Enhanced biotransformation of the minor ginsenosides in red ginseng extract by Penicillium decumbens β-glucosidase

Compound K (C-K) and Rh2, which are present at low levels in ginseng and ginseng extracts, have higher intestinal absorption rates than other ginsenosides. Here, we attempted to convert ginsenoside Rb1 to C-K using a beta-glucosidase from Penicillium decumbens. Ten commercially available enzymes were screened to identify en-zymes that can convert ginsenoside Rb1 to C-K, resulting in the selection of a P. decumbens-derived beta-glucosidase. beta-Glucosidase showed maximum activity at pH 4.0 and 60 degrees C; its substrate specificity for ginsenoside Rb1 was investigated. The main glucoside-hydrolyzing pathways were as follows: ginsenoside Rb1 or Rd -> gypenoside XVII -> F2 -> C-K and ginsenoside Rg3 -> Rh2. The P. decumbens-derived 8-glucosidase was used to generate C-K and Rh2 using protopanaxadiol-type ginsenosides as substrates. Additionally, to apply this enzyme to the commercialized red ginseng extract products, the contents of C-K and Rh2 in the total ginsenosides significantly (p < 0.05) increased up to 36-fold and 8.9-fold, respectively, higher than prior to subjecting to biotransforma-tion. To the best of our knowledge, this is the first report of the dual biotransformation of C-K and Rh2 by a food-grade commercial enzyme. This study demonstrates that the use of a specific beta-glucosidase may increase C-K and Rh2 contents in the ginseng extract through a simple biotransformation process and, thus, enhance its health benefits.

Automated summary

This study successfully converted ginsenoside Rb1 to Compound K (C-K) using a beta-glucosidase from Penicillium decumbens, increasing the content of C-K and Rh2 in ginseng extracts. By a simple biotransformation process, enhancing the health benefits of ginseng extracts.