Primary Study On Selective Reduction Of Securinine And Dehydrocostuslactone By Aspergillus Sp.

Chiral synthesis with biocatalyst has gained increasing interest during recent years for its exquisite selectivity, high efficiency,security and friendly environment. Up to now, there are some successful application of oxidoreductases, transferases, hydrolases and lyases in the asymmetric synthesis. It is estimated that 25% of all the biotransformations performed involve oxidoreductases. Dehydrogenases have been widely used for the stereoselective reduction of carbonyl groups or carbon-carbon double bonds to prepare chiral molecules from prochiral substrates.A new isolate named Aspergillus sp.D-1 was screened from 11 different strains of fungi and it has ability to bioconvert securinine into 14,15-dihydrosecurinine in over 98% yield by analysis of its spectra such as UV, IR, MS, ¹H, ¹³C-NMR and NOESY. The fact that the reduction of the conjugated γ,δ-double bond of unsaturated lactone in securinine, a xenobiotic compound, has not yet been reported in fungi.Among a variety of compounds, the dehydrocostuslactone was biotransformed by Aspergillus sp. D-1. The product was identified as 11α,13-dihydrodehydrocostuslactone by analysis of its spectra. Thus, it was suggested that Aspergillus sp .D-1 selectively reducted exocyclic α,β-double bond of unsaturated lactone in dehydrocostuslactone in over 94% yield.The dehydrocostuslactone was cultivated for 4 days with Aspergillus niger 3.739 and Aspergillus niger 3.795 respectively. In the time course of biotransformation, dehydrocostus lactone was almost converted into 11,13-dihydrodehydrocostuslactone for 24 h, and it was slowly converted into other metabolites after 96h.