Quinine Quinine, molecular formula C 20 H 24 N 2 O 2 , is a white crystalline
quinoline alkaloid, isolated from Cinchona bark (Cinchona succirubra), and
is well known as an antimalarial drug. Quinine is extremely bitter, and also
possesses antipyretic, analgesic and anti-inflammatory properties. While
quinine is still the drug of choice for the treatment of Falciparum malaria, it
can be also used to treat nocturnal leg cramps and arthritis. Quinine is an
extremely basic compound, and is available in its salt forms, e.g. sulphate,
hydrochloride and gluconate.
Despite being a wonder drug against malaria, quinine in therapeutic doses
can cause various side-effects, e.g. nausea, vomiting and cinchonism, and in
some patients pulmonary oedema. It may also cause paralysis if accidentally
injected into a nerve. An overdose of quinine may have fatal consequences.
Non-medicinal uses of quinine include its uses as a flavouring agent in tonic
water and bitter lemon.
Quinidine Quinidine, molecular formula C 20 H 24 N 2 O 2 , is a stereoisomer
of quinine found in Cinchona bark. Chemically, it is known as (2-ethenyl4-azabicyclo[2.2.2]oct-5-yl)-(6-methoxyquinolin-4-yl)-methanol, or 6
0 -
methoxycinchonan-9-ol. It is used as a Class 1 anti-arrhythmic agent.
Intravenous injection of quinidine is also used in the treatment of P.
falciparum malaria. Among the adverse effects, quinidine induces
thrombocytopenia (low platelet counts) and may lead to thrombocytic
purpurea.
Isoquinoline alkaloids
Isoquinoline is in fact an isomer of quinoline, and chemically known as
benzo[c]pyridine or 2-benzanine. Any alkaloids that possess an isoquinoline
skeleton are known as isoquinoline alkaloids, e.g. papaverine and morphine.
The isoquinoline backbone is biosynthesized from the aromatic amino acid
tyrosine.
Isoquinoline itself is a colourless hygroscopic liquid at room temperature.
It has an unpleasant odour. It is slightly soluble in water but well soluble in
ethanol, acetone, ether and other common organic solvents. Isoquinoline is a
weak base with a pK a of 8.6.
Isoquinoline alkaloids play an important part in medicine. A number of
these alkaloids are available as drugs. Some examples of isoquinoline
derivatives with medicinal values are summarized in the following table.
In addition to their medicinal uses, isoquinolines are used in the manufacture of dyes, paints and insecticides, and as a solvent for the extraction of
resins.
6.2 ALKALOIDS
295
quinoline alkaloid, isolated from Cinchona bark (Cinchona succirubra), and
is well known as an antimalarial drug. Quinine is extremely bitter, and also
possesses antipyretic, analgesic and anti-inflammatory properties. While
quinine is still the drug of choice for the treatment of Falciparum malaria, it
can be also used to treat nocturnal leg cramps and arthritis. Quinine is an
extremely basic compound, and is available in its salt forms, e.g. sulphate,
hydrochloride and gluconate.
Despite being a wonder drug against malaria, quinine in therapeutic doses
can cause various side-effects, e.g. nausea, vomiting and cinchonism, and in
some patients pulmonary oedema. It may also cause paralysis if accidentally
injected into a nerve. An overdose of quinine may have fatal consequences.
Non-medicinal uses of quinine include its uses as a flavouring agent in tonic
water and bitter lemon.
Quinidine Quinidine, molecular formula C 20 H 24 N 2 O 2 , is a stereoisomer
of quinine found in Cinchona bark. Chemically, it is known as (2-ethenyl4-azabicyclo[2.2.2]oct-5-yl)-(6-methoxyquinolin-4-yl)-methanol, or 6
0 -
methoxycinchonan-9-ol. It is used as a Class 1 anti-arrhythmic agent.
Intravenous injection of quinidine is also used in the treatment of P.
falciparum malaria. Among the adverse effects, quinidine induces
thrombocytopenia (low platelet counts) and may lead to thrombocytic
purpurea.
Isoquinoline alkaloids
Isoquinoline is in fact an isomer of quinoline, and chemically known as
benzo[c]pyridine or 2-benzanine. Any alkaloids that possess an isoquinoline
skeleton are known as isoquinoline alkaloids, e.g. papaverine and morphine.
The isoquinoline backbone is biosynthesized from the aromatic amino acid
tyrosine.
Isoquinoline itself is a colourless hygroscopic liquid at room temperature.
It has an unpleasant odour. It is slightly soluble in water but well soluble in
ethanol, acetone, ether and other common organic solvents. Isoquinoline is a
weak base with a pK a of 8.6.
Isoquinoline alkaloids play an important part in medicine. A number of
these alkaloids are available as drugs. Some examples of isoquinoline
derivatives with medicinal values are summarized in the following table.
In addition to their medicinal uses, isoquinolines are used in the manufacture of dyes, paints and insecticides, and as a solvent for the extraction of
resins.
6.2 ALKALOIDS
295