Ginsenosides Biotransformation By Fulvia Fulva Ciferri

Ginsenosides are the major active components of ginseng. Some saponins such as ginsenosides Rg3, Rh2, C-K and Rd were called minor ginsenosides as they are rare or even non-existent in ginseng, which have remarkable physiological activities There are only one or more monosaccharide residues in ginsenosides Rb1. So, preparation of minor ginsenosides by limited hydrolysis of major ginsenosides gets increasing attentions. Chemical hydrolysis and bioconversion could achieve this process. Bioconversion was more advantageous due to its mild condition, simple procedure, high selectivity and no by-products.The main results obtained from this work are as follows:1. First, 77.2 g ginseng total saponins (GTS) were obtained from 1.6 kg dry changbaishan-ginseng using water extraction followed by ethanol precipitation and macroporous resin chromatography. The yield was 4.8%. Then, protopanaxadiol and protopanaxatriol type saponins were separated from GTS by silica column chromatography. Then, 1.18 g fraction-Ⅰ, 6.78 g fraction-Ⅱand 0.85 g fraction-Ⅲwas obtained from 9.3 g protopanaxadiol using the same way. 200 mg fraction-Ⅱwas separated further to three fractions by HPLC: Sample-1 83.4 mg, Sample-2 21.3 mg, Sample-3 26.4 mg. The yields were 15.2%, 3.8% and 4.8%, respectively. The purities of the three samples were all above 95% by HPLC analysis. The three samples were verified to be ginsenoside Rb1, Rc and Rb2 by NMR, respectively.2. The ginsenosides-converting study of Fulvia fulva Ciferr indicated that this strain can only transform ginsenoside Rb1 to a single product without hydrolyzing other ginsenosides, the conversion rate could be 100%. In this paper, 5mg ginsenoside Rb1-converting product was obtained. The strain was first incubated with 30mg Rb1 on rotary shaker (130rpm) at 30℃for 6d. Then the mycelium was removed by filtration and the filtrate was centrifuged at 10000 g for 20 min to remove spores. The ginsenoside contained in the supernatant was extracted by water-saturation n-butanol, then separated by HPLC. The ginsenoside Rb1-converting product was defined to be ginsenoside Rd by NMR. These results indicated that Fulvia fulva Ciferr can product exocellularβ-glucosidase which could just hydrolyzing theβ-(1→6)-glucosidic bond at C-20 position of ginsenoside Rb1. With these characteristics, it can be potentially used in the biotransformation process of ginsenoside Rb1.