Biotransformation of digitoxigenin by Fusarium ciliatum

Abstract

A biotransformação da digitoxigenina (1) por Fusarium ciliatum foi investigada. O cardenolídeo 1 foi obtido a partir da hidrólise ácida da digitoxina e a reação também forneceu os produtos secundários 14-15 -digitoxigenina (2) e 8-14 -digitoxigenina (3). A reação de biotransformação foi realizada em um período de 5 dias e três produtos foram isolados e identificados a partir de análises espectrométricas: digoxigenina (4), digoxigenona (5) e digitoxigenona (6). A obtenção dos dois últimos cardenolídeos nas condições empregadas é inédita. A investigação da cinética da reação de biotransformação indicou 6 como o primeiro produto a ser formado, seguido dos derivados hidroxilados 4 e 5, sugerindo o envolvimento de enzima distintas na hiroxilação em 12 e na oxidação em C-3 da digitoxigenina (1). A reação de biotransformação também foi realizada com a digitoxina, mas F. ciliatum se mostrou incapaz de promover sua hidroxilação.The biotransformation of digitoxigenin (1) by Fusarium ciliatum was investigated. The cardenolide 1 was obtained by the acid hydrolysis of digitoxin and the reaction also afforded two side products, identified as [14][15] -digitoxigenin (2) and 8-14 -digitoxigenin (3) by spectroscopic analysis. The biotransformation reaction was carried out in a 5 days process and three products were isolated and had their structures elucidated as digoxigenin (4), digoxigenone (5) and digitoxigenone (6). The investigation of the biotransformation kinetics disclosed 6 as the first derivative to be formed, followed by the more polar hydroxylated products 4 and 5, suggesting the involvement of different enzymes in 12 hydroxylation and C-3 oxydation of digitoxigenin (1). The production of 5 and 6 under the employed conditions has never been reported. The biotransformation reaction was also undertaken with digitoxin, but F. ciliatum has been unable to promote its hydroxylation.

Analisis Glikosida Kardioaktif Digoksin Menggunakan Ultra Performance Liquid Chromatography (Uplc)

“…Lanatoside C dan digoksin turunannya secara industri diperoleh dari daun Digitalis lanata dan lanatosida A merupakan hasil produk samping (Padua et al, 2005).…”

Biotransformation of digitoxigenin by Cochliobolus lunatus

“…The biotransformation of steroidal compounds by fungi has been extensively evaluated, including reactions with cardiac glycosides (Pádua et al 9 and references herein; Table 3 of the present work). Digoxin, a Digitalis cardenolide, is still the drug of choice for the treatment of congestive heart failure, acting as a selective inhibitor of the Na + ,K + ATPase enzyme.…”

“…The ecological relations of these organisms include the metabolism of different secondary compounds, a feature sustained by diversified enzymatic systems, both intra and extra cellular, capable of carrying out numerous reactions. 6-8 Such attributes suggest fungi as suitable organisms to perform biotransformation reactions.The biotransformation of steroidal compounds by fungi has been extensively evaluated, including reactions with cardiac glycosides (Pádua et al 9 and references herein; Table 3 of the present work). Digoxin, a Digitalis cardenolide, is still the drug of choice for the treatment of congestive heart failure, acting as a selective inhibitor of the Na + ,K + ATPase enzyme.…”

“…Biotransformation of cardenolides has been investigated either as a strategy to obtain new derivatives or to convert the A-type cardenolides into the corresponding C-type compounds, which have clinical relevance. 9 The main reactions obtained so far for cardenolide biotransformation were hydroxylation in different positions of the steroidal skeleton, oxidation, glycosylation, epimerization and esterification of the hydroxyl group at C-3 (see Table 3 for references). Analysis of those data indicate that in general plant cell cultures hydroxylize position 5β, whereas the major hydroxylation sites carried out by fungi and bacteria are 7β and 12β.…”

“…Water was purified using a Milli-Q 50 purification system (Millipore, USA). Digitoxigenin, [α] D +197° (CH 2 Cl 2 ; c.0.14), employed in the biotransformation experiments, was obtained by hydrolysis of digitoxin as previously described by Pádua et al 9 …”