Prof. Dr. Amani S. Awaad

Professor of PharmacognosyPharmacognosy Department,

College of Pharmacy Salman Bin Abdulaziz

University,

Al-Kharj. KSA.

Email: amaniawaad@hotmail.com

Pharmacognosy -2

PHG 322

What are Purine alkaloids

Occurrence, Characters and Activities of Purine alkaloids

Pyridine & piperidine alkaloid

Occurrence, uses, Characters and Activities of Pyridine & piperidine

Pyrrolyzidine alkaloid

Occurrence, Characters and Activities of Pyrrolyzidine alkaloid

Tropane alkaloid

Occurrence, uses, Characters and Activities of Tropane alkaloid

Typical/hetrocyclic alkaloids

5-Purine Alkaloids

xanthine

Theophylline caffeineTheobromine

They are all methyl

derivatives of xanthine

Purines are derivatives of a heterocyclic nucleus consisting of a six-membered Pyrimidine ring

fused to a five-membered Imidazole ring.

Purines are Psudo alkaloids (Are not derived from amino acids but have nitrogen in a

heterocyclic ring) (True alkaloid- protoalkaloid- pseudoalkaloid)

5-Purine Alkaloids

Purine Alkaloids

5-Purine Alkaloids

Occurrence, Characters and Activities

• These alkaloids are weak bases, they give no precipitate with Mayer's reagent.

• They have Amphoteric Character

• Peculiar solubility in warm water and in chlorinated solvents.

• Caffeine :- completely Water soluble. Sublimable.

• Theobromine: Sparingly soluble in water. Sublimable. Amphoteric

• Theophylline: - Sparingly soluble in water

Occurrence

Characters

Theobroma cacao tree, Folia Theae (Tea Lea), Thea sinensis

(Chinese Tea) (Family Teas; Theaceae). Sеmina Coffeae (Fam.

– Rubiaceae) Coffeine [Tea leaves (2- 5%), Coffee seeds (1-2

%), Cola leaves (2- 3%), Gurana seeds (2.5- 5 %) and Cacao

seeds, (0.2- 0.5 %)].

5-Purine Alkaloids

Occurrence, Characters and Activities

Paraxanthine (84%): Increases lipolysis, leading to elevated glycerol and free fatty acid

levels.

Theobromine (12%): Dilates blood vessels and increases urine volume.

Theophylline (4%): Relaxes smooth muscles of the bronchi, and is used to treat asthma.

Each of these metabolites is further metabolized and then excreted in the urine.

Chemical structure of Caffeine and the

three primary metabolites that it is

metabolized into inside the liver

Side effects:tacchycardia ,Epigastric pain ,Nausea, Vomiting , Headaches , Nervousness

Insomnia ,tremors

ActivitiesCaffeine: stimulates CNS and has a weak diuretic action.

Theobromine: Has little CNS stimulant action, but has more diuretic activity, and has

smooth muscle relaxant effect.

Theophylline: Has low CNS stimulant action and is an effective diuretic, but it is an

important smooth muscle relaxant & used for relief of bronchial spasms

Caffeine is metabolized in the liver by the cytochrome P450 oxidase enzyme system into

three metabolic dimethylxanthines, which each have their own effects on the body

5-Purine Alkaloids

Murexide test: (caffeine, theobromine and theophylline).

Crystals of caffeine + drops of concentrated HCl and traces of KClO3

→evaporated on water bath → red color is produced wich turns to violet onexposure to ammonia vapor.

Tannic acid test: (caffeine and theophylline):

A concentrated solution of the alkaloid + tannic acid → white precipitate isobtained that dissolves in excess of the reagent.

Ferrous sulfate test: (theobromine):

To a solution of the alkaloid + drops of concentrated HCl + few drops of

Br2 water + a drop of FeSO4 + few drops of ammonia→ Blue color.

