Alkaloids are a class of
basic,
naturally occurring organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...
s that contain at least one
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
atom. This group also includes some related compounds with neutral
and even weakly
acidic properties. Some synthetic compounds of similar structure may also be termed alkaloids. In addition to
carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon ma ...
,
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-to ...
and
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
, alkaloids may also contain
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
,
sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formul ...
and, more rarely, other elements such as
chlorine
Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...
,
bromine
Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table ( halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simi ...
, and
phosphorus
Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ea ...
.
[Chemical Encyclopedia: alkaloids](_blank)
xumuk.ru
Alkaloids are produced by a large variety of organisms including
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...
,
fungi
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately fr ...
,
plants, and
animal
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 ...
s. They can be purified from crude extracts of these organisms by
acid-base extraction, or solvent extractions followed by silica-gel
column chromatography.
Alkaloids have a wide range of
pharmacological activities including
antimalarial (''e.g.''
quinine
Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to '' Plasmodium falciparum'' that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg ...
),
antiasthma (''e.g.''
ephedrine),
anticancer (''e.g.''
homoharringtonine),
cholinomimetic (''e.g.''
galantamine),
vasodilatory
Vasodilation is the widening of blood vessels. It results from relaxation of smooth muscle cells within the vessel walls, in particular in the large veins, large arteries, and smaller arterioles. The process is the opposite of vasoconstrictio ...
(''e.g.''
vincamine),
antiarrhythmic (''e.g.''
quinidine),
analgesic (''e.g.''
morphine
Morphine is a strong opiate that is found naturally in opium, a dark brown resin in poppies ('' Papaver somniferum''). It is mainly used as a pain medication, and is also commonly used recreationally, or to make other illicit opioids. T ...
),
antibacterial
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention ...
(''e.g.''
chelerythrine),
and
antihyperglycemic activities (''e.g.''
piperine
Piperine, along with its isomer chavicine, is the alkaloid responsible for the pungency of black pepper and long pepper. It has been used in some forms of traditional medicine.
Preparation
Due to its poor solubility in water, piperine is typi ...
).
Many have found use in
traditional
A tradition is a belief or behavior (folk custom) passed down within a group or society with symbolic meaning or special significance with origins in the past. A component of cultural expressions and folklore, common examples include holidays or ...
or
modern medicine
Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pra ...
, or as starting points for
drug discovery
In the fields of medicine, biotechnology and pharmacology, drug discovery is the process by which new candidate medications are discovered.
Historically, drugs were discovered by identifying the active ingredient from traditional remedies or b ...
. Other alkaloids possess
psychotropic (''e.g.''
psilocin) and
stimulant
Stimulants (also often referred to as psychostimulants or colloquially as uppers) is an overarching term that covers many drugs including those that increase activity of the central nervous system and the body, drugs that are pleasurable and inv ...
activities (''e.g.''
cocaine
Cocaine (from , from , ultimately from Quechua: ''kúka'') is a central nervous system (CNS) stimulant mainly used recreationally for its euphoric effects. It is primarily obtained from the leaves of two Coca species native to South Am ...
,
caffeine
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine chemical classification, class. It is mainly recreational drug use, used recreationally as a Nootropic, cognitive enhancer, increasing alertness and attentional perfor ...
,
nicotine
Nicotine is a naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and '' Duboisia hopwoodii'') and is widely used recreationally as a stimulant and anxiolytic. As a pharmaceutical drug, it is use ...
,
theobromine
Theobromine, also known as xantheose, is the principal alkaloid of '' Theobroma cacao'' (cacao plant). Theobromine is slightly water- soluble (330 mg/L) with a bitter taste. In industry, theobromine is used as an additive and precursor to ...
), and have been used in
entheogenic rituals or as
recreational drugs. Alkaloids can be
toxic
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a sub ...
too (''e.g.''
atropine
Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically given ...
,
tubocurarine).
Although alkaloids act on a diversity of metabolic systems in humans and other animals, they almost uniformly evoke a
bitter taste
The gustatory system or sense of taste is the sensory system that is partially responsible for the perception of taste (flavor). Taste is the perception produced or stimulated when a substance in the mouth reacts chemically with taste receptor ...
.
The boundary between alkaloids and other nitrogen-containing natural compounds is not clear-cut.
[Robert A. Meyers ''Encyclopedia of Physical Science and Technology'' – Alkaloids, 3rd edition. ] Compounds like
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...
peptide
Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. ...
s,
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
s,
nucleotide
Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecu ...
s,
nucleic acid
Nucleic acids are biopolymers, macromolecules, essential to all known forms of life. They are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main ...
,
amine
In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent ...
s, and
antibiotics
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and preventio ...
are usually not called alkaloids. Natural compounds containing nitrogen in the
exocyclic position (
mescaline
Mescaline or mescalin (3,4,5-trimethoxyphenethylamine) is a naturally occurring psychedelic protoalkaloid of the substituted phenethylamine class, known for its hallucinogenic effects comparable to those of LSD and psilocybin.
Biological ...
,
serotonin
Serotonin () or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Its biological function is complex and multifaceted, modulating mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and va ...
,
dopamine
Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic chemical of the catecholamine and phenethylamine families. Dopamine constitutes about 80% o ...
, etc.) are usually classified as
amine
In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent ...
s rather than as alkaloids. Some authors, however, consider alkaloids a special case of amines.
[ Aniszewski, p. 110]
Naming
The name "alkaloids" (german: Alkaloide, links=no) was introduced in 1819 by the German chemist
Carl Friedrich Wilhelm Meißner, and is derived from late Latin root and the Greek-language suffix -('like').
