The Double-Bond Configuration of Corynanthean Alkaloids and Its Impact on Monoterpenoid Indole Alkaloid Biosynthesis.
Chemistry
; 22(16): 5749-55, 2016 Apr 11.
Article
en En
| MEDLINE
| ID: mdl-26933928
ABSTRACT
Experimental evidence is provided for the coherence of the double-bond geometry and the occurrence of "secondary cyclizations" in the biosynthesis of monoterpenoid indole alkaloids. Biosynthetically, akuammiline, C-mavacurine, and Strychnos alkaloids are proposed to be derived from the corynanthean alkaloid geissoschizine, a key intermediate in the biosynthetic pathway of these monoterpenoid indole alkaloids. This process occurs by so-called "secondary cyclizations" from geissoschizine or its derivatives. Although corynanthean alkaloids like geissoschizine incorporate E or Z double bonds located at C19-C20, the alkaloids downstream in the biosynthesis exclusively exhibit the E double bond. This study shows that secondary cyclizations preferentially occur with the E isomer of geissoschizine or its derivatives. This is attributed to the flexibility of the quinolizidine system of the corynanthean alkaloids, which can adopt a cis or trans conformation. For the secondary cyclization to take place, the cis-quinolizidine conformation is required. Experimental evidence supports the hypothesis that the E double bond of geissoschizine induces the cis conformation, whereas the Z double bond induces the trans conformation, which prohibits secondary cyclization of the Z compounds.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Alcaloides Indólicos
/
Strychnos
/
Alcaloides de Triptamina Secologanina
Idioma:
En
Revista:
Chemistry
Asunto de la revista:
QUIMICA
Año:
2016
Tipo del documento:
Article
País de afiliación:
Alemania