Color tests

6-Alkaloids of the Pyridine

nucleus

10

Typical/hetrocyclic alkaloids

1. Pyridine alone: e.g. trigonelline

2. Pyridone: e.g. ricinine.

3. Pyridine with nitrogenous rings (pyrrole-ring): e.g. tobacco alkaloids

4. Tetrahydropyridine: e.g. Areca alkaloids

5.Piperidine. E.g. pepper , conium, lobelia and pomegranate.

6-Alkaloids of the Pyridine nucleus

This group of Alkaloids Derived from Aspartic Acid

Alkaloids of the Pyridine group could be divided into 4

subgroups and the nucleus of the molecule is one of the

following nuclei:

In plants, it is the condensation of aspartic acid and glyceraldehydes

which leads to nicotinic acid, which is the precursor of other alkaloids

of this group such as Areca alkaloids, nicotine, nicotelline, anabasine

and ricinine. Nicotine is biosynthesized from nicotinic acid and

ornithine or putrescine

N

N

H

CH3

Pyridine alone Pyridine with nitrogenous

rings

Tetrahydropyridine Pyridone

Piperridine

6-Alkaloids of the Pyridine nucleus

In plants, it is the

condensation of aspartic acid

and glyceraldehydes which

leads to nicotinic acid, which

is the precursor of other

alkaloids of this group such as

Areca alkaloids, nicotine,

nicotelline, anabasine and

ricinine. Nicotine is

biosynthesized from nicotinic

acid and ornithine or

putrescine

Biosynthesis

6-Alkaloids of the Pyridine nucleus

Drugs Containing Pyridine Alkaloids

1) Drugs contain Pyridine alone

Wood Betony

Family: Labiatae

Latin name: Stachys officinalis

Wood betony was at one time commonly used as a medicinal plant in

the treatment of a wide range of disorders, especially as a nervine and

tonic for treating maladies of the head and as an external application to

wounds. It also stimulates the digestive system and the liver, having an

overall tonic effect upon the body.

Active constituents:

Trigonelline, Stachydrine and Betonine

Medicinal use

6-Alkaloids of the Pyridine nucleus

Drugs Containing Pyridine Alkaloids

2) Drugs Containing Pyridone

Synonym: Ricinus africanus Willd.

Family: Euphorbiaceae

Medicinal Uses

R. communis leaves are tied on the nails affected for the treatment of

onychomycosis in District Jacobabad (Sindh). R. communis is anti- abortive,

antibacterial, fungicidal,

It possessed ant nociceptive and wound healing properties. Extract of R.

communis is known for it antioxidant and insecticidal activities.

Constituents

ricinine, ergostfucosterol, and probucol components

ricinine

6-Alkaloids of the Pyridine nucleus

Drugs Containing Pyridine Alkaloids

3) Drugs Containing Pyridine with nitrogenous rings

Tobacco alkaloids

Nicotine is colorless to pale yellow, very hygroscopic, oily, very strong volatile oil

base.

Nicotiana tabacum (Fam: Solanaceae)

The leaves of the tobacco plant are used for production of Cigarettes. They

are toxic plants which contain alkaloids.

nicotine plus five minor alkaloids found in tobacco smoke (as nornicotine, the N-

oxidized derivatives of nicotine, nicotyrine, anabasine and anatabine.)

Constituents

N

N

H

CH3

Volatile

liquids

N

N

H

H

CH3N

N

H

(-)-nicotine

(major)

nor-nicotine

CH3N

N

H

nicoteine

non-volatile

liquid

16

6-Alkaloids of the Pyridine nucleus

Drugs Containing Pyridine Alkaloids

Tobacco alkaloids

Nicotine is colorless to pale yellow, very hygroscopic, oily, very strong volatile oil base.

CH3N

N

H

less basic

2 basic N atoms

form salts with acids

3) Drugs Containing Pyridine with nitrogenous rings

6-Alkaloids of the Pyridine nucleus

Drugs Containing Pyridine Alkaloids

3) Drugs Containing Pyridine with nitrogenous rings

tobacco alkaloids

Nicotine possesses a high affinity to the gangilionic-(nicotinic)

cholinergic- receptors. So, it stimulates all autonomic ganglia, it acts

on the CNS causing tremors and conclusions, it is also stimulates the

respiratory and vomiting centers. It acts on the smooth muscle of the

intestine, by increasing tone and motor activity.

