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In
chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during a with other . ...

chemistry
, a glycoside is a
molecule A molecule is an electrically Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position In physics, motion is the phenomenon ...

molecule
in which a
sugar Sugar is the generic name for sweet-tasting, soluble carbohydrate is a disaccharide A disaccharide (also called a double sugar or ''biose'') is the sugar formed when two monosaccharides are joined by glycosidic linkage. Like monosacc ...

sugar
is bound to another
functional group In organic chemistry, a functional group is a substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions re ...
via a
glycosidic bond A glycosidic bond or glycosidic linkage is a type of covalent bond A covalent bond is a chemical bond A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may ...
. 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 protein Proteins are large s and s that comprise one or more long chains of . Proteins perform a vast array of functions within organisms, including , , , providing and , and from one location to another. Proteins diff ...
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 Substitution may refer to: Arts and media *Chord substitution, in music, swapping one chord for ...

hydrolysis
, 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 medical diagnosis, diagnose, cure, therapy, treat, or preventive medicine, prevent disease. Drug therapy (pharmacotherapy) ...

medication
s. Several species of ''
Heliconius ''Heliconius'' comprises a colorful and widespread genus of Nymphalidae, 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 So ...

Heliconius
'' 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 An anomer is a type of geometric variation found at certain atoms in carbohydrate is a disaccharide found in animal milk. It consists of a molecule of D-galactose and a molecule of D-glucose bonded by beta-1-4 glycosidic linkage. A carbohy ...
to another group via a
glycosidic bond A glycosidic bond or glycosidic linkage is a type of covalent bond A covalent bond is a chemical bond A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may ...
. Glycosides can be linked by an O- (an ''
O-glycoside In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they un ...
''), N- (a ''
glycosylamine 120px, Cyclic hemiaminal ether bond derived from an aldehyde Glycosylamines are a class of biochemical compounds consisting of a Glycosyl, glycosyl group attached to an amine, amino group, -NR2. They are also known as N-glycosides,. as they are a ty ...
''), S-(a ''
thioglycoside In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they un ...
''), or C- (a ''
C-glycoside In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they un ...
'') glycosidic bond. According to the
IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering OrganizationsNational Adhering Organizations in chemistry are the organizations that work as the authoritative power over chemist ...
, the name "''C''-glycoside" is a
misnomer A misnomer is a name that is incorrectly or unsuitably applied. Misnomers often arise because something was named long before its correct nature was known, or because an earlier form of something has been replaced by a later form to which the nam ...
; 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 OrganizationsNational Adhering Organizations in chemistry are the organizations that work as the authoritative power over chemist ...
, which recommends the
Haworth projection 275px, Haworth projection of the structures for α-D-glucopyranose and L-Glucose, α-L-glucopyranose. A Haworth projection is a common way of writing a structural formula to represent the cyclic molecular geometry, structure of monosaccharides with ...
to correctly assign
stereochemicals. Stereochemistry focuses on stereoisomer In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dime ...
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 Polysaccharides (), or polycarbohydrates, are the most abundant found in . They are long chain carbohydrates composed of units bound together by . This carbohydrate can react with water () using as catalyst, which produces constituent sugars ...
s. The sugar group is then known as the ''glycone'' and the non-sugar group as the ''
aglyconeAn aglycone (aglycon or genin) is the compound remaining after the glycosyl group on a glycoside In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atom ...
'' or ''genin'' part of the glycoside. The glycone can consist of a single sugar group (
monosaccharide Monosaccharides (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is ap ...
), two sugar groups (
disaccharide A disaccharide (also called a double sugar or ''biose'') is the sugar Sugar is the generic name for sweet-tasting, soluble carbohydrate is a disaccharide found in animal milk. It consists of a molecule of D-galactose and a molecule of ...
), or several sugar groups (
oligosaccharide An oligosaccharide (/ˌɑlɪgoʊˈsækəˌɹaɪd/; from the Greek ὀλίγος ''olígos'', "a few", and σάκχαρ ''sácchar'', "sugar") is a saccharide is a disaccharide A disaccharide (also called a double sugar or ''biose'') is the sug ...
). The first glycoside ever identified was
amygdalin Amygdalin (from Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: ...