[In the penultimate sentence of his article, W. Meissner (1819) "Über Pflanzenalkalien: II. Über ein neues Pflanzenalkali (Alkaloid)" (On plant alkalis: II. On a new plant alkali (alkaloid)), ''Journal für Chemie und Physik'', 25 : 379–381 ; available on-line at:]
Hathi Trust
– Meissner wrote: "Überhaupt scheint es mir auch angemessen, die bis jetzt bekannten Pflanzenstoffe nicht mit dem Namen Alkalien, sondern Alkaloide zu belegen, da sie doch in manchen Eigenschaften von den Alkalien sehr abweichen, sie würden daher in dem Abschnitt der Pflanzenchemie vor den Pflanzensäuren ihre Stelle finden." (I.e., "In general, it seems appropriate to me to impose on the currently known plant substances not the name 'alkalis' but 'alkaloids', since they differ greatly in some properties from the alkalis; among the chapters of plant chemistry, they would therefore find their place before plant acids .) However, the term came into wide use only after the publication of a review article, by Oscar Jacobsen in the chemical dictionary of
Albert Ladenburg
Albert Ladenburg (July 2, 1842August 15, 1911) was a German chemist.
Early life and education
Ladenburg was a member of the well-known Jewish in Mannheim. He was educated at a Realgymnasium at Mannheim and then, after the age of 15, at the t ...
in the 1880s.
There is no unique method for naming alkaloids.
Hesse
Hesse (, , ) or Hessia (, ; german: Hessen ), officially the State of Hessen (german: links=no, Land Hessen), is a state in Germany. Its capital city is Wiesbaden, and the largest urban area is Frankfurt. Two other major historic cities are ...
, p. 5 Many individual names are formed by adding the suffix "ine" to the species or genus name. For example,
atropine
Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically given ...
is isolated from the plant ''
Atropa belladonna'';
strychnine
Strychnine (, , US chiefly ) is a highly toxic, colorless, bitter, crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents. Strychnine, when inhaled, swallowed, or absorbed through the e ...
is obtained from the seed of the
Strychnine tree
''Strychnos nux-vomica'', the strychnine tree, also known as nux vomica, poison fruit, semen strychnos, and quaker buttons, is a deciduous tree native to India and to southeast Asia. It is a medium-sized tree in the family Loganiaceae that grows ...
(''Strychnos nux-vomica'' L.).
Where several alkaloids are extracted from one plant their names are often distinguished by variations in the suffix: "idine", "anine", "aline", "inine" etc. There are also at least 86 alkaloids whose names contain the root "vin" because they are extracted from ''
vinca'' plants such as ''Vinca rosea'' (''
Catharanthus roseus''); these are called
''vinca'' alkaloids.
History
Alkaloid-containing plants have been used by humans since ancient times for therapeutic and recreational purposes. For example, medicinal plants have been known in
Mesopotamia
Mesopotamia ''Mesopotamíā''; ar, بِلَاد ٱلرَّافِدَيْن or ; syc, ܐܪܡ ܢܗܪ̈ܝܢ, or , ) is a historical region of Western Asia situated within the Tigris–Euphrates river system, in the northern part of the ...
from about 2000 BC.
[ Aniszewski, p. 182] The ''
Odyssey
The ''Odyssey'' (; grc, Ὀδύσσεια, Odýsseia, ) is one of two major ancient Greek epic poems attributed to Homer. It is one of the oldest extant works of literature still widely read by modern audiences. As with the '' Iliad'', ...
'' of Homer referred to a gift given to Helen by the Egyptian queen, a drug bringing oblivion. It is believed that the gift was an opium-containing drug. A Chinese book on houseplants written in 1st–3rd centuries BC mentioned a medical use of
ephedra and
opium poppies. Also,
coca leaves have been used by South American Indians since ancient times.
Extracts from plants containing toxic alkaloids, such as
aconitine and
tubocurarine, were used since antiquity for poisoning arrows.
Studies of alkaloids began in the 19th century. In 1804, the German chemist
Friedrich Sertürner isolated from opium a "soporific principle" ( la, principium somniferum, links=no), which he called "morphium", referring to
Morpheus, the Greek god of dreams; in German and some other Central-European languages, this is still the name of the drug. The term "morphine", used in English and French, was given by the French physicist
Joseph Louis Gay-Lussac.
A significant contribution to the chemistry of alkaloids in the early years of its development was made by the French researchers
Pierre Joseph Pelletier
Pierre-Joseph Pelletier (, , ; 22 March 1788 – 19 July 1842) was a French chemist and pharmacist who did notable research on vegetable alkaloids, and was the co-discoverer with Joseph Bienaimé Caventou of quinine, caffeine, and strychnine. ...
and
Joseph Bienaimé Caventou, who discovered
quinine
Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to '' Plasmodium falciparum'' that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg ...
(1820) and
strychnine
Strychnine (, , US chiefly ) is a highly toxic, colorless, bitter, crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents. Strychnine, when inhaled, swallowed, or absorbed through the e ...
(1818). Several other alkaloids were discovered around that time, including
xanthine
Xanthine ( or ; archaically xanthic acid; systematic name 3,7-dihydropurine-2,6-dione) is a purine base found in most human body tissues and fluids, as well as in other organisms. Several stimulants are derived from xanthine, including caffein ...
(1817),
atropine
Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically given ...
(1819),
caffeine
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine chemical classification, class. It is mainly recreational drug use, used recreationally as a Nootropic, cognitive enhancer, increasing alertness and attentional perfor ...
