Alkaloids are a class of naturally occurring organic compounds that mostly contain basic nitrogen atoms. 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, hydrogen and nitrogen, alkaloids may also contain oxygen, sulfur and, more rarely, other elements such as chlorine, bromine, and phosphorus.
Alkaloids are produced by a large variety of organisms including bacteria, fungi, plants, and animals. They can be purified from crude extracts of these organisms by acid-base extraction. Alkaloids have a wide range of pharmacological activities including antimalarial (e.g. quinine), antiasthma (e.g. ephedrine), anticancer (e.g. homoharringtonine), cholinomimetic (e.g. galantamine), vasodilatory (e.g. vincamine), antiarrhythmic (e.g. quinidine), analgesic (e.g. morphine), antibacterial (e.g. chelerythrine), and antihyperglycemic activities (e.g. piperine). Many have found use in traditional or modern medicine, or as starting points for drug discovery. Other alkaloids possess psychotropic (e.g. psilocin) and stimulant activities (e.g. cocaine, caffeine, nicotine, theobromine), and have been used in entheogenic rituals or as recreational drugs. Alkaloids can be toxic too (e.g. atropine, tubocurarine). Although alkaloids act on a diversity of metabolic systems in humans and other animals, they almost uniformly evoke a bitter taste.
The boundary between alkaloids and other nitrogen-containing natural compounds is not clear-cut. Compounds like amino acid peptides, proteins, nucleotides, nucleic acid, amines, and antibiotics are usually not called alkaloids. Natural compounds containing nitrogen in the exocyclic position (mescaline, serotonin, dopamine, etc.) are usually classified as amines rather than as alkaloids. Some authors, however, consider alkaloids a special case of amines.
The name "alkaloids" (German: Alkaloide) was introduced in 1819 by the German chemist Carl Friedrich Wilhelm Meißner, and is derived from late Latin root alkali (which, in turn, comes from the Arabic al-qalwī – "ashes of plants") and the suffix -οειδής – "like".[nb 1] 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 in the 1880s.
There is no unique method of naming alkaloids. Many individual names are formed by adding the suffix "ine" to the species or genus name. For example, atropine is isolated from the plant Atropa belladonna; strychnine is obtained from the seed of the Strychnine tree (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.
Alkaloid-containing plants have been used by humans since ancient times for therapeutic and recreational purposes. For example, medicinal plants have been known in the Mesopotamia at least around 2000 BC. The Odyssey 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.
Studies of alkaloids began in the 19th century. In 1804, the German chemist Friedrich Sertürner isolated from opium a "soporific principle" (Latin: principium somniferum), which he called "morphium" in honor of 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 and Joseph Bienaimé Caventou, who discovered quinine (1820) and strychnine (1818). Several other alkaloids were discovered around that time, including xanthine (1817), atropine (1819), caffeine (1820), coniine (1827), nicotine (1828), colchicine (1833), sparteine (1851), and cocaine (1860). The development of the chemistry of alkaloids was accelerated by the emergence of spectroscopic and chromatographic 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. He produced coniine by reacting 2-methylpyridine with acetaldehyde and reducing the resulting 2-propenyl pyridine with sodium.
Compared with most other classes of natural compounds, alkaloids are characterized by a great structural diversity. There is no uniform classification. 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-, and pyridine-like) or biochemical precursor (ornithine, lysine, tyrosine, tryptophan, etc.). However, they require compromises in borderline cases; for example, nicotine contains a pyridine fragment from nicotinamide and a pyrrolidine part from ornithine and therefore can be assigned to both classes.
Alkaloids are often divided into the following major groups:
Some alkaloids do not have the carbon skeleton characteristic of their group. So, galanthamine and homoaporphines do not contain isoquinoline fragment, but are, in general, attributed to isoquinoline alkaloids.
