Yeon-Ju Kim

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.

Ginseng saponins and the treatment of osteoporosis: mini literature review

The ginseng plant (Panax ginseng Meyer) has a large number of active ingredients including steroidal saponins with a dammarane skeleton as well as protopanaxadiol and protopanaxatriol, commonly known as ginsenosides, which have antioxidant, anticancer, antidiabetic, anti-adipocyte, and sexual enhancing effects. Though several discoveries have demonstrated that ginseng saponins (ginsenosides) as the most important therapeutic agent for the treatment of osteoporosis, yet the molecular mechanism of its active metabolites is unknown. In this review, we summarize the evidence supporting the therapeutic properties of ginsenosides both in vivo and in vitro, with an emphasis on the different molecular agents comprising receptor activator of nuclear factor kappa-B ligand, receptor activator of nuclear factor kappa-B, and matrix metallopeptidase-9, as well as the bone morphogenetic protein-2 and Smad signaling pathways.

Isolation of a novel catalase (Cat1) gene from Panax ginseng and analysis of the response of this gene to various stresses.

A cDNA clone containing a catalase (CAT1) gene, designated PgCat1, was isolated from Panax ginseng C.A. Meyer (Korean ginseng). PgCat1 is predicted to encode a precursor protein of 492 amino acid residues, and its sequence shares high degrees of homology with a number of other CAT1s. Genomic DNA hybridization analysis indicated that PgCat1 represents a multi-gene family. Reverse transcriptase (RT)-PCR results showed that PgCat1 expressed at different levels in leaves, stem, roots of P. ginseng seedlings. Different stresses, heavy metals, plant hormones, osmotic agents, high light irradiance, abiotic stresses, triggered a significant induction of PgCat1. The positive responses of PgCat1 to the various stimuli suggested that P. ginseng PgCat1 may help to protect the plant against reactive oxidant related environmental stresses.

Isolation of Sesquiterpene Synthase Homolog from Panax ginseng C.A. Meyer

Sesquiterpenes are found naturally in plants and insects as defensive agents or pheromones. They are produced in the cytosolic acetate/mevalonate pathway for isoprenoid biosynthesis. The inducible sesquiterpene synthases (STS), which are responsible for the transformation of the precursor farnesyl diphosphate, appear to generate very few olefinic products that are converted to biologically active metabolites. In this study, we isolated the STS gene from Panax ginseng C.A. Meyer, designated PgSTS, and investigated the correlation between its expression and various abiotic stresses using real-time PCR. PgSTS cDNA was observed to be 1,883 nucleotides long with an open reading frame of 1,707 bp, encoding a protein of 568 amino acids. The molecular mass of the mature protein was determined to be 65.5 kDa, with a predicted isoelectric point of 5.98. A GenBank BlastX search revealed the deduced amino acid sequence of PgSTS to be homologous to STS from other plants, with the highest similarity to an STS from Lycopersicon hirsutum (55% identity, 51% similarity). Real-time PCR analysis showed that different abiotic stresses triggered significant induction of PgSTS expression at different time points.

Lysobacter soli sp. nov., isolated from soil of a ginseng field.

Strain DCY21(T), a Gram-negative, gliding and rod-shaped aerobic bacterium was isolated from soil of a ginseng field in the Republic of Korea and characterized using a polyphasic approach in order to determine its taxonomic position. Comparative 16S rRNA gene sequence analysis revealed that strain DCY21(T) clustered with the species of the genus Lysobacter. It was closely related to Lysobacter gummosus LMG 8763(T) (97.9 %), Lysobacter capsici YC5194(T) (97.6 %), Lysobacter antibioticus DSM 2044(T) (97.5 %), Lysobacter niastensis DSM 18481(T) (97.2 %) and Lysobacter enzymogenes DSM 2043(T) (96.9 %). The major cellular fatty acids of strain DCY21(T) were iso-C(15 : 0) (34.3 %), iso-C(17 : 1)omega9c (19.5 %) and iso-C(17 : 0) (17.2 %) and the major isoprenoid quinone was Q-8. The major polar lipids of strain DCY21(T) were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidyl-N-methylethanolamine. The G+C content of the total DNA was 65.4 mol%. The DNA-DNA relatedness values, and biochemical and physiological characteristics strongly supported the genotypic and phenotypic differentiation of strain DCY21(T) from species of the genus Lysobacter. Strain DCY21(T) therefore represents a novel species, for which the name Lysobacter soli sp. nov. is proposed. The type strain is DCY21(T) (=KCTC 22011(T) =LMG 24126(T)).

Sediminibacterium ginsengisoli sp. nov., isolated from soil of a ginseng field, and emended descriptions of the genus Sediminibacterium and of Sediminibacterium salmoneum.

A Gram-negative bacterium, designated DCY13(T), was isolated from soil of a ginseng field in South Korea. Comparative analysis of 16S rRNA gene sequences showed that strain DCY13(T) shared the highest sequence similarity (95.0 %) with Sediminibacterium salmoneum NBRC 103935(T) and 87.6-91.4 % sequence similarity with other members of the family Chitinophagaceae. Cells were non-spore-forming rods, catalase- and oxidase-positive, motile by gliding and facultatively anaerobic. The only respiratory quinone was menaquinone 7 (MK-7) and the major fatty acids were iso-C17 : 0 3-OH, iso-C15 : 0 and iso-C15 : 1 G. The G+C content of the genomic DNA was 47.5±1.0 mol%. In addition to phosphatidylethanolamine, the major polar lipids were two unidentified aminophospholipids, one unidentified aminolipid and three unidentified polar lipids. The major cell-wall sugars were ribose, xylose and galactose. It is proposed that strain DCY13(T) represents a novel species in the genus Sediminibacterium, for which the name Sediminibacterium ginsengisoli sp. nov. is proposed. The type strain is DCY13(T) ( = KCTC 12833(T)  = JCM 15794(T)  = DSM 22335(T)). Emended descriptions of the genus Sediminibacterium and of Sediminibacterium salmoneum are also proposed.