(1820),
coniine
Coniine is a poisonous chemical compound, an alkaloid present in and isolable from poison hemlock (''Conium maculatum''), where its presence has been a source of significant economic, medical, and historico-cultural interest; coniine is also produ ...
(1827),
nicotine
Nicotine is a naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and '' Duboisia hopwoodii'') and is widely used recreationally as a stimulant and anxiolytic. As a pharmaceutical drug, it is use ...
(1828),
colchicine (1833),
sparteine
Sparteine is a class 1a antiarrhythmic agent; a sodium channel blocker. It is an alkaloid and can be extracted from scotch broom. It is the predominant alkaloid in '' Lupinus mutabilis'', and is thought to chelate the bivalent cations calcium and ...
(1851), and
cocaine
Cocaine (from , from , ultimately from Quechua: ''kúka'') is a central nervous system (CNS) stimulant mainly used recreationally for its euphoric effects. It is primarily obtained from the leaves of two Coca species native to South Am ...
(1860). The development of the chemistry of alkaloids was accelerated by the emergence of
spectroscopic and
chromatographic
In chemical analysis, chromatography is a laboratory technique for the separation of a mixture into its components. The mixture is dissolved in a fluid solvent (gas or liquid) called the ''mobile phase'', which carries it through a system (a ...
methods in the 20th century, so that by 2008 more than 12,000 alkaloids had been identified.
The first complete synthesis of an alkaloid was achieved in 1886 by the German chemist
Albert Ladenburg
Albert Ladenburg (July 2, 1842August 15, 1911) was a German chemist.
Early life and education
Ladenburg was a member of the well-known Jewish in Mannheim. He was educated at a Realgymnasium at Mannheim and then, after the age of 15, at the t ...
. He produced
coniine
Coniine is a poisonous chemical compound, an alkaloid present in and isolable from poison hemlock (''Conium maculatum''), where its presence has been a source of significant economic, medical, and historico-cultural interest; coniine is also produ ...
by reacting 2-methylpyridine with
acetaldehyde
Acetaldehyde (IUPAC systematic name ethanal) is an organic chemical compound with the formula CH3 CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is a colorless liquid or gas, boiling near room temperature. It is one of the ...
and
reducing the resulting 2-propenyl pyridine with sodium.
Classifications
Compared with most other classes of natural compounds, alkaloids are characterized by a great structural diversity. There is no uniform classification.
Hesse
Hesse (, , ) or Hessia (, ; german: Hessen ), officially the State of Hessen (german: links=no, Land Hessen), is a state in Germany. Its capital city is Wiesbaden, and the largest urban area is Frankfurt. Two other major historic cities are ...
, p. 11 Initially, when knowledge of chemical structures was lacking, botanical classification of the source plants was relied on. This classification is now considered obsolete.
More recent classifications are based on similarity of the carbon skeleton (''e.g.'',
indole-,
isoquinoline
Isoquinoline is a heterocyclic aromatic organic compound. It is a structural isomer of quinoline. Isoquinoline and quinoline are benzopyridines, which are composed of a benzene ring fused to a pyridine ring. In a broader sense, the term isoquin ...
-, and
pyridine
Pyridine is a basic heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid w ...
-like) or biochemical precursor (
ornithine,
lysine,
tyrosine
-Tyrosine or tyrosine (symbol Tyr or Y) or 4-hydroxyphenylalanine is one of the 20 standard amino acids that are used by cells to synthesize proteins. It is a non-essential amino acid with a polar side group. The word "tyrosine" is from the G ...
,
tryptophan, etc.).
However, they require compromises in borderline cases;
for example,
nicotine
Nicotine is a naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and '' Duboisia hopwoodii'') and is widely used recreationally as a stimulant and anxiolytic. As a pharmaceutical drug, it is use ...
contains a pyridine fragment from
nicotinamide
Niacinamide or Nicotinamide (NAM) is a form of vitamin B3 found in food and used as a dietary supplement and medication. As a supplement, it is used by mouth to prevent and treat pellagra (niacin deficiency). While nicotinic acid (niacin) ma ...
and a
pyrrolidine part from ornithine and therefore can be assigned to both classes.
[ Dewick, p. 307]
Alkaloids are often divided into the following major groups:
# "True alkaloids" contain
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
in the
heterocycle and originate from
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...
s.
[ Plemenkov, p. 223] Their characteristic examples are
atropine
Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically given ...
,
nicotine
Nicotine is a naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and '' Duboisia hopwoodii'') and is widely used recreationally as a stimulant and anxiolytic. As a pharmaceutical drug, it is use ...
, and
morphine
Morphine is a strong opiate that is found naturally in opium, a dark brown resin in poppies ('' Papaver somniferum''). It is mainly used as a pain medication, and is also commonly used recreationally, or to make other illicit opioids. T ...
. This group also includes some alkaloids that besides the nitrogen heterocycle contain
terpene
Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n > 1. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. Terpenes ...
(''e.g.'',
evonine) or peptide fragments (''e.g.''
ergotamineHesse
Hesse (, , ) or Hessia (, ; german: Hessen ), officially the State of Hessen (german: links=no, Land Hessen), is a state in Germany. Its capital city is Wiesbaden, and the largest urban area is Frankfurt. Two other major historic cities are ...
