Production of the Rare Ginsenoside Rh2-MIX (20(S)-Rh2, 20(R)-Rh2, Rk2, and Rh3) by Enzymatic Conversion Combined with Acid Treatment and Evaluation of Its Anti-Cancer Activity.

The ginsenoside Rh2 has strong anti-cancer, anti-inflammatory, and anti-diabetic effects. However, the application of ginsenoside Rh2 is restricted because of the small amounts found in Korean white and red ginsengs. To enhance the production of ginsenoside Rh2-MIX (comprising 20(S)-Rh2, 20(R)-Rh2, Rk2, and Rh3 as a 10-g unit) with high specificity, yield, and purity, a new combination of enzymatic conversion using the commercial enzyme Viscozyme L followed by acid treatment was developed. Viscozyme L treatment at pH 5.0 and 50°C was used initially to transform the major ginsenosides Rb1, Rb2, Rc, and Rd into ginsenoside F2, followed by acid-heat treatment using citric acid 2% (w/v) at pH 2.0 and 121°C for 15 min. Scale-up production in a 10-L jar fermenter, using 60 g of the protopanaxadiol-type ginsenoside mixture from ginseng roots, produced 24 g of ginsenoside Rh2-MIX. Using 2 g of Rh2-MIX, 131 mg of 20(S)-Rh2, 58 mg of 20(R)-Rh2, 47 mg of Rk2, and 26 mg of Rh3 were obtained at over 98% chromatographic purity. Then, the anti-cancer effect of the four purified ginsenosides was investigated on B16F10, MDA-MB-231, and HuH-7 cell lines. As a result, these four rare ginsenosides markedly inhibited the growth of the cancer cell lines. These results suggested that rare ginsenoside Rh2-MIX could be exploited to prepare an anti-cancer supplement in the functional food and pharmaceutical industries.

Sphingosinicella ginsenosidimutans sp. nov., with ginsenoside converting activity.

The Gram-reaction-negative, strictly aerobic, non-motile, nonspore-forming, and rod-shaped bacterial strain designated BS11(T) was isolated from the compost and its taxonomic position was investigated by using a polyphasic approach. Strain BS11(T) grew optimally at 30-37°C and at pH 7.0 in the absence of NaCl on nutrient agar. Strain BS11(T) displayed ß-glucosidase activity that was responsible for its ability to transform ginsenoside Rb1 (one of the dominant active components of ginseng) to Rd. On the basis of 16S rRNA gene sequence similarity, strain BS11(T) was shown to belong to the family Sphingomonadaceae and was related to Sphingosinicella vermicomposti YC7378(T) (96.3% sequence similarity), S. xenopeptidilytica 3-2W4(T) (96.2%), S. microcystinivorans Y2(T) (96.1%), and S. soli KSL-125(T) (95.9%). The G+C content of the genomic DNA was 64.9%. The major menaquinone was Q-10 and the major fatty acids were summed feature 7 (comprising C18:1 ω7c/ω9t/ω12t; 40.6%), C16:0 (22.5%), C17:1 ω6c (13.7%) and C17:0 (9.1%). DNA and chemotaxonomic data supported the affiliation of strain BS11(T) to the genus Sphingosinicella. Strain BS11(T) could be differentiated genotypically and phenotypically from the recognized species of the genus Sphingosinicella. The novel isolate therefore represents a novel species, for which the name Sphingosinicella ginsenosidimutans sp. nov. is proposed, with the type strain BS11(T) (=KACC 16619T =JCM 18201(T)).