Enhanced production of ginsenoside Rh2(S) from PPD-type major ginsenosides using BglSk cloned from Saccharibacillus kuerlensis together with two glycosidase in series

Boosting the catalytic efficiency of UGT51 for efficient production of rare ginsenoside Rh2

Ginsenoside Rh2(S) is well-known for its therapeutic potential against diverse conditions, including some cancers, inflammation, and diabetes. The enzymatic activity of uridine diphosphate glycosyltransferase 51 (UGT51) from Saccharomyces cerevisiae plays a pivotal role in the glycosylation process between UDP-glucose (donor) and protopanaxadiol (acceptor), to form ginsenoside Rh2. However, the catalytic efficiency of the UGT51 has remained a challenging task. To this end, we employed site-directed mutagenesis on UGT51 to improve its catalytic efficiency for enhanced production of ginsenoside Rh2. The mutated structure, featuring four key mutations (E805A, S998A, R1031A, and L1032A), exhibited heightened stability, binding affinity, and active site accessibility for protopanaxadiol (PPD) compared to the wild type. Under in vitro conditions, three mutants (E805A, R1031A, and L1032A) demonstrated 10%, 58%, and 65% higher enzymatic activities compared to the wild strain. Notably, the double mutant R1031A/L1032A exhibited an 85% increase in activity. Employing a fed-batch technology with PPD as the substrate yielded a Rh2 production of 4.663 g/L. The molecular dynamics (MD) simulations were employed to investigate the movements and dynamic dynamics of UGT51 mutations and PPD complexes. The root mean square deviation (RMSD) analysis revealed substantial alterations in structural conformation, particularly in the R1031A/L1032A mutations, correlating with boosted catalytic efficiency. Furthermore, the root mean square fluctuation (RMSF) simulation study aligned with both the RMSD and the solvent-accessible surface area (SASA) analyses. The computationally guided site-directed mutagenesis approach holds promise for extending its application to the development of commercially significant enzymes.

Rare ginsenosides: A unique perspective of ginseng research

BACKGROUND

Rare ginsenosides (Rg3, Rh2, C-K, etc.) refer to a group of dammarane triterpenoids that exist in low natural abundance, mostly produced by deglycosylation or side chain modification via physicochemical processing or metabolic transformation in gut, and last but not least, exhibited potent biological activity comparing to the primary ginsenosides, which lead to a high concern in both the research and development of ginseng and ginsenoside-related nutraceutical and natural products. Nevertheless, a comprehensive review on these promising compounds is not available yet.

AIM OF REVIEW

In this review, recent advances of Rare ginsenosides (RGs) were summarized dealing with the structurally diverse characteristics, traditional usage, drug discovery situation, clinical application, pharmacological effects and the underlying mechanisms, structure-activity relationship, toxicity, the stereochemistry properties, and production strategies.

KEY SCIENTIFIC CONCEPTS OF REVIEW

A total of 144 RGs with diverse skeletons and bioactivities were isolated from Panax species. RGs acted as natural ligands on some specific receptors, such as bile acid receptors, steroid hormone receptors, and adenosine diphosphate (ADP) receptors. The RGs showed promising bioactivities including immunoregulatory and adaptogen-like effect, anti-aging effect, anti-tumor effect, as well as their effects on cardiovascular and cerebrovascular system, central nervous system, obesity and diabetes, and interaction with gut microbiota. Clinical trials indicated the potential of RGs, while high quality data remains inadequate, and no obvious side effects was found. The stereochemistry properties induced by deglycosylation at C (20) were also addressed including pharmacodynamics behaviors, together with the state-of-art analytical strategies for the identification of saponin stereoisomers. Finally, the batch preparation of targeted RGs by designated strategies including heating or acid/ alkaline-assisted processes, and enzymatic biotransformation and biosynthesis were discussed. Hopefully, the present review can provide more clues for the extensive understanding and future in-depth research and development of RGs, originated from the worldwide well recognized ginseng plants.

Advancements in enzymatic biotransformation and bioactivities of rare ginsenosides: A review

Ginsenoside, the principal active constituent of ginseng, exhibits enhanced bioavailability and medicinal efficacy in rare ginsenosides compared to major ginsenosides. Current research is focused on efficiently and selectively removing sugar groups attached to the major ginsenoside sugar chains to convert them into rare ginsenosides that meet the demands of medical industry and functional foods. The methods for preparing rare ginsenosides encompass chemical, microbial, and enzymatic approaches. Among these, the enzyme conversion method is highly favored by researchers due to its exceptional specificity and robust efficiency. This review summarizes the biological activities of different rare ginsenosides, explores the various glycosidases used in the biotransformation of different major ginsenosides as substrates, and elucidates their respective corresponding biotransformation pathways. These findings will provide valuable references for the development, utilization, and industrial production of ginsenosides.

