Metals/bisulfite system involved generation of 24-sulfonic-25-ene ginsenoside Rg1, a potential quality control marker for sulfur-fumigated ginseng

Ginseng is a most popular health-promoting food with ginsenosides as its main bioactive ingredients. Illegal sulfur-fumigation causes ginsenosides convert to toxic sulfur-containing derivatives, and reduced the efficacy/safety of ginseng. 24-sulfo-25-ene ginsenoside Rg1 (25-ene SRg1), one of the sulfur-containing derivatives, is a potential quality control marker of fumigated ginseng, but with low accessibility owing to its unknown generation mechanism. In this study, metals/bisulfite system involved generation mechanism was investigated and verified. The generation of 25-ene SRg1 in sulfur-fumigated ginseng is that SO2, formed during sulfur-fumigation, reacted with water and ionized into HSO3-. On the one hand, under the metals/bisulfite system, HSO3- generates HSO5- and free radicals which converted ginsenoside Rg1 to 24,25-epoxide Rg1; on the other hand, as a nucleophilic group, HSO3- reacted with 24,25-epoxide Rg1 and further dehydrated to 25-ene SRg1. This study provided a technical support for the promotion of 25-ene SRg1 as the characteristic quality control marker of sulfur-fumigated ginseng.

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.

Heterogeneous Transformation of Ginsenoside Rb1 with Ethanol Using Heteropolyacid-Loaded Mesoporous Silica and Identification by HPLC-MS

Rare ginsenosides with major pharmacological effects are barely present in natural ginseng and are required to be obtained by transformation. In the current study, ginsenoside Rb1 was chemically transformed with the involvement of ethanol molecules to prepare rare ginsenosides using the synthesized heterogeneous catalyst 12-HPW@MeSi. A total of 16 transformation products were obtained and identified using high-performance liquid chromatography coupled with multistage tandem mass spectrometry and high-resolution mass spectrometry. Ethanol molecules were involved in the production of 6 transformation products by adding to the C-20(21), C-20(22), or C-24(25) double bonds on the aglycone to produce ethoxyl groups at the C-25 and C-20 positions. Transformation pathways of ginsenoside Rb1 are summarized, which involve deglycosylation, elimination, cycloaddition, epimerization, and addition reactions. In addition, 12-HPW@MeSi was recyclable through a simple centrifugation, maintaining an 85.1% conversion rate of Rb1 after 3 cycles. This work opens up an efficient and recycled process for the preparation of rare ginsenosides with the involvement of organic molecules.

How to More Effectively Obtain Ginsenoside Rg5: Understanding Pathways of Conversion

Ginsenoside Rg5, a relatively uncommon secondary ginsenoside, exhibits notable pharmacological activity and is commonly hypothesized to originate from the dehydration of Rg3. In this work, we compared different conversion pathways using Rb1, R-Rg3 and S-Rg3 as the raw material under simple acid catalysis. Interestingly, the results indicate that the conversion follows this reaction activity order Rb1 > S-Rg3 > R-Rg3, which is contrary to the common understanding of Rg5 obtained from Rg3 by dehydration. Our experimental results have been fully confirmed by theoretical calculations and a NOESY analysis. The DFT analysis reveals that the free energies of S-Rg3 and R-Rg3 in generating carbocation are 7.56 mol/L and 7.57 mol/L, respectively, which are significantly higher than the free energy of 1.81 mol/L when Rb1 generates the same carbocation. This finding aligns with experimental evidence suggesting that Rb1 is more prone to generating Rg5 than Rg3. The findings from the nuclear magnetic resonance (NMR) analysis suggest that the fatty chains (C22-C27) in R-Rg3 and S-Rg3 adopt a Gauche conformation and an anti conformation with C16-C17 and C13-C17, respectively, due to the relatively weak repulsive van der Waals force. Therefore, the configuration of R-Rg3 is more conducive to the formation of intramolecular hydrogen bonds between 20C-OH and 12C-OH, whereas S-Rg3 lacks this capability. Consequently, this also explains the fact that S-Rg3 is more prone to dehydration to generate Rg5 than R-Rg3. Additionally, our research reveals that the synthetic route of Rg5 derived from protopanaxadiol (PPD)-type ginsenosides (including Rb1, Rb2, Rb3, Rc and Rd) exhibits notable advantages in terms of efficacy, purity and yield when compared to the pathway originating from Rg3. Moreover, this study presents a highly effective and practical approach for the extensive synthesis of Rg5, thereby facilitating the exploration of its pharmacological properties and potential application in drug discovery.

Advances on hormone-like activity of Panax ginseng and ginsenosides

Traditional Chinese medicine (TCM) has been paid much attentions due to the prevention and treatment of steroid hormone disorders. Ginseng, the root of Panax ginseng C. A. Meyer (Araliaceae), is one of the most valuable herbs in complementary and alternative medicines around the world. A series of dammarane triterpenoid saponins, also known as phytosteroids, were reported as the primary ingredients of Ginseng, and indicated broad spectral pharmacological actions, including anti-cancer, anti-inflammation and anti-fatigue. The skeletons of the dammarane triterpenoid aglycone are structurally similar to the steroid hormones. Both in vitro and in vivo studies showed that Ginseng and its active ingredients have beneficial hormone-like role in hormonal disorders. This review thus summarizes the structural similarities between hormones and dammarane ginsenosides and integrates the analogous effect of Ginseng and ginsenosides on prevention and treatment of hormonal disorders published in recent twenty years (1998-2018). The review may provide convenience for anticipate structure-function relationship between saponins structure and hormone-like effect.

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.

Interactions Between Gut Microbiota, Host, and Herbal Medicines: A Review of New Insights Into the Pathogenesis and Treatment of Type 2 Diabetes

Herbal medicines (HMs) are a major subset of complementary and alternative medicine. They have been employed for the efficient clinical management of type 2 diabetes mellitus (T2DM) for centuries. However, the related underlying mechanisms still remain to be elucidated. It has been found out that microbiota is implicated in the pathogenesis and treatment of T2DM. An interplay between gut microbiota and host occurs mainly at the gastrointestinal mucosal barrier. The host movements influence the composition and abundance of gut microbiota, whereas gut microbiota in turn modulate the metabolic and immunological activities of the host. Intestinal dysbiosis, endotoxin-induced metabolic inflammation, immune response disorder, bacterial components and metabolites, and decreased production of short-chain fatty acids are considered significant pathogenic mechanisms underlying T2DM. The interaction between gut microbiota and HMs during T2DM treatment has been investigated in human, animal, and in vitro studies. HMs regulate the composition of beneficial and harmful bacteria and decrease the inflammation caused by gut microbiota. Furthermore, the metabolism of gut microbiota modulates HM biotransformation. In this review, we have summarized such research findings, with the aim to improve our understanding of the pathogenesis and potential therapeutic mechanisms of HMs in T2DM and to provide new insights into specific targeted HM-based therapies and drug discovery.