It acts on the cardiovascular system, by inducing vasoconstriction and

an increase in arterial blood pressure. In the long run, nicotine is

responsible for the genesis of cardiovascular, pulmonary diseases.

It is used in the form of chewing gum or transdermal system for

relieving the symptoms of withdrawal of cigarettes.

It is also used for treating aphid and other insect infestation.

Pharmacological actions

Little use in medicine (high toxicity)

In small doses (respiratory stimulant)

In larger doses (respiratory depre)

Increases incidence of abortion

Main use:

Insecticide & anthelmintic in veterinary

medicine

N

N

H

CH3

6-Alkaloids of the Pyridine nucleus

Drugs Containing Pyridine Alkaloids

4) Drugs Containing Tetrahydropyridine

Source :

It is the dried, ripe seed of Areca catechu (Fam. Arecaceae).

The seed of this plant known as betel nut is an ingredient of

betel.

Origen:

popular masticatory in India and southern Asia. The tree is

widely cultivated from India and Sri-lanka to the south of

China and the Philippines, in Indonesia and Tanzania.

Contents:

Areca contains several alkaloids (0.2-0.5%) that are reduced

pyridine derivatives. Among them are, arecoline, arecaidine,

guavacine and guavacoline

Betel Palm

[Areca alkaloids]

6-Alkaloids of the Pyridine nucleusDrugs Containing Pyridine Alkaloids

5) Drugs Containing Tetrahydropyridine

Arecoline is parasympathomimetic, which acts on muscarinic receptors, and at high

doses. On nicotinic receptors.

This results in multiple actions: e.g. vasodilation, hypotension, and reflex tachycardia

at low doses, stimulation of intestinal tone and peristalsis, increase in secretions

(hypersalivations, sweatining) myosis and bladder contraction.

Areca is mixed with lime, tobacco, Gambir or saffron and rolled in betel leaf.

The mixture is used as a stimulant masticatory in India and East Indies.

Areca is classified as an antihelmentic in veterinary practice and is employed as a

vermicide and taeniafuge

Betel is suspected of inducing buccal cancer due to the cytotoxic and teratogenic

N-nitrose-amines formed from the alkaloids of the betel nut, in particular 3-(N-

nitrosomethylamino)-propioaldehyde (NMPA).

Pharmacology & use

Arecoline

6-Alkaloids of the Pyridine nucleus

Drugs Containing Pyridine Alkaloids

5.Piperidine

Piperidine alkaloids are identified by their saturated heterocyclic

ring, i.e., piperidine nucleus

e.g. alkaloids of:

a. Conium.

b. Lobelia.

c. pepper.

d. pomegranate.

This group biosynthetically derived from Lysines

6-Alkaloids of the Pyridine nucleus

Drugs Containing Pyridine Alkaloids

5.Piperidine

a. Conium alkaloids

This group occurred in Conium maculatum which has a worldwide

distribution; it is a very common plant species, a member of the

family Apiaceae (formerly Umbelliferae),

This group represent the best known piperidine alkaloid poisons

Coniine the most important toxic principle of Hemlock, It is found

in the seeds of Cicuta maculata L (Water Hemlock).

Contents : It contains; coniine , N-methylconiine, conhydrine,

seudoconh.drine,

Coniine paralyzes muscles by blocking the nicotinic receptor on the post-

synaptic membrane of the neuromuscular junction causing a flaccid

paralysis and death

6-Alkaloids of the Pyridine nucleus

Drugs Containing Pyridine Alkaloids

5.Piperidine

b. lobelia

Occurrence: Its the dried leaves and flowering tops of Lobelia inflate (Fam. Lobeliaceae).

Contents: It contains 14 alkaloids (0.2 to 0.5%) including (-)-lobeline, meso-lobelanine and

meso-lobelanidine. The chief constituents is (2R, 6S, 8S)(-)-lobeline.

Lobeline occurs as colorless crystals that are slightly soluble in water but readily soluble in

hot alcohol.

