An alkaloid is a nitrogenous organic molecule that has a strong pharmacological effect on humans and

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An alkaloid is a nitrogenous organic molecule
that has a strong pharmacological effect on
humans and animals. The name derives from the
word alkaline originally, the term was used to
describe the chemical property of them. Alkaloids
are found as secondary metabolites in plants
(e.g., in potatoes and tomatoes), animals (e.g.,
in shellfish) and fungi, and can be extracted
from their sources by treatment with acids
(usually hydrochloric acid or sulfuric
acid). Usually alkaloids are derivatives of amino
acids. Even though many alkaloids are poisonous
(such as strychnine or coniine), some are used in
medicine as analgesics (pain relievers) or
anaesthetics, particularly morphine and codeine.
Most alkaloids have a very bitter taste.
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Pyridine group piperine, coniine, trigonelline,
pilocarpine, nicotine. Pyrrolidine group
hygrine, cuscohygrine, nicotine Tropane group
atropine, cocaine, ecgonine, scopolamine
Quinoline group quinine, quinidine, strychnine,
brucine, Isoquinoline group The opium alkaloids
(morphine, codeine, thebaine, papaverine,
narcotine) Phenethylamine group mescaline,
ephedrine, amphetamine, methamphetamine, Indole
group Tryptamines psilocybin, serotonin,
melatonin Ergolines the ergot alkaloids
(ergine, ergotamine, lysergic acid, etc.), LSD
Beta-carbolines harmine, yohimbine, reserpine,
emetine Purine group Xanthines caffeine,
theobromine, theophylline Terpenoid group
Aconite alkaloids aconitine Steroids solanine,
samandarin Betaines (quaternary ammonium
compounds) muscarine, choline, neurine Pyrazole
group pyrazole
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Caffeine is a xanthine alkaloid found in the
leaves and beans of the coffee tree, in tea and
in small quantities in cocoa and the kola nut. In
plants, caffeine acts as a natural pesticide that
paralyzes and kills many insects feeding upon
them. Caffeine is a central nervous system (CNS)
stimulant, having the effect of warding off
drowsiness and restoring alertness.
Caffeine-containing beverages, such as coffee and
tea, enjoy great popularity, making caffeine the
world's most popular psychoactive drug. In
nature, caffeine is found with widely varying
concentrations of the other xanthine alkaloids
theophylline and theobromine, which are cardiac
stimulants.
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Theophylline is a methylxanthine drug used in
therapy for respiratory diseases under a variety
of brand names. As a member of the xanthine
family, it bears structural and pharmacological
similarity to caffeine. It is naturally found in
black tea and green tea. The main actions of
theophylline are relaxing of bronchial smooth
muscle positive inotropic (increasing heart
muscle contractility and efficiency) positive
chronotropic (increasing heart rate) increase of
blood pressure increase of renal blood flow
some anti-inflammatory effects.
Theobromine has very different effects on the
human body from caffeine it is a mild, lasting
stimulant with a mood improving effect, whereas
caffeine has a strong, immediate effect and
increases stress. In medicine, it is used as a
diuretic, vasodilator, and myocardial
stimulant. It was recently discovered that
theobromine has an antitussive effect superior to
codeine by suppressing vagus nerve activ
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Morphine, the principal active agent in opium
(extract of papaver somniferum), is a powerful
opioid analgesic drug. Like other opiates,
morphine acts directly on the central nervous
system (CNS) to relieve pain, and at synapses of
the arcuate nucleus, in particular. Side effects
include impairment of mental performance,
euphoria, drowsiness, lethargy, and blurred
vision. It also decreases hunger, inhibits the
cough reflex, and produces constipation. Morphine
is usually highly addictive when compared to
other substances, and tolerance and physical and
psychological dependence develop quickly.
Patients on morphine often report insomnia and
nightmares. Morphine was first isolated in 1804
by the German pharmacist Friedrich Wilhelm Adam
Sertürner, who named it "morphium" after
Morpheus, the god of dreams in Greek mythology.
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Papaverine is approved to treat spasms of the
gastointestinal tract, bile ducts and ureter and
for use as a cerebral and coronary vasodilator in
subarachnoid hemorrhage and coronary artery
bypass surgery. Papaverine may also be used as a
smooth muscle relaxant in microsurgery where it
applied directly to blood vessels.
