| |
[摘要]：The enzymatic preparation of a monoacetyl derivative of the corticosteroid cortexolone, through a transesterification reaction, is described. The heterologous Rhizopus oryzae lipase, immobilized on three different supports, proved to be an efficient catalyst in the acylation reaction using a complex substrate such as cortexolone. Immobilization of the enzyme on Lewatit 1600 resin at pH = 7 and 25 degrees C was the best condition for catalysis of the acetylation reaction. The influence of various reaction parameters, such as the nature of the acetylating agent, the solvent, the temperature, and the ratios of acetylating agent to substrate, and enzyme to substrate, was evaluated. Using the response surface methodology and a central composite rotatable design, the specific yield of acetylated cortexolone was optimized by means of the study of the effect of the enzyme (E)/substrate (S) and the acylating agent (A)/substrate ratios. The ratios of 5 (E/S) and 31.6 (A/S) were predicted as the optimal values to reach the maximum specific yield of the product (P): 1.59 mmol P/mmol A center dot g E. The mild reaction conditions and low environmental impact make the biocatalytic procedure a convenient way to prepare the reported derivative of this biologically active steroid. |
|
