High-performance liquid chromatography coupled with tandem mass spectrometry applied for metabolic study of ginsenoside Rb1 on rat

Biotransformation of Ginsenoside Rb1 to Ginsenoside Rd and 7 Rare Ginsenosides Using Irpex lacteus with HPLC-HRMS/MS Identification

The biotransformation of ginsenosides using microorganisms represents a promising and ecofriendly approach for the production of rare ginsenosides. The present study reports on the biotransformation of ginsenoside Rb1 using the fungus Irpex lacteus, resulting in the production of ginsenoside Rd and seven rare ginsenosides with novel structures. Employing high-performance liquid chromatography coupled with high-resolution tandem mass spectrometry, the identities of the transformation products were rapidly determined. Two sets of isomers with molecular weights of 980.56 and 962.55 were discovered among the seven rare ginsenosides, which were generated through the isomerization of the olefin chain in the protopanaxadiol (PPD)-type ginsenoside skeleton. Each isomer exhibited characteristic fragment ions and neutral loss patterns in their tandem mass spectra, providing evidence of their unique structures. Time-course experiments demonstrated that the transformation reaction reached equilibrium after 14 days, with Rb1 initially generating Rd and compound 5, followed by the formation of other rare ginsenosides. The biotransformation process catalyzed by I. lacteus was found to involve not only the typical deglycosylation reaction at the C-20 position but also hydroxylation at the C-22 and C-23 positions, as well as hydrogenation, transfer, and cyclization of the double bond at the C-24(25) position. These enzymatic capabilities extend to the structural modification of other PPD-type ginsenosides such as Rc and Rd, revealing the potential of I. lacteus for the production of a wider range of rare ginsenosides. The transformation activities observed in I. lacteus are unprecedented among fungal biotransformations of ginsenosides. This study highlights the application of a medicinal fungi-based biotransformation strategy for the generation of rare ginsenosides with enhanced structural diversity, thereby expanding the variety of bioactive compounds derived from ginseng.

Ginsenoside Rb1, a principal effective ingredient of Panax notoginseng, produces pain antihypersensitivity by spinal microglial dynorphin A expression

Panax notoginseng (Chinese ginseng, Sanqi), one of the major ginseng species, has been traditionally used to alleviate different types of chronic pain. The raw P. notoginseng powder is commonly available in China as a non-prescription drug to treat various aliments including arthritic pain. However, strong scientific evidence is needed to illustrate its pain antihypersensitive effects, effective ingredients and mechanism of action. The oral P. notoginseng powder dose-dependently alleviated formalin-induced tonic hyperalgesia, and its total ginsenosides remarkably inhibited neuropathic pain hypersensitivity. Ginsenoside Rb1, the most abundant ginsenoside of P. notoginseng, dose-dependently produced neuropathic pain antihypersensitivity. Conversely, ginsenosides Rg1, Re and notoginseng R1, the other major saponins from P. notoginseng, failed to inhibit formalin-induced tonic pain or mechanical allodynia in neuropathic pain. Ginsenoside Rb1 metabolites ginsenosides Rg3, Compound-K and protopanaxadiol also had similar antineuropathic pain efficacy to ginsenoside Rb1. Additionally, intrathecal ginsenoside Rb1 specifically stimulated dynorphin A expression which was colocalized with microglia but not neurons or astrocytes in the spinal dorsal horn and primary cultured cells. Pretreatment with microglial metabolic inhibitor minocycline, dynorphin A antiserum and specific κ-opioid receptor antagonist GNTI completely blocked Rb1-induced mechanical antiallodynia in neuropathic pain. Furthermore, the specific glucocorticoid receptor (GR) antagonist Dex-21-mesylate (but not GPR30 estrogen receptor antagonist G15) also entirely attenuated ginsenoside Rb1-related antineuropathic pain effects. All these results, for the first time, show that P. notoginseng alleviates neuropathic pain and ginsenoside Rb1 is its principal effective ingredient. Furthermore, ginsenoside Rb1 inhibits neuropathic pain by stimulation of spinal microglial dynorphin A expression following GR activation.

