4. Cinchona alkaloids
Cinchona is the dried stem and root barks of
Cinchona succirubra (known as Red
Cinchona), C. Ledgeriana., C. calisaya
(known as yellow cinchona), and C.
officinalis (known as pale cinchona) Family
5. Structural features of Cinchona alkaloids
1- The basic skeleton of Cinchona
alkaloids is Ruban-9-Ol.
2- Ruban nucleus is a combined skeleton
formed from a quinoline ring attached to
a quinuclidine ring (a bicyclic ring
contain N) through methylene group.
6. 3- In Rubanol, the methylene group is
oxidized to a secondary alcoholic
group and the carbon atom becomes
4- Cinchona alkaloids are Di-acidic bases
(due to presence of 2N atoms) they can
form both neutral and acidic salts .
8. Isolation of Cinchona alkaloids
The separation is based on the difference in solubility of the different
alkaloids and their salts.
1- Quinine mono-sulfate is sparingly soluble in H2O.
2- Cinchonine is almost insoluble in ether.
3- l- isomers tartrates, quinine and cinchonidine H2O- insoluble, while d-
isomers tartrates, cinchonine and quinidine are H2O- soluble.
Quinine is a diacidic base. It forms 3 types of sulfates:
Quinine (l-isomer) gives quinidine (d-isomer) when warmed with KOH
in amyl alcohol.
Quinine and cinchonidine are levorotatory.
Quinidine and cinchonine are dextrorotatory.
◘ Quinine monosulfate (neutral and H2O insol.)
◘ Quinine bisulfate (acidic and H2O soluble)
◘ Quinine tetrasulfate (more H2O soluble)
12. 1- For cinchona:
Show blue fluorescence with dil. acids (as dil H2SO4).
2- Quinine and
When few drops of bromine water are added to 2-3 ml of weakly
acidic solution of quinine salt, followed by addition of 0.5-1 ml of
strong ammonia solution emerald green color (Thalleoquin )
(This reaction is also given by quinidine but not with cinchonine and
Tests for identity
16. Alkaloids of Ipecacuanha
Ipecacuanha is derived from the dried rhizome and roots
of Cephaelis ipecacuanha or C. acuminata (Rubiaceae).
The principal alkaloids, e.g. Emetine, Cephaeline and
They possess a skeleton with
1- two tetrahydroisoquinoline ring systems,
2- plus a terpenoid-derive molecule (secologanin).
So Ipeca alkaloids are e.g.
Terpenoid Tetrahydroisoquinoline Alkaloids
19. Pow dered root and rhizome
- Extraction with alcohol,
- Purification by lead acetate method
Coloring matter & Non-alkaloidal
- Evaporation to dryness
- Extraction with dil. HCl
Alkaloidal bases and salts
- Extraction with ether
Phenolic alkaloids (as phenates)
(Cephaeline & Psychotrine)
- Acidification with HCl
- Alkalinization with NH4OH
- Extraction with ether
Aqueous layer Ether layer
- Extraction with CHCl3 - Evaporation
Aqueous alkaline solution
20. Actions and Uses
1) As an expectorant and emetic.
Emetine has a more expectorant
and less emetic action than
2) Treatment of amoebic dysentery.
3) The alkaloids have anti-tumor
22. Chemical Tests:
1- Ipecacuanha alkaloids in HCl + Ca-hypochlorite
2- Froehd’s Reagent (Sulphomolybdic acid):
◘ With Emetine and Cephaline Dirty green color
(the color with Emetine fades by addition of HCl).
◘ With Psycotrine Pale green color
23. Chemical Tests:
3) Cephaline and Psychotrine (phenolic alkaloids) +
p-nitrodiazobenzene dye soluble in NaOH
4) Psycotrine + Conc. H2SO4 + HNO3 Cherry red
24. Curare Alkaloids (arrow poison)
Curare is the dried crude extract obtained from
Chondrodendron tomentosum (Menispermaceae).
Uses: Curare was used by i.m or i.v. as skeletal
muscle relaxant, especially in surgical operations
such as abdominal surgery, where tense muscles needed
to be relaxed.
1) Saturated aqueous solution + FeCl3 Green color
2) Solution of the alkaloidal HCl + Na2CO3 Yellow