Main classes of monomeric alkaloids are listed in the table below:
|Class||Major groups||Main synthesis steps||Examples|
|Alkaloids with nitrogen heterocycles (true alkaloids)|
||Ornithine or arginine → putrescine → N-methylputrescine → N-methyl-Δ1-pyrroline ||Cuscohygrine, hygrine, hygroline, stachydrine|
Substitution in positions 3, 6 or 7
|Ornithine or arginine → putrescine → N-methylputrescine → N-methyl-Δ1-pyrroline ||Atropine, scopolamine, hyoscyamine|
Substitution in positions 2 and 3
|Cocaine, ecgonine |
||Non-esters||In plants: ornithine or arginine → putrescine → homospermidine → retronecine ||Retronecine, heliotridine, laburnine |
|Complex esters of monocarboxylic acids||Indicine, lindelophin, sarracine |
|Macrocyclic diesters||Platyphylline, trichodesmine|
|1-aminopyrrolizidines (lolines)||In fungi: L-proline + L-homoserine → N-(3-amino-3-carboxypropyl)proline → norloline||Loline, N-formylloline, N-acetylloline|
||Lysine → cadaverine → Δ1-piperideine ||Sedamine, lobeline, anaferine, piperine |
|Octanoic acid → coniceine → coniine ||Coniine, coniceine |
||Lupinine group||Lysine → cadaverine → Δ1-piperideine ||Lupinine, nupharidin |
|Cytisine group||Cytisine |
|Sparteine group||Sparteine, lupanine, anahygrine|
|Matrine group||Matrine, oxymatrine, allomatridine|
|Ormosanine group||Ormosanine, piptantine|
||Lysine → δ-semialdehyde of α-aminoadipic acid → pipecolic acid → 1 indolizidinone ||Swainsonine, castanospermine |
||Simple derivatives of pyridine||Nicotinic acid → dihydronicotinic acid → 1,2-dihydropyridine ||Trigonelline, ricinine, arecoline |
|Polycyclic noncondensing pyridine derivatives||Nicotine, nornicotine, anabasine, anatabine |
|Polycyclic condensed pyridine derivatives||Actinidine, gentianine, pediculinine |
|Sesquiterpene pyridine derivatives||Nicotinic acid, isoleucine ||Evonine, hippocrateine, triptonine |
|Isoquinoline derivatives and related alkaloids 
||Simple derivatives of isoquinoline ||Tyrosine or phenylalanine → dopamine or tyramine (for alkaloids Amarillis) ||Salsoline, lophocerine |
|Derivatives of 1- and 3-isoquinolines ||N-methylcoridaldine, noroxyhydrastinine |
|Derivatives of 1- and 4-phenyltetrahydroisoquinolines ||Cryptostilin |
|Derivatives of 5-naftil-isoquinoline ||Ancistrocladine |
|Derivatives of 1- and 2-benzyl-izoquinolines ||Papaverine, laudanosine, sendaverine|
|Cularine group||Cularine, yagonine |
|Pavines and isopavines ||Argemonine, amurensine |
|Benzopyrrocolines ||Cryptaustoline |
|Protoberberines ||Berberine, canadine, ophiocarpine, mecambridine, corydaline |
|Phthalidisoquinolines ||Hydrastine, narcotine (Noscapine) |
|Spirobenzylisoquinolines ||Fumaricine |
|Ipecacuanha alkaloids||Emetine, protoemetine, ipecoside |
|Benzophenanthridines ||Sanguinarine, oxynitidine, corynoloxine |
|Aporphines ||Glaucine, coridine, liriodenine |
|Proaporphines ||Pronuciferine, glaziovine |
|Homoaporphines ||Kreysiginine, multifloramine |
|Homoproaporphines ||Bulbocodine |
|Morphines||Morphine, codeine, thebaine, sinomenine |
|Homomorphines ||Kreysiginine, androcymbine |
|Tropoloisoquinolines ||Imerubrine |
|Azofluoranthenes ||Rufescine, imeluteine |
|Amaryllis alkaloids||Lycorine, ambelline, tazettine, galantamine, montanine |
|Erythrina alkaloids||Erysodine, erythroidine |
|Phenanthrene derivatives ||Atherosperminine |
|Protopines ||Protopine, oxomuramine, corycavidine |
|Aristolactam ||Doriflavin |
||Tyrosine → tyramine ||Annuloline, halfordinol, texaline, texamine|
||Ibotenic acid → Muscimol||Ibotenic acid, Muscimol|
||1-Deoxy-D-xylulose 5-phosphate (DOXP), tyrosine, cysteine ||Nostocyclamide, thiostreptone |
||3,4-Dihydro-4-quinazolone derivatives||Anthranilic acid or phenylalanine or ornithine ||Febrifugine|