UPLC-MS/MS assay for the simultaneous determination of pyrotinib and its oxidative metabolite in rat plasma: Application to a pharmacokinetic study

Pyrotinib is an irreversible EGFR/HER2 inhibitor that has been approved for the treatment of breast cancer. The aim of this work was to establish a quantification method for the simultaneous determination of pyrotinib and its metabolite pyrotinib-lactam in rat plasma using UPLC-MS/MS. After simple protein precipitation with acetonitrile, the analytes and internal standard (neratinib) were separated on an ACQUITY BEH C₁₈ column (2.1 × 50 mm, 1.7 μm) using a mobile phase of water containing 0.1% formic acid and acetonitrile. The detection was performed using selected reaction monitoring mode with precursor-to-product ion transitions at m/z 583.2 > 138.1 for pyrotinib, m/z 597.2 > 152.1 for pyrotinib-lactam, and m/z 557.2 > 112.1 for internal standard. The assay exhibited excellent linearity in the concentration range of 0.5-1000 ng/mL for pyrotinib and pyrotinib-lactam. The assay met the criteria of the United States Food and Drug Administration-validated bioanalytical methods and was successfully applied to a pharmacokinetic study of pyrotinib and its metabolite for the first time. Our results demonstrated that pyrotinib rapidly converted into pyrotinib-lactam, whose in vivo exposure was 21% that of pyrotinib.

Metabolic study of ginsenoside Rg3 and glimepiride in type 2 diabetic rats by liquid chromatography coupled with quadrupole-Orbitrap mass spectrometry

RATIONALE

Ginsenoside Rg3 and glimepiride have been applied to treat type 2 diabetes (T2DM) because of their good hypoglycemic effects. In this study, the effects of ginsenoside Rg3 acting synergistically with glimepiride were investigated in liver microsomes from rats with type 2 diabetes.

METHODS

An in vitro incubation system with normal rat liver microsomes (RLM) and type 2 diabetic rat liver microsomes (TRLM) was developed. The system also included two experimental groups consisting of RLM and TRLM pretreated with ginsenoside Rg3 and glimepiride (named the RLMR and TRLMR groups, respectively). The metabolism in the different groups was analyzed by ultra-performance liquid chromatography coupled with quadrupole-orbitrap mass spectrometry (UPLC/Q-Orbitrap MS).

RESULTS

The results showed that the concentration of glimepiride increased in RLM and TRLM after treatment with ginsenoside Rg3. Five metabolites (M1-M5) of glimepiride were found, and they were named 3N-hydroxyglimepiride, hydroxyglimepiride, 1,2-epoxy ether-3-hydroxyglimepiride, 1N-hydroxyglimepiride and 1N,2C,S,O,O-epoxy ether-3-hydroxyglimepiride. The metabolite of ginsenoside Rg3 was ginsenoside Rh2.

CONCLUSIONS

An in vitro incubation system with RLM and TRLM was developed. The system revealed pathways that produce glimepiride metabolites. Ginsenoside Rg3 may inhibit the activity of cytochrome P450 enzymes in vitro. The present study showed that ginsenoside Rg3 and glimepiride may be combined for the treatment of T2DM.

Evaluation of storage period of fresh ginseng for quality improvement of dried and red processed varieties

Background

Dried and red ginseng are well-known types of processed ginseng and are widely used as healthy food. The dried and red ginseng quality may vary with the storage period of raw ginseng. Therefore, herein, the effect of the storage period of fresh ginseng on processed ginseng quality was evaluated through multicomponent quantification with statistical analysis.

Methods

A method based on ultrahigh performance liquid chromatography coupled to triple quadrupole mass spectrometry in multiple-reaction monitoring mode (UPLC-MRM-MS) was developed for quantitation of ginsenosides and oligosaccharides in dried and red ginseng. Principal component analysis and partial least squares discriminant analysis were conducted to evaluate the dynamic distributions of ginsenosides and oligosaccharides after different storage periods.

