Reticuline
Chemical compound
From Wikipedia, the free encyclopedia
Reticuline is a tetrahydroisoquinoline alkaloid. It is also classified as a benzylisoquinoline alkaloid.[1] It is produced in the opium poppy plant from the amino acid tyrosine, initially as (S)-reticuline, which is a precursor to other alkaloids, including papaverine[2] and stylopine.[3] Another large group of alkaloids including morphine are made after (S)-reticuline has been converted in the poppy to its enantiomer, (R)-reticuline.[4]
-reticuline.svg)
(S)-(+)-reticuline | |
| Names | |
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| IUPAC name
3,10-Dimethoxy-8,8a-secoberbine-2,9-diol | |
| Systematic IUPAC name
(1S)-1-[(3-Hydroxy-4-methoxyphenyl)methyl]-6-methoxy-2-methyl-1,2,3,4-tetrahydroisoquinolin-7-ol | |
| Identifiers | |
3D model (JSmol) |
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| 95671 | |
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| ECHA InfoCard | 100.006.920 |
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PubChem CID |
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CompTox Dashboard (EPA) |
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| Properties | |
| C19H23NO4 | |
| Molar mass | 329.396 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Occurrence
Reticuline is found in opium and a variety of plants including Lindera aggregata,[5] Annona squamosa,[6] and Ocotea fasciculata.[7]
Physiological effects
In rodents, reticuline possesses potent central nervous system depressing effects.[7] It is the precursor of morphine and many other alkaloids. It is also toxic to dopaminergic neurons causing a form of atypical parkinsonism known as Guadeloupean Parkinsonism.[8]
Biosynthesis
Benzylisoquinoline alkaloids produced in the opium poppy are derived from the amino acid tyrosine. A sequence of enzyme-catalysed reactions produces (S)-norcoclaurine which goes through three further transformations to give (S)-3'-hydroxy-N-methylcoclaurine. (S)-reticuline is made when the enzyme 3'-hydroxy-N-methyl-(S)-coclaurine 4'-O-methyltransferase adds a methyl group using S-adenosyl methionine as its cofactor.[4][9]
-3'-hydroxy-N-methylcoclaurine.svg)
Although (S)-reticuline can be metabolised into a diverse range of alkaloids including papaverine and stylopine, the route to morphinan alkaloids proceeds solely via its enantiomer, (R)-reticuline.[4] This is formed by oxidation from the (S) isomer, giving the reticulinylium cation, followed by reduction back to reticuline but of opposite stereochemistry. In the opium poppy, this is accomplished by a fusion protein which combines the function of the enzymes 1,2-dehydroreticuline synthase and 1,2-dehydroreticulinium reductase (NADPH).[10][11][12]
-reticuline.svg)
This is an irreversible step in the biosynthesis of morphinan alkaloids.[4]
Metabolism
Reticuline oxidase uses (S)-reticuline and oxygen to produce the benzylisoquinoline scoulerine, with hydrogen peroxide as a by-product.[13]
(S)-reticuline can undergo oxidative coupling to give (S)-corytuberine which is further metabolised to magnoflorine in Japanese goldthread.[4][14]
-corytuberine.svg)
Salutaridine synthase uses (R)-reticuline, NADPH, and oxygen to produce salutaridine.[15]
Salutaridine can then be transformed progressively to thebaine, oripavine, and morphine.[4]