Therapeutic potential of ginseng leaf extract in inhibiting mast cell-mediated allergic inflammation and atopic dermatitis-like skin inflammation in DNCB-treated mice

Ginseng leaves are known to contain high concentrations of bioactive compounds, such as ginsenosides, and have potential as a treatment for various conditions, including fungal infections, cancer, obesity, oxidative stress, and age-related diseases. This study assessed the impact of ginseng leaf extract (GLE) on mast cell-mediated allergic inflammation and atopic dermatitis (AD) in DNCB-treated mice. GLE reduced skin thickness and lymph node nodules and suppressed the expression and secretion of histamine and pro-inflammatory cytokines. It also significantly lowered the production of inflammatory response mediators including ROS, leukotriene C4 (LTC4), prostaglandin E2 (PGE2), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS). GLE inhibited the phosphorylation of MAPKs (ERK, P38, JNK) and the activation of NF-κB, which are both linked to inflammatory cytokine expression. We demonstrated that GLE's inhibitory effect on mast cell-mediated allergic inflammation is due to the blockade of the NF-κB and inflammasome pathways. Our findings suggest that GLE can be an effective therapeutic agent for mast-cell mediated and allergic inflammatory conditions.

Ketonization of Ginsenoside C-K by Novel Recombinant 3-β-Hydroxysteroid Dehydrogenases and Effect on Human Fibroblast Cells

BACKGROUND AND OBJECTIVE

The ginsenoside compound K (C-K) (which is a de-glycosylated derivative of major ginsenosides) is effective in the treatment of cancer, diabetes, inflammation, allergy, angiogenesis, aging, and has neuroprotective, and hepatoprotective than other minor ginsenosides. Thus, a lot of studies have been focused on the conversion of major ginsenosides to minor ginsenosides using glycoside hydrolases but there is no study yet published for the bioconversion of minor ginsenosides into another high pharmacological active compound. Therefore, the objective of this study to identify a new gene (besides the glycoside hydrolases) for the conversion of minor ginsenosides C-K into another highly pharmacological active compound.

METHODS AND RESULTS

Lactobacillus brevis which was isolated from Kimchi has showed the ginsenoside C-K altering capabilities. From this strain, a novel potent decarboxylation gene, named HSDLb1, was isolated and expressed in Escherichia coli BL21 (DE3) using the pMAL-c5X vector system. Recombinant HSDLb1 was also characterized. The HSDLb1 consists of 774 bp (258 amino acids residues) with a predicted molecular mass of 28.64 kDa. The optimum enzyme activity was recorded at pH 6.0-8.0 and temperature 30 °C. Recombinant HSDLb1 effectively transformed the ginsenoside C-K to 12-β-hydroxydammar-3-one-20(S)-O-β-D-glucopyranoside (3-oxo-C-K). The experimental data proved that recombinant HSDLb1 strongly ketonized the hydroxyl (-O-H) group at C-3 of C-K via the following pathway: C-K → 3-oxo-C-K. In vitro study, 3-oxo-C-K showed higher solubility than C-K, and no cytotoxicity to fibroblast cells. In addition, 3-oxo-C-K induced the inhibitory activity of ultraviolet A (UVA) against matrix metalloproteinase-1 (MMP-1) and promoted procollagen type I synthesis. Based on these expectations, we hypothesized that 3-oxo-C-K can be used in cosmetic products to block UV radiations and anti-ageing agent. Furthermore, we expect that 3-oxo-C-K will show higher efficacy than C-K for the treatment of cancer, ageing and other related diseases, for which more studies are needed.

Microorganisms for Ginsenosides Biosynthesis: Recent Progress, Challenges, and Perspectives

Ginsenosides are major bioactive compounds present in the Panax species. Ginsenosides exhibit various pharmaceutical properties, including anticancer, anti-inflammatory, antimetastatic, hypertension, and neurodegenerative disorder activities. Although several commercial products have been presented on the market, most of the current chemical processes have an unfriendly environment and a high cost of downstream processing. Compared to plant extraction, microbial production exhibits high efficiency, high selectivity, and saves time for the manufacturing of industrial products. To reach the full potential of the pharmaceutical resource of ginsenoside, a suitable microorganism has been developed as a novel approach. In this review, cell biological mechanisms in anticancer activities and the present state of research on the production of ginsenosides are summarized. Microbial hosts, including native endophytes and engineered microbes, have been used as novel and promising approaches. Furthermore, the present challenges and perspectives of using microbial hosts to produce ginsenosides have been discussed.