Codeine or methylmorphine is an opioid used for
its analgesic, antitussive and antidiarrheal
properties. It is marketed as the salts codeine
sulfate and codeine phosphate. Codeine is an
alkaloid found in opium in concentrations ranging
from 0.7 to 2.5 percent. While codeine can be
extracted from opium, most codeine used in the
world is synthesized from morphine through the
process of O-methylation.
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narcotin
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A minor constituent of opium, thebaine or
paramorphine is chemically similar to both
morphine and codeine, but produces stimulatory
rather than depressant effects. Thebaine is not
used therapeutically, but is converted into a
variety of compounds including codein,
hydrocodone, hydromorphon, oxycodon, oxymorphon,
nalbuphine, naloxone, naltrexone, buprenorphine
and etorphine.
Heroin or diacetylmorphine is a semi-synthetic
opioid. It is the 3,6-diacetyl derivative of
morphine and is synthesised from it by
acetylation. The white crystalline form is
commonly the hydrochloride salt, diacetylmorphine
hydrochloride. It is highly addictive when
compared to other substances, although occasional
use without symptoms of withdrawal has been
noted. It is illegal to manufacture, possess, or
sell heroin in most of the countries of the
world. Popular street names fo heroin include
dope, diesel, smack, scag and H.
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Tubocurarine chloride is a competitive
neuromuscular blocker, used to paralyse patients
undergoing anaesthesia. It is one of the
chemicals that can be obtained from curare,
itself an extract of Chondodendron tomentosum, a
plant found in South American jungles which is
used as a source of arrow poison. The correct
chemical structure was only elucidated circa
1970, even though the plant had been known since
the Spanish Conquest.
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Ergot is the common name of a fungus in the genus
Claviceps. The fungus is parasitic on certain
grains and grasses. There are about 50 known
species of Claviceps, most of them in the
tropical regions. Economically important species
are Claviceps purpurea (parasitic on grasses and
cereals),
D-lysergic acid diethylamide, commonly called
LSD, is a powerful semisynthetic psychedelic drug
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Muscarine, L-()-muscarine, or muscarin is a
natural product found in certain mushrooms,
particularly in Inocybe and Clitocyb species. It
was first isolated from Amanita muscaria in 1869.
It was the first parasympathomimetic substance
ever studied and causes profound activation of
the peripheral parasympathetic nervous system
that may end in convulsions and death.
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Aconitine is a highly poisonous alkaloid derived
from the aconite plant. It is a neurotoxin that
opens TTX-sensitive Na channels in the heart and
other tissues, and is used for creating models of
cardiac arrhythmia.
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Mescaline or 3,4,5-trimethoxy phenethylamine is a
psychedelic hallucinogenic drug and entheogen of
the phenethylamine family. It is either
synthesized (as mescaline sulfate) or extracted
from the peyote cactus (Lophophora williamsii),
the San Pedro cactus (Echinopsis pachanoi), or
the Peruvian Torch cactus (Echinopsis peruviana).
It is also found in a number of other members of
the Cactaceae.
Ephedrine is a sympathomimetic amine commonly
used as a decongestant and to treat hypotension
associated with regional anaesthesia. Chemically,
it is an alkaloid derived from various plants in
the genus Ephedra (family Ephedraceae). It is
usually marketed as the ephedrine hydrochloride
and ephedrine sulfate.
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Amphetamine (alpha-methyl-phenethylamine), also
known as speed, is a synthetic stimulant used to
suppress the appetite, control weight, and treat
disorders including narcolepsy and
Attention-deficit hyperactivity disorder. It is
also used recreationally and for performance
enhancement (these uses are illegal in most
countries).
MDMA (3,4-methylenedioxy methamphetamine), most
commonly known today by the street name ecstasy
or XTC, is a synthetic entactogen of the
phenethylamine family whose primary effect is to
stimulate the secretion of and inhibit the
re-uptake of large amounts of serotonin as well
as dopamine and norepinephrine in the brain,
causing a general sense of openness, empathy,
energy, euphoria, and well-being. Tactile
sensations are enhanced for some users, making
general physical contact with others more
pleasurable but, contrary to popular mythology
it generally does not have aphrodisiac effects.