NO OH

CH3

6-Alkaloids of the Pyridine nucleus

Drugs Containing Pyridine Alkaloids

5.Piperidine

b. lobelia

Lobeline produces similar, but weaker, pharmacologic effects

to those of nicotine on the peripheral circulation, and the

central nervous system.

Lobeline is a respiratory stimulant, which enhances and

accelerates the respiratory movements by improving the

reactivity of the brain stem centers to carbon dioxide. In

addition, it is ganglionic stimulant and β-adrenergic

bronchodilator. Lobeline sulfate is still commercialized as an

adjuvant in smoking cessation program

Pharmacology & use:

6-Alkaloids of the Pyridine nucleus

Drugs Containing Pyridine Alkaloids

5.Piperidine

c. pepper.

Black Pepper

Constituents : The peppery odor is due to 1 to 3.5% of an essential oil rich

in terpenoid hydrocarbons and the pungent taste to Piperidine amides (5-

10%). The chief constituent is piperine (insecticide), an amide of Piperidine

and of piperic acid. The other amides are piperidines (piperanine, piperettine)

piperolein A and piperolein B, pyrrolidines (piperyline).

Black pepper consists of the dried fruit of Piper nigrum (Fam. Piperaceae),

a perennial plant originally from the southwest of India and cultivated also

in Indonesia, Sri Lanka and South America (Brazil)

Peppers are frequently used in Ayurvedic medicine. Piperine is CNS

depressant and anticonvulsant in rats. Some of its synthetic derivatives have

been used in China as anti-epileptic. Black pepper is used as stomachic.

Uses

6-Alkaloids of the Pyridine nucleus

Drugs Containing Pyridine Alkaloids

5.Piperidine

c. pepper.

Chemical Tests of Piperine:

1. On the addition of Wagner's reagent to alcoholic solution of

piperine, steel blue needle crystals of piperine periodide are

formed.

2. Piperine on treating with platinum chloride solution gives

orange red needles.

3. Piperine on treating wit H2SO4 gives a red color.

7-Alkaloids of the Pyridine nucleus

5.Piperidine

d- Pomegranate alkaloids.

Occurrence: the fruit rind, root bark and stem bark of Punica

granatum. The plant is shrub widespread in North (Fam. Punicaceae)

Constituents : the bark contains 0.5-0.7% total alkaloids: (-) pelletierine, isopelletierine,

and N-methylated analogs.

Major alkaloid: pelltierine (liquid) . pelletierine tannate (mixture, solid)

Pomegranates have astringent properties because of the alkaloids (pelletierine tannate)

pelletierine tannate; present in the bark of the stems and roots

and have been used for many years as an anthelmintic:

removing tapeworms

27

Typical/hetrocyclic alkaloids

7-pyrrolyzidin

Pyrrolizidine alkaloids have a Pyrrolizidine (hexahydro-1-H-pyrrolizidine) basic

structure.

They have essentially been isolated only from Asteraceae and Boraginaceae. In both

families, they were found in many genera:

Eupatorium, Petasites, Senecio, Tussilago, and other Asteraceae, and Anchusa,

Echium, Heliotropium, Symphtum and other Boraginaceae.

Therapeutic interest in these alkaloids is almost nil, despite the fact that some are

cytostatic in vitro.

They are responsible for serious toxic symptoms observed in human, and more in

animals. They are hepatotoxic, carcinogenic and mutagenic.

For such compounds occur in plants recommended in traditional medicines

(coltsfoot, hemp, agrimony, comfrey, borage etc), it is not reasonable to give advice

for traditional healers or person taking such plants

7-Pyrrolizidine Alkaloids

Ornithine derived Alkaloids

Pyrrolizidine alkaloids are produced by plants as a defense mechanism against insect herbivore

29

Typical/hetrocyclic alkaloids

7-Alkaloids of the Tropane group

8-Alkaloids of the Tropane group

Chemistry

Tropane alkaloids have in common

a nitrogen-containing bicyclic

structural element azabicyclo-[3, 2,

1] octane.

