Biotransformation of ginsenosides by hydrolyzing the sugar moieties of ginsenosides using microbial glycosidases

Production of rare ginsenosides by biotransformation of Panax notoginseng saponins using Aspergillus fumigatus

Panax notoginseng saponins (PNS) are the main active components of Panax notoginseng. But after oral administration, they need to be converted into rare ginsenosides by human gut microbiota and gastric juice before they can be readily absorbed into the bloodstream and exert their effects. The sources of rare ginsenosides are extremely limited in P. notoginseng and other medical plants, which hinders their application in functional foods and drugs. Therefore, the production of rare ginsenosides by the transformation of PNS using Aspergillus fumigatus was studied in this research. During 50 days at 25 ℃ and 150 rpm, A. fumigatus transformed PNS to 14 products (1-14). They were isolated by varied chromatographic methods, such as silica gel column chromatography, Rp-C18 reversed phase column chromatography, semi-preparative HPLC, Sephadex LH-20 gel column chromatography, and elucidated on the basis of their 1H-NMR, 13C-NMR and ESIMS spectroscopic data. Then, the transformed products (1-14) were isolated and identified as Rk3, Rh4, 20 (R)-Rh1, 20 (S)-Protopanaxatriol, C-K, 20 (R)-Rg3, 20 (S)-Rg3, 20 (S)-Rg2, 20 (R)-R2, Rk1, Rg5, 20 (S)-R2, 20 (R)-Rg2, and 20 (S)-I, respectively. In addition, all transformed products (1-14) were tested for their antimicrobial activity. Among them, compounds 5 (C-K) and 7 [20 (S)-Rg3] showed moderate antimicrobial activities against Staphylococcus aureus and Candida albicans with MIC values of 6.25, 1.25 μg/mL and 1.25, 25 μg/mL, respectively. This study lays the foundation for production of rare ginsenosides.

Identify Regioselective Residues of Ginsenoside Hydrolases by Graph-Based Active Learning from Molecular Dynamics

Identifying the catalytic regioselectivity of enzymes remains a challenge. Compared to experimental trial-and-error approaches, computational methods like molecular dynamics simulations provide valuable insights into enzyme characteristics. However, the massive data generated by these simulations hinder the extraction of knowledge about enzyme catalytic mechanisms without adequate modeling techniques. Here, we propose a computational framework utilizing graph-based active learning from molecular dynamics to identify the regioselectivity of ginsenoside hydrolases (GHs), which selectively catalyze C6 or C20 positions to obtain rare deglycosylated bioactive compounds from Panax plants. Experimental results reveal that the dynamic-aware graph model can excellently distinguish GH regioselectivity with accuracy as high as 96-98% even when different enzyme-substrate systems exhibit similar dynamic behaviors. The active learning strategy equips our model to work robustly while reducing the reliance on dynamic data, indicating its capacity to mine sufficient knowledge from short multi-replica simulations. Moreover, the model's interpretability identified crucial residues and features associated with regioselectivity. Our findings contribute to the understanding of GH catalytic mechanisms and provide direct assistance for rational design to improve regioselectivity. We presented a general computational framework for modeling enzyme catalytic specificity from simulation data, paving the way for further integration of experimental and computational approaches in enzyme optimization and design.

Preparation of in vivo intermediate metabolites of soybean saponins with improved bioactivity by in vitro deacetylation and deglucosylation

Unlike natural soyasaponins and their aglycones formed by enzymatic hydrolysis in the human intestine, in vivo intermediate soyasaponin metabolites are difficult to prepare. Therefore, the pharmacological activities of in vivo intermediate soyasaponins remain uninvestigated. Herein, in vivo intermediate soyasaponins with purities of >90% were prepared by in vitro deacetylation (alkaline treatment) and deglucosylation (β-glucosidase treatment) of natural soyasaponins using preparative high-performance liquid chromatography. These compounds exhibited higher anti-inflammatory and antioxidant activities than natural soyasaponins in in vitro bioassays, suggesting that the intermediate soyasaponins can be used as improved bioactive food supplements. To the best of our knowledge, this is the first study reporting the in vitro preparation and bioassays of in vivo intermediate soyasaponin metabolites formed in the human intestine.

Conversion of notoginsenoside R1 to 3β,12β-dihydroxydammar-(E)-20(22),24-diene-6-O-β-D-xylopyranosyl-(1→2)-β-D-glucopyranoside by Lactiplantibacillus plantarum S165 enhanced protective effects of LPS-induced intestinal epithelial barrier injury in Caco-2 cells

AIMS

Microbial transformation to modify saponins and enhance their biological activities has received increasing attention in recent years. This study aimed to screen the strain that can biotransform notoginsenoside R1, identify the product and study its biological activity.

METHODS AND RESULTS

A lactic acid bacteria strain S165 with glycosidase-producing activity was isolated from traditional Chinese fermented foods, which was identified and grouped according to API 50 CHL kit and 16S rDNA sequence analysis. Subsequently, notoginsenoside R1 underwent a 30-day fermentation period by the strain S165, and the resulting products were analyzed using High-performance liquid chromatography (HPLC), Ultra-performance liquid chromatography (UPLC)-mass spectrometry (MS)/MS, and 13C-Nuclear magnetic resonance (NMR) techniques. Employing a model of Lipopolysaccharide (LPS)-induced damage to Caco-2 cells, the damage of Caco-2 cells was detected by Hoechst 33 258 staining, and the activity of notoginsenoside R1 biotransformation product was investigated by CCK-8 and western blotting assay. The strain S165 was identified as Lactiplantibacillus plantarum and was used to biotransform notoginsenoside R1. Through a 30-day biotransformation, L. plantarum S165 predominantly converts notoginsenoside R1 into 3β,12β-dihydroxydammar-(E)-20(22),24-diene-6-O-β-D-xylopyranosyl-(1→2)-β-D-glucopyranoside, temporarily named notoginsenoside T6 (NGT6) according to HPLC, UPLC-MS/MS, and 13C-NMR analysis. Results from CCK-8 and Hoechst 33258 staining indicated that the ability notoginsenoside T6 to alleviate the intestinal injury induced by LPS in the Caco-2 cell was stronger than that of notoginsenoside R1. In addition, Western blotting result showed that notoginsenoside T6 could prevent intestinal injury by protecting tight junction proteins (Claudin-1, Occludin, and ZO-1).

CONCLUSION

Notoginsenoside R1 was biotransformed into the notoginsenoside T6 by L. plantarum S165, and the biotransformed product showed an enhanced intestinal protective effect in vitro.

Production and pharmaceutical research of minor saponins in Panax notoginseng (Sanqi): Current status and future prospects

Panax notoginseng (Burk.) F.H. Chen is a traditional medicinal herb known as Sanqi or Tianqi in Asia and is commonly used worldwide. It is one of the main raw ingredients of Yunnan Baiyao, Fu fang dan shen di wan, and San qi shang yao pian. It is also a source of cardiotonic pill used to treat cardiovascular diseases in China, Korea, and Russia. Approximately 270 Panax notoginseng saponins have been isolated and identified as the major active components. Although the absorption and bioavailability of saponins are predominantly dependent on the gastrointestinal biotransformation capacity of an individual, minor saponins are better absorbed into the bloodstream and act as active substances than major saponins. Notably, minor saponins are absent or are present in minimal quantities under natural conditions. In this review, we focus on the strategies for the enrichment and production of minor saponins in P. notoginseng using physical, chemical, enzyme catalytic, and microbial methods. Moreover, pharmacological studies on minor saponins derived from P. notoginseng over the last decade are discussed. This review serves as a meaningful resource and guide, offering scholarly references for delving deeper into the exploration of the minor saponins in P. notoginseng.