, p. 84). The piperidine alkaloids
coniine
Coniine is a poisonous chemical compound, an alkaloid present in and isolable from poison hemlock (''Conium maculatum''), where its presence has been a source of significant economic, medical, and historico-cultural interest; coniine is also produ ...
and
coniceine may be regarded as true alkaloids (rather than pseudoalkaloids: see below)
Hesse
Hesse (, , ) or Hessia (, ; german: Hessen ), officially the State of Hessen (german: links=no, Land Hessen), is a state in Germany. Its capital city is Wiesbaden, and the largest urban area is Frankfurt. Two other major historic cities are ...
, p. 31 although they do not originate from amino acids.
[ Dewick, p. 381]
# "Protoalkaloids", which contain
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
(but not the nitrogen heterocycle) and also originate from amino acids.
Examples include
mescaline
Mescaline or mescalin (3,4,5-trimethoxyphenethylamine) is a naturally occurring psychedelic protoalkaloid of the substituted phenethylamine class, known for its hallucinogenic effects comparable to those of LSD and psilocybin.
Biological ...
,
adrenaline and
ephedrine.
# Polyamine alkaloids – derivatives of
putrescine
Putrescine is an organic compound with the formula (CH2)4(NH2)2. It is a colorless solid that melts near room temperature. It is classified as a diamine. Together with cadaverine, it is largely responsible for the foul odor of putrefying flesh ...
,
spermidine
Spermidine is a polyamine compound () found in ribosomes and living tissues and having various metabolic functions within organisms. It was originally isolated from semen.
Function
Spermidine is an aliphatic polyamine. Spermidine synthase (SPDS ...
, and
spermine
Spermine is a polyamine involved in cellular metabolism that is found in all eukaryotic cells. The precursor for synthesis of spermine is the amino acid ornithine. It is an essential growth factor in some bacteria as well. It is found as a ...
.
# Peptide and cyclopeptide alkaloids.
# Pseudoalkaloids – alkaloid-like compounds that do not originate from amino acids. This group includes
terpene
Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n > 1. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. Terpenes ...
-like and
steroid
A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and ...
-like alkaloids, as well as
purine
Purine is a heterocyclic aromatic organic compound that consists of two rings ( pyrimidine and imidazole) fused together. It is water-soluble. Purine also gives its name to the wider class of molecules, purines, which include substituted purines ...
-like alkaloids such as
caffeine
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine chemical classification, class. It is mainly recreational drug use, used recreationally as a Nootropic, cognitive enhancer, increasing alertness and attentional perfor ...
,
theobromine
Theobromine, also known as xantheose, is the principal alkaloid of '' Theobroma cacao'' (cacao plant). Theobromine is slightly water- soluble (330 mg/L) with a bitter taste. In industry, theobromine is used as an additive and precursor to ...
,
theacrine
Theacrine, also known as 1,3,7,9-tetramethyluric acid, is a purine alkaloid found in Cupuaçu (''Theobroma grandiflorum'') and in a Chinese tea known as kucha () ('' Camellia assamica var. kucha''). It shows anti-inflammatory and analgesic effect ...
and
theophylline.
[ Aniszewski, p. 12] Some authors classify as pseudoalkaloids such compounds such as
ephedrine and
cathinone
Cathinone (also known as benzoylethanamine, or β-keto-amphetamine) is a monoamine alkaloid found in the shrub ''Catha edulis'' (khat) and is chemically similar to ephedrine, cathine, methcathinone and other amphetamines. It is probably the mai ...
. Those originate from the amino acid
phenylalanine, but acquire their nitrogen atom not from the amino acid but through
transamination.
[ Dewick, p. 382]
Some alkaloids do not have the carbon skeleton characteristic of their group. So,
galanthamine
Galantamine is used for the treatment of cognitive decline in mild to moderate Alzheimer's disease and various other memory impairments. It is an alkaloid that has been isolated from the bulbs and flowers of ''Galanthus nivalis'' (Common snowdrop ...
and homoaporphines do not contain
isoquinoline
Isoquinoline is a heterocyclic aromatic organic compound. It is a structural isomer of quinoline. Isoquinoline and quinoline are benzopyridines, which are composed of a benzene ring fused to a pyridine ring. In a broader sense, the term isoquin ...
fragment, but are, in general, attributed to isoquinoline alkaloids.
Main classes of monomeric alkaloids are listed in the table below:
Properties
Most alkaloids contain oxygen in their molecular structure; those compounds are usually colorless crystals at ambient conditions. Oxygen-free alkaloids, such as
nicotine
Nicotine is a naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and '' Duboisia hopwoodii'') and is widely used recreationally as a stimulant and anxiolytic. As a pharmaceutical drug, it is use ...
or
coniine
Coniine is a poisonous chemical compound, an alkaloid present in and isolable from poison hemlock (''Conium maculatum''), where its presence has been a source of significant economic, medical, and historico-cultural interest; coniine is also produ ...
,
are typically volatile, colorless, oily liquids.
[ Grinkevich, p. 131] Some alkaloids are colored, like
berberine
Berberine is a quaternary ammonium salt from the protoberberine group of benzylisoquinoline alkaloids found in such plants as ''Berberis vulgaris'' (barberry), ''Berberis aristata'' (tree turmeric), ''Mahonia aquifolium'' (Oregon grape), ''Hydras ...
(yellow) and
sanguinarine (orange).
Most alkaloids are weak bases, but some, such as
theobromine
Theobromine, also known as xantheose, is the principal alkaloid of '' Theobroma cacao'' (cacao plant). Theobromine is slightly water- soluble (330 mg/L) with a bitter taste. In industry, theobromine is used as an additive and precursor to ...
and
theophylline, are
amphoteric.
