Benylisoquinoline

From DrugPedia: A Wikipedia for Drug discovery

1-Benzylisoquinoline is the structural backbone of many alkaloids with a wide variety of structures, including papaverine, codeine, morphine, apomorphine, berberine, protopine and tubocurarine.

Biosynthesis

Plants producing benzylisoquinoline alkaloids have a common biosynthetic pathway, making use of two units of L-tyrosine. One tyrosine molecule is metabolised to dopamine which constitutes the isoquinoline part, while the benzylic part is mostly formed from tyramine, itself the decarboxylation product of tyrosine.

Many benzylisoquinolines have a methylated nitrogen atom as well as functional groups containing oxygen (-OH, -OCH3, -OCH2O-) in positions 6, 7, 3' and 4'. The latter come from the precursors mentioned above, namely tyrosine, dopamine and their derivatives.

Examples of benzylisoquinoline alkaloids

Papaverine

Apomorphine (one additional ring closure)

Morphine (two additional ring closures)

Berberine (one additional ring closure with incorporated N-methyl)

Protopine (with opened pyridine ring)

Tubocurarine (composed of two benzylisoquinoline units)

References

Benzylisoquinoline biosynthesis by cultivated plant cells and isolated enzymes