Alkaloids pptx

1. ALKALOIDS
By
Sayee Pramod Dhavan
M.PHARM
PHARMACOGNOSY DEPARTMENT

2. INTRODUCTION
Definition –
The term alkaloid derived from two words Alk means
Alkali and Oid means like which is basic nitrogenous
compounds contains one or more nitrogen in
heterocyclic ring system.
 They are secondary metabolites of plants.
 The term Alkaloid was proposed by W. Meissnerin,
German Pharmacist, in 1819.
 Alkaloids are basic in nature . They form water
soluble salts.

3. Forms of Alkaloids :
 Free bases
 Salts with Organic acids
e.g. Oxalic acid, Acetic Acid
 Salts with Inorganic acids
e.g. HCl , H2SO4
 Salts With Special acids
e.g. Meconic acid in Opium,
Quinic acid in Cinchona
 Glycosidal form
e.g. Solanine in Solanum

4. CLASSIFICATION

5. TRUE ALKALOIDS
 True alkaloids are also known as Typical Alkaloids that
are derived from amino acids and have nitrogen in a
heterocyclic ring.
 True Alkaloids are Toxic, show a wide range of
Physiological Activity.
 True Alkaloids normally occur in Plants.
 They are basic in nature.
 E.g. Atropine, Emetine, Morphine, Quinine, Colchicine.

6. PROTO ALKALOIDS
 The Proto Alkaloids also known as Amino Alkaloids are simple
amines.
 Proto Alkaloids are derived from Amino Acids and do not have
nitrogen ring in a heterocyclic ring.
 They are basic in nature.
 E.g. Mescaline, Ephedrine

7. PSEUDO ALKALOIDS
 They are not derived from Amino Acid Precursors but
have Nitrogen in a Heterocyclic ring.
 They are Basic in nature.
 It includes mainly steroidal and terpenoid alkaloids
and purines.
 E.g. Steroidal Alkaloids – Conessine,
Purines – Caffeine.

8. EXAMPLES
 All parts : e.g. Datura
 Barks : e.g. Chinchona, Kurchi
 Seeds : e.g. Nux Vomica, Areca
 Roots : e.g. Aconite, Rauwolfia
 Fruits : e.g. Black pepper, Conicum
 Leaves : e.g. Tobacco, Coca
 Latex : e.g. Opium

9. 1.EPHEDRINE
 Also known as Ma- Huang.
 Used in Chinese medicine for more than 5,000 years.
 Chemical formula : C10H15NO
 Molecular Weight : 165.23 g/mole
 Melting point – 37-39 degree Celsius
 Boiling point : 253-255 degree Celsius
 Brand Name : Akovaz, Corphedra
 Drug class : Decongestants , Vasopresors
 Ephedrine is an Alkaloidal amine having sympathomimetic
action.

10.  Chemical constituents : Ephedrine, Nor – ephedrine, N – methyl
ephedrine, Pseudo ephedrine, Nor – pseudo ephedrine.
 Botanical Name : Ephedra vulgaris

11. BIOSYNTHESIS
 Biosynthesis of ephedrine by ephedra begins with L-
phenylalanine.
 Phenylalanine is the initial precursor of ephedrine &
pseudoephedrine and catalyzed by phenylalanine ammonia
lyase (PAL).

12.  Phenylalanine first forms cinnamoyl – CoA via the enzymes
phenylalanine ammonia – lyase and acyl CoA ligase.

13.  The cinnamoyl CoA is then reacted with a hydratase to attach
the alcohol functional group.
 The product is then reacted with a retro-aldolase, forming
Benzaldehyde.

14.  Benzaldehyde undergo dehydrogenase to form benzoic acid.
 After undergoing condensation with pyruvate to form 1-
phenylpropane-1,2-dione. This reaction catalysed by a ThDP –
dependant carboligase.
 Transmission of 1 – phenylpropane-1,2-dione yields
cathinone.

15.  Then cathinone is reduced to norephedrine. In the end, N-
methylation to form ephedrine.

16. ISOLATION

17. USES
 Ephedrine shows sympathomimetic activity.
 It is used as Bronchodilator in Asthma.
 It is used in allergic conditions like Hay fever, Bronchitis,
Whooping cough, etc.
 Used as Vasoconstrictive properties.
 Used in weight loss.
 Ephedrine increases blood pressure and heart rate.

18. 2.QUININE
 Quinine is a well known antimalarial drug, was obtained from
the bark of Chinchona species.
 Chinchona bark contains about 30 alkaloids but its
antimalarial activity is mainly due to
• Quinine
• Quinidine
• Cinchonine
• Cinchonidine
 Quinine is natural white crystalline Alkaloid.

19. CHEMICAL CONSTITUENTS :
 Quinine is a cinchona alkaloid that is Cinchonidine in which
the hydrogen at the 6 – position of the quinoline ring is
substituted by methoxy.
 Quinine is a cinchona alkaloid that belongs to the aryl amino
alcohol group of drugs.

20. BIOSYNTHESIS

21. ISOLATION
 The cinchona bark is stripped off and dried in the sun. This is
then crushed to a fine powder.
This dry powder is well mixed with 30% of its weight with
calcium hydroxide to make a paste. It is allowed to stand for
few hours.
This mass is then transferred to Soxhlet apparatus and
extraction is carried out with benzene. Subsequently benzene
extract is shaken with successive portions of 5% sulphuric acid.
 The aqueous acid extract is adjusted to pH 6.5 with diluted
sodium hydroxide and cool. Crystals of neutral quinine
sulphate are formed.

22. USES
 Quinine is used mainly as anti – malarial in dose of 2gm of
quinine sulphate for 14 days.
 Used as cardiac depressant.
 Used as anti – inflammatory.
 Anti – pyretic
 Analgesic
 Used as skeletal muscle relaxant.
 Used for abortification.

23. 3. STRYCHNINE
 Strychnine is one of the most deadly known poisons.
 It is an alkaloid obtained from the seeds of strychnos Nux
vomica.
 Strychnine is a highly toxic , colourless and bitter crystalline
alkaloid used as a pesticide, particularly for killing small
vertebrates such as birds and rodents.

24. ISOLATION & BIOSYNTHESIS :

25. USES
 Strychnine is used as pesticide / vermin killer, particularly to
kill rats.
 Appetite stimulant and general tonic in small doses.
 Used in synthetic chemistry.
 Used historically in small doses to strengthen muscle
contractions, such as heart and bowel stimulant.