[Fungal biotransformation of ginsenoside Rg3]

Ginsenosides are important bioactive compounds in Ginseng. Sugar chains of ginsenosides are closely related to the bioactivity. Rare ginsenosides can be achieved by modifying sugar chains through biotransformation. Samples of Ginseng root soils, collected from Changbai Mountain, were used to screen active microorganism which can transform total ginsenosides and single ginsenoside, so as to obtain anti-tumor components.

The strains were isolated and screened on solid transfer medium and yield transfer process for active strains. Then the active strains were tested for their biotransformation properties by using different purified ginsenosides, including ginsenoside Rg3. The biotransformation products were separated and purified through column chromatography on silica gel (300mesh), and identified by spectral analysis and physical constants. Simultaneously, the active strain was identified based on morphological characteristics of colonies, conidium and conidiophore, as well as ITS-5.8S rDNA sequences.

Total 68 fungal strains were isolated and 12 active strains showed positive activity on total ginsenosides. One strain, SYP2353, was found to have the strong activity on Rg3.

The active strain SYP2353 was identified as Myrothecium verrucaria, and the biotransformation products of Rg3 were identified to be rare ginsenoside Rh2 and aglycon PPD.