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


Related compounds

Molecules containing an N-glycosidic bond are known as
glycosylamine 120px, Cyclic hemiaminal ether bond derived from an aldehyde Glycosylamines are a class of biochemical compounds consisting of a Glycosyl, glycosyl group attached to an amine, amino group, -NR2. They are also known as N-glycosides,. as they are a ty ...
s and are not discussed in this article. (Many authors in
biochemistry Biochemistry or biological chemistry, is the study of es within and relating to living s. A sub-discipline of both and , biochemistry may be divided into three fields: , and . Over the last decades of the 20th century, biochemistry has beco ...

biochemistry
call these compounds ''N-glycosides'' and group them with the glycosides; this is considered a misnomer, and discouraged by
IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering OrganizationsNational Adhering Organizations in chemistry are the organizations that work as the authoritative power over chemist ...
.) Glycosylamines and glycosides are grouped together as
glycoconjugates Glycoconjugates is the general classification for carbohydrates – referred to as glycan, glycans – which are covalent bond, covalently linked with other chemical species such as protein, proteins, peptide, peptides, lipid, lipids, and other com ...
; other glycoconjugates include
glycoproteins Glycoproteins are protein Proteins are large biomolecules or macromolecules that are comprised of one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including ...
,
glycopeptides Glycopeptides are peptides that contain carbohydrate Moiety (chemistry), moieties (glycans) Covalent bond, covalently attached to the side chains of the amino acid residues that constitute the peptide. Over the past few decades it has been recogn ...
,
peptidoglycans Peptidoglycan or murein is a polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy image of pent ...
,
glycolipids Glycolipids are lipids In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiolog ...

glycolipids
, and
lipopolysaccharides Lipopolysaccharides (LPS) are large molecules consisting of a lipid and a polysaccharide composed of O-antigen, outer core and inner core joined by a covalent bond; they are found in the Bacterial outer membrane, outer membrane of Gram-negative ...
.


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 A covalent bond is a chemical bond A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may ...
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 Substitution may refer to: Arts and media *Chord substitution, in music, swapping one chord for ...

hydrolysis
in the presence of
acid An acid is a or capable of donating a (hydrogen ion H+) (a ), or, alternatively, capable of forming a with an (a ). The first category of acids are the proton donors, or s. In the special case of , proton donors form the H3O+ and are ...
and can be hydrolyzed by
alkali In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds composed of ato ...

alkali
. There are also numerous
enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates in ...

enzyme
s that can form and break glycosidic bonds. The most important cleavage enzymes are the
glycoside hydrolases 1HNY, a glycoside hydrolase Glycoside hydrolases (also called glycosidases or glycosyl hydrolases) catalysis, catalyze the hydrolysis of glycosidic bonds in polysaccharide, complex sugars. They are extremely common enzymes with roles in nature incl ...
, and the most important synthetic enzymes in nature are
glycosyltransferases Most glycosyltransferase enzymes form one of two folds: GT-A or GT-B Glycosyltransferases (GTFs, Gtfs) are enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules ...
. 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 glycosidationFischer glycosidation (or Fischer glycosylation) refers to the formation of a glycoside by the reaction of an aldoseAn aldose is a monosaccharide Monosaccharides (from Greek '' monos'': single, ''sacchar'': sugar), also called simple sugars, are t ...

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 A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held together by ...

silver carbonate
or
mercuric oxide Mercury(II) oxide, also called mercuric oxide or simply mercury oxide, has a formula of 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 very rarely found. History ...
.


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 with the . Glucose is the most abundant , a subcategory of s. Glucose is mainly made by and most during from water and carbon dioxide, using energy from sunlight, where it is used to make in s, the most abundant carbohydr ...

glucose
, then the molecule is a
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 Hydrolysis, hydrolysed by purely chemical means, or decomposed by fermentation (biochemistry), ...
; if it is
fructose Fructose, or fruit sugar, is a ketonic simple sugar Monosaccharides (from Greek language, Greek ''wikt:μόνος, monos'': single, ''sacchar'': sugar), also called simple sugars, are the simplest form of sugar and the most basic units (monomers ...

fructose
, then the molecule is a fructoside; if it is
glucuronic acid Glucuronic acid (from Greek γλυκύς "sweet" and οὖρον "urine") is a uronic acid that was first isolated from urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys throu ...

