Yanyong Mao, B. Mao, WeiPing Fan
2005
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Journal
Chinese Journal of Bioprocess Engineering
Abstract
Bio-transformational 11#alpha#-hydroxylation of canrenone has been studied by using immobilized whole cells of Aspergillus ochraceus NG0216. It was showed that the optimal immobilization process was that the wet cells with mass concentration 15% was immobilized by 3% sodium alginate and solidified by 4% calcium chloride for 1 h. Optimal mass concentration of canrenone was 10 g/L. Optimal pH and temperature were 6.0 and 28 ℃. The conversation rtae of 11#alpha#-hydroxylating rate of canrenone exceeded 85% by the above immobilized cells under the optimal conditions. After solid-liquid separation and extract by ethyl acetate the crude hydroxycanrenone was obtained and purified by re-crystallization. Structural characterization of purified hydroxycanrenone was conducted by means of MS, NMR, and element assay. Result of HPLC showed that content of hydroxycanrenone of purified crystals was up to 99.7% through thrice re-crystallization in ethyl acetate. The purified crystals appeared canary acicular. It was proved that the product of bio-catalyzed oxidation by immobilized whole cells was 11#alpha#-hydroxycanrenone, its melting point was 240℃, and its [#alpha#_(D)~(20) in ethyl acetate is -12.825°