Results

Eighteen PPD, PPT and OLE ginsenosides and nine reducing and nonreducing oligosaccharides were identified and quantified. With storage period extension, the ginsenoside content in the processed ginseng increased slightly in the first 2 weeks and decreased gradually in the following 9 weeks. The content of reducing oligosaccharides decreased continuously as storage time extending, while that of the nonreducing oligosaccharides increased. Chemical conversions occurred during storage, based on which potential chemical markers for the storage period evaluation of fresh ginseng were screened.

Conclusion

According to ginsenoside and oligosaccharide distributions, it was found that the optimal storage period was 2 weeks and that the storage period of fresh ginseng should not exceed 4 weeks at 0 °C. This study provides deep insights into the quality control of processed ginseng and comprehensive factors for storage of raw ginseng.

Dammarane-type leads panaxadiol and protopanaxadiol for drug discovery: Biological activity and structural modification

Based on the definite therapeutic benefits, such as neuroprotective, cardioprotective, anticancer, anti-diabetic and so on, the Panax genus which contains many valuable plants, including ginseng (Panax ginseng C.A. Meyer), notoginseng (Panax notoginseng) and American ginseng (Panax quinquefolius L.), attracts research focus. Actually, the biological and pharmacological effects of the Panax genus are mainly attributed to the abundant ginsenosides. However, the low membrane permeability and the gastrointestinal tract influence seriously limit the absorption and bioavailability of ginsenosides. The acid or base hydrolysates of ginsenosides, 20 (R,S)-panaxadiol and 20 (R,S)-protopanaxadiol showed improved bioavailability and diverse pharmacological activities. Moreover, relative stable skeletons and active hydroxyl group at C-3 position and other reactive sites are suitable for structural modification to improve biological activities. In this review, the pharmacological activities of panaxadiol, protopanaxadiol and their structurally modified derivatives are comprehensively summarized.

Pharmacokinetic and metabolic studies of ginsenoside Rb3 in rats using RRLC-Q-TOF-MS

Ginsenoside Rb3 is one of major ginsenosides in Panax ginseng with effect on cardio-vascular and central nervous system. The aim of this study is to develop a rapid resolution liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (RRLC-Q-TOF-MS) method for pharmacokinetic study of ginsenoside Rb3 and simultaneous determination of metabolites in rats. The results showed that the concentration-time profile of ginsenoside Rb3 conformed to a two-compartment pharmacokinetic model after intravenous administration at the dosage of 2.0 mg/kg for rats. The mean plasma elimination half-lives were 13.77 ± 1.23 min and 2045.70 ± 156.20 min for the distribution and exterminate phases t1/2α and t1/2β. In the metabolic study, prototype ginsenoside Rb3 and deglycosylation metabolites were characterized by comparison with the retention time of the standard compounds, accurate mass measurement and the characteristic fragment ions obtained from MS/MS. Two major metabolites Mb1 and M2' were tentatively identified in rat urine samples after intravenous administration, and four possible metabolites Mb1, F2, M2' and CK were detected in rat feces samples after oral administration. The deglycosylation was found to be the major metabolic pathways of ginsenoside Rb3 in rat. The in vivo metabolic pathway of ginsenoside Rb3 was summarized.

LC-MS based metabolic and metabonomic studies of Panax ginseng

INTRODUCTION

Panax ginseng has received much attention as a valuable health supplement with medicinal potential. Its chemical diversity and multiple pharmacological properties call for comprehensive methods to better understand the effects of ginseng and ginsenosides. Liquid chromatography-mass spectrometry (LC-MS) based metabonomic approaches just fit the purpose.

OBJECTIVE

Aims to give a review of recent progress on LC-MS based pharmacokinetic, metabolic, and phytochemical metabolomic studies of ginseng, and metabonomic studies of ginseng intervention effects.

METHODS

The review has four sections: the first section discusses metabolic studies of ginsenosides based on LC-MS, the second focuses on ginsenoside-drug interactions and pharmacokinetic interaction between herb compounds based on LC-MS, the third is phytochemical metabolomic studies of ginseng based on LC-MS, and the fourth deals with metabonomic studies of ginseng intervention effects based on LC-MS.