[G. A. Spille]
''Caffeine''
CRC Press, 1997 Many alkaloids dissolve poorly in water but readily dissolve in
organic solvents, such as
diethyl ether
Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colourless, highly volatile, sweet-smelling ("ethereal odour"), extremely flammable li ...
,
chloroform
Chloroform, or trichloromethane, is an organic compound with formula C H Cl3 and a common organic solvent. It is a colorless, strong-smelling, dense liquid produced on a large scale as a precursor to PTFE. It is also a precursor to various ...
or
1,2-dichloroethane
The chemical compound 1,2-dichloroethane, commonly known as ethylene dichloride (EDC), is a chlorinated hydrocarbon. It is a colourless liquid with a chloroform-like odour. The most common use of 1,2-dichloroethane is in the production of vin ...
.
Caffeine
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine chemical classification, class. It is mainly recreational drug use, used recreationally as a Nootropic, cognitive enhancer, increasing alertness and attentional perfor ...
,
cocaine
Cocaine (from , from , ultimately from Quechua: ''kúka'') is a central nervous system (CNS) stimulant mainly used recreationally for its euphoric effects. It is primarily obtained from the leaves of two Coca species native to South Am ...
,
codeine
Codeine is an opiate and prodrug of morphine mainly used to treat pain, coughing, and diarrhea. It is also commonly used as a recreational drug. It is found naturally in the sap of the opium poppy, ''Papaver somniferum''. It is typically ...
and
nicotine
Nicotine is a naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and '' Duboisia hopwoodii'') and is widely used recreationally as a stimulant and anxiolytic. As a pharmaceutical drug, it is use ...
are slightly soluble in water (with a solubility of ≥1g/L), whereas others, including
morphine
Morphine is a strong opiate that is found naturally in opium, a dark brown resin in poppies ('' Papaver somniferum''). It is mainly used as a pain medication, and is also commonly used recreationally, or to make other illicit opioids. T ...
and
yohimbine are very slightly water-soluble (0.1–1 g/L). Alkaloids and acids form salts of various strengths. These salts are usually freely soluble in water and
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
and poorly soluble in most organic solvents. Exceptions include
scopolamine hydrobromide, which is soluble in organic solvents, and the water-soluble quinine sulfate.
Most alkaloids have a bitter taste or are poisonous when ingested. Alkaloid production in plants appeared to have evolved in response to feeding by herbivorous animals; however, some animals have evolved the ability to detoxify alkaloids. Some alkaloids can produce developmental defects in the offspring of animals that consume but cannot detoxify the alkaloids. One example is the alkaloid
cyclopamine, produced in the leaves of
corn lily. During the 1950s, up to 25% of lambs born by sheep that had grazed on corn lily had serious facial deformations. These ranged from deformed jaws to
cyclopia (see picture). After decades of research, in the 1980s, the compound responsible for these deformities was identified as the alkaloid 11-deoxyjervine, later renamed to cyclopamine.
Distribution in nature
Alkaloids are
generated by various living organisms, especially by
higher plants
Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They al ...
– about 10 to 25% of those contain alkaloids. Therefore, in the past the term "alkaloid" was associated with plants.
Hesse
Hesse (, , ) or Hessia (, ; german: Hessen ), officially the State of Hessen (german: links=no, Land Hessen), is a state in Germany. Its capital city is Wiesbaden, and the largest urban area is Frankfurt. Two other major historic cities are ...
, p.4
The alkaloids content in plants is usually within a few percent and is inhomogeneous over the plant tissues. Depending on the type of plants, the maximum concentration is observed in the leaves (for example,
black henbane),
fruit
In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering.
Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in partic ...
s or
seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosper ...
s (
Strychnine tree
''Strychnos nux-vomica'', the strychnine tree, also known as nux vomica, poison fruit, semen strychnos, and quaker buttons, is a deciduous tree native to India and to southeast Asia. It is a medium-sized tree in the family Loganiaceae that grows ...
), root (''
Rauvolfia serpentina
''Rauvolfia serpentina'', the Indian snakeroot, devil pepper, or serpentine wood, is a species of flower in the milkweed family Apocynaceae. It is native to the Indian subcontinent and East Asia (from India to Indonesia).
''Rauvolfia'' is ...
'') or bark (
cinchona). Furthermore, different tissues of the same plants may contain different alkaloids.
Beside plants, alkaloids are found in certain types of
fungi
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately fr ...
, such as
psilocybin in the fungus of the genus ''
Psilocybe
''Psilocybe'' ( ) is a genus of gilled mushrooms, growing worldwide, in the family Hymenogastraceae. Most or nearly all species contain the psychedelic compounds psilocybin and psilocin.
Taxonomy
Taxonomic history
A 2002 study of the m ...
'', and in animals, such as
bufotenin in the skin of some toads
and a number of insects, markedly ants.
Many marine organisms also contain alkaloids. Some
amines, such as
adrenaline and
serotonin
Serotonin () or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Its biological function is complex and multifaceted, modulating mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and va ...
, which play an important role in higher animals, are similar to alkaloids in their structure and biosynthesis and are sometimes called alkaloids.
Extraction
Because of the structural diversity of alkaloids, there is no single method of their extraction from natural raw materials.
Hesse
Hesse (, , ) or Hessia (, ; german: Hessen ), officially the State of Hessen (german: links=no, Land Hessen), is a state in Germany. Its capital city is Wiesbaden, and the largest urban area is Frankfurt. Two other major historic cities are ...
, p. 116 Most methods exploit the property of most alkaloids to be soluble in organic solvents
but not in water, and the opposite tendency of their salts.
