The Study of Regioselective Acylation of Geniposide by Using Whole-Cell Biocatalysts in Organic Solvents

Le résumé fourni par la source

Geniposide, the predominant bioactive constituent identified in the traditional Chinese medicine herb Gardenia jasminoides, demonstrates clinically significant pharmacological properties. However, the clinical application of geniposide is significantly limited by its insufficient lipophilicity and consequent compromised oral bioavailability. To enhance the lipophilicity and bioavailability of geniposide, a novel whole-cell-mediated catalytic approach was developed for the first time. Aspergillus oryzae whole cells exhibited the highest catalytic activity among microbial strains screened for geniposide decanoylation in the organic solvents. The optimal reaction conditions were identified as follows: acetonitrile served as the reaction solvent, with a substrate molar ratio of 15:1, a whole-cell dosage of 20 mg/mL, and the reaction temperature maintained at 50 °C. Under these optimized conditions, the initial reaction rate was 6.1 mmol/L·h, the conversion reached 99%, and the regioselectivity exceeded 99%. In addition, nine geniposide esters were successfully synthesized, exhibiting outstanding conversion efficiency and high regioselectivities. The pronounced regioselectivity exhibited by Aspergillus oryzae cells toward the 6′-hydroxy group of the glycoside ring in geniposide can be attributed to the lower steric hindrance at this position relative to other hydroxyl moieties, which may enter into the enzyme’s active site more easily to attack the acyl-enzyme intermediate.

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