Cooperated biotransformation of ginsenoside extracts into ginsenoside 20( S )‐Rg3 by three thermostable glycosidases

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.

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.

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.

Combinatorial Enzymatic Catalysis for Bioproduction of Ginsenoside Compound K

Ginsenoside compound K (CK) is an emerging functional food or pharmaceutical product. To date, there are still challenges to exploring effective catalytic enzymes for enzyme-catalyzed manufacturing processes and establishing enzyme-catalyzed processes. Herein, we identified three ginsenoside hydrolases BG07 (glucoamylase), BG19 (β-glucosidase), and BG23 (β-glucosidase) from Aspergillus tubingensis JE0609 by transcriptome analysis and peptide mass fingerprinting. Among them, BG23 was expressed in Komagataella phaffii with a high volumetric activity of 235.73 U mL-1 (pNPG). Enzymatic property studies have shown that BG23 is an acidic (pH adaptation range of 4.5-7.0) and mesophilic (thermostable < 50 °C) enzyme. Moreover, a one-pot combinatorial enzyme-catalyzed strategy based on BG23 and BGA35 (β-galactosidase from Aspergillus oryzae) was established, with a high CK yield of 396.7 mg L-1 h-1. This study explored the ginsenoside hydrolases derived from A. tubingensis at the molecular level and provided a reference for the efficient production of CK.

Progress in the Conversion of Ginsenoside Rb1 into Minor Ginsenosides Using β-Glucosidases

In recent years, minor ginsenosides have received increasing attention due to their outstanding biological activities, yet they are of extremely low content in wild ginseng. Ginsenoside Rb1, which accounts for 20% of the total ginsenosides, is commonly used as a precursor to produce minor ginsenosides via β-glucosidases. To date, many research groups have used different approaches to obtain β-glucosidases that can hydrolyze ginsenoside Rb1. This paper provides a compilation and analysis of relevant literature published mainly in the last decade, focusing on enzymatic hydrolysis pathways, enzymatic characteristics and molecular mechanisms of ginsenoside Rb1 hydrolysis by β-glucosidases. Based on this, it can be concluded that: (1) The β-glucosidases that convert ginsenoside Rb1 are mainly derived from bacteria and fungi and are classified as glycoside hydrolase (GH) families 1 and 3, which hydrolyze ginsenoside Rb1 mainly through the six pathways. (2) Almost all of these β-glucosidases are acidic and neutral enzymes with molecular masses ranging from 44-230 kDa. Furthermore, the different enzymes vary widely in terms of their optimal temperature, degradation products and kinetics. (3) In contrast to the GH1 β-glucosidases, the GH3 β-glucosidases that convert Rb1 show close sequence-function relationships. Mutations affecting the substrate binding site might alter the catalytic efficiency of enzymes and yield different prosapogenins. Further studies should focus on elucidating molecular mechanisms and improving overall performances of β-glucosidases for better application in food and pharmaceutical industries.

Ultrahigh-performance liquid chromatography coupled to ion mobility quadrupole time-of-flight mass spectrometry profiling and unveiling the transformation of ginsenosides by the dual conditions of citric acid and high-pressure steaming

RATIONALE

Many methods have been reported for the production of rare ginsenosides, including heat treatment, acid hydrolysis, alkaline hydrolysis, enzymatic hydrolysis, and microbial transformation. However, the conversion of original ginsenosides to rare ginsenosides under the dual conditions of citric acid and high-pressure steam sterilization has rarely been reported.

METHODS

In this study, a method involving ultrahigh-performance liquid chromatography coupled to ion mobility quadrupole time-of-flight mass spectrometry was developed for analysis of chemical transformation of protopanaxatriol (PPT)-type ginsenosides Rg₁ and Re, protopanaxadiol (PPD)-type ginsenoside Rb₁ , and total ginsenosides in the dual conditions of citric acid and high-pressure steam sterilization. An internal ginsenoside database containing 126 known ginsenosides and 18 ginsenoside reference compounds was established to identify the transformation products and explore possible transformation pathways and mechanisms.

RESULTS

A total of 54 ginsenosides have been preliminarily identified in the transformation products of PPD-type ginsenosides Rg₁ and Re, PPD-type ginsenoside Rb₁ , and total ginsenosides, and the possible transformation pathways were as follows: Rg₁ , Re → 20(S)-Rh₁₂ , 20(R)-Rh₁₂ ; Rg₁ , Re → 20(S)-Rh₁ , 20(R)-Rh₁  → Rk₃ , Rh₄ , Rh₅ ; Rb₁  → gypenoside LXXV; Rb₁  → 20(S)-Rg₃ , 20(R)-Rg₃  → Rk₁ , Rg₅ ; Re → 20(S)-Rg₂ , 20(R)-Rg₂  → 20(S)-Rf₂ , 20(R)-Rf₂ , Rg₄ , F₄ .

CONCLUSIONS

The results elucidated the possible transformation pathways and mechanisms of ginsenosides in the dual conditions of citric acid and high-pressure steam sterilization, which were helpful for revealing the mechanisms of ginsenosides and enhanced safety and quality control of pharmaceuticals and nutraceuticals. Meanwhile, a simple, efficient, and practical method was developed for the production of rare ginsenosides, which has the potential to produce diverse rare ginsenosides on an industrial scale.

Enhancement of biotransformation of ginsenosides in white ginseng roots by aerobic co-cultivation of Bacillus subtilis and Trichoderma reesei

In the present work, the biotransformation of ginsenosides in white ginseng roots was innovatively investigated using the aerobic fermentation by the co-cultivation of Bacillus subtilis and Trichoderma reesei. It is found that in the co-cultivation mode, the optimal nitrogen source was corn steep liquor, and the loading of ginseng powder and inoculation proportion of B. subtilis and T. reesei were 15 g/L and 1:4, respectively. The total ginsenoside yield and production of minor ginsenosides in the co-cultivation mode obviously enhanced in comparison to the monoculture mode. Meanwhile, the maximal total ginsenoside yield of 21.79% and high hydrolase activities were achieved using the staged inoculation at the inoculation proportion of 1:4 in the co-cultivation mode, the production of minor ginsenosides such as Rg3 and Rh1, Rh2 was significantly strengthened, and the pharmacological activities of the fermented solution obviously improved. The enhancement of ginsenoside transformation can be mainly attributed to hydrolysis of the produced hydrolases and metabolism of two probiotics. This result clearly reveals that using the staged inoculation in co-cultivation fermentation mode was favor of the ginsenoside biotransformation in ginseng due to non-synchronous cell growth and different metabolic pathways of both probiotics. This work can provide a novel method for enhancing ginsenoside transformation of ginseng.Key points• Co-cultivation fermentation significantly promoted ginsenoside biotransformation.• The staged inoculation in co-culture mode was an optimal operation method.• The pharmacological activity of the co-cultured solution was significantly enhanced.