Most plants contain several alkaloids. Their mixture is extracted first and then individual alkaloids are separated.
[ Grinkevich, p. 132] Plants are thoroughly ground before extraction.
Most alkaloids are present in the raw plants in the form of salts of organic acids.
The extracted alkaloids may remain salts or change into bases.
Base extraction is achieved by processing the raw material with alkaline solutions and extracting the alkaloid bases with organic solvents, such as 1,2-dichloroethane, chloroform, diethyl ether or benzene. Then, the impurities are dissolved by weak acids; this converts alkaloid bases into salts that are washed away with water. If necessary, an aqueous solution of alkaloid salts is again made alkaline and treated with an organic solvent. The process is repeated until the desired purity is achieved.
In the acidic extraction, the raw plant material is processed by a weak acidic solution (''e.g.'',
acetic acid in water, ethanol, or methanol). A base is then added to convert alkaloids to basic forms that are extracted with organic solvent (if the extraction was performed with alcohol, it is removed first, and the remainder is dissolved in water). The solution is purified as described above.
Alkaloids are separated from their mixture using their different solubility in certain solvents and different reactivity with certain reagents or by
distillation
Distillation, or classical distillation, is the process of separating the components or substances from a liquid mixture by using selective boiling and condensation, usually inside an apparatus known as a still. Dry distillation is the he ...
.
A number of alkaloids are identified from
insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...
s, among which the
fire ant venom
Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a st ...
alkaloids known as
solenopsins have received greater attention from researchers. These insect alkaloids can be efficiently extracted by solvent immersion of live fire ants
or by centrifugation of live ants followed by silica-gel chromatography purification. Tracking and dosing the extracted solenopsin ant alkaloids has been described as possible based on their absorbance peak around 232 nanometers.
Biosynthesis
Biological precursors of most alkaloids are
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...
s, such as
ornithine,
lysine,
phenylalanine,
tyrosine
-Tyrosine or tyrosine (symbol Tyr or Y) or 4-hydroxyphenylalanine is one of the 20 standard amino acids that are used by cells to synthesize proteins. It is a non-essential amino acid with a polar side group. The word "tyrosine" is from the G ...
,
tryptophan,
histidine
Histidine (symbol His or H) is an essential amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated –NH3+ form under biological conditions), a carboxylic acid group (which is in the ...
,
aspartic acid
Aspartic acid (symbol Asp or D; the ionic form is known as aspartate), is an α-amino acid that is used in the biosynthesis of proteins. Like all other amino acids, it contains an amino group and a carboxylic acid. Its α-amino group is in the pro ...
, and
anthranilic acid
Anthranilic acid is an aromatic acid with the formula C6H4(NH2)(CO2H) and has a sweetish taste. The molecule consists of a benzene ring, ''ortho''-substituted with a carboxylic acid and an amine. As a result of containing both acidic and basic ...
.
[ Plemenkov, p. 253] Nicotinic acid can be synthesized from tryptophan or aspartic acid. Ways of alkaloid biosynthesis are too numerous and cannot be easily classified.
However, there are a few typical reactions involved in the biosynthesis of various classes of alkaloids, including synthesis of
Schiff bases
In organic chemistry, a Schiff base (named after Hugo Schiff) is a compound with the general structure ( = alkyl or aryl, but not hydrogen). They can be considered a sub-class of imines, being either secondary ketimines or secondary aldim ...
and
Mannich reaction.
Synthesis of Schiff bases
Schiff bases can be obtained by reacting amines with ketones or aldehydes. These reactions are a common method of producing C=N bonds.
[ Dewick, p. 19]
In the biosynthesis of alkaloids, such reactions may take place within a molecule,
such as in the synthesis of piperidine:
Mannich reaction
An integral component of the Mannich reaction, in addition to an amine and a
carbonyl compound, is a
carbanion, which plays the role of the nucleophile in the
nucleophilic addition to the ion formed by the reaction of the amine and the carbonyl.
The Mannich reaction can proceed both intermolecularly and intramolecularly:
Dimer alkaloids
In addition to the described above monomeric alkaloids, there are also
dimer
Dimer may refer to:
* Dimer (chemistry), a chemical structure formed from two similar sub-units
** Protein dimer, a protein quaternary structure
** d-dimer
* Dimer model, an item in statistical mechanics, based on ''domino tiling''
* Julius Dimer ( ...
ic, and even
trimeric and
tetramer
A tetramer () ('' tetra-'', "four" + '' -mer'', "parts") is an oligomer formed from four monomers or subunits. The associated property is called ''tetramery''. An example from inorganic chemistry is titanium methoxide with the empirical formula ...
ic alkaloids formed upon condensation of two, three, and four monomeric alkaloids. Dimeric alkaloids are usually formed from monomers of the same type through the following mechanisms:
*
Mannich reaction, resulting in, ''e.g.'', voacamine
*
Michael reaction (villalstonine)
* Condensation of aldehydes with amines (toxiferine)
* Oxidative addition of phenols (dauricine, tubocurarine)
*
Lactonization
Lactones are cyclic carboxylic esters, containing a 1-oxacycloalkan-2-one structure (), or analogues having unsaturation or heteroatoms replacing one or more carbon atoms of the ring.
Lactones are formed by intramolecular esterification of the co ...
(carpaine).
File:Voacamine chemical structure.png, Voacamine
File:Villalstonine.svg, Villalstonine
Villalstonine is a bisindole alkaloid isolated from ''Alstonia'' with ''in vitro'' antiplasmodial
''Plasmodium'' is a genus of unicellular eukaryotes that are obligate parasites of vertebrates and insects. The life cycles of ''Plasmodium'' sp ...