Repressing effect of transformed ginsenoside Rg3-mix against LPS-induced inflammation in RAW264.7 macrophage cells

BACKGROUND

Rg3-ginsenoside, a protopanaxadiol saponin, is a well-known adaptogen used for the prevention of cancer and inflammation. However, despite its distinct biological activity, the concentration of Rg3 in the total ginseng extract is insufficient for therapeutic applications. This study aims to convert PPD-class of major ginsenosides into a mixture of minor ginsenoside, to analyze its immune-regulatory role in macrophage cells.

RESULTS

Using heat and organic acid treatment, three major ginsenosides, Rc, Rd, and Rb1, were converted into a mixture of minor ginsenosides, GRg3-mix [Rg3(S), Rg3(R), Rg5, and Rk1]. Purity and content analysis of the transformed compound were performed using thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC), compared with their standards. Preceding with the anti-inflammatory activity of GRg3-mix, lipopolysaccharide (LPS)-stimulated murine RAW264.7 macrophage cells were treated with various concentrations of GRg3-mix (6.25, 12.5, 25, and 50 μg/mL). The cell viability assay revealed that the level of cell proliferation was increased, while the nitric oxide (NO) assay showed that NO production decreased dose-dependently in activated RAW264.7 cells. The obtained results were compared to those of pure Rg3(S) ≥ 98% (6.25, 12.5, and 25 μg/mL). Preliminary analysis of the CCK-8 and NO assay demonstrated that GRg3-mix can be used as an anti-inflammatory mediator, but mRNA and protein expression levels were evaluated for further confirmation. The doses of GRg3-mix significantly suppressed the initially upregulated mRNA and protein expression of inflammation-related enzymes and cytokines, namely inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), nuclear transcription factor kappa B (NF-κB), tumor necrosis factor (TNF-α), and interleukins (IL-6 and IL1B), as measured by reverse transcription-polymerase chain reaction and western blotting.

CONCLUSIONS

Our pilot data confirmed that the mixture of minor ginsenosides, namely GRg3-mix, has high anti-inflammatory activity and has an easy production procedure.

Protopanaxadiol-Enriched Rice Extracts Suppressed Oxidative and Melanogenic Activities in Melan-a Cells

Concerns about hyperpigmentation and skin appearance have led to increasing research into the prevention and altering of skin pigmentation. Natural compounds may be of interest in the search for skin-lightening actives. Protopanaxadiol (PPD), a gut microbiome-induced ginseng metabolite, has been reported to have anti-melanogenic effects. This study aimed to evaluate the antioxidative and anti-melanogenic effects of PPD-enriched rice seed extracts on melan-a cells. The antioxidant and cytotoxicity activities of the extracts were investigated in melan-a cells before measuring their responses to melanogenic activities. The extracts significantly enhanced the antioxidant potency compared with normal rice seed extract. PPD-enriched rice seed extracts (i) significantly downregulated microphthalmia-associated transcription factor, which led to a reduction in tyrosinase and tyrosinase-related protein-1 and -2, (ii) decrease in the cellular tyrosinase activity and melanin content, (iii) reduction in the number of melanin-containing cells, (iv) promotion of melanogenesis downregulators, phosphorylation of extracellular signal-regulated kinase 1/2 and protein kinase B, and (v) downregulation of the phosphorylated p38 mitogen-activated protein kinase and melanin synthesis. These results indicate the feasibility of PPD-enriched rice seed extracts as a novel agent for suppressing melanogenesis and controlling hyperpigmentation.

Humibacter ginsenosidimutans sp. nov., with ginsenoside-converting activity isolated from activated sludge