glucuronic acid
, then the molecule is a
glucuronide A glucuronide, also known as glucuronoside, is any substance produced by linking glucuronic acid Glucuronic acid (from Greek γλυκύς "sweet" and οὖρον "urine") is a uronic acid that was first isolated from urine Urine is a liquid ...
; 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 Alpha-amylase, (α-amylase) is an enzyme that hydrolysis, hydrolyses alpha bonds of large, alpha-linked polysaccharides, such as starch and glycogen, yielding shorter chains thereof, dextrin, dextrins, and maltose. It is the major form of amyl ...
can only hydrolyze α-linkages; others, such as
emulsin Beta-glucosidase is an enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enz ...
, 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 In chemistry, alcohol is an organic compound that carries at least one hydroxyl functional group (−OH) bound to a Saturated and unsaturated compounds, saturated carbon atom. The term alcohol originally referred to the primary alcohol ethan ...

alcohol
ic glycoside is
salicin Salicin is an alcoholic β-glucoside Image:Decyl-glucoside-2D-skeletal.png, Chemical structure of decyl glucoside, a plant-derived glucoside used as a surfactant. A glucoside is a glycoside that is derived from glucose. Glucosides are common in ...

salicin
, which is found in the genus ''
Salix Willows, also called sallows and osiers, from the genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classifica ...

Salix
''. Salicin is converted in the body into
salicylic acid Salicylic acid is an organic compound with the formula HOC6H4CO2H. A colorless, bitter-tasting solid, it is a precursor to and a active metabolite, metabolite of aspirin (acetylsalicylic acid). It is a plant hormone, and has been listed by the ...

salicylic acid
, which is closely related to
aspirin Aspirin, also known as acetylsalicylic acid (ASA), is a medication A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug Uncoated tablets, consisting of about 90% acetylsalicy ...

aspirin
and has
analgesic An analgesic or painkiller is any member of the group of used to achieve analgesia, relief from . They are distinct from s, which temporarily affect, and in some instances completely eliminate, . Analgesic choice is also determined by the type ...
,
antipyretic An antipyretic (, from ''anti-'' 'against' and ' 'feverish') is a substance that reduces fever Fever, also referred to as pyrexia, is defined as having a temperature Temperature is a physical quantity that expresses hot and cold. It ...
, and
antiinflammatoryAnti-inflammatory (or antiinflammatory) is the property of a substance or treatment that reduces inflammation or Swelling (medical), swelling. Anti-inflammatory drugs make up about half of analgesics, remedying pain by reducing inflammation as oppose ...
effects.


Anthraquinone glycosides

These glycosides contain an aglycone group that is a derivative of
anthraquinone Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic hydrocarbon, aromatic organic compound with formula . Isomers include various quinone derivatives. The term anthraquinone, however refers to the isomer, 9,10-anthraquino ...
. They have a
laxative Laxatives, purgatives, or aperients are substances that loosen human feces, stools and increase defecation, bowel movements. They are used to treat and prevent constipation. Laxatives vary as to how they work and the side effects they may have. C ...
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 plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "a ...
plants except the family
Liliaceae The lily family In human society A society is a Social group, group of individuals involved in persistent Social relation, social interaction, or a large social group sharing the same spatial or social territory, typically subject ...

Liliaceae
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. The ...
s. They are present in
senna Senna may refer to: Individuals * Ayrton Senna (1960–1994), Brazilian F1 driver and triple World Champion * Bruno Senna (born 1983), F1 driver and nephew of Ayrton Senna * Viviane Senna (born 1958), IAS president and sister of Ayrton Senna * D ...
,
rhubarb Rhubarb is the fleshy, edible stalks ( petioles) of species and hybrids (culinary rhubarb) of '' Rheum'' in the family Polygonaceae The Polygonaceae are a family In human society A society is a Social group, group of individuals ...

rhubarb
and ''
Aloe ''Aloe'' ( , ), also written ''Aloë'', is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology Biology is the natural science that studies life and livin ...