They are; 8-methyl-8-azabicyclo

(3, 2, 1) octanes.

Approximately 200 alkaloids are

known in this group, and they are

distributed in Solanaceae,

Erythroxylaceae and more

sporadically in Convolvulaceae,

Euphorpiaceae, Brasicaceae and

Oleaceae.

8-Alkaloids of the Tropane group

Structure:

Tropane alkaloids are esters of tropane alcohols and of

acids of different structures,either aliphatic or aromatic.

These tropane alcohols are divided into two series based

on the orientation of hydroxyl group at 3-position;

derivatives of α-ol are the most common & those of tropan-

3β-ol are specific to Erythroxylaceae

The tropanols are often hydroxylated at the 6- or 7-position or both,

and sometimes 6, 7-epoxidized

8-Alkaloids of the Tropane group

Structure:

Almost all of the alkaloids of the Erythroxylaceae are esters of ecogenin, which is tropan-3β-ol substituted at the 2-

position and in the β configuration by carboxyl group.The acids may be aliphatic (acetic, butyric, isovaleric, tiglic and

angelic acids) or aromatic (tropic, truxilic, cinnamic, benzoic acids).

NH3C1

2

34

5

6

7

NH3C1

2

34

5

6

7

HO

NH3C1

2

3

4

5

6

7

OHNH3C

14

5

6

7

OH

COOH

NH3C1

2

34

O

= N CH3

1 2

3

456

7

8N CH3

1 2

456

7

8

Tropane

= HO

Tropanol or Tropine (3-hydroxytropane)

= N CH3

1 2

456

7

8 OH

Pseudotropine Ecogenin

HO

=N CH3

1 2

45

8 OHO

Scopine

8-Alkaloids of the Tropane group

Biosynthesis

Ornithine is rapidly decarboxylated to putrescin,

which is then methylated. The oxidation of N-

methylputrescin leads to 4-methylaminobutanol,

which is subsequently cyclized to a salt of N-

methyl-∆1 pyrrolinium, which is thought to react

with acetoacetate-unit to yield the 1-

methylpyrrolidine-2-acetoacetic acid (Hygric

acid). The oxidation of pyrrolidine and a

subsequent Mannich reaction complete the

tropane nucleus. Tropic acid has been formed

from phenylalanine by intramolecular migration

of carboxyl group from C-2 TO C-3 with

retention of configuration. The reaction

mechanism remains unknown.

8-Alkaloids of the Tropane group

Tropane alkaloids are identified by the following reactions:

1- Vitali-Morin Reaction

After treating with fuming nitric acid and redissolving the

residue with acetone, by adding solution of potassium hydroxide

in methanol, purple color is developed, which is changed to red.

2- Garrard Reaction

Atropine and hyoscyamine react with 2% solution of mercuric

chloride in 50% alcohol to produce a red color. Scopolamine

gives white precipitate.

3- Schaer’s Reaction

Tropane alkaloids gives with a prepared solution of 1 volume

of 30% H2O2 mixed with 10 volumes of concentrated H2SO4 a

green color.

Characterization of Tropane Alkaloids:

8-Alkaloids of the Tropane group

Tropane alkaloids represented in two class:

a) Solanaceous alkaloids

b)Erythroxylon (Coca) Alkaloids

The principal alkaloids of medicinal interest in this group are

1- (-) hyoscyamine. This fragile ester is rapidly converted, in acidic as well

as basic conditions, to tropanols and tropic acid, and the latter is

transformed by intramolecular dehydration, into apotropic (atropic acid),

which is optically inactive.

2- Racemate of hyoscyamine: a simple reflux in chloroform is enough to

transform hyoscyamine into (±) atropine.

3- Hyoscine (scopolamine), which is converted by acidic or basic

hydrolysis to scopine and tropic acid.