Bioconversion, Pharmacokinetics, and Therapeutic Mechanisms of Ginsenoside Compound K and Its Analogues for Treating Metabolic Diseases

Rare ginsenoside compound K (CK) is an intestinal microbial metabolite with a low natural abundance that is primarily produced by physicochemical processing, side chain modification, or metabolic transformation in the gut. Moreover, CK exhibits potent biological activity compared to primary ginsenosides, which has raised concerns in the field of ginseng research and development, as well as ginsenoside-related dietary supplements and natural products. Ginsenosides Rb1, Rb2, and Rc are generally used as a substrate to generate CK via several bioconversion processes. Current research shows that CK has a wide range of pharmacological actions, including boosting osteogenesis, lipid and glucose metabolism, lipid oxidation, insulin resistance, and anti-inflammatory and anti-apoptosis properties. Further research on the bioavailability and toxicology of CK can advance its medicinal application. The purpose of this review is to lay the groundwork for future clinical studies and the development of CK as a therapy for metabolic disorders. Furthermore, the toxicology and pharmacology of CK are investigated as well in this review. The findings indicate that CK primarily modulates signaling pathways associated with AMPK, SIRT1, PPARs, WNTs, and NF-kB. It also demonstrates a positive therapeutic effect of CK on non-alcoholic fatty liver disease (NAFLD), obesity, hyperlipidemia, diabetes, and its complications, as well as osteoporosis. Additionally, the analogues of CK showed more bioavailability, less toxicity, and more efficacy against disease states. Enhancing bioavailability and regulating hazardous variables are crucial for its use in clinical trials.

Increasing the Amounts of Bioactive Components in American Ginseng (Panax quinquefolium L.) Leaves Using Far-Infrared Irradiation

Both the roots and leaves of American ginseng contain ginsenosides and polyphenols. The impact of thermal processing on enhancing the biological activities of the root by altering its component composition has been widely reported. However, the effects of far-infrared irradiation (FIR), an efficient heat treatment method, on the bioactive components of the leaves remain to be elucidated. In the present study, we investigated the effects of FIR heat treatment between 160 and 200 °C on the deglycosylation and dehydration rates of the bioactive components in American ginseng leaves. As the temperature was increased, the amounts of common ginsenosides decreased while those of rare ginsenosides increased. After FIR heat treatment of American ginseng leaves at an optimal 190 °C, the highest total polyphenolic content and kaempferol content were detected, the antioxidant activity was significantly enhanced, and the amounts of the rare ginsenosides F4, Rg6, Rh4, Rk3, Rk1, Rg3, and Rg5 were 41, 5, 37, 64, 222, 17, and 266 times higher than those in untreated leaves, respectively. Moreover, the radical scavenging rates for 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and the reducing power of the treated leaf extracts were 2.17, 1.86, and 1.77 times higher, respectively. Hence, FIR heat treatment at 190 °C is an efficient method for producing beneficial bioactive components from American ginseng leaves.

How Can Deep Eutectic Systems Promote Greener Processes in Medicinal Chemistry and Drug Discovery?

Chemists in the medicinal chemistry field are constantly searching for alternatives towards more sustainable and eco-friendly processes for the design and synthesis of drug candidates. The pharmaceutical industry is one of the most polluting industries, having a high E-factor, which is driving the adoption of more sustainable processes not only for new drug candidates, but also in the production of well-established active pharmaceutical ingredients. Deep eutectic systems (DESs) have emerged as a greener alternative to ionic liquids, and their potential to substitute traditional organic solvents in drug discovery has raised interest among scientists. With the use of DESs as alternative solvents, the processes become more attractive in terms of eco-friendliness and recyclability. Furthermore, they might be more effective through making the process simpler, faster, and with maximum efficiency. This review will be focused on the role and application of deep eutectic systems in drug discovery, using biocatalytic processes and traditional organic chemical reactions, as new environmentally benign alternative solvents. Furthermore, herein we also show that DESs, if used in the pharmaceutical industry, may have a significant effect on lowering production costs and decreasing the impact of this industry on the quality of the environment.

Production of ginsenoside compound K from American ginseng extract by fed-batch culture of Aspergillus tubingensis

Compound K (C-K), one of the most bioactive ginsenoside, is produced by hydrolyzing the glycoside moieties of protopanaxadiol (PPD)-type glycosylated ginsenosides in the ginseng extract. To enhance the biotransformation of PPD-type ginsenosides in American ginseng extract (AGE) into C-K, the optimization of the feed type, concentration, and period for the carbon source sucrose and the reactant AGE was performed in fed-batch fermentation of Aspergillus tubingensis using a fermenter. The concentration (3.94 g/L) and productivity (27.4 mg/L/h) of C-K after feed optimization in fed-batch fermentation increased 3.1-fold compared to those (1.29 g/L and 8.96 mg/L/h) in batch fermentation, and a molar conversion of 100% was achieved. To the best of our knowledge, this is the first trial of fed-batch fermentation to convert ginseng extract into deglycosylated ginsenoside and the highest reported C-K concentration and productivity using ginseng extract via fermentation. After ethanol and resin treatments, C-K solids with purities of 59% and 96% were obtained from the fermentation broth as food- and pharmaceutical-grade products, respectively.

Ginsenosides and Polysaccharides from Ginseng Co-Fermented with Multi-Enzyme-Coupling Probiotics Improve In Vivo Immunomodulatory Effects

The active components of ginseng, such as ginsenosides and polysaccharides, have high therapeutic value in treating cancer, decreasing obesity, and enhancing immunity. However, simple primary ginseng treatment cannot maximize this medicinal potential. Therefore, in this study, Panax ginseng was co-fermented with multi-enzyme-coupling probiotics to obtain a fermentation broth with higher levels of ginsenosides, polysaccharides, and probiotics. When compared to other treatment methods for cyclophosphamide-induced immunosuppression in mice, the results reveal that the P. ginseng fermentation broth treated with multi-enzyme-coupling probiotics could significantly improve the immune function of immunosuppressive mice and restore intestinal flora stability. Overall, this processing method will provide a novel strategy for promoting the application of ginseng and the relief of immunosuppression.

Health benefits of saponins and its mechanisms: perspectives from absorption, metabolism, and interaction with gut

Saponins, consisting of sapogenins as their aglycones and carbohydrate chains, are widely found in plants and some marine organisms. Due to the complexity of the structure of saponins, involving different types of sapogenins and sugar moieties, investigation of their absorption and metabolism is limited, which further hinders the explanation of their bioactivities. Large molecular weight and complex structures limit the direct absorption of saponins rendering their low bioavailability. As such, their major modes of action may be due to interaction with the gastrointestinal environment, such as enzymes and nutrients, and interaction with the gut microbiota. Many studies have reported the interaction between saponins and gut microbiota, that is, the effects of saponins on changing the composition of gut microbiota, and gut microbiota playing an indispensable role in the biotransformation of saponins into sapogenins. However, the metabolic routes of saponins by gut microbiota and their mutual interactions are still sparse. Thus, this review summarizes the chemistry, absorption, and metabolic pathways of saponins, as well as their interactions with gut microbiota and impacts on gut health, to better understand how saponins exert their health-promoting functions.