File:Toxiferine I.png, Toxiferine
File:Dauricine.svg, Dauricine
Dauricine is a plant metabolite, chemically classified as a phenol, an aromatic ether, and an isoquinoline alkaloid. It has been isolated from the Asian vine Menispermum ''dauricum'', commonly known as Asian moonseed, and the North American vine ...
File:Tubocurarine.svg, Tubocurarine
File:Carpaine.png, Carpaine
, Section2={{Chembox Properties
, Formula = C28H50N2O4
, MolarMass = 478.70 g/mol
, MeltingPt = 121 °C
Carpaine is one of the major alkaloid components of papaya leaves which has been studied for its cardiovascular effects. Circulatory eff ...
There are also dimeric alkaloids formed from two distinct monomers, such as the ''vinca'' alkaloids
vinblastine and vincristine,
which are formed from the coupling of
catharanthine
Catharanthine is a terpene indole alkaloid produced by the medicinal plant ''Catharanthus roseus'' and ''Tabernaemontana divaricata''. Catharanthine is derived from strictosidine, but the exact mechanism by which this happens is currently unknown ...
and
vindoline
Vindoline is a chemical precursor to vinblastine.
Vindoline is formed through biosynthesis from Tabersonine.
See also
* Lochnericine
Lochnericine is a major monoterpene indole alkaloid present in the roots of ''Catharanthus roseus''. It is al ...
.
The newer
semi-synthetic chemotherapeutic agent
vinorelbine is used in the treatment of
non-small-cell lung cancer.
It is another derivative dimer of vindoline and catharanthine and is synthesised from
anhydrovinblastine, starting either from
leurosine or the monomers themselves.
Biological role
Alkaloids are among the most important and best-known
secondary metabolites, i.e. biogenic substances not directly involved in the normal
growth
Growth may refer to:
Biology
* Auxology, the study of all aspects of human physical growth
* Bacterial growth
* Cell growth
* Growth hormone, a peptide hormone that stimulates growth
* Human development (biology)
* Plant growth
* Secondary grow ...
,
development, or
reproduction of the organism. Instead, they generally mediate ecological
interactions
Interaction is action that occurs between two or more objects, with broad use in philosophy and the sciences. It may refer to:
Science
* Interaction hypothesis, a theory of second language acquisition
* Interaction (statistics)
* Interactions ...
, which may produce a selective advantage for the organism by increasing its
survivability or
fecundity. In some cases their function, if any, remains unclear. An early hypothesis, that alkaloids are the final products of
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
metabolism
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run ...
in plants, as
urea
Urea, also known as carbamide, is an organic compound with chemical formula . This amide has two amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid.
Urea serves an important ...
and
uric acid are in mammals, was refuted by the finding that their concentration fluctuates rather than steadily increasing.
[Robert A. Meyers ''Encyclopedia of Physical Science and Technology'' – Alkaloids, 3rd edition. ]
Most of the known functions of alkaloids are related to protection. For example,
aporphine alkaloid
liriodenine
Liriodenine is a bio-active isolate of the Chinese medicinal herb '' Zanthoxylum nitidum''. It was isolated for the first time, at least with the name liriodenine, from the heartwood of ''Liriodendron tulipifera'', the common yellow poplar of the ...
produced by the
tulip tree protects it from parasitic mushrooms. In addition, the presence of alkaloids in the plant prevents insects and
chordate
A chordate () is an animal of the phylum Chordata (). All chordates possess, at some point during their larval or adult stages, five synapomorphies, or primary physical characteristics, that distinguish them from all the other taxa. These fi ...
animals from eating it. However, some animals are adapted to alkaloids and even use them in their own metabolism. Such alkaloid-related substances as
serotonin
Serotonin () or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Its biological function is complex and multifaceted, modulating mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and va ...
,
dopamine
Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic chemical of the catecholamine and phenethylamine families. Dopamine constitutes about 80% o ...
and
histamine
Histamine is an organic nitrogenous compound involved in local immune responses, as well as regulating physiological functions in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Since histamine was discover ...
are important
neurotransmitter
A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse. The cell receiving the signal, any main body part or target cell, may be another neuron, but could also be a gland or muscle cell.
Neu ...
s in animals. Alkaloids are also known to regulate plant growth. One example of an organism that uses alkaloids for protection is the ''
Utetheisa ornatrix'', more commonly known as the ornate moth. Pyrrolizidine alkaloids render these larvae and adult moths unpalatable to many of their natural enemies like coccinelid beetles, green lacewings, insectivorous hemiptera and insectivorous bats. Another example of alkaloids being utilized occurs in the
poison hemlock moth (''Agonopterix alstroemeriana).'' This moth feeds on its highly toxic and alkaloid-rich host plant
poison hemlock (''Conium maculatum'') during its larval stage. ''A. alstroemeriana'' may benefit twofold from the toxicity of the naturally-occurring alkaloids, both through the unpalatability of the species to predators and through the ability of ''A. alstroemeriana'' to recognize ''
Conium maculatum
''Conium maculatum'', colloquially known as hemlock, poison hemlock or wild hemlock, is a highly poisonous biennial herbaceous flowering plant in the carrot family Apiaceae, native to Europe and North Africa. A hardy plant capable of living ...
'' as the correct location for oviposition. A
fire ant venom
Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a st ...
alkaloid known as
solenopsin has been demonstrated to protect queens of
invasive fire ants during the foundation of new nests, thus playing a central role in the spread of this pest ant species around the world.