|1,4-Dihydro-4-quinazolone derivatives||Glycorine, arborine, glycosminine|
|Pyrrolidine and piperidine quinazoline derivatives||Vazicine (peganine) |
||Anthranilic acid ||Rutacridone, acronicine|
||Simple derivatives of quinoline derivatives of 2–quinolones and 4-quinolone||Anthranilic acid → 3-carboxyquinoline ||Cusparine, echinopsine, evocarpine|
|Furanoquinoline derivatives||Dictamnine, fagarine, skimmianine|
|Quinines||Tryptophan → tryptamine → strictosidine (with secologanin) → korinanteal → cinhoninon ||Quinine, quinidine, cinchonine, cinhonidine |
||Non-isoprene indole alkaloids|
|Simple indole derivatives ||Tryptophan → tryptamine or 5-hydroxitriptofan ||Serotonin, psilocybin, dimethyltryptamine (DMT), bufotenin |
|Simple derivatives of β-carboline ||Harman, harmine, harmaline, eleagnine |
|Pyrroloindole alkaloids ||Physostigmine (eserine), etheramine, physovenine, eptastigmine|
|Semiterpenoid indole alkaloids|
|Ergot alkaloids||Tryptophan → chanoclavine → agroclavine → elimoclavine → paspalic acid → lysergic acid ||Ergotamine, ergobasine, ergosine|
|Monoterpenoid indole alkaloids|
|Corynanthe type alkaloids||Tryptophan → tryptamine → strictosidine (with secologanin) ||Ajmalicine, sarpagine, vobasine, ajmaline, yohimbine, reserpine, mitragynine, group strychnine and (Strychnine brucine, aquamicine, vomicine )|
|Iboga-type alkaloids||Ibogamine, ibogaine, voacangine|
|Aspidosperma-type alkaloids||Vincamine, vinca alkaloids, vincotine, aspidospermine|
||Directly from histidine||Histamine, pilocarpine, pilosine, stevensine|
||Xanthosine (formed in purine biosynthesis) → 7 methylxantosine → 7-methyl xanthine → theobromine → caffeine ||Caffeine, theobromine, theophylline, saxitoxin |
|Alkaloids with nitrogen in the side chain (protoalkaloids)|
||Tyrosine or phenylalanine → dioxyphenilalanine → dopamine → adrenaline and mescaline tyrosine → tyramine phenylalanine → 1-phenylpropane-1,2-dione → cathinone → ephedrine and pseudoephedrine ||Tyramine, ephedrine, pseudoephedrine, mescaline, cathinone, catecholamines (adrenaline, noradrenaline, dopamine)|
|Colchicine alkaloids 
||Tyrosine or phenylalanine → dopamine → autumnaline → colchicine ||Colchicine, colchamine|
||Glutamic acid → 3-ketoglutamic acid → muscarine (with pyruvic acid)||Muscarine, allomuscarine, epimuscarine, epiallomuscarine|
||Phenylalanine with valine, leucine or isoleucine||Capsaicin, dihydrocapsaicin, nordihydrocapsaicin, vanillylamine|
||ornithine → putrescine → spermidine → spermine||Paucine |
||Verbascenine, aphelandrine |
|Peptide (cyclopeptide) alkaloids|
|Peptide alkaloids with a 13-membered cycle ||Nummularine C type||From different amino acids ||Nummularine C, Nummularine S |
|Ziziphine type||Ziziphine A, sativanine H |
|Peptide alkaloids with a 14-membered cycle ||Frangulanine type||Frangulanine, scutianine J |
|Scutianine A type||Scutianine A |
|Integerrine type||Integerrine, discarine D |
|Amphibine F type||Amphibine F, spinanine A |
|Amfibine B type||Amphibine B, lotusine C |
|Peptide alkaloids with a 15-membered cycle ||Mucronine A type||Mucronine A |
|Pseudoalkaloids (terpenes and steroids)|
||Lycoctonine type||Mevalonic acid → Isopentenyl pyrophosphate → geranyl pyrophosphate ||Aconitine, delphinine |
||Cholesterol, arginine||Solasodine, solanidine, veralkamine, batrachotoxin|
Most alkaloids contain oxygen in their molecular structure; those compounds are usually colorless crystals at ambient conditions. Oxygen-free alkaloids, such as nicotine or coniine, are typically volatile, colorless, oily liquids. Some alkaloids are colored, like berberine (yellow) and sanguinarine (orange).