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Piperine is the alkaloid responsible for the
taste and smell of black pepper. It has also been
used in some forms of traditional medicine and as
an insecticide. Piperine has been found to
inhibit human P-glycoprotein and CYP3A4, enzymes
important for the metabolism and transport of
xenobiotics and metabolites
Coniine or (S)-2-propylpiperidine, is a
poisonous alkaloid found in poison hemlock and
the Yellow Pitcher Plant, and contributes to
hemlock's fetid smell. It is a neurotoxin which
disrupts the central nervous system. It is toxic
to all classes of livestock and humans less than
0.2g (0.007oz) is fatal to humans, with death
caused by respiratory paralysis.
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Pilocarpine is a muscarinic alkaloid obtained
from the leaves of tropical American shrubs from
the genus Pilocarpus. It acts as a muscarinic
receptor agonist in the para sympathetic nervous
system.
Pilocarpine has been used in the treatment of
chronic open-angle glaucoma and acute
angle-closure glaucoma for over 100 years. It
acts on a subtype of muscarinic receptor (M3)
found on the iris sphincter muscle, causing the
muscle to contract and produce miosis. This opens
the trabecular meshwork through increased tension
on the scleral spur. This action facilitates the
rate that aqueous humor leaves the eye to
decrease intraocular pressure.
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Nicotine is a pyrrolidine-like alkaloid found
naturally in the nightshade family of plants,
such as tobacco and tomatoes. It constitutes 0.3
to 5 of the tobacco plant by dry weight, with
biosynthesis taking place in the roots, and
accumulates in the leaves. It is a potent nerve
poison and is included in many insecticides. In
lower concentrations, the substance is a
stimulant and is one of the main factors leading
to the habit-forming qualities of tobacco
smoking. Nicotine seems to provide both a
stimulant and a depressant effect, and it is
likely that the effect it has at any time is
determined by the mood of the user, the
environment and the circumstances of use. Studies
have suggested that low doses have a stimulant
effect, whilst higher doses have depressant
effect. Nicotine has limited carcinogenic
effects, inhibiting the body's ability to destroy
potentially cancerous cells. However, nicotine
does not promote the development of cancer in
healthy cells. In addition to the tobacco plant,
nicotine is also found in lower quantities in
other members of the Solanaceae (nightshade)
family, which includes tomato, potato, eggplant
(aubergine), and green pepper. Nicotine alkaloids
are also found in the leaves of the coca plant.
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Tropane (8-methyl-8-aza-bicyclo3.2.1octane) is
a bicyclic organic compound. It is mainly known
for a group of alkaloids derived from it (called
tropane alkaloids), which include, among others,
atropine and cocaine. Tropane alkaloids occur in
plants of the families Solanaceae (mandrake,
henbane, deadly nightshade, Datura species) and
Erythroxylaceae (coca). 8-Aza-bicyclo3.2.1octan
e (tropane without the 8-methyl group) is known
as nortropane or nor-tropane.
20
Cocaine is a tropane alkaloid that is obtained
from the leaves of the coca plant. It is a
stimulant of the central nervous system and an
appetite suppressant, creating what has been
described as a euphoric sense of happiness and
increased energy. Though most often used
recreationally for this effect, cocaine is also a
topical anesthetic that was used in eye and
throat surgery in the 19th and early 20th
centuries. Cocaine can be psychologically
addictive, and its possession, cultivation, and
distribution is illegal for non-medicinal /
non-government sanctioned purposes in virtually
all parts of the world.
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Atropine is a tropane alkaloid extracted from the
deadly nightshade (Atropa belladonna) and other
plants of the family Solanaceae. It is a
secondary metabolite of these plants and serves
as a drug with a wide variety of effects. Being
potentially deadly, it derives its name from
Atropos, one of the three Fates who, according to
Greek mythology, chose how a person was to die.
Generally, atropine lowers the "rest and digest"
activity of all muscles and glands regulated by
the parasympathetic nervous system. This occurs
because atropine is a competitive antagonist of
the muscarinic acetylcholine receptors.
(Acetylcholine is the neurotransmitter used by
the parasympathetic nervous system.) Therefore,
it may cause swallowing difficulties and reduced
secretions.