Gypenoside biotransformation into ginsenoside F2 by endophytic Aspergillus niger from Gynostemma pentaphyllum

Ginsenoside F2 is a protopanaxadiol saponin compound with various biological activities, including antioxidant, anti-inflammatory, and anticancer properties. Ginsenoside F2 can be found in ginseng, but in low quantities. Therefore, ginsenoside F2 production predominantly relies on the biotransformation of various ginsenosides, such as ginsenosides Rb1 and Rd. In this study, we reported the production of ginsenoside F2 by gypenoside biotransformation with Aspergillus niger JGL8, isolated from Gynostemma pentaphyllum. Ginsenoside F2 could be produced by two different biotransformation pathways, namely Gyp-V-Rd-F2 and Gyp-XVII-F2. The product exhibited antioxidant activity against free radicals (DPPH) with IC₅₀ value of 29.54 µg/mL. Optimal biotransformation conditions were a pH of 5.0, temperature of 40 °C, and 2 mg/mL of substrate. Enzyme kinetic parameters revealed that the hydrolysis rate of Gyp-V, Rd, and Gyp-XVII was 0.625, 0.588, and 0.417 mM/h, respectively. In conclusion, we demonstrated that gypenoside is a substitutable substrate for ginsenoside F2 biotransformation.

Advances in the biosynthesis and metabolic engineering of rare ginsenosides

Rare ginsenosides are the deglycosylated secondary metabolic derivatives of major ginsenosides, and they are more readily absorbed into the bloodstream and function as active substances. The traditional preparation methods hindered the potential application of these effective components. The continuous elucidation of ginsenoside biosynthesis pathways has rendered the production of rare ginsenosides using synthetic biology techniques effective for their large-scale production. Previously, only the progress in the biosynthesis and biotechnological production of major ginsenosides was highlighted. In this review, we summarized the recent advances in the identification of key enzymes involved in the biosynthetic pathways of rare ginsenosides, especially the glycosyltransferases (GTs). Then the construction of microbial chassis for the production of rare ginsenosides, mainly in Saccharomyces cerevisiae, was presented. In the future, discovery of more GTs and improving their catalytic efficiencies are essential for the metabolic engineering of rare ginsenosides. This review will give more clues and be helpful for the characterization of the biosynthesis and metabolic engineering of rare ginsenosides. KEY POINTS: • The key enzymes involved in the biosynthetic pathways of rare ginsenosides are summarized. • The recent progress in metabolic engineering of rare ginsenosides is presented. • The discovery of glycosyltransferases is essential for the microbial production of rare ginsenosides in the future.

Engineered Glycosidase for Significantly Improved Production of Naturally Rare Vina-Ginsenoside R7

Ginsenosides are the main bioactive ingredients in plants of the genus Panax. Vina-ginsenoside R7 (VG-R7) is one of the rare high-value ginsenosides with health benefits. The only reported method for preparing VG-R7 involves inefficient and low-yield isolation from highly valuable natural resources. Notoginsenoside Fc (NG-Fc) isolated in the leaves and stems of Panax notoginseng is a suitable substrate for the preparation of VG-R7 via specific hydrolysis of the outside xylose at the C-20 position. Here, we first screened putative enzymes belonging to the glycoside hydrolase (GH) families 1, 3, and 43 and found that KfGH01 can specifically hydrolyze the β-d-xylopyranosyl-(1 → 6)-β-d-glucopyranoside linkage of NG-Fc to form VG-R7. The I248F/Y410R variant of KfGH01 obtained by protein engineering displayed a k_cat/K_M value (305.3 min^-1 mM^-1) for the reaction enhanced by approximately 270-fold compared with wild-type KfGH01. A change in the shape of the substrate binding pockets in the mutant allows the substrate to sit closer to the catalytic residues which may explain the enhanced catalytic efficiency of the engineered enzyme. This study identifies the first glycosidase for bioconversion of a ginsenoside with more than four sugar units, and it will inspire efforts to investigate other promising enzymes to obtain valuable natural products.

The Application of Ethnomedicine in Modulating Megakaryocyte Differentiation and Platelet Counts

Megakaryocytes (MKs), a kind of functional hematopoietic stem cell, form platelets to maintain platelet balance through cell differentiation and maturation. In recent years, the incidence of blood diseases such as thrombocytopenia has increased, but these diseases cannot be fundamentally solved. The platelets produced by MKs can treat thrombocytopenia-associated diseases in the body, and myeloid differentiation induced by MKs has the potential to improve myelosuppression and erythroleukemia. Currently, ethnomedicine is extensively used in the clinical treatment of blood diseases, and the recent literature has reported that many phytomedicines can improve the disease status through MK differentiation. This paper reviewed the effects of botanical drugs on megakaryocytic differentiation covering the period 1994-2022, and information was obtained from PubMed, Web of Science and Google Scholar. In conclusions, we summarized the role and molecular mechanism of many typical botanical drugs in promoting megakaryocyte differentiation in vivo, providing evidence as much as possible for botanical drugs treating thrombocytopenia and other related diseases in the future.

Biotransformation of Platycosides, Saponins from Balloon Flower Root, into Bioactive Deglycosylated Platycosides

Platycosides, saponins from balloon flower root (Platycodi radix), have diverse health benefits, such as antioxidant, anti-inflammatory, anti-tussive, anti-cancer, anti-obesity, anti-diabetes, and whitening activities. Deglycosylated platycosides, which show greater biological effects than glycosylated platycosides, are produced by the hydrolysis of glycoside moieties in glycosylated platycosides. In this review, platycosides are classified according to the chemical structures of the aglycone sapogenins and also divided into natural platycosides, including major, minor, and rare platycosides, depending on the content in Platycodi radix extract and biotransformed platycosides. The biological activities of platycosides are summarized and methods for deglycosylation of saponins, including physical, chemical, and biological methods, are introduced. The biotransformation of glycosylated platycosides into deglycosylated platycosides was described based on the hydrolytic pathways of glycosides, substrate specificity of glycosidases, and specific productivities of deglycosylated platycosides. Methods for producing diverse and/or new deglycosylated platycosides are also proposed.

Characterization of a novel thermophilic beta-glucosidase from Thermotoga sp. and its application in the transformation of notoginsenoside R1

A novel β-glucosidase (Thglu3) was identified from Thermotoga sp. which had biotransformation activity for notoginsenoside R1 (NR-R1). Sequence analysis of Thglu3 revealed that it could be classified into glycoside hydrolase family 3 (GH3). The gene encoding a 719-amino acid protein was cloned and expressed in Escherichia coli. The recombinant enzyme was purified, and its molecular weight was approximately 81 kDa. The recombinant Thglu3 exhibited an optimal activity at 75 °C and pH 6.4. The β-glucosidase had high selectivity for cleaving the outer glucose moiety at the C20 position of NR-R1, which produced the more pharmacologically active notoginsenoside R2 (NR-R2). Under the optimal reaction conditions for gram-scale production, 30 g NR-R1 was transformed to NR-R2 using 20 g crude enzyme at pH 6.4 and 75 °C within 1 h with a molar yield of 93%. This study was the first report of the highly efficient and selective gram-scale transformation of NR-R2 from NR-R1 by a thermophilic β-glucosidase.

Cloning and characterization of thermophilic endoglucanase and its application in the transformation of ginsenosides

A novel endoglucanase (BcelFp) was identified from Fervidobaterium pennivorans DSM9078 which had biotransformation activity for protopanaxadiol (PPD)-type ginsenosides. Sequence analysis of BcelFp revealed that it could be classified into glycoside hydrolase family 5 (GH5). The gene encoding a 323-amino acid protein was cloned and expressed in Escherichia coli. The recombinant enzyme was purified, and its molecular weight was approximate 37 kDa. The recombinant BcelFp exhibited an optimal activity at 95 oC and pH 5.5 and showed high thermostability. The endoglucanase had high selectivity for cleaving the outer glucose moiety at the C3 carbon of ginsenoside Rb1, Rb2, Rc and Rd, which produced stronger pharmacologically active gypenoside XVII (GypXVII), Compound O (CO), Compound Mc1 (CMc1) and F2, respectively. The Km values for Rb1, Rb2, Rc and Rd were 3.66 ± 0.04 µM, 4.02 ± 0.12 µM, 5.95 ± 0.03 µM, 0.67 ± 0.006 µM, respectively. The kcat/Km value of BcelFp for ginsenoside Rd was 27.91 mM-1s-1, which was much higher than that of the previously enzymes. This study was the first report of the highly efficient and selective transformation of GypXVII, CO, CMc1 and F2 from Rb1, Rb2, Rc and Rd by a GH5-family thermophilic endoglucanase.