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 A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance th ...

coumarin
or a derivative. An example is
apterin
apterin
which is reported to dilate the
coronary arteries The coronary arteries are the arterial blood vessels of coronary circulation Coronary circulation is the circulation of blood in the blood vessels that supply the cardiac muscle, heart muscle (myocardium). Coronary arteries supply oxygen saturat ...
as well as block
calcium channelA calcium channel is an ion channel s (typically four per channel), 2 - outer vestibule, 3 - Potassium channel#Selectivity filter, selectivity filter, 4 - diameter of selectivity filter, 5 - phosphorylation site, 6 - cell membrane. Ion channels are ...
s. Other coumarin glycosides are obtained from dried leaves of ''
Psoralea corylifolia ''Psoralea corylifolia'' (Babchi) is a plant used in Indian and Chinese traditional medicine. The seeds of this plant contain a variety of coumarins, including psoralen. Etymology ''Psoralea'' is from the Greek ''psoraleos'' meaning 'scabby', and ...
''.


Chromone glycosides

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


Cyanogenic glycosides

In this case, the aglycone contains a
cyanohydrin 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 R2C(OH)CN, where R is H, alkyl, or aryl. Cyanohydrins are industria ...

cyanohydrin
group. Plants that make cyanogenic glycosides store them in the
vacuole A vacuole () is a membrane-bound organelle In cell biology, an organelle is a specialized subunit, usually within a cell (biology), cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts o ...
, but, if the plant is attacked, they are released and become activated by enzymes in the
cytoplasm In cell biology Cell biology (also cellular biology or cytology) is a branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes ...
. These remove the sugar part of the molecule, allowing the cyanohydrin structure to collapse and release toxic
hydrogen cyanide
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 Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the An ...

bud
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 plant Vascular plants (from Latin ''vasculum'': duct), also known as Tracheophyta (the tracheophytes , from Greek τραχεῖα ἀρτηρία ''trācheia art ...

ferns
and as recent as
angiosperm Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ...

angiosperm
s. 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 Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: ...

amygdalin
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 ''Prunus maximowi ...

prunasin
which are made by the
bitter almond The almond (''Prunus dulcis'', syn. ''Prunus amygdalus'') is a species of tree native to Iran Iran ( fa, ایران ), also called Persia and officially the Islamic Republic of Iran ( fa, جمهوری اسلامی ایران ), is a ...
tree; other species that produce cyanogenic glycosides are
sorghum ''Sorghum'' is a genus of about 25 species of flowering plants in the grass family ( Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species, '' Sorghum bicolor'', was originally ...

sorghum
(from which , the first cyanogenic glycoside to be identified, was first isolated),
barley Barley (''Hordeum vulgare''), a member of the grass family Poaceae () or Gramineae () is a large and nearly ubiquitous family In human society, family (from la, familia) is a group of people related either by consanguinity (by recogn ...

barley
,
flax Flax, also known as common flax or linseed, is a flowering plant, ''Linum usitatissimum'', in the family Linaceae. It is cultivated as a food and fiber crop in regions of the world with temperate climates. Textiles made from flax are known in Wes ...

flax
,
white clover ''Trifolium repens'', the white clover (also known as Dutch clover, Ladino clover, or Ladino), is a herbaceous perennial plant in the bean family Fabaceae (previously referred to as Leguminosae). It is native to Europe, including the British Isle ...
, and
cassava ''Manihot esculenta'', commonly called cassava (), manioc, or yuca (among numerous regional names) is a woody shrub A shrub (or bush, but this is more of a gardening term) is a small- to medium-sized perennial woody plant. Unlike herb ...

cassava
, 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 methyla ...

linamarin
and . Amygdalin and a synthetic derivative,
laetrile Amygdalin (from Greek language, Ancient Greek: ' "almond") is a naturally occurring chemical compound best known for being falsely promoted as a cancer cure. It is found in many plants, but most notably in the seeds (kernels) of apricots, bitter ...

laetrile
, were investigated as potential drugs to treat cancer and were heavily promoted as
alternative medicine Alternative medicine is any practice that aims to achieve the healing effects of medicine Medicine is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds ...
; 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, ...

Dryas iulia
'' and ''
Parnassius smintheus ''Parnassius smintheus'', the Rocky Mountain parnassianJim P. Brock and K. Kaufman. Kaufman Field Guide to Butterflies of North America, New York, NY:Houghton Mifflin, 2003. or Rocky Mountain apollo, is a high-altitude butterfly found in the Rocky ...
'', 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 Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenol Polyphenols () are a large family of naturally occurring s characterized by multiples of units. They are abunda ...
. Examples of this large group of glycosides include: *
Hesperidin Hesperidin is a flavanone glycoside found in citrus fruits. Its aglycone form is called hesperetin. Its name is derived from the word "hesperidium", for fruit produced by citrus trees. Hesperidin was first isolated in 1828 by French chemist Lebr ...

