginseng), which has a long history of use in traditional ...
are
triterpene Triterpenes are a class of chemical compounds composed of three terpene units with the molecular formula C30H48; they may also be thought of as consisting of six isoprene units. Animals, plants and fungi all produce triterpenes, including squa ...
glycosides and ginseng saponins from ''
Panax ginseng ''Panax ginseng'', ginseng, also known as Asian ginseng, Chinese ginseng, or Korean ginseng, is a species of plant whose root is the original source of ginseng. It is a perennial plant that grows in the mountains of East Asia. Names ''Panax gi ...
'' (Chinese ginseng) and ''Panax quinquefolius'' (
American ginseng American ginseng (''Panax quinquefolius'') is a herbaceous perennial plant in the ivy family, commonly used as an herb in traditional Chinese medicine. It is native to eastern North America, though it is also cultivated in China. Since the 18th ...
). In general, the use of the term saponin in organic chemistry is discouraged, because many plant constituents can produce
foam Foams are materials formed by trapping pockets of gas in a liquid or solid. A bath sponge and the head on a glass of beer are examples of foams. In most foams, the volume of gas is large, with thin films of liquid or solid separating the ...
, and many
triterpene Triterpenes are a class of chemical compounds composed of three terpene units with the molecular formula C30H48; they may also be thought of as consisting of six isoprene units. Animals, plants and fungi all produce triterpenes, including squa ...
-glycosides are amphipolar under certain conditions, acting as a surfactant. More modern uses of saponins in biotechnology are as
adjuvants In pharmacology, an adjuvant is a drug or other substance, or a combination of substances, that is used to increase the efficacy#Pharmacology, efficacy or Potency (pharmacology), potency of certain drugs. Specifically, the term can refer to: * Adju ...
in
vaccines A vaccine is a biological preparation that provides active acquired immunity to a particular infectious or malignant disease. The safety and effectiveness of vaccines has been widely studied and verified.< ...
:
Quil A Quillaia is the milled inner bark or small stems and branches of the soapbark ( ''Quillaja saponaria'', Molina). Other names include ''Murillo bark extract'', ''Panama bark extract'', ''Quillaia extract'', ''Quillay bark extract'', and ''Soapbark ...
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-effect of
hemolysis Hemolysis or haemolysis (), also known by several other names, is the rupturing ( lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may occur in vivo ...
. Saponins are also natural ruminal antiprotozoal agents that are potential to improve ruminal microbial fermentation reducing ammonia concentrations and methane production in ruminant
animals Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in ...
.


Steroidal glycosides or cardiac glycosides

Here the aglycone part is a steroidal nucleus. These glycosides are found in the plant genera ''
Digitalis ''Digitalis'' ( or ) is a genus of about 20 species of herbaceous perennial plants, shrubs, and biennials, commonly called foxgloves. ''Digitalis'' is native to Europe, western Asia, and northwestern Africa. The flowers are tubular in shap ...
'', ''
Scilla ''Scilla'' () is a genus of about 30 to 80 species of bulb-forming perennial herbaceous plants in the family Asparagaceae, subfamily Scilloideae. Sometimes called the squills in English, they are native to woodlands, subalpine meadows, and sea ...
'', and ''
Strophanthus ''Strophanthus'' is a genus of flowering plants in the family Apocynaceae, first described as a genus in 1802. It is native primarily to tropical Africa, extending to South Africa, with a few species in Asia from southern India to New Guinea and ...
''. They are used in the treatment of heart diseases, e.g.,
congestive heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, ...
(historically as now recognised does not improve survivability; other agents are now preferred) and arrhythmia.


Steviol glycosides

These sweet glycosides found in the stevia plant ''Stevia rebaudiana'' Bertoni have 40–300 times the sweetness of sucrose. The two primary glycosides, stevioside and rebaudioside A, are used as natural
sweeteners A sugar substitute is a food additive that provides a sweetness like that of sugar while containing significantly less food energy than sugar-based sweeteners, making it a zero-calorie () or low-calorie sweetener. Artificial sweeteners may be d ...
in many countries. These glycosides have steviol as the aglycone part.
Glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...
or rhamnose-glucose combinations are bound to the ends of the aglycone to form the different compounds.


Iridoid glycosides

These contain an
iridoid Iridoids are a type of monoterpenoids in the general form of cyclopentanopyran, found in a wide variety of plants and some animals. They are biosynthetically derived from 8-oxogeranial. Iridoids are typically found in plants as glycosides, mos ...
group; e.g.
aucubin Aucubin is an iridoid glycoside. Iridoids are commonly found in plants and function as defensive compounds. Iridoids decrease the growth rates of many generalist herbivores. Natural occurrences Aucubin, as other iridoids, is found in asterids ...
, geniposidic acid, theviridoside,
loganin Loganin is one of the best-known of the iridoid glycosides. It is named for the Loganiaceae, having first been isolated from the seeds of a member of that plant family, namely those of ''Strychnos nux-vomica''. It also occurs in ''Alstonia boonei' ...
,
catalpol Catalpol is an iridoid glucoside. This natural product falls in the class of iridoid glycosides, which are simply monoterpenes with a glucose molecule attached. Natural occurrence First isolated in 1962, catalpol was named for plants in the ge ...
.


Thioglycosides

As the name implies (q.v.
thio- The prefix thio-, when applied to a chemical, such as an ion, means that an oxygen atom in the compound has been replaced by a sulfur atom. This term is often used in organic chemistry. For example, from the word ''ether,'' referring to an ox ...
), these compounds contain sulfur. Examples include
sinigrin Sinigrin is a glucosinolate that belongs to the family of glucosides found in some plants of the family Brassicaceae such as Brussels sprouts, broccoli, and the seeds of black mustard (''Brassica nigra''). Whenever sinigrin-containing plant tis ...
, found in
black mustard ''Brassica nigra'', or black mustard, is an annual plant cultivated for its dark-brown-to-black seeds, which are commonly used as a spice. It is native to tropical regions of North Africa, temperate regions of Europe, and parts of Asia. Desc ...
, and
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 (''Brassica nigra'') seeds which contain sinigrin, mustard from white mustard seeds has o ...
, found in
white mustard White mustard (''Sinapis alba'') is an annual plant of the family Brassicaceae. It is sometimes also referred to as ''Brassica alba'' or ''B. hirta''. Grown for its seeds, used to make the condiment mustard, as fodder crop, or as a green manure ...
.


See also

*
Carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or m ...
*
Carbohydrate chemistry Carbohydrate chemistry is a subdiscipline of chemistry primarily concerned with the detection, synthesis, structure, and function of carbohydrates. Due to the general structure of carbohydrates, their synthesis is often preoccupied with the selec ...
* Chemical glycosylation *
Glycorandomization Glycorandomization, is a drug discovery and drug development technology platform to enable the rapid diversification of bioactive small molecules, drug leads and/or approved drugs through the attachment of sugars. Initially developed as a facile me ...
* Glycosylation *
Natural products A natural product is a natural compound or substance produced by a living organism—that is, found in nature. In the broadest sense, natural products include any substance produced by life. Natural products can also be prepared by chemical sy ...


References


External links


Definition of glycosides
from the
IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...
Compendium of Chemical Terminology, the "
Gold Book The International Union of Pure and Applied Chemistry publishes many books which contain its complete list of definitions. The definitions are divided into seven "colour books": Gold, Green, Blue, Purple, Orange, White, and Red. There is also an e ...
"
IUPAC naming rules for glycosides
{{Authority control Carbohydrate chemistry