Novel Split Intein-Mediated Enzymatic Channeling Accelerates the Multimeric Bioconversion Pathway of Ginsenoside

Cascade reaction systems, such as protein fusion and synthetic protein scaffold systems, can both spatially control the metabolic flux and boost the productivity of multistep enzymatic reactions. Despite many efforts to generate fusion proteins, this task remains challenging due to the limited expression of complex enzymes. Therefore, we developed a novel fusion system that bypasses the limited expression of complex enzymes via a post-translational linkage. Here, we report a split intein-mediated cascade system wherein orthogonal split inteins serve as adapters for protein ligation. A genetically programmable, self-assembled, and traceless split intein was utilized to generate a biocatalytic cascade to produce the ginsenoside compound K (CK) with various pharmacological activities, including anticarcinogenic, anti-inflammatory, and antidiabetic effects. We used two types of split inteins, consensus atypical (Cat) and Rma DnaB, to form a covalent scaffold with the three enzymes involved in the CK conversion pathway. The multienzymatic complex with a size greater than 240 kDa was successfully assembled in a soluble form and exhibited specific activity toward ginsenoside conversion. Furthermore, our split intein cascade system significantly increased the CK conversion rate and reduced the production time by more than 2-fold. Our multienzymatic cascade system that uses split inteins can be utilized as a platform for regulating multimeric bioconversion pathways and boosting the production of various high-value substances.

Production of Minor Ginsenoside CK from Major Ginsenosides by Biotransformation and Its Advances in Targeted Delivery to Tumor Tissues Using Nanoformulations

For over 2000 years, ginseng (roots of Panax ginseng C.A. Meyer) has been used as a traditional herbal medicine. Ginsenosides are bioactive compounds present in ginseng responsible for the pharmacological effects and curing various acute diseases as well as chronic diseases including cardiovascular disease, cancer and diabetes. Structurally, ginsenosides consist of a hydrophobic aglycone moiety fused with one to four hydrophilic glycoside moieties. Based on the position of sugar units and their abundance, ginsenosides are classified into major and minor ginsenosides. Despite the great potential of ginsenosides, major ginsenosides are poorly absorbed in the blood circulation, resulting in poor bioavailability. Interestingly, owing to their small molecular weight, minor ginsenosides exhibit good permeability across cell membranes and bioavailability. However, extremely small quantities of minor ginsenosides extracted from ginseng plants cannot fulfill the requirement of scientific and clinical studies. Therefore, the production of minor ginsenosides in mass production is a topic of interest. In addition, their poor solubility and lack of targetability to tumor tissues limits their application in cancer therapy. In this review, various methods used for the transformation of major ginsenosides to minor ginsenoside compound K (CK) are summarized. For the production of CK, various transformation methods apply to major ginsenosides. The challenges present in these transformations and future research directions for producing bulk quantities of minor ginsenosides are discussed. Furthermore, attention is also paid to the utilization of nanoformulation technology to improve the bioavailability of minor ginsenoside CK.

New insights into the role and mechanisms of ginsenoside Rg1 in the management of Alzheimer's disease

Alzheimer's disease (AD) is a common neurodegenerative disorder in the elderly characterized by memory loss and cognitive dysfunction. The pathogenesis of AD is complex. One-targeted anti-AD drugs usually fail to delay AD progression. Traditional Chinese medicine records have documented the use of the roots of Panax ginseng (ginseng roots) and its prescriptions to treat dementia. Ginsenoside Rg1, the main ginsenoside component of ginseng roots, exhibits a certain therapeutic effect in the abovementioned diseases, suggesting its potential in the management of AD. Therefore, we combed the pathogenesis of AD and currently used anti-AD drugs, and reviewed the availability, pharmacokinetics, and pharmaceutic studies of ginsenoside Rg1. This review summarizes the therapeutic effects and mechanisms of ginsenoside Rg1 and its deglycosylated derivatives in AD in vivo and in vitro. The main mechanisms include improvement in Aβ and Tau pathologies, regulation of synaptic function and intestinal microflora, and reduction of inflammation, oxidative stress, and apoptosis. The underlying mechanisms mainly involve the regulation of PKC, MAPK, PI3K/Akt, CDK5, GSK-3β, BDNF/TrkB, PKA/CREB, FGF2/Akt, p21WAF1/CIP1, NF-κB, NLRP1, TLR3, and TLR4 signaling pathways. As the effects and underlying mechanisms of ginsenoside Rg1 on AD have not been systematically reviewed, we have provided a comprehensive review and shed light on the future directions in the utilization of ginsenoside Rg1 and ginseng roots as well as the development of anti-AD drugs.

Increased Production of Ginsenoside Compound K by Optimizing the Feeding of American Ginseng Extract during Fermentation by Aspergillus tubingensis

The ginsenoside compound K (C-K) is widely used in traditional medicines, nutritional supplements, and cosmetics owing to its diverse pharmacological activities. Although many studies on C-K production have been conducted, fermentation is reported to produce C-K with low concentration and productivity. In the present study, addition of an inducer and optimization of the carbon and nitrogen sources in the medium were performed using response surface methodology to increase the C-K production via fermentation by Aspergillus tubingensis, a generally recognized as safe fungus. The optimized inducer and carbon and nitrogen sources were 2 g/l rice straw, 10 g/l sucrose, and 10 g/l soy protein concentrate, respectively, and they resulted in a 3.1-fold increase in the concentration and productivity of C-K (0.22 g/l and 1.52 mg/l/h, respectively) compared to those used before optimization without inducer (0.071 g/l and 0.49 mg/l/h, respectively). The feeding methods of American ginseng extract (AGE), including feeding timing, feeding concentration, and feeding frequency, were also optimized. Under the optimized conditions, A. tubingensis produced 3.96 mM (2.47 g/l) C-K at 144 h by feeding two times with 8 g/l AGE at 48 and 60 h, with a productivity of 17.1 mg/l/h. The concentration and productivity of C-K after optimization of feeding methods were 11-fold higher than those before the optimization (0.22 g/l and 1.52 mg/l/h, respectively). Thus, the optimization for the feeding methods of ginseng extract is an efficient strategy to increase C-K production. To our knowledge, this is the highest reported C-K concentration and productivity via fermentation reported so far.

Biotransformation, Pharmacokinetics, and Pharmacological Activities of Ginsenoside Rd Against Multiple Diseases

Panax ginseng C.A. Mey. has a history of more than 4000 years and is widely used in Asian countries. Modern pharmacological studies have proved that ginsenosides and their compounds have a variety of significant biological activities on specific diseases, including neurodegenerative diseases, certain types of cancer, gastrointestinal disease, and metabolic diseases, in which most of the interest has focused on ginsenoside Rd. The evidentiary basis showed that ginsenoside Rd ameliorates ischemic stroke, nerve injury, cancer, and other diseases involved in apoptosis, inflammation, oxidative stress, mitochondrial damage, and autophagy. In this review, we summarized available reports on the molecular biological mechanisms of ginsenoside Rd in neurological diseases, cancer, metabolic diseases, and other diseases. We also discussed the main biotransformation pathways of ginsenoside Rd obtained by fermentation.