Paenibacillus yonginensis DCY84T induces changes in Arabidopsis thaliana gene expression against aluminum, drought, and salt stress

Current agricultural production methods, for example the improper use of chemical fertilizers and pesticides, create many health and environmental problems. Use of plant growth-promoting bacteria (PGPB) for agricultural benefits is increasing worldwide and also appears to be a trend for the future. There is possibility to develop microbial inoculants for use in agricultural biotechnology, based on these beneficial plant-microbe interactions. For this study, ten bacterial strains were isolated from Yongin forest soil for which in vitro plant-growth promoting trait screenings, such as indole acetic acid (IAA) production, a phosphate solubilization test, and a siderophore production test were used to select two PGPB candidates. Arabidopsis thaliana plants were inoculated with Paenibacillus yonginensis DCY84(T) and Micrococcus yunnanensis PGPB7. Salt stress, drought stress and heavy metal (aluminum) stress challenges indicated that P. yonginensis DCY84(T)-inoculated plants were more resistant than control plants. AtRSA1, AtVQ9 and AtWRKY8 were used as the salinity responsive genes. The AtERD15, AtRAB18, and AtLT178 were selected to check A. thaliana responses to drought stress. Aluminum stress response was checked using AtAIP, AtALS3 and AtALMT1. The qRT-PCR results indicated that P. yonginensis DCY84(T) can promote plant tolerance against salt, drought, and aluminum stress. P. yonginensis DCY84(T) also showed positive results during in vitro compatibility testing and virulence assay against X. oryzae pv. oryzae Philippine race 6 (PXO99). Better germination rates and growth parameters were also recorded for the P. yonginensis DCY84(T) Chuchung cultivar rice seed which was grown on coastal soil collected from Suncheon. Based on these results, P. yonginensis DCY84(T) can be used as a promising PGPB isolate for crop improvement.

Hymenobacter ginsengisoli sp. nov., isolated from soil of a ginseng field

A Gram-stain-negative, non-motile, red bacterium, designated DCY57(T), was isolated from soil of a ginseng field in a mountainous region of Chungnam province in South Korea. Strain DCY57(T) grew with 0-1 % (w/v) NaCl and the optimum temperature for growth was 30 °C. Strain DCY57(T) contained MK-7 as the predominant menaquinone. The polyamine was sym-homospermidine. The major fatty acids were C(16:1)ω5c, iso-C(15:0), anteiso-C(15:0) and summed feature 3 (containing C(16:1)ω7c and/or C(16:1)ω6c). The major polar lipids were phosphatidylethanolamine, unknown aminophospholipids, unknown aminolipids and unknown lipids. The DNA G+C content was 58.9 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain DCY57(T) was most closely related to members of the genus Hymenobacter. The isolate exhibited 91.7 % 16S rRNA gene sequence similarity with H. soli PB17(T), 94.5 % with H. flocculans A2-50A(T) and 95.8 % with H. metalli A2-91(T). On the basis of the evidence presented in this study, strain DCY57(T) represents a novel species within the genus Hymenobacter, for which the name Hymenobacter ginsengisoli sp. nov. is proposed. The type strain is DCY57(T) ( = KCTC 23674(T) = JCM 17841(T)).

Rhodanobacter soli sp. nov., isolated from soil of a ginseng field.

Strain DCY45(T) was isolated from soil of a ginseng field in Pocheon Province, Korea. Strain DCY45(T) was Gram-negative, oxidase- and catalase-positive, motile and rod-shaped and produced yellow pigments on R2A agar. The organism grew optimally at 30 °C and at pH 7.0. The G+C content of the genomic DNA was 65.4 mol%. The predominant respiratory quinone was Q-8. The major fatty acids were iso-C(17 : 1)ω9c, iso-C(16 : 0) and iso-C(15 : 0). Phylogenetic analysis based on the 16S rRNA gene sequence was used to determine the taxonomic position of strain DCY45(T), which is most closely related to species of the genus Rhodanobacter, with similarity levels of 96.0-98.4 %; DNA-DNA relatedness with related strains was lower than 60 %. Strain DCY45(T) differed significantly from related type strains in phenotypic characteristics. On the basis of these phenotypic, genotypic and chemotaxonomic studies, strain DCY45(T) represents a novel species of the genus Rhodanobacter, for which the name Rhodanobacter soli sp. nov. is proposed. The type strain is DCY45(T) (=KCTC 22620(T) =JCM 16126(T)).

Identification of BACE1 inhibitors from Panax ginseng saponins-An Insilco approach

BACE1, a β secretase candidate enzyme, initiates the Alzheimers disease (AD) pathogenesis via amyloid β (Aβ) peptide production serving as a potential therapeutic target. Previous experimental evidence suggested that ginsenosides, a key component of Panax ginseng, are effective against AD. In this study, we implemented a molecular modeling method to reveal the inhibitory action of ginsenosides on BACE1 activity. We selected 12 ginsenosides and performed molecular docking studies to evaluate its interaction with the BACE1 active site, which is essential for inhibition. Further ADMET filtration was applied to find drug-like molecules with a specific ability to cross blood brain barrier (BBB), and to determine toxicity. The BACE1-ginsenosides complex was further subjected to a molecular dynamics simulation to study the stability of the complex and its hydrogen bond interactions. In summary, our findings show ginsenosides CK, F1, Rh1 and Rh2 are potential BACE1 inhibitors from Panax ginseng.