Phenol oxidative coupling in the biogenesis of the macrocyclic spermine alkaloids aphelandrine and orantine in Aphelandra sp.
Planta
; 213(3): 411-7, 2001 Jul.
Article
de En
| MEDLINE
| ID: mdl-11506364
ABSTRACT
A crucial step in the biosynthesis of the spermine alkaloid aphelandrine and its diastereoisomer orantine is an intramolecular cyclization of the intermediate (S)-dihydroxyverbacine. In order to elucidate this step of the biosynthetic pathway, microsomes from the roots of Aphelandra squarrosa Nees were incubated with unlabeled and (D8)-labeled (S)-dihydroxyverbacine. It was shown that the microsomal fraction catalyzes the intramolecular coupling of (S)-dihydroxyverbacine to aphelandrine. This was proven by microsomal transformation of (D8)-labeled (S)-dihydroxyverbacine to (D8)-labeled aphelandrine. The reaction absolutely requires NAPDH and O2. The underlying reaction mechanism is probably an oxidative phenol coupling catalyzed by an aphelandrine synthase. This enzyme is proposed to be a cytochrome P-450 oxidase. The intramolecular cyclization of (S)-dihydroxyverbacine represents an important point in the biogenesis of the aphelandrine-type alkaloids.
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Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Phénols
/
Acanthaceae
/
Alcaloïdes
/
Composés hétérocycliques avec 4 noyaux ou plus
/
Lactames
Langue:
En
Journal:
Planta
Année:
2001
Type de document:
Article
Pays d'affiliation:
Suisse