Enzymatic Biotransformation of Gypenoside XLIX into Gylongiposide I and Their Antiviral Roles against Enterovirus 71 In Vitro

Biotransformation of specific saponins in the valuable medical plants to increase their bioavailability and pharmaceutical activities has attracted more and more attention. A gene encoding a thermophilic glycoside hydrolase from Fervidobaterium pennivorans DSM9078 was cloned and expressed in Escherichia coli. The purified recombinant enzyme, exhibiting endoglucanase cellulase activity, was used to transform gypenoside XLIX into gylongiposide I via highly selective and efficient hydrolysis of the glucose moiety linked to the C21 position in gypenoside XLIX. Under the optimal reaction conditions for large scale production of gylongiposide I, 35 g gypenoside XLIX was transformed by using 20 g crude enzyme at pH 6.0 and 80 °C for 4 h with a molar yield of 100%. Finally, 11.51 g of gylongiposide I was purified using a silica gel column with 91.84% chromatographic purity. Furthermore, inhibitory activities of gypenoside XLIX and gylongiposide I against Enterovirus 71 (EV71) were investigated. Importantly, the EC50 of gypenoside XLIX and gylongiposide I calculated from viral titers in supernatants was 3.53 μM and 1.53 μM, respectively. Moreover, the transformed product gylongiposide I has better anti-EV71 activity than the glycosylated precursor. In conclusion, this enzymatic method would be useful in the large-scale production of gylongiposide I, which would be a novel potent anti-EV71 candidate.

The Rhizosphere Microbiome of Ginseng

The rhizosphere of ginseng contains a wide range of microorganisms that can have beneficial or harmful effects on the plant. Root exudates of ginseng, particularly ginsenosides and phenolic acids, appear to select for particular microbial populations through their stimulatory and inhibitory activities, which may account for the similarities between the rhizosphere microbiomes of different cultivated species of Panax. Many practices of cultivation attempt to mimic the natural conditions of ginseng as an understory plant in hilly forested areas. However, these practices are often disruptive to soil, and thus the soil microbiome differs between wild and cultivated ginseng. Changes in the microbiome during cultivation can be harmful as they have been associated with negative changes of the soil physiochemistry as well as the promotion of plant diseases. However, isolation of a number of beneficial microbes from the ginseng rhizosphere indicates that many have the potential to improve ginseng production. The application of high-throughput sequencing to study the rhizosphere microbiome of ginseng grown under a variety of conditions continues to greatly expand our knowledge of the diversity and abundance of those organisms as well as their impacts of cultivation. While there is much more to be learnt, many aspects of the ginseng rhizosphere microbiome have already been revealed.

Production of Deglucose-Apiose-Xylosylated Platycosides from Glycosylated Platycosides by Crude Enzyme from Aspergillus tubingensis

Platycosides, Platycodi radix (Platycodon grandiflorus root) saponins, are used as food supplements and exert diverse pharmacological activities. Deglycosylation of saponins enhances their biological efficacy, and deglycosylated platycosides are produced mainly through enzymatic hydrolysis. However, the types of available deglycosylated platycosides remain limited because of a lack of hydrolyzing enzymes that can act on specific glycosides in glycosylated platycosides. In this study, a crude enzyme from Aspergillus tubingensis converted platycoside E (PE) and polygalacin D₃ (PGD3) into deglucose-apiose-xylosylated (deGAX)-platycodin D (PD) and deGAX-polygalacin D (PGD), respectively. The products were identified through LC/MS analysis by specifically hydrolyzing all glucose residues at C-3, and apiose and xylose residues at C-28 of platycoside. The hydrolytic activity of the crude enzyme obtained after the cultivation of the fungus using citrus pectin and corn steep solid as carbon and nitrogen sources, respectively, in culture medium was increased compared with those using other carbon and nitrogen sources. The crude enzyme from A. tubingensis was the most effective in producing deGAX platycoside at pH 5.0 and 60°C. The crude enzyme produced 0.32 mg/ml deGAX-PD and 0.34 mg/ml deGAX-PGD from 1 mg/ml PE and 1 mg/ml PGD3 (at pH 5.0 and 60°C) for 12 and 10 h, with productivities of 32.0 and 42.5 mg/l/h and molar yields of 62.1 and 59.6%, respectively. To the best of our knowledge, this is the first study to produce deGAX platycosides from glycosylated platycosides.

Bioconversion of Ginsenosides in American Ginseng Extraction Residue by Fermentation with Ganoderma lucidum Improves Insulin-like Glucose Uptake in 3T3-L1 Adipocytes

Ginseng is one of the most popular traditional Chinese medicines that have been widely used in China and other Asian countries for thousands of years. Ginsenosides are the unique bioactive saponins occurring in ginseng, and their biological activities have been extensively investigated. A large amount of ginseng residue is produced as waste product due to its applications in manufacturing functional food products, even though it may still contain bioactive components. Thus, the objective of this study was to investigate the hypoglycemic activities of American ginseng extraction residue (AmR) via fermentation with Ganoderma lucidum. Our results showed that the total phenolic contents and β-glucosidase activity of AmR profoundly increased after fermentation with G. lucidum. In 3T3-L1 adipocytes, stimulation of glucose uptake by treatment with AmR was not significant, while fermented AmR (FAmR) exhibited insulin-like glucose-uptake-stimulatory effects. Importantly, the hypoglycemic effects of FAmR were positively associated with the amount of the deglycosylated minor ginsenosides Rg1, Rg3, and compound K. Taken together, our current findings suggest that bioconversion of AmR by fermentation with G. lucidum may be a feasible and eco-friendly approach to developing a functional ingredient for the management of diabetes, while also resolving the problem of ginseng waste.

Improved production of deglucosylated platycodin D from saponins from balloon flower leaf by a food-grade enzyme using high hydrostatic pressure

Platycosides, saponins contained in balloon flower, which have been used as food health supplements for respiratory diseases, have diverse pharmacological effects. Platycosides exhibit better pharmacological activity by hydrolyzing their own sugars. However, to date, there have been no studies on the production of deglucosylated platycodin D suitable for food applications. In this study, Pluszyme 2000P, which was derived from Aspergillus niger, a food-grade microorganism, was used to completely convert platycoside E into deglucosylated platycodin D. For an efficient and economical production of deglucosylated platycodin D, the productivity was improved approximately 2.4 times by application of high hydrostatic pressure and the discarded balloon flower leaf was used as a substrate. As a result, deglucosylated platycodin D was produced with the highest concentration (3.49 mg/mL) and productivity (581.7 mg/L/h) reported so far. Our results contribute to functional saponin production and the related food industries.

Production of Minor Ginsenosides C-K and C-Y from Naturally Occurring Major Ginsenosides Using Crude β-Glucosidase Preparation from Submerged Culture of Fomitella fraxinea

Minor ginsenosides, such as compounds (C)-K and C-Y, possess relatively better bioactivity than those of naturally occurring major ginsenosides. Therefore, this study focused on the biotransformation of major ginsenosides into minor ginsenosides using crude β-glucosidase preparation isolated from submerged liquid culture of Fomitella fraxinea (FFEP). FFEP was prepared by ammonium sulfate (30–80%) precipitation from submerged culture of F. fraxinea. FFEP was used to prepare minor ginsenosides from protopanaxadiol (PPD)-type ginsenoside (PPDG-F) or total ginsenoside fraction (TG-F). In addition, biotransformation of major ginsenosides into minor ginsenosides as affected by reaction time and pH were investigated by TLC and HPLC analyses, and the metabolites were also identified by UPLC/negative-ESI-Q-TOF-MS analysis. FFEP biotransformed ginsenosides Rb1 and Rc into C-K via the following pathways: Rd → F2 → C-K for Rb1 and both Rd → F2→ C-K and C-Mc1 → C-Mc → C-K for Rc, respectively, while C-Y is formed from Rb2 via C-O. FFEP can be applied to produce minor ginsenosides C-K and C-Y from PPDG-F or TG-F. To the best of our knowledge, this study is the first to report the production of C-K and C-Y from major ginsenosides by basidiomycete F. fraxinea.