Most alkaloids are weak bases, but some, such as theobromine and theophylline, are amphoteric. Many alkaloids dissolve poorly in water but readily dissolve in organic solvents, such as diethyl ether, chloroform or 1,2-dichloroethane. Caffeine, cocaine, codeine and nicotine are slightly soluble in water (with a solubility of ≥1g/L), whereas others, including morphine 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 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.
Alkaloids are generated by various living organisms, especially by higher plants – about 10 to 25% of those contain alkaloids. Therefore, in the past the term "alkaloid" was associated with plants.
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 (black henbane), fruits or seeds (Strychnine tree), root (Rauwolfia serpentina) or bark (cinchona). Furthermore, different tissues of the same plants may contain different alkaloids.
Beside plants, alkaloids are found in certain types of fungi, such as psilocybin in the fungus of the genus Psilocybe, and in animals, such as bufotenin in the skin of some toads. Many marine organisms also contain alkaloids. Some amines, such as adrenaline and serotonin, which play an important role in higher animals, are similar to alkaloids in their structure and biosynthesis and are sometimes called alkaloids.
Because of the structural diversity of alkaloids, there is no single method of their extraction from natural raw materials. 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. 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.
Biological precursors of most alkaloids are amino acids, such as ornithine, lysine, phenylalanine, tyrosine, tryptophan, histidine, aspartic acid, and anthranilic acid. 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 and 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.
In addition to the described above monomeric alkaloids, there are also dimeric, and even trimeric and tetrameric 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:
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 and vindoline. 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.
The role of alkaloids for living organisms that produce them is still unclear. It was initially assumed that the alkaloids are the final products of nitrogen metabolism in plants, as urea in mammals. It was later shown that alkaloid concentrations varies over time, and this hypothesis was refuted.
Most of the known functions of alkaloids are related to protection. For example, aporphine alkaloid liriodenine produced by the tulip tree protects it from parasitic mushrooms. In addition, the presence of alkaloids in the plant prevents insects and chordate 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, dopamine and histamine are important neurotransmitters 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. asltroemeriana 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 as the correct location for oviposition.
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, including the following:
|Atropine, scopolamine, hyoscyamine||anticholinergic|
|Caffeine||stimulant, adenosine receptor antagonist|
|Colchicine||remedy for gout|
|Ergot alkaloids||Vasoconstriction, hallucinogenic, Uterotonic|
|Nicotine||stimulant, nicotinic acetylcholine receptor agonist|
|Physostigmine||inhibitor of acetylcholinesterase|
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, an opioid receptor antagonist, is a derivative of thebaine that is present in opium.
Prior to the development of a wide range of relatively low-toxic synthetic pesticides, some alkaloids, such as salts of nicotine and anabasine, were used as insecticides. Their use was limited by their high toxicity to humans.
Preparations of plants containing alkaloids and their extracts, and later pure alkaloids, have long been used as psychoactive substances. Cocaine, caffeine, and cathinone are stimulants of the central nervous system. Mescaline and many of indole alkaloids (such as psilocybin, dimethyltryptamine and ibogaine) have hallucinogenic effect. Morphine and codeine are strong narcotic pain killers.
There are alkaloids that do not have strong psychoactive effect themselves, but are precursors for semi-synthetic psychoactive drugs. For example, ephedrine and pseudoephedrine are used to produce methcathinone and methamphetamine. Thebaine is used in the synthesis of many painkillers such as oxycodone.