Applications
In medicine
Medical use of alkaloid-containing plants has a long history, and, thus, when the first alkaloids were isolated in the 19th century, they immediately found application in clinical practice. Many alkaloids are still used in medicine, usually in the form of salts widely used including the following:
Many synthetic and semisynthetic drugs are structural modifications of the alkaloids, which were designed to enhance or change the primary effect of the drug and reduce unwanted side-effects. For example,
naloxone
Naloxone, sold under the brand names Narcan (4 mg) and Kloxxado (8 mg) among others, is a medication used to reverse or reduce the effects of opioids. It is commonly used to counter decreased breathing in opioid overdose. Effects begin withi ...
, an
opioid receptor antagonist, is a derivative of
thebaine that is present in
opium
Opium (or poppy tears, scientific name: ''Lachryma papaveris'') is dried latex obtained from the seed capsules of the opium poppy '' Papaver somniferum''. Approximately 12 percent of opium is made up of the analgesic alkaloid morphine, which ...
.
File:Thebaine skeletal.svg, Thebaine
File:Naloxone.svg, Naloxone
Naloxone, sold under the brand names Narcan (4 mg) and Kloxxado (8 mg) among others, is a medication used to reverse or reduce the effects of opioids. It is commonly used to counter decreased breathing in opioid overdose. Effects begin withi ...
In agriculture
Prior to the development of a wide range of relatively low-toxic synthetic
pesticide
Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and ...
s, some alkaloids, such as salts of nicotine and
anabasine, were used as
insecticides. Their use was limited by their high toxicity to humans.
Use as psychoactive drugs
Preparations of plants containing alkaloids and their extracts, and later pure alkaloids, have long been used as
psychoactive substances
A psychoactive drug, psychopharmaceutical, psychoactive agent or psychotropic drug is a chemical substance, that changes functions of the nervous system, and results in alterations in perception, mood, consciousness, cognition or behavior.
Th ...
.
Cocaine
Cocaine (from , from , ultimately from Quechua: ''kúka'') is a central nervous system (CNS) stimulant mainly used recreationally for its euphoric effects. It is primarily obtained from the leaves of two Coca species native to South Am ...
,
caffeine
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine chemical classification, class. It is mainly recreational drug use, used recreationally as a Nootropic, cognitive enhancer, increasing alertness and attentional perfor ...
, and
cathinone
Cathinone (also known as benzoylethanamine, or β-keto-amphetamine) is a monoamine alkaloid found in the shrub ''Catha edulis'' (khat) and is chemically similar to ephedrine, cathine, methcathinone and other amphetamines. It is probably the mai ...
are
stimulant
Stimulants (also often referred to as psychostimulants or colloquially as uppers) is an overarching term that covers many drugs including those that increase activity of the central nervous system and the body, drugs that are pleasurable and inv ...
s of the
central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...
.
Mescaline
Mescaline or mescalin (3,4,5-trimethoxyphenethylamine) is a naturally occurring psychedelic protoalkaloid of the substituted phenethylamine class, known for its hallucinogenic effects comparable to those of LSD and psilocybin.
Biological ...
and many indole alkaloids (such as
psilocybin,
dimethyltryptamine and
ibogaine) have
hallucinogenic effect.
Morphine
Morphine is a strong opiate that is found naturally in opium, a dark brown resin in poppies ('' Papaver somniferum''). It is mainly used as a pain medication, and is also commonly used recreationally, or to make other illicit opioids. T ...
and
codeine
Codeine is an opiate and prodrug of morphine mainly used to treat pain, coughing, and diarrhea. It is also commonly used as a recreational drug. It is found naturally in the sap of the opium poppy, ''Papaver somniferum''. It is typically ...
are strong narcotic pain killers.
There are alkaloids that do not have strong psychoactive effect themselves, but are
precursor
Precursor or Precursors may refer to:
* Precursor (religion), a forerunner, predecessor
** The Precursor, John the Baptist
Science and technology
* Precursor (bird), a hypothesized genus of fossil birds that was composed of fossilized parts of u ...
s for semi-synthetic psychoactive drugs. For example,
ephedrine and
pseudoephedrine
Pseudoephedrine (PSE) is a sympathomimetic drug of the phenethylamine and amphetamine chemical classes. It may be used as a nasal/sinus decongestant, as a stimulant, or as a wakefulness-promoting agent in higher doses.
It was first charact ...
are used to produce
methcathinone and
methamphetamine
Methamphetamine (contracted from ) is a potent central nervous system (CNS) stimulant that is mainly used as a recreational drug and less commonly as a second-line treatment for attention deficit hyperactivity disorder and obesity. Methamp ...
.
[ Veselovskaya, pp. 51–52] Thebaine is used in the synthesis of many painkillers such as
oxycodone.
See also
*
Amine
In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent ...
*
Base (chemistry)
*
List of poisonous plants
*
Mayer's reagent
Mayer's reagent is an alkaloidal precipitating reagent used for the detection of alkaloids in natural products. Mayer's reagent is freshly prepared by dissolving a mixture of mercuric chloride (1.36 g) and of potassium iodide (5.00 g) in water (100 ...
*
Natural products
*
Palau'amine
Palau'amine is a toxic alkaloid compound synthesized naturally by certain species of sea sponges. The name of the molecule derives from the island nation of Palau, near where the first sponge species discovered to produce it, ''Stylotella agminata ...
*
Secondary metabolite
Explanatory notes
Citations
General and cited references
*
*
*
*
*
*
*
*
*
*
*
*
*
External links
*
*
{{Authority control