Qualitatively and quantitatively investigating the metabolism of 20(S)-protopanaxadiol-type ginsenosides by gut microbiota of different species

Ginsenosides Rb1, Rb2, Rb3 and Rc, four major protopanaxadiol (PPD)-type ginsenosides, can be metabolized by gut microbiota. The composition of gut microbiota varies in different species. Existing publications have reported the metabolite fates of ginsenosides by gut microbiota from single species. However, their microbiota-related metabolic species differences have not been evaluated yet. In current study, in vitro anaerobic incubations of PPD-type ginsenosides with gut microbiota from humans, rabbits and rats were conducted. The metabolites of each ginsenoside were then identified by LC-MS. A total of 15 metabolites from the four ginsenosides were identified. The major metabolic pathways were stepwise removals of the C-20 and C-3 sugar moieties to obtain aglycone PPD. The results showed that the hydrolysis rate of C-20 terminal β-D-glucopyranosyl was significantly higher than those of α-L-arabinopyranosyl, β-D-xylopyranosyl and α-L-arabinofuranosyl in different species. The activity of β-glucosidase, the metabolic rates of parent compounds and the formation rates of their metabolites were significantly higher in gut microbiota from rabbits than from humans and rats. Our research draws researchers' attention to the species differences of microbiota-related drug metabolism.

Phytochemistry of ginsenosides: Recent advancements and emerging roles

Ginsenosides, a group of tetracyclic saponins, accounts for the nutraceutical and pharmaceutical relevance of the ginseng (Panax sp.) herb. Owing to the associated therapeutic potential of ginsenosides, their demand has been increased significantly in the last two decades. However, a slow growth cycle, low seed production, and long generation time of ginseng have created a gap between the demand and supply of ginsenosides. The biosynthesis of ginsenosides involves an intricate network of pathways with multiple oxidation and glycosylation reactions. However, the exact functions of some of the associated genes/proteins are still not completely deciphered. Moreover, ginsenoside estimation and extraction using analytical techniques are not feasible with high efficiency. The present review is a step forward in recapitulating the comprehensive aspects of ginsenosides including their distribution, structural diversity, biotransformation, and functional attributes in both plants and animals including humans. Moreover, ginsenoside biosynthesis in the potential plant sources and their metabolism in the human body along with major regulators and stimulators affecting ginsenoside biosynthesis have also been discussed. Furthermore, this review consolidates biotechnological interventions to enhance the biosynthesis of ginsenosides in their potential sources and advancements in the development of synthetic biosystems for efficient ginsenoside biosynthesis to meet their rising industrial demands.

Improved Bioactivity of 3-O-β-D-Glucopyranosyl Platycosides in Biotransformed Platycodon grandiflorum Root Extract by Pectinase from Aspergillus aculeatus

Platycodon grandiflorum (balloon flower) root (Platycodi radix, PR) is used as a health supplement owing to its beneficial bioactive properties. In the present study, the anti-inflammatory, antioxidant, and whitening effects of deglycosylated platycosides (saponins) from PR biotransformed by pectinase from Aspergillus aculeatus were investigated. The bioactivities of the platycosides improved when the number of sugar moieties attached to the aglycone platycosides was decreased. The deglycosylated saponins exhibited higher lipoxygenase inhibitory activities (anti-inflammatory activities) than the precursor platycosides and the anti-inflammatory compound baicalein. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the pectinase-treated PR extract was higher than that of the non-treated PR extract. The trolox-equivalent antioxidant capacity (TEAC) assay showed improved values as the saponins were hydrolyzed. The tyrosinase inhibitory activities (whitening effects) of deglycosylated platycosides were higher than those of the precursor platycosides. Furthermore, 3-O-β-D-glucopyranosyl platycosides showed higher anti-inflammatory, antioxidant, and whitening activities than their precursor glycosylated platycosides. Therefore, 3-O-β-D-glucopyranosyl platycosides may improve the beneficial effects of nutritional supplements and cosmetic products.

Production of Bioactive Deapiosylated Platycosides from Glycosylated Platycosides in Balloon Flower Root Using the Crude Enzyme from the Food-Available Fungus Rhizopus oryzae

Extract from balloon flower root (Platycodi radix) containing platycosides as saponins is a beneficial food additive and is used for their savory taste and the alleviation of respiratory diseases. Deglycosylated platycosides show greater pharmacological effects than glycosylated platycosides. However, there are no reports on the conversion of glycosylated platycosides into deapiosylated platycosides. In this study, we showed that the crude enzyme from Rhizopus oryzae, a generally recognized as safe (GRAS) fungus isolated from meju (fermented soybean brick), completely converted glycosylated platycosides in Platycodi radix extract into deapiosylated platycosides: deapiosylated platycodin D (deapi-PD), deapiosylated platycodin A (deapi-PA), deapiosylated polygalacin D (deapi-PGD), and deapiosylated platyconic acid A (deapi-PCA). Among these, deapi-PA and deapi-PCA were first identified using liquid chromatography/mass spectrometry. The anti-inflammatory and antioxidant effects of deapiosylated platycosides were greater than those of the precursor glycosylated platycosides. These deapiosylated platycosides could improve the properties of functional food additives.

Pharmacokinetics of Ginsenoside Compound K From a Compound K Fermentation Product, CK-30, and From Red Ginseng Extract in Healthy Korean Subjects

Natural protopanaxadiol ginsenosides exhibit low absorption in the human intestine. However, ginsenoside compound K (CK) with 1 conjugated glucose molecule exhibits favorable absorption. The purpose of this study was to compare the pharmacokinetics of ginsenoside CK from a CK fermentation product, CK-30, and from a red ginseng extract. A randomized, open-label, 2-treatment, 2×2 crossover study was conducted. The volunteers were randomly divided into 2 groups. One group received CK-30, and the other group received 2.94 g of a red ginseng extract. After a 7-day washout period, the subjects received an alternative treatment for a single dose. The pharmacokinetic parameters, including the maximum plasma concentration (C_max ) and area under the plasma concentration-time curve from time 0 to time of last measurable concentration, were calculated. The median time to reach C_max of ginsenoside CK after administration of CK-30 was 3.0 hours, whereas the corresponding value of the red ginseng extract was 10.0 hours. Compared with the red ginseng extract, CK-30 resulted in a higher systemic exposure to ginsenoside CK, with a 118.3-fold increase in C_max and a 135.1-fold increase in area under the plasma concentration-time curve from time 0 to time of last measurable concentration. The systemic exposure to ginsenoside CK was significantly higher after administration of CK-30 than red ginseng extract.

Polymorphic Characterization, Pharmacokinetics, and Anti-Inflammatory Activity of Ginsenoside Compound K Polymorphs

Polymorphism exhibits different physicochemical properties, which can impact the bioavailability and bioactivity of solid drugs. This study focused on identifying the polymorphs of ginsenoside compound K (CK) and studying their different behaviors in pharmacokinetics (PK) and pharmacodynamics (PD). Four CK polymorphs (form I, II, III, and IV) from organic solvents were characterized by scanning electron microscope (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and powder X-ray diffraction (PXRD). A feasible LC-MS/MS method was exploited to determine the PK parameters. Form II displayed the most exposure, followed by form I, III, and IV. Notably, all forms showed sex dimorphism, and the bioavailability in the female group was about two-fold higher than in the male group. The PD properties were investigated in carrageenan-induced acute paw inflammation, and form II at 20 mg/kg showed significant inhibition of edema by 42.7%. This study clarified the polymorphic, PK, and PD characters of four crystal forms of CK, and the data suggested that form II had the best efficacy for drug development.