Affinisine is a monoterpenoid indole alkaloid which can be isolated from plants of the genus Tabernaemontana. Structurally it can be considered a member of the sarpagine alkaloid family and may be synthesized from tryptophan via a Pictet-Spengler reaction. Limited pharmacological testing has indicated that it may be an effective inhibitor of both acetylcholinesterase and butyrylcholinesterase.Akuammicine
Akuammicine is an alkaloid found in Vinca minor and Aspidosperma. It is a μ-opioid receptor agonists while also agonizing (but to a much lower, clinically insignificant degree) the κ and δ-opioid receptors. Agonistic activity at both human variants of the σ-sigma receptors has been indicated but is not yet proven, so have possible mechanisms of action at the NMDA receptor (antagonist) and glycine receptor.Akuammine
Akuammine (vincamajoridine) is an indole alkaloid. It is the most abundant alkaloid found in the seeds from the tree Picralima nitida, commonly known as akuamma, comprising 0.56% of the dried powder. It has also been isolated from Vinca major. Akuammine is structurally related to both yohimbine and mitragynine, both of which are alkaloid plant products with pharmacological properties.Anticholinergic
An anticholinergic agent is a substance that blocks the neurotransmitter acetylcholine in the central and the peripheral nervous system. These agents inhibit parasympathetic nerve impulses by selectively blocking the binding of the neurotransmitter acetylcholine to its receptor in nerve cells. The nerve fibers of the parasympathetic system are responsible for the involuntary movement of smooth muscles present in the gastrointestinal tract, urinary tract, lungs, and many other parts of the body. Anticholinergics are divided into three categories in accordance with their specific targets in the central and peripheral nervous system: antimuscarinic agents, ganglionic blockers, and neuromuscular blockers.Batrachotoxin
Batrachotoxin (BTX) is an extremely potent cardiotoxic and neurotoxic steroidal alkaloid found in certain species of beetles, birds, and frogs. Batrachotoxin was derived from the Greek word βάτραχος bátrachos "frog". Structurally-related chemical compounds are often referred to collectively as batrachotoxins. It is an extremely poisonous alkaloid. In certain frogs this alkaloid is present mostly on the skin. Such frogs are among those used for poisoning darts. Batrachotoxin binds to and irreversibly opens the sodium channels of nerve cells and prevents them from closing, resulting in paralysis - no antidote is known.Canadine
Canadine is a protoberberine alkaloid which can act as a calcium channel blocker. It is also one of the many alkaloids found in Corydalis yanhusuo from the family of Papaveraceae.Coclaurine
Coclaurine is a nicotinic acetylcholine receptor antagonist which has been isolated from a variety of plant sources including Nelumbo nucifera, Sarcopetalum harveyanum, Ocotea duckei, and others. It belongs to the class of tetrahydroisoquinoline alkaloids. Dimerization of coclaurine leads to the biscoclaurine alkaloids such as cepharanthine.Conodurine
Conodurine is an acetylcholinesterase inhibitor and butyrylcholinesterase inhibitor isolated from Tabernaemontana.Ergoline
Ergoline derivatives comprise a diverse group of chemical compounds whose structural skeleton is the alkaloid ergoline. Ergoline derivatives are used clinically for the purpose of vasoconstriction (5-HT1 receptor agonists—ergotamine) and in the treatment and alleviation of migraines (used with caffeine) and Parkinson's disease. Some ergoline alkaloids found in ergot fungi are implicated in the condition ergotism, which causes convulsive and gangrenous symptoms. Others are psychedelic substances, including LSD and some alkaloids in Argyreia nervosa, Ipomoea tricolor and related species.Erythravine
Erythravine is a tetrahydroisoquinoline alkaloid found in the plant Erythrina mulungu and other species of the genus Erythrina.Gigactonine
Gigactonine is an alkaloid isolated from Aconitum with hERG-inhibiting activity.Harmala alkaloid
Several alkaloids that function as monoamine oxidase inhibitors (MAOIs) are found in the seeds of Peganum harmala (also known as Harmal or Syrian Rue), as well as tobacco leaves including harmine, harmaline, and harmalol, which are members of a group of substances with a similar chemical structure collectively known as harmala alkaloids. These alkaloids are of interest for their use in Amazonian shamanism, where they are derived from other plants. The harmala alkaloid harmine, once known as telepathine and banisterine, is a naturally occurring beta-carboline alkaloid that is structurally related to harmaline, and also found in the vine Banisteriopsis caapi. Tetrahydroharmine is also found in B. caapi and P. harmala. Dr. Alexander Shulgin has suggested that harmine may be a breakdown product of harmaline. Harmine and harmaline are reversible MAOIs of the MAO-A isoform of the enzyme, and can stimulate the central nervous system by inhibiting the metabolism of monoamine compounds such as serotonin and norepinephrine.
