Sie befinden Sich nicht im Netzwerk der Universität Paderborn. Der Zugriff auf elektronische Ressourcen ist gegebenenfalls nur via VPN oder Shibboleth (DFN-AAI) möglich. mehr Informationen...
Biosynthesis of ursolic acid derivatives by microbial metabolism of ursolic acid with Nocardia sp. strains—Proposal of new biosynthetic pathways
Ist Teil von
Process biochemistry (1991), 2010-07, Vol.45 (7), p.1043-1051
Ort / Verlag
Elsevier Ltd
Erscheinungsjahr
2010
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Our studies of the microbial-metabolism of triterpenoid ursolic acid by various
Nocardia sp. strains, have led to the proposal of two novel pathways to produce triterpenoid derivatives.
Nocardia sp. NRRL 5646,
Nocardia sp. 44822 and
Nocardia sp. 44000 generated the following ursolic acid derivatives: ursolic acid methyl ester, ursonic acid, ursonic acid methyl ester, 3-oxoursa-1,12-dien-28-oic acid and 3-oxoursa-1,12-dien-28-oic acid methyl ester.
Nocardia sp. 45077 synthesized ursonic acid and 3-oxoursa-1,12-dien-28-oic acid while
Nocardia sp. 46002 produced only ursonic acid and
Nocardia sp. 43069 showed no metabolism at all. The conversion of ursolic acid by
Nocardia sp. NRRL 5646 was independent of the medium used for the fermentation. An increase in temperature from 28
°C to 36
°C doubled the reaction rate of the biotransformation. The analysis of ursane metabolites was done by HPLC, while their structures were established using HPLC–APCI
pos-MS/MS and HPLC–NMR spectroscopy. The pseudo molecular ion peaks were determined by HPLC–APCI
pos-MS and used to measure their molecular weight. The product ion spectra of the metabolites showed the characteristic fragments of Δ
12-oleanes and Δ
12-ursanes indicating that a substitution in ring A or B was responsible for the decrease in molecular weight.
Based on these results, two new biosynthetic pathways are proposed. These new pathways can presumably be used as strategic routes for the biotechnological production of triterpenoid derivatives. It is assumed that a 3β-hydroxysteroid dehydrogenase and a 3-ketosteroid-Δ
1-dehydrogenase are involved in the transformation of the steroid.