Ameliorative effects of ginsenosides on myelosuppression induced by chemotherapy or radiotherapy

BACKGROUND

and ethnopharmacological relevance: As the major side effect of radiotherapy or chemotherapy, myelosuppression usually leads to anemia, hemorrhage, immunosuppression, and even fatal infections, which may discontinue the process of cancer treatment. As a result, more and more attention is paid to the treatment of myelosuppression. Ginseng, root of Panax ginseng Meyer (Panax ginseng C. A. Mey), is considered as the king of herbs in the Orient, particularly in China, Korea and Japan. Ginsenosides, the most important active ingredients of ginseng, have been shown to have a variety of therapeutic effects, such as neuroprotective, anti-cancer and anti-diabetic properties. Considering that ginsenosides are closely associated with the pathogenesis of myelosuppression, researchers have carried out a few experiments on ginsenosides to attenuate myelosuppression induced by chemotherapy or radiotherapy in recent years.

AIM OF THE STUDY

To summarize previous studies about the effects of ginsenosides on alleviating myelosuppression and the mechanisms of action.

METHODS

Literatures in this review were searched in PubMed, China National Knowledge Infrastructure (CNKI), Web of Science, and ScienceDirect.

RESULTS

Ginsenosides play an important role in relieving myelosuppression predominantly by restoring hematopoiesis and immunity.

CONCLUSION

Ginsenosides might be potential candidates for the treatment of myelosuppression induced by chemotherapy or radiotherapy.

Biotransformation of Ginsenoside Rb1 to Ginsenoside CK by Strain XD101: a Safe Bioconversion Strategy

Ginsenoside Rb1 is the main predominant component in Panax species. In this study, an eco-friendly and convenient preparation method for ginsenoside CK has been established, and five strains of β-glucosidase-producing microorganisms were screened out from the soil of a Panax notoginseng planting field using Esculin-R2A agar. Aspergillus niger XD101 showed that it has excellent biocatalytic activity for ginsenosides; one of the isolates can convert ginsenoside Rb1 to CK using extracellular enzyme from the mycelium. Mycelia of A. niger were cultivated in wheat bran media at 30 °C for 11 days. By the removal of mycelia from cultured broth, enzyme salt fractionation by ammonium sulfate (70%, v/v) precipitation, and dialysis, sequentially, crude enzyme preparations from fermentation liquid supernatant were obtained. The enzymatic transformed Rb1 as the following pathways: Rb1→Rd→F2→CK. The optimized reaction conditions are at reaction time of 72 h, in the range of pH 4-5, and temperature of 50-60 °C. Active minor ginsenosides can be obtained by a specific bioconversion via A. niger XD101 producing the ginsenoside-hydrolyzing β-glucosidase. In addition, the crude enzyme can be resulted in producing ginsenoside CK via conversion of ginsenoside Rb1 at high conversion yield (94.4%). FDA generally regarded, A.niger as safe microorganism. Therefore, these results indicate that A. niger XD10 may provide an alternative method to prepare ginsenoside CK without food safety issues in the pharmaceutical industry.

Complete Bioconversion of Protopanaxadiol-Type Ginsenosides to Compound K by Extracellular Enzymes from the Isolated Strain Aspergillus tubingensis

A compound K-producing fungus was isolated from meju (fermented soybean brick) and identified as the generally recognized as safe (GRAS) strain Aspergillus tubingensis. The extracellular enzymes obtained after the cultivation of 6 days in the medium with 20 g/L citrus pectin as an inducer showed the highest compound K-producing activity among the inducers tested. Under the optimized conditions of 0.05 mM MgSO₄, 55 °C, pH 4.0, 13.4 mM protopanaxadiol (PPD)-type ginsenosides, and 11 mg/mL enzymes, the extracellular enzymes from A. tubingensis completely converted PPD-type ginsenosides in the ginseng extract to 13.4 mM (8.35 mg/mL) compound K after 20 h, with the highest concentration and productivity among the results reported so far. As far as we know, this is the first GRAS enzyme to completely convert all PPD-type ginsenosides to compound K.

Cloning and Production of Thermostable Enzymes for the Hydrolysis of Steryl Glucosides in Biodiesel

Vegetable oil-derived biodiesels have a major quality problem due to the presence of precipitates formed by steryl glucosides, which clog filters and injectors of diesel engines. An efficient, scalable, and cost-effective method to hydrolyze steryl glucosides using thermostable enzymes has been developed. Here, methods to discover, express in recombinant microorganisms and manufacture enzymes with SGase activity, as well as methods to treat biodiesel with such enzymes, and to measure the content of steryl glucosides in biodiesel samples are presented.

Highly regioselective biotransformation of ginsenoside Rg1 to 25-OH derivatives of 20(S/R)-Rh1 by Cordyceps Sinensis

25-OH ginsenosides are potent and rare prodrugs in natural sources. However current strategies for such modification always end up in undesirable side products and unsatisfied yield that hinders them from further applications. Herein, ginsenoside Rg1 was thoroughly converted into 20(S/R)-Rh1 and 25-OH-20(S/R)-Rh1 by Cordyceps Sinensis in an optimum medium. The chemical correctness of either 25-OH-20(S/R)-Rh1 epimers was validated by LC-IT-TOF-MSn and ¹³C NMR spectrometry. The biocatalytic pathway was established as Rg1 → 20(S/R)-Rh1 → 25-OH-20(S/R)-Rh1. The molar bioconversion rate for total 25-OH-20(S/R)-Rh1 was calculated to be 82.5%, of which S-configuration accounted for 43.2% while R-configuration 39.3%. These two 25-OH derivatives are direct hydration products from 20(S/R)-Rh1 without other side metabolites, suggesting this is a highly regioselective process. In conclusion, this biocatalytic system could be harnessed to facilitate the preparation of diversified 25-OH ginsenosides with high yields of the target compound and simple chemical background in the reaction mixture.

Efficient production of the anti-aging drug Cycloastragenol: insight from two Glycosidases by enzyme mining

The telomerase activator cycloastragenol (CA) is regarded as a potential anti-aging drug with promising applications in the food and medical industry. However, one remaining challenge is the low efficiency of CA production. Herein, we developed an enzyme-based approach by applying two enzymes (β-xylosidase: Xyl-T; β-glucosidase: Bgcm) for efficient CA production. Both key glycosidases, mined by activity tracking or homology sequence screening, were successfully over-expressed and showed prominent enzymatic activity profiles, including widely pH stability (Xyl-T: pH 3.0-8.0; Bgcm: pH 4.0-10.0), high catalytic efficiency (k_cat/K_m: 0.096 mM^-1s^-1 (Xyl-T) and 3.08 mM^-1s^-1 (Bgcm)), and mesophilic optimum catalytic temperature (50 °C). Besides, the putative catalytic residues (Xyl-T: Asp311/Glu 521; Bgcm: Asp311/Glu 521) and the potential substrate-binding mechanism of Xyl-T and Bgcm were predicted by comprehensive computational analysis, providing valuable insight into the hydrolysis of substrates at the molecular level. Notably, a rationally designed two-step reaction process was introduced to improve the CA yield and increased up to 96.5% in the gram-scale production, providing a potential alternative for the industrial CA bio-production. In essence, the explored enzymes, the developed enzyme-based approach, and the obtained knowledge from catalytic mechanisms empower researchers to further engineer the CA production and might be applied for other chemicals synthesis. KEY POINTS: • A β-xylosidase and a β-glucosidase were mined to hydrolyze ASI into CA. • The two recombinant glycosidases showed prominent catalytic profiles. • Two-step enzymatic catalysis for CA production from ASI was developed. Graphical abstract.

