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Mammalian Alkaloids: O ‐methylation of ( S )‐ and ( R )‐dideoxynorlaudanosoline‐1‐carboxylic acid by catechol O ‐methyltransferase and identification of a yellow pigment obtained at physiological pH
Author(s) -
Rozwadowska Maria Danuta,
Chrzanowska Maria,
Brossi Arnold,
Creveling Cyrus R.,
Bembenek Michael E.,
Abell Creed W.
Publication year - 1988
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19880710703
Subject(s) - chemistry , decarboxylation , catechol , monoamine oxidase , methylation , oxidative deamination , carboxylic acid , oxidative decarboxylation , stereochemistry , methyltransferase , substrate (aquarium) , enzyme , medicinal chemistry , biochemistry , dna , catalysis , oceanography , geology
O ‐Methylation of optically active 3′,4′‐dideoxynorlaudanosoline‐l‐carboxylic acids 1 with O ‐methyltransferase in vitro afforded almost exclusively the 7‐ O ‐methylated acids 3 . A similar result was obtained with the yellow quinonemethide 4A obtained from 1 at neutral or slightly alkaline pH by oxidative decarboxylation and affording the 3,4‐dihydroisoquinoline 15 on methylation with catechol O ‐methyltransferase (COMT). The structure of quinonemethide 4A was determined on the basis of spectral data, by its conversion into isoquinolines of established structure, and by synthesis. Quinonemethide 4A was found to be a weak inhibitor of monoamine oxidase A (MAO A) but not a substrate. Nonenzymatic oxidative decarboxylation of dopamine‐derived tetrahydroisoquinoline‐l‐carboxylic acids to quinonemethides may be a major factor in biochemical experimentation and should be considered in the interpretation of data.