Quinoline alkaloids are naturally occurring

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

s from the group of

alkaloid Alkaloids are a broad class of natural product, naturally occurring organic compounds that contain at least one nitrogen atom. Some synthetic compounds of similar structure may also be termed alkaloids. Alkaloids are produced by a large varie ...

s, which are chemically derived from quinoline. Some quinoline alkaloids show

antiseptic An antiseptic ( and ) is an antimicrobial substance or compound that is applied to living tissue to reduce the possibility of sepsis, infection, or putrefaction. Antiseptics are generally distinguished from ''antibiotics'' by the latter's abil ...

convulsive A convulsion is a medical condition where the body muscles contract and relax rapidly and repeatedly, resulting in uncontrolled shaking. Because epileptic seizures typically include convulsions, the term ''convulsion'' is often used as a synonym ...

or antineoplastic effects.

Examples

Alkaloids with a quinoline partial structure are widespread and are usually further subdivided according to their occurrence and biogenetic origin. Among the quinoline alkaloids are the cinchona alkaloids

quinine Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to ''Plasmodium falciparum'' that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg ...

and

quinidine Quinidine is a class I antiarrhythmic agent, class IA antiarrhythmic agent used to treat heart rhythm disturbances. It is a diastereomer of Antimalarial medication, antimalarial agent quinine, originally derived from the bark of the cinchona tre ...

, which are important due to their therapeutic potential, furthermore cinchonine and cinchonidine, as well as some furoquinoline alkaloids and acridine alkaloids.

Strychnine Strychnine (, , American English, US chiefly ) is a highly toxicity, toxic, colorless, bitter, crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents. Strychnine, when inhaled, swallowed, ...

and

brucine Brucine is an alkaloid closely related to strychnine, most commonly found in the ''Strychnos nux-vomica'' tree. Brucine poisoning is rare, since it is usually ingested with strychnine, and strychnine is more toxic than brucine. In chemical synth ...

, alkaloids of the nux vomica, which have a hydrogenated quinoline system, are also counted among the quinoline alkaloids. Also nitramarine (1-(2-quinolinyl)-β-carboline) belongs to the quinoline alkaloids. File:Quinine.svg,

Quinine Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to ''Plasmodium falciparum'' that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg ...

File:Cinchonidine.svg,

Cinchonidine Cinchonidine is an alkaloid found in ''Cinchona officinalis'' and ''Gongronema latifolium''. It is used in asymmetric synthesis in organic chemistry. See also * Cinchonine Cinchonine is an alkaloid found in ''Cinchona officinalis''. It is use ...

File:Cinchonine.svg,

Cinchonine Cinchonine is an alkaloid found in ''Cinchona officinalis''. It is used in asymmetric synthesis in organic chemistry. It is a stereoisomer and pseudo-enantiomer of cinchonidine. It is structurally similar to quinine, an antimalarial drug. It i ...

File:Quinidine.svg,

Quinidine Quinidine is a class I antiarrhythmic agent, class IA antiarrhythmic agent used to treat heart rhythm disturbances. It is a diastereomer of Antimalarial medication, antimalarial agent quinine, originally derived from the bark of the cinchona tre ...

File:Strychnine2.svg,

Occurrence

The quinoline alkaloids are mainly found in plants, as in

Rutaceae The Rutaceae () is a family (biology), family, commonly known as the rueRUTACEAE
in Bo ...

and

Rubiaceae Rubiaceae () is a family (biology), family of flowering plants, commonly known as the coffee, madder, or bedstraw family. It consists of terrestrial trees, shrubs, lianas, or herbs that are recognizable by simple, opposite leaves with Petiole ( ...

, but also in microorganisms and animals. Quinoline is furthermore comprised as a partial structure in the redox factor PQQ (

pyrroloquinoline quinone Pyrroloquinoline quinone (PQQ), also called methoxatin'','' is a redox cofactor and antioxidant. Quinoprotein glucose dehydrogenase is used as a glucose sensor in bacteria. PQQ stimulates growth in bacteria. History It was discovered by J. G. ...

) and in quinoenzymes.

Biosynthesis

Biogenetically, there are several proven pathways for the formation of the quinoline system in plants.

Tryptophan Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α-carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromat ...

e as well as

anthranilic acid Anthranilic acid is an aromatic acid with the formula C6H4(NH2)(CO2H) and has a sweetish taste. The molecule consists of a benzene ring, ''ortho''-substituted with a carboxylic acid and an amine. As a result of containing both acidic and basic f ...

can act as a precursor. The second precursor molecule is either a

hemiterpene Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n ≥ 2. Terpenes are major biosynthetic building blocks. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predomi ...

or a

monoterpene Monoterpenes are a class of terpenes that consist of two isoprene units and have the molecular formula C10H16. Monoterpenes may be linear (acyclic) or contain rings (monocyclic and bicyclic). Modified terpenes, such as those containing oxygen func ...

(e.g.

secologanin Secologanin is a secoiridoid monoterpene synthesized from geranyl pyrophosphate in the mevalonate pathway. Secologanin then proceeds with dopamine or tryptamine to form ipecac and terpene indole alkaloids, respectively. Biosynthesis Secologa ...

e in cinchona alkaloids).

Literature

* {{RömppOnline, Name=Chinolin-Alkaloide , Datum=26. Juni 2014 , ID=RD-03-01309 Alkaloids