Main Alkaloids are:

1- Cocaine. 2- Cinnamylcocaine. 3. truxilline.Cinnamylcocainetruxilline

Datura stramonium Hyoscyamus niger Atropa belladonna Hyoscyamus muticu

a) Solanaceous alkaloids

8-Alkaloids of the Tropane group

Solanaceous alkaloids come from the solanaceae .

a) Solanaceous alkaloids

8-Alkaloids of the Tropane group

Contents :Some of the alkaloids

they produce are: Atropine ,

Hyoscyamine & Hyoscine.

Tropane

The 3-hydroxy derivative

Esterification of tropine with tropic acid

Tropine tropate

Tropine

Hyoscyamine is the pure optical isomer;

(+)Hyoscyamine, (-)Hyoscyamine.

Atropine is the racemic of hyoscyamine.

Atropine = (±)Hyoscyamin

Hyoscine is an ester of l-

tropic acid with copoline

base.

NCH3 O

OHO

O

Scopoline base

Tropic Acid

8-Alkaloids of the Tropane group

Drugs containing tropane alkaloids1) Deadly Nightshade (Belladonna)

The drug consists of the dried leaves and flowering or fruiting tops of Atropa belladonna

or its varieties (Fam. Solanaceae).

The plant is a perennial herb, growing up to one meter in height, indigenous to central and

southern Europe and Asia.

Both leaves and roots yield alkaloids in concentration ranging up to more than 1%. About

75% of alkaloid mixture is L-hyoscyamine, and atropine. Atropin occurs only in traces in

fresh plant material. Small quantities of scopolamine (2%) and their dehydration products

(apoatropine and aposcopolamine).

The belladonna leaves contain small quantity of a coumarins, namely scopoletol.

Besides small amounts of bases are found in the roots but not in the leaves

(belladonine, cuscohygrine and scopolamine)

a) Solanaceous alkaloids

8-Alkaloids of the Tropane group

Drugs containing tropane alkaloids

2) Thorn apple (Stramonium)

It consists of the dried leaves and flowering or fruiting tops with branches of Datura

stramonium or of its variety (Fam. Solanaceae). The plant is an annual herb attaining the height

of 2 meters, indigenous to the region of Caspian Sea, introduced in waste places in Europe and

North America.

The concentration of total alkaloids in the leaf ranges from 0.2 to 0.5% and at the time of the

harvest, hyoscyamine and scopolamine represent 2/3 and 1/3 of the total alkaloids, respectively

3) Henbane

The drug consists of the dried leaves with or without the stem and flowering or

fruiting top of Hyoscyamus niger (Fam. Solanaceae). The plant is annual or

biennial herb indigenous to Europe, Western Asia, and North Africa and cultivated

in Russia, Balkan, England and Germany. The concentration of alkaloids is

between 0.04-0.15%. hyoscyamine is the chief constit

4)Egyptian Henbane

The drug consists of the dried leaves and flowering tops of Hyoscyamus

muticus (Fam. Solanaceae), yields about 1.5% of total alkaloids containing

mainly hyoscyamine. The plant is indigenous and cultivated in Egypt.

a) Solanaceous alkaloids

8-Alkaloids of the Tropane group

Drugs containing tropane alkaloids

Pharmacological Activity of the tropane Alkaloid

Hyoscyamine and Atropine have the same activity. They are parasympatholytics. They

block the muscarinergic and cholinergic receptors by forming cationic, anionic and polar

bonds with the receptors. Hyoscyamine has a potent activity than the racemic atropine.

Hyoscyamine is the major natural alkaloid with negative optical rotation (l- form).

During extraction hyoscyamine racemizes to the optically inactive dl Atropine.

Both alkaloids composed of tropine base and tropic acid

1- AtropineAtropine acts by competitive and reversible inhibition of acetylcholine binding onto its receptors, and this antagonism

leads, in the organs in question, to sympathomimetics-like effects, such as:

It increases the heart rate by suppressing vagal inhibition. Atropine induces relaxation and motor inhibition: it decreases

intestinal tone and peristalsis, paralyzes the ureter, increases bladder pressure, decreases biliary duct tone, and blocks the

bronchoconstricting effect of acetylcholine. Secretions of saliva, sweat, gastric, pancreatic, bronchial, and lachrymal secretions

are all decreased. Atropine induces mydriasis.

a) Solanaceous alkaloids

8-Alkaloids of the Tropane group

Drugs containing tropane alkaloids

Pharmacological Activity of the tropane Alkaloid

Atropine sulfate has an anti-cholinergic effect (parasympatholytic activity).