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Scopolamine, also known as hyoscine, is a tropane
alkaloid drug obtained from plants of the
Solanaceae family (Nightshade), such as henbane
or jimson weed (Datura stramonium). It is part of
the secondary metabolites of plants. It is
structurally similar to the neurotransmitter
acetylcholine and acts by blocking the muscarinic
acetylcholine receptors it is thus classified as
an anticholinergic. In medicine, it is usually
used in the form scopolamine hydrobromide. It can
be used as a depressant of the central nervous
system, though it can cause delirium in the
presence of pain, mydriasis (pupillary dilation),
and cycloplegia (paralysis of the eye muscles).
When combined with morphine, it produces a
tranquilized state known as twilight sleep and
amnesia. Although originally used in obstetrics
it is now considered dangerous.
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Quinine, C20H24N2O2, is a natural white
crystalline alkaloid having antipyretic,
anti-malarial and analgesic properties and a
bitter taste. It is a stereoisomer of quinidine.
Quinine was the primary agent used in the
treatment of malaria until it was supplanted by
more effective synthetic drugs like quinacrine,
chloroquine, and primaquine. Quinine may still be
used to treat resistant malaria, nocturnal leg
cramps, and arthritis. The theorized mechanism of
action for quinine and related anti-malarial
drugs is that these drugs are toxic to the
malaria parasite. Quinine was extracted from the
bark of the South American cinchona tree,
isolated and named in 1820 by French researchers
Pierre Joseph Pelletier and Joseph Caventou. The
name was derived from the original Quechua
(Native American) word for the cinchona tree
bark, "Quina" or "Quina-Quina", which roughly
means "bark of bark" or "holly bark". The large
scale use of quinine started around 1850,
although it had been used in un-extracted form by
Europeans since at least the early 1600s. Quinine
was first used to treat malaria in Rome in 1631.
In addition to its anti-malarial properties,
quinine is an effective muscle relaxant.
Quinine is a flavour component of tonic water.
According to tradition, the bitter taste of
anti-malarial quinine tonic led British colonials
in India to mix it with gin, thus creating the
gin and tonic cocktail, which is still popular
today in both India and Great Britain, and in
other former British colonies.
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Strychnine is a very toxic (LD50 1 mg/kg),
colourless crystalline alkaloid used as a
pesticide, particularly for killing small
vertebrates such as rodents. Strychnine causes
muscular convulsions and eventually asphyxia or
sheer exhaustion. The most common source is from
the seeds of the Strychnos nux-vomica tree.
Strychnine is one of the most bitter substances
in the world. Its taste is detectable in
concentrations as low as 1 ppm.

Brucine is a bitter alkaloid closely related to
strychnine. It can be found in some plant
species, the most well-known variety being the
Strychnos nux-vomica tree, found in South-East
Asia. While brucine is related to strychnine it
is not as poisonous. Brucine does have certain
medical uses. It is primarily used in the
regulation of high blood pressure, and other
comparatively benign cardiac ailments.
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Psilocybin, is a psychedelic alkaloid of the
tryptamine family. It is present in many species
of fungi, notoriously those of the genus
Psilocybe, such as Psilocybe cubensis and
Psilocybe semilanceata (Liberty Caps), but also
reportedly isolated from a dozen or so other
genera. Psilocybin-containing mushrooms are
commonly called magic mushrooms. Effects of
psilocybin are comparable to those of LSD.
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Yohimbine is a selective competitive
alpha2-adrenergic receptor antagonist and is used
for treating erectile dysfunction. It is claimed
to be an aphrodisiac. It is also used as a weight
loss supplement as it increases norepinephrine
(noradrenaline) levels.
Reserpine is an indole alkaloid antipsychotic and
antihypertensive drug known to irreversibly bind
to storage vesicles of neurotransmitters such as
dopamine, norepinephrine, and serotonin.
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Solanine is a glycoalkaloid poison found in
species of the nightshade family. It can occur
naturally in the any part of the plant, including
the leaves, fruit, and tubers. It is very toxic
even in small quantities. Solanine has both
fungicidal and pesticidal properties, and it is
one of the plant's natural defenses.
tomatidin