The harmala alkaloids occur in alcohol in concentrations of roughly 3%, though tests have documented anywhere from 2-7% or even higher, as natural sources tend to vary widely in chemical makeup. Harmala alkaloids are also found in the Banisteriopsis caapi vine, the key plant ingredient in the sacramental beverage Ayahuasca, in concentrations that range between 0.31-8.43% for harmine, 0.03-0.83% for harmaline and 0.05-2.94% for tetrahydroharmine.
Although other psychoactive plants are occasionally added to Ayahuasca to achieve visionary states of consciousness, the recipes vary greatly and no single combination is common. Peganum harmala, normally consumed as a tea or used as an incense, is mentioned in classical Persian literature both as a sacred sacrament and as a medicine. The harmala alkaloids are not especially psychedelic, even at higher dosages, when hypnagogic visions, alongside vomiting and diarrhea, become the main effect.
Harmala alkaloids are also found in many other plants, such as passion flower. The leaves of P. incarnata have been reported variously to give 0.005%, 0.12 mg%, and nil, of harman alkaloids.Pericine
Pericine is one of a number of indole alkaloids found in the tree Picralima nitida, commonly known as akuamma. As with some other alkaloids from this plant such as akuammine, pericine has been shown to bind to mu opioid receptors in vitro, and has an IC50 of 0.6 μmol, within the range of a weak analgesic. It may also have convulsant effects.Pericine has been prepared in the laboratory by total synthesis.Retronecine
Retronecine is a pyrrolizidine alkaloid found in a variety of plants in the genera Senecio and Crotalaria, and the family Boraginaceae. It is the most common central core for other pyrrolizidine alkaloids.Solasodamine
Solasodamine is a poisonous tetrasaccharide chemical compound of solasodine that occurs in plants of the Solanaceae family.Solasodine
Solasodine is a poisonous alkaloid chemical compound that occurs in plants of the Solanaceae family. Solasonine and solamargine are glycoalkaloid derivatives of solasodine. Solasodine is teratogenic to hamster fetuses in a dose of 1200 to 1600 mg/kg.
Literature survey reveals that solasodine has diuretic, anticancer, antifungal, cardiotonic, antispermatogenetic, antiandrogenic, immunomodulatory, antipyretic and various effects on central nervous system.Solauricine
Solauricine is a poisonous glycoalkaloid chemical compound that occurs in plants of the Solanaceae family.Ungeremine
Ungeremine is a betaine-type alkaloid isolated from Nerine bowdenii and related plants such as Pancratium maritimum. Pharmacologically, it is of interest as an acetylcholinesterase inhibitor and accordingly as possibly relevant to Alzheimer's disease. It also has been investigated as a bactericide.Voacangine
Voacangine (12-methoxyibogamine-18-carboxylic acid methyl ester) is an alkaloid found predominantly in the rootbark of the Voacanga africana tree, as well as in other plants such as Tabernanthe iboga, Tabernaemontana africana, Trachelospermum jasminoides and Ervatamia yunnanensis. It is an iboga alkaloid which commonly serves as a precursor for the semi-synthesis of ibogaine. It has also been demonstrated in animals to have similar anti-addictive properties to ibogaine itself.