Hesperidin
(aglycone:
hesperetin Hesperetin is the 4'-methoxy derivative of eriodictyol, a flavonoid#Subgroups, flavanone. Hesperetin's 7-O-glycoside, hesperidin, is a naturally occurring flavanon-glycoside, the main flavonoid in lemons and sweet oranges. Hesperetin (and naringeni ...

hesperetin
, glycone:
rutinose Rutinose is the disaccharide A disaccharide (also called a double sugar or ''biose'') is the sugar Sugar is the generic name for sweet-tasting, soluble carbohydrate is a disaccharide found in animal milk. It consists of a molecule of ...

rutinose
) *
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's bitter ...

Naringin
(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 hydrox ...

naringenin
, glycone: rutinose) *
Rutin Rutin, also called rutoside, quercetin-3-O-rutinoside and sophorin, is the glycoside In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical elem ...

Rutin
(aglycone:
quercetin Quercetin is a plant flavonol Flavonols are a class of flavonoids that have the 3-hydroxyflavone backbone (IUPAC name : 3-hydroxy-2-phenylchromen-4-one). Their diversity stems from the different positions of the phenols, phenolic hydroxyl, -OH g ...

quercetin
, glycone: rutinose) *
Quercitrin Quercitrin is a glycoside In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, structure, properties, beha ...

Quercitrin
(aglycone: quercetin, glycone:
rhamnose Rhamnose (Rha, Rham) is a naturally occurring deoxy sugar Image:Alpha-L-Rhamnopyranose.svg, 150px, rhamnose Deoxy sugars are sugars that have had a hydroxyl group replaced with a hydrogen atom. Examples include: * Deoxyribose, or 2-deoxy-D-rib ...
) Among the important effects of flavonoids are their
antioxidant Antioxidants are that inhibit , a that can produce and s that may damage the of organisms. Antioxidants such as s or (vitamin C) may act to inhibit these reactions. To balance , plants and animals maintain complex systems of overlapping an ...

antioxidant
effect. They are also known to decrease
capillary A capillary is a small blood vessel The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an organ system that permits blood to circulate ...

capillary
fragility.


Phenolic glycosides

Here, the aglycone is a simple
phenol Phenol (also called carbolic acid) is an aromatic forms of benzene (top) combine to produce an average structure (bottom) In chemistry, aromaticity is a property of cyclic compound, cyclic (ring (chemistry), ring-shaped), plane (geometry), p ...
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 enzyme inhibitor, inhibits tyrosinas ...
found in the ''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 Lysis ( ; Greek λύσις ''lýsis'', "a loosing" from λύειν ''lýein'', "to unbind") is the breaking down of the membrane of a cell, often by ...

hemolysis
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 language, Greek ''erythros'' for "red" and ''k ...

red blood cell
s. Saponin glycosides are found in
liquorice Liquorice ( UK) or licorice ( US) ( ; also ) is the common name Common may refer to: Places * Common, a townland in County Tyrone, Northern Ireland * Boston Common Boston Common (also known as the Common) is a central public park in dow ...

liquorice
. Their medicinal value is due to their
expectorant Mucoactive agents are a class of chemical agents which aid in the clearance of mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it ...
,
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 involved ...
and
anti-inflammatoryAnti-inflammatory (or antiinflammatory) is the property of a substance or treatment that reduces inflammation or swelling. Anti-inflammatory drugs make up about half of analgesics, remedying pain by reducing inflammation as opposed to opioids, whic ...
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 vertebra ...
and other
steroid hormones A steroid hormone is a steroid , a steroid with 27 carbon atoms. Its core ring system (ABCD), composed of 17 carbon atoms, is shown with IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of ...
such as
progesterone Progesterone (P4) is an endogenous Endogenous substances and processes are those that originate from within a system such as an organism, Tissue (biology), tissue, or Cell (biology), cell. Endogenous substances and processes contrast with exo ...

progesterone
; for example in
Dioscorea ''Dioscorea'' is a genus of over 600 species of flowering plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may re ...
wild yamWild yam may refer to: * ''Dioscorea dregeana'' in Africa * ''Dioscorea villosa'' in North America {{Short pages monitor