Lin-Hu Quan

Enzymatic biotransformation of ginsenoside Rb1 to compound K by recombinant β-glucosidase from Microbacterium esteraromaticum.

We cloned and characterized a β-glucosidase (bgp3) gene from Microbacterium esteraromaticum isolated from ginseng field. The bgp3 gene consists of 2,271 bp encoding 756 amino acids which have homology to the glycosyl hydrolase family 3 protein domain. The molecular mass of purified Bgp3 was 80 kDa, as determined by SDS-PAGE. The enzyme (Bgp3) catalyzed the conversion of ginsenoside Rb1 to the more pharmacologically active minor ginsenoside Rd and compound K. The Bgp3 hydrolyzed the outer glucose moiety attached to the C-20 position of ginsenoside Rb1, followed by hydrolysis of the inner glucose moiety attached to the C-3 position. Using 0.1 mg mL(-1) enzyme in 20 mM sodium phosphate buffer at 40 °C and pH 7.0, 1.0 mg mL(-1) ginsenoside Rb1 was transformed into 0.46 mg mL(-1) compound K within 60 min with a corresponding molar conversion yield of 77%. Bgp3 hydrolyzed the ginsenoside Rb1 along the following pathway: Rb1 → Rd → compound K.

Biotransformation of Ginsenoside Rb 1 to Prosapogenins, Gypenoside XVII, Ginsenoside Rd, Ginsenoside F 2 , and Compound K by Leuconostoc mesenteroides DC102

Ginsenoside Rb1is the main component in ginsenosides. It is a protopanaxadiol-type ginsenoside that has a dammarane-type triterpenoid as an aglycone. In this study, ginsenoside Rb1 was transformed into gypenoside XVII, ginsenoside Rd, ginsenoside F2 and compound K by glycosidase from Leuconostoc mesenteroides DC102. The optimum time for the conversion was about 72 h at a constant pH of 6.0 to 8.0 and the optimum temperature was about 30℃. Under optimal conditions, ginsenoside Rb1 was decomposed and converted into compound K by 72 h post-reaction (99%). The enzymatic reaction was analyzed by highperformance liquid chromatography, suggesting the transformation pathway: ginsenoside Rb1→ gypenoside XVII and ginsenoside Rd→ginsenoside F2→compound K.

Enzymatic Transformation of Ginsenoside Rb1 by Lactobacillus pentosus Strain 6105 from Kimchi

Ginsenoside (ginseng saponin), the principal component of ginseng, is responsible for the pharmacological and biological activities of ginseng. We isolated lactic acid bacteria from Kimchi using esculin agar, to produce β-glucosidase. We focused on the bio-transformation of ginsenoside. Phylogenetic analysis was performed by comparing the 16S rRNA sequences. We identified the strain as Lactobacillus (strain 6105). In order to determine the optimal conditions for enzyme activity, the crude enzyme was incubated with 1 mM ginsenoside Rb1 to catalyse the reaction. A carbon substrate, such as cellobiose, lactose, and sucrose, resulted in the highest yields of β-glucosidase activity. Biotransformations of ginsenoside Rb1 were analyzed using TLC and HPLC. Our results confirmed that the microbial enzyme of strain 6105 significantly transformed ginsenoside as follows: Rb1→gypenoside XVII, Rd→F2 into compound K. Our results indicate that this is the best possible way to obtain specific ginsenosides using microbial enzymes from 6105 culture.

Bioconversion of ginsenoside Rb1 into compound K by Leuconostoc citreum LH1 isolated from kimchi

About 40 different types of ginsenoside (ginseng saponin), a major pharmacological component of ginseng, have been identified along with their physiological activities. Among these, compound K has been reported to prevent the development of and the metastasis of cancer by blocking the formation of tumors and suppressing the invasion of cancerous cells. In this study, ginsenoside Rb1 was converted into compound K via interaction with the enzyme secreted by β-glucosidase active bacteria, Leuconostoc citreum LH1, extracted from kimchi. The optimum time for the conversion of Rb1 to compound K was about 72 hrs at a constant pH of 6.0 and an optimum temperature of about 30oC. Under optimal conditions, ginsenoside Rb1 was decomposed and converted into compound K by 72 hrs post-reaction (99%). Both TLC and HPLC were used to analyze the enzymatic reaction. Ginsenoside Rb1 was consecutively converted to ginsenoside Rd, F2, and compound K via the hydrolyses of 20-C β-(1 → 6)-glucoside, 3-C β-(1 → 2)glucoside, and 3-C β-glucose of ginsenoside Rb1.

Stenotrophomonas ginsengisoli sp. nov., isolated from a ginseng field

A Gram-negative, non-spore-forming, rod-shaped bacterium, designated strain DCY01(T), was isolated from soil from a ginseng field in South Korea and was characterized in order to determine its taxonomic position. 16S rRNA gene sequence analysis revealed that strain DCY01(T) belonged to the Gammaproteobacteria and was most closely related to Stenotrophomonas koreensis KCTC 12211(T) (98.4 % similarity), Stenotrophomonas humi R-32729(T) (97.2 %), Stenotrophomonas terrae R-32768 (97.1 %), Stenotrophomonas maltophilia DSM 50170(T) (96.9 %) and Stenotrophomonas nitritireducens DSM 12575(T) (96.8 %). Chemotaxonomic analyses revealed that strain DCY01(T) possessed a quinone system with Q-8 as the predominant compound, and iso-C(15 : 0) (28.2 %), C(16 : 0) 10-methyl (13.2 %), iso-C(15 : 1) F (10.8 %) and C(15 : 0) (7.5 %) as major fatty acids, corroborating assignment of strain DCY01(T) to the genus Stenotrophomonas. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The results of DNA-DNA hybridization and physiological and biochemical tests clearly demonstrated that strain DCY01(T) represents a species distinct from recognized Stenotrophomonas species. Based on these data, DCY01(T) (=KCTC 12539(T)=NBRC 101154(T)) should be classified as the type strain of a novel species of the genus Stenotrophomonas, for which the name Stenotrophomonas ginsengisoli sp. nov. is proposed.