It is used in medicine as:

1. A mydriatic (causes dilatation of the eye pupil).

2. An antispasmodic (relaxes the intestinal and bronchial smooth

muscles).

3. A pre-anesthetic medication to stop body secretions.

4. A CNS stimulant.

5. An antidote to organophosphorus insecticide.

1- Atropine

a) Solanaceous alkaloids

8-Alkaloids of the Tropane group

Drugs containing tropane alkaloids

Pharmacological Activity of the tropane Alkaloid

The parasympatholytics activity of this alkaloid is identical to that of atropine, but much less marked,

especially of the myocardium. It possesses sedative, depressant, and hypnotic with amnesia.

The belladonna leaf is commonly administered in the form of tincture.

The drug extract serves for therapeutic effect of spasms of GI-tract, combined with antacid for treating

hyperacidity, .

All the parts of the plant are toxic, especially the berries, which attract young children: the ingestion of two

to five berries can be fatal (10 to 20 for adults).

Datura Stramonium has a pharmacological activity resembling that of Atropa belladonna:

parasympatholytics and antispasmodic.

Henbane is a mild parasympatholytics and a CNS sedative. Intoxication is exceptional and not serious (the

seeds are really rich in alkaloids and therefore truly toxic)

2- Scopolamine(Hyoscine)

a) Solanaceous alkaloids

The action of Scopolamine (Hyoscine) differs from that of Atropine and Hyoscyamine in: It has no central

nervous system stimulation effect, but in high doses it causes hallucination .

Hyoscine HBr is commonly used in as sedative Has antiemetic effect

8-Alkaloids of the Tropane groupb)Erythroxylon (Coca) Alkaloids

Coca or coca leaves are the dried leaves of Erythroxylum coca and

Erythroxylum novogranatense var. truxillense (Fam. Erythroxylaceae).

The plants are shrubs or small trees attaining a height at about 2 meter

indigenous to certain areas of South America.

It was nearly five thousand years ago that the native of the Andes began

cultivating, optimizing and using coca for the production of its leaves.

The alkaloid concentration ranges from 0.5 and 1.5% depending

on the species, the variety, the geographical origin and other

factors

8-Alkaloids of the Tropane group

b)Erythroxylon (Coca) Alkaloids

The chief alkaloid (30-50%) is the cocaine, which is an ester, volatile as a free base, namely

(methylbenzoylecogenine)

Contents

NH 3C O H

C

O

O H

E cogon in e

1- Derivatives of Ecogenin:

e.g. cocaine, cinnamylcocaine

The leaves contain three basic types of alkaloids according to the principal nucleus in the molecule:

2- Derivatives of

pseudotropine: e.g.

Tropacoacain

3- Derivatives of

pyrrolidine: e.g. hygrine &

coscohygrine

Tropacoacain

methylbenzoylecogenine

8-Alkaloids of the Tropane group

b)Erythroxylon (Coca) Alkaloids

Uses

Cocaine is the major Alkaloid in Coca leaves and its diester

Alkaloid. Heating at 160 0C in conc. HCl leads to hydrolyses of cacaine to

MeOH, Benzoic acid and Ecogonine base

Cocaine is a local anesthetic.

It blocks ion channels in neuron membranes, and interrupts the propagation of action potentials

corresponding to the sensory message.

Cocaine is also sympathomimetics. It acts as an adrenergic stimulant by noradrenalin reuptake

blockage. This adrenergic stimulation produces hyperthermia, mydriasis and vasoconstriction.

Centrally, the stimulation results in a sensation of euphoria with intellectual stimulation and

other effects sought by drug addicts

NCH3 O

O

COOMe

Benzoic acid

Ecgonine base

Cocaine has a CNS stimulant activity so is one of the widely abused drug