Biotransformation of Protopanaxadiol-Type Ginsenosides in Korean Ginseng Extract into Food-Available Compound K by an Extracellular Enzyme from Aspergillus niger

Compound K (C-K) is one of the most pharmaceutically effective ginsenosides, but it is absent in natural ginseng. However, C-K can be obtained through the hydrolysis of protopanaxadiol-type ginsenosides (PPDGs) in natural ginseng. The aim of this study was to obtain the high concentration of food-available C-K using PPDGs in Korean ginseng extract by an extracellular enzyme from Aspergillus niger KACC 46495. A. niger was cultivated in the culture medium containing the inducer carboxymethyl cellulose (CMC) for 6 days. The extracellular enzyme extracted from A. niger was prepared from the culture broth by filtration, ammonium sulfate, and dialysis. The extracellular enzyme was used for C-K production using PPDGs. The glycoside-hydrolyzing pathways for converting PPDGs into C-K by the extracellular enzyme were Rb1 → Rd → F2 → C-K, Rb2 → Rd or compound O → F2 or compound Y → C-K, and Rc → Rd or compound Mc1 → F2 or compound Mc → C-K. The extracellular enzyme from A. niger at 8.0 mg/ml, which was obtained by the induction of CMC during the cultivation, converted 6.0 mg/ml (5.6 mM) PPDGs in Korean ginseng extract into 2.8 mg/ml (4.5 mM) food-available C-K in 9 h, with a productivity of 313 mg/l/h and a molar conversion of 80%. To the best of our knowledge, the productivity and concentration of C-K of the extracellular enzyme are the highest among those by crude enzymes from wild-type microorganisms.

Diversity of Ginsenoside Profiles Produced by Various Processing Technologies

Ginseng is a traditional medicinal herb commonly consumed world-wide owing to its unique family of saponins called ginsenosides. The absorption and bioavailability of ginsenosides mainly depend on an individual's gastrointestinal bioconversion abilities. There is a need to improve ginseng processing to predictably increase the pharmacologically active of ginsenosides. Various types of ginseng, such as fresh, white, steamed, acid-processed, and fermented ginsengs, are available. The various ginseng processing methods produce a range ginsenoside compositions with diverse pharmacological properties. This review is intended to summarize the properties of the ginsenosides found in different Panax species as well as the different processing methods. The sugar moiety attached to the C-3, C-6, or C-20 deglycosylated to produce minor ginsenosides, such as Rb1, Rb2, Rc, Rd→Rg3, F2, Rh2; Re, Rf→Rg1, Rg2, F1, Rh1. The malonyl-Rb1, Rb2, Rc, and Rd were demalonylated into ginsenoside Rb1, Rb2, Rc, and Rd by dehydration. Dehydration also produces minor ginsenosides such as Rg3→Rk1, Rg5, Rz1; Rh2→Rk2, Rh3; Rh1→Rh4, Rk3; Rg2→Rg6, F4; Rs3→Rs4, Rs5; Rf→Rg9, Rg10. Acetylation of several ginsenosides may generate acetylated ginsenosides Rg5, Rk1, Rh4, Rk3, Rs4, Rs5, Rs6, and Rs7. Acid processing methods produces Rh1→Rk3, Rh4; Rh2→Rk1, Rg5; Rg3→Rk2, Rh3; Re, Rf, Rg2→F1, Rh1, Rf2, Rf3, Rg6, F4, Rg9. Alkaline produces Rh16, Rh3, Rh1, F4, Rk1, ginsenoslaloside-I, 20(S)-ginsenoside-Rh1-60-acetate, 20(R)-ginsenoside Rh19, zingibroside-R1 through hydrolysis, hydration addition reactions, and dehydration. Moreover, biological processing of ginseng generates the minor ginsenosides of Rg3, F2, Rh2, CK, Rh1, Mc, compound O, compound Y through hydrolysis reactions, and synthetic ginsenosides Rd12 and Ia are produced through glycosylation. This review with respect to the properties of particular ginsenosides could serve to increase the utilization of ginseng in agricultural products, food, dietary supplements, health supplements, and medicines, and may also spur future development of novel highly functional ginseng products through a combination of various processing methods.

Prebiotics enhance the biotransformation and bioavailability of ginsenosides in rats by modulating gut microbiota

Background

Gut microbiota mainly function in the biotransformation of primary ginsenosides into bioactive metabolites. Herein, we investigated the effects of three prebiotic fibers by targeting gut microbiota on the metabolism of ginsenoside Rb1 in vivo.

Methods

Sprague Dawley rats were administered with ginsenoside Rb1 after a two-week prebiotic intervention of fructooligosaccharide, galactooligosaccharide, and fibersol-2, respectively. Pharmacokinetic analysis of ginsenoside Rb1 and its metabolites was performed, whilst the microbial composition and metabolic function of gut microbiota were examined by 16S rRNA gene amplicon and metagenomic shotgun sequencing.

Results

The results showed that peak plasma concentration and area under concentration time curve of ginsenoside Rb1 and its intermediate metabolites, ginsenoside Rd, F2, and compound K (CK), in the prebiotic intervention groups were increased at various degrees compared with those in the control group. Gut microbiota dramatically responded to the prebiotic treatment at both taxonomical and functional levels. The abundance of Prevotella, which possesses potential function to hydrolyze ginsenoside Rb1 into CK, was significantly elevated in the three prebiotic groups (P < 0.05). The gut metagenomic analysis also revealed the functional gene enrichment for terpenoid/polyketide metabolism, glycolysis, gluconeogenesis, propanoate metabolism, etc.

Conclusion

These findings imply that prebiotics may selectively promote the proliferation of certain bacterial stains with glycoside hydrolysis capacity, thereby, subsequently improving the biotransformation and bioavailability of primary ginsenosides in vivo.

Advances in the Production of Minor Ginsenosides Using Microorganisms and Their Enzymes

Abstract Minor ginsenodes are of great interest due to their diverse pharmacological activities such as their anti-cancer, anti-diabetic, neuroprotective, immunomodulator, and anti-inflammatory effects. The miniscule amount of minor ginsenosides in ginseng plants has driven the development of their mass production methods. Among the various production methods for minor ginsenosides, the utilization of microorganisms and their enzymes are considered as highly specific, safe, and environmentally friendly. In this review, various minor ginsenosides production strategies, namely utilizing microorganisms and recombinant microbial enzymes, for biotransforming major ginsenosides into minor ginsenoside, as well as constructing synthetic minor ginsenosides production pathways in yeast cell factories, are described and discussed. Furthermore, the present challenges and future research direction for producing minor ginsenosides using those approaches are discussed.

Biotransformation of Glycosylated Saponins in Balloon Flower Root Extract into 3-O-β-D-Glucopyranosyl Platycosides by Deglycosylation of Pectinase from Aspergillus aculeatus

Platycodon grandiflorum root (Platycodi radix) saponins, platycosides, have been used as health supplements and food items for the treatment of respiratory disorders and pulmonary diseases. Deglycosylated saponins have been known to exert stronger biological effects than their glycosylated forms. In the present study, glycosylated platycosides in Platycodi radix extract were biotransformed into deglycosylated 3-O-β-D-glucopyranosyl platycosides, including 3-O-β-Dglucopyranosyl platycodigenin, 3-O-β-D-glucopyranosyl polygalacic acid, and 3-O-β-Dglucopyranosyl platyconic acid, by pectinase from Aspergillus aculeatus. This is the first report on the quantitative enzymatic production of 3-O-β-D-glucopyranosyl platycosides. The chemical structures of 3-O-β-D-glucopyranosyl platycosides were identified with LC/MS. Moreover, the biotransformation pathways of the three types of platycosides in Platycodi radix into 3-O-β-Dglucopyranosyl platycosides were established.