A novel Gram-stain-positive, thin rod-shaped, non-motile, aerobic and creamy-white pigmented bacterium (designated strain WJ7-1T) was isolated from activated sludge sampled in Suwon, Republic of Korea. 16S rRNA gene sequence analysis indicated that the isolate belongs to the genus Humibacter , family Microbacteriaceae , with a sequence similarity of 97.9 % to its nearest neighbour Humibacter albus KACC 20986T. Strain WJ7-1T contained menaquinone (MK)-10 (16.0 %), 11 (48.5 %) and 12 (35.5 %) as major respiratory quinones. The predominant cellular fatty acids (>15 %) were anteiso-C17 : 0, iso-C16 : 0 and anteiso-C15 : 0. The peptidoglycan of strain WJ7-1T contained the diagnostic diamino acid ornithine and 2,4-diaminobutyric acid alanine. Alanine, glutamic acid and glycine were also present in the cell wall. The characteristic whole-cell sugars present were glucose, galactose, xylose and rhamnose. The polar lipids consisted of phosphatidylglycerol, diphosphatidylglycerol, an unidentified glycolipid and two unidentified phospholipids. Strain WJ7-1T possessed ginsenoside-converting (β-glucosidase) activity, which enabled it to transform ginsenoside protopanaxadiol-type Rb1 (one of the dominant active components of ginseng) to compound K. The genome size of strain WJ7-1T has 4.2 Mbp and the G+C content is 68.3 mol%. Average nucleotide identity, amino acid identity and digital DNA–DNA hybridization values between strain WJ7-1T and the closely related strain were 79.8, 36.1 and 23.5 %, respectively, indicating that strain WJ7-1T represents a novel species of the genus Humibacter . Strain WJ7-1T could be distinguished from the other members of the genus Humibacter by a number of chemotaxonomic and phenotypic characteristics. Based on polyphasic taxonomic analysis, strain WJ7-1T (=KACC 19729T=LMG 30802T) represents a novel species within the genus Humibacter , for which the name Humibacter ginsenosidimutans sp. nov. is proposed.

Progress in research of glycoside hydrolases in the intestine

Glycoside hydrolases are a class of enzymes that hydrolyze glycosides and play an important role in the metabolic transformation of glycosides in the intestine, but the number of glycoside hydrolases encoded and expressed in the body is limited, and most glycoside hydrolases are produced from intestinal bacteria genes. Gut microbiota and the secreted glycoside hydrolases participate in the deglycosylation of glycosides and improve their bioavailability. In this paper, we review the definition and types of glucoside hydrolases, their sources from the gut microbiota, and transformation of glycosides by the gut microbiota. We also discuss the relationship between the gut microbiota, glucoside hydrolases, and glucoside deglycosylation transformation products, with an aim to provide a reference for efficient production of enzymes and glycoside conversion products, and mining of new drug resources.

Chryseobacterium panacisoli sp. nov., isolated from ginseng-cultivation soil with ginsenoside-converting activity

A Gram-stain-negative, non-motile, non-spore-forming, aerobic, rod-shaped and yellow-pigmented bacterium, designated strain Gsoil 183^T, was isolated from ginseng-cultivation soil sampled in Pocheon Province, Republic of Korea. This bacterium was characterized to determine its taxonomic position by using a polyphasic approach. Strain Gsoil 183^T grew at 10-37 °C and at pH 5.0-9.0 on tryptic soy agar. Strain Gsoil 183^T had β-glucosidase activity, which was responsible for its ability to convert ginsenoside Rb1 (one of the dominant active components of ginseng) to F2. Based on 16S rRNA gene sequencing, strain Gsoil 183^T clustered with species of the genus Chryseobacterium and appeared to be closely related to Chryseobacterium sediminis LMG 28695^T (99.1 % sequence similarity), Chryseobacterium lactis NCTC 11390^T (98.6%), Chryseobacterium rhizoplanae LMG 28481^T (98.6%), Chryseobacterium oncorhynchi CCUG 60105^T (98.5%), Chryseobacterium viscerum CCUG 60103^T (98.4%) and Chryseobacterium joostei DSM 16927^T (98.3%). Menaquinone MK-6 was the predominant respiratory quinone and the major fatty acids were iso-C_15 : 0, iso-C_17 : 0-3OH and summed feature 3 (C_16 : 1  ω6c and/or C_16 : 1  ω7c). The polar lipids were phosphatidylethanolamine, six unidentified glycolipids, five unidentified aminolipids and three unidentified lipids. The G+C content of the genomic DNA was 36.6 mol%. Digital DNA-DNA hybridization between strain Gsoil 183^T and the type strains of C. sediminis, C. lactis, C. rhizoplanae, C. oncorhynchi, C. viscerum and C. joostei resulted in values below 70 %. Strain Gsoil 183^T could be differentiated genotypically and phenotypically from the recognized species of the genus Chryseobacterium. The isolate therefore represents a novel species, for which the name Chryseobacterium panacisoli sp. nov. is proposed, with the type strain Gsoil 183^T (=KACC 15033^T=LMG 23397^T).