Aporphine alkaloids


Aporphine alkaloids are naturally occurring chemical compounds from the group of alkaloids. After the benzylisoquinoline alkaloids they are the second largest group of isoquinoline alkaloids.
Up to now, 85 aporphine alkaloids have been isolated from plants of 15 families; the best known representative is apomorphine. The aporphine alkaloids are of interest mainly because of their similarity to morphine.: Parent compound of the aporphine alkaloids

Occurrence

The aporphine alkaloids are most commonly found in plants.
For example, isoboldine can be found in the plants Beilschmiedia, Nandina, Horn poppy and other plants. As the name suggests, glaucine was first found in the horn-poppy and usually the name of the alkaloids is derived from the plants in which they were first found.
Corydin as a further representative of the aporphine alkaloids is found in the lark spurs, heart flowers and also in the horny poppy.

Examples

The aporphine alkaloids differ in their different substituents and their position on the base structure. Furthermore, their stereochemistry is partly different, most often they are -configured, but e.g. glaucine, bulbocapnine and isothebaine are -configured.

Biosynthesis

Reticulin 1 is oxidized in the first step, resulting in a mesomery-stabilized diradical with the boundary structures 2a and 2b. Cyclization results in a fourth six-membered ring: corytuberin 3, which then dehydrates to bulbocapnin 4. Schematic diagram:

Chemistry

The aporphine alkaloids are of particular interest because of their proximity to morphine and benzylisoquinoline alkaloids. For example, as the name suggests, morphine can be used to produce apomorphine. This can be done by adding an acid under the influence of heat.
The proaporphin alkaloids and the aporphin alkaloids share a framework isomerism.
The aporphine alkaloids usually have a stereocentre.
The -configured glaucine can be synthesized from -glaucine.

Use

lowers blood pressure and is also a powerful emetic. It is mainly used as a remedy for Parkinson's disease because of its stimulating effect on dopamine receptors.
In African traditional medicine, the plant Cassytha is considered a medicine against cancer. A study showed that the plant contains many aporphine alkaloids and that the three main alkaloids actinodaphnin, cassythin and dicentrin have an indeed in vitro effect on cancer cells.
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Literature