Enantio- And Chemoselective Oxidation Of Omeprazole Sulfide To Enantiopure (S)-Omeprazole With Whole-Cells Of Aspergillus Carbonarius

Development of a biocatalytic method for the preparation of (S)-omeprazole (esomeprazole) in enantiomerically pure form is in great demand in pharmaceutical industry. A newly isolated fungal strain has been described, which converted omeprazole sulfide (5-methoxy-2-[(4-methoxy-3,5-dimethyl-2-pyridinyemethyllthio-1H-benzoimidazole) to (S)-enantiomer of omeprazole (5-Methoxy-2-1(4-methoxy-3,5-dimethyl-2-pyridinyemethyll sulfinyl-1H-benzimidazole) in > 95% e.e. The fungal strain was identified as Aspergillus carbonarius. A conversion of 91.8% was achieved at substrate concentration of 0.05 gmL(-1) with the suspension of cells of A. carbonarius in phosphate buffer pH 8.0 at 30 degrees C. The brcatalyst was chemoselective for oxidation of sulfide to sulfoxide as no trace of corresponding sulfone could be detected during the reaction.