Transcript quinine, quinidine, cinchonine

Quinoline Alkaloids
In general, the alkaloids containing essentially the ‘quinoline’ nucleus
include a series of alkaloids obtained exclusively from the cinchona
bark, the major members of this particular group are, namely: quinine,
quinidine, cinchonine and cinchonidine. More than twenty five
alkaloids have been isolated and characterized either from the Yellow
Cinchona, or from the Red Cinchona (Family: Rubiaceae). The
aforesaid alkaloids are also found in their hybrids as well as in
the Cuprea Bark obtained from Remijia pedunculata and Remijia
purdieana belonging to the natural order Rubiaceae. However, it has
been revealed that an average commercial yield of the cinchona
alkaloids in the dry bark materials from the said plant materials are as
follows:
quinine
(5.7%);
quinidine
(0.10.3%); cinchonine and cinchonidine (0.2-0.4%). Nevertheless, the
other closely related minor alkaloids are present in relatively smaller
quantities.
.
Basic Structures of Cinchona Alkaloids The various quinoline
alkaloids, which possess potent medicinal activities are,
namely: quinine, quinidine, cinchonine, and cinchonidine. It is
interesting to observe that these alkaloids not only have a
closely related structure but also similar medicinal
characteristics. These alkaloids possess the basic skeleton of
9’-rubanol that is derived from the parent compound known as
ruban. Thus, ruban is obtained from the combination
of two distinct heterocyclic nuclii, namely: (a) 4-methyl
quinoline nucleus, and (b) quinuclidine nucleus. However, this
particular nomenclature was suggested by Rabe so as to
simplify the naming of such compounds and also to signify its
origin from the natural order Rubiaceae
Properties
• Quinine is very slightly soluble in H2O, soluble in ethanol, chloroform,
ether, benzene and other organic solvents.
• Quinine is a diacidic base. It forms 2 types of sulfates:
– Quinine sulfate (neutral and H2O insoluble).
– Quinine bisulfate (acidic and H2O soluble).
• Quinine (l-isomer) gives quinidine (d-isomer) among other products when
warmed with KOH in amyl alcohol.
• Quinine is levorotatory, while quinidine is dextrorotatory.
4. Tartrates of Quinine and Cinchonidine are insoluble, whereas the tartrates
of Cinchonine and Quinidine are soluble in water.
Tests for identification
1- Fluorescence test:
Solution of the alkaloid in oxygenated acids (e.g H2SO4, HNO3 or
phosphoric acid)  blue fluorescence (+ ve with quinine and
quinidine).
2- Thalleoquine test:
Aqueous solution of the alkaloidal salt + Br2 /H2O (few drops till the
appearance of yellow color) + NH4OH  emerald green color
(+ ve with quinine and quinidine).
3- Rosequin test (Erythroquinine test):
Aqueous solution of the alkaloidal salt + dil HCl + Br2 /H2O (few drops
till the
appearance of yellow color) + CHCl3 + pot.
Ferrocyanide + NH4OH 
red color in the CHCl3 layer (+ ve with quinine and quinidine).
Uses
• Quinine is used mainly as anti-malarial in a dose
of 2g of quinine sulfate or other salt for 14 days.
• Quinidine is used as a cardiac depressant (antiarrhythmic), particularly to inhibit auricular
fibrillation in a dose of 0.6-1.6 g of quinidine
sulfate daily.
• Cinchonine and cinchonidine are used as antiinflammatory.
• Quinine is used as a flavor in carbonated
beverages.