RESULTS

LC-MS based metabonomic research on ginseng include analysis of single ginsenoside and total ginsenosides. The theory of multi-components and multi-targeted mechanisms helps to explain ginseng effects.

CONCLUSION

LC-MS based metabonomics is a promising way to comprehensively assess ginseng. It is valuable for quality control and mechanism studies of ginseng.

Systematic screening and characterization of Qi-Li-Qiang-Xin capsule-related xenobiotics in rats by ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry

Qi-Li-Qiang-Xin capsule (QLQX), a well-known traditional Chinese medicine prescription (TCMP), is consisted of eleven commonly used herbal medicines, has been widely used for the treatment of chronic heart failure (CHF). However, the absorbed components and related metabolites after oral administration of QLQX are still remaining unknown. In the present work, a reliable and effective method using ultra performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UPLC/Q-TOF-MS) was established to identify QLQX-related xenobiotics in rats. Based on a representative structure based homologous xenobiotics identification (RSBHXI) strategy, a total of eleven compounds (salvianolic acid B, formononetin, benzoylmesaconine, alisol A, sinapine thiocyanate, naringin, tanshinone IIA, ginsenoside Rg1, ginsenoside Rb1, astragaloside IV and periplocin), bearing different chemical core structures, were selected and investigated for their metabolism in vivo. And then, comprehensive metabolic profiles of the holistic multi-ingredients in QLQX were achieved. As a result, a total of 121 QLQX-related xenobiotics (47 prototypes and 74 metabolites) were identified or tentatively characterized, among them eight prototypes (mesaconine, hypaconine, songorine, fuziline, neoline, talatizamine formononetin, neocryptotanshinone) and two metabolites (calycosin-gluA, formononetin-guA) were relatively the main existing xenobiotics exposed in blood. All absorbed prototype constituents were mainly from six composed herbal medicines (Aconiti lateralis radix, Astragali radix, Ginseng radix, Alismatis rhizoma, Salvia miltiorrhiza radix, Periploca cortex). The main metabolic reactions were methylation, hydrogenation, hydroxylation, oxidization, sulfation and glucuronidation. This is the first study on in vivo metabolism of QLQX. These results enabled us to focus on several high exposure ingredients in the discovery of effective substances of QLQX, however further pharmacokinetic study on these QLQX-related xenobiotics are needed to be carried out.

Ginseng polysaccharides enhanced ginsenoside Rb1 and microbial metabolites exposure through enhancing intestinal absorption and affecting gut microbial metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Polysaccharides and small molecules commonly co-exist in decoctions of traditional Chinese medicines (TCMs). Our previous study outlined that ginseng polysaccharides (GP) could interact with co-existing ginsenosides to produce synergistic effect in an over-fatigue and acute cold stress model via gut microbiota involved mechanisms.

AIM OF THE STUDY

This study aimed to verify the interactions by examining the impact of GP on oral pharmacokinetics of ginsenoside Rb1 (Rb1), the dominant protopanoxadiol (PPD)-type ginsenoside in Ginseng, on a dextran sulphate sodium (DSS) induced experimental colitis model which was characterized by gut dysbiosis, and to delineate the underlying mechanisms in vitro.

MATERIALS AND METHODS

Rats received drinking water (normal group), 5% DSS (UC group), or 5% DSS plus daily oral administration of GP (GP group) for 7 days and fecal samples were collected on day -3, 0 and 6. On day 7 all animals received an oral dosage of Rb1 and blood samples were withdrawn for pharmacokinetic study. The in vitro metabolism study of Rb1 in gut microbiota from normal and UC rats and the transport study of Rb1 across Caco-2 cell monolayer were carried out in presence/absence of GP. Rb1 and its bacterial metabolites ginsenoside Rd (Rd), ginsenoside F2 (F2), Compound K (CK) and PPD were determined using LC-MS/MS. Total and target bacteria in fecal samples were determined by using 16S rRNA-based RT-PCR. β-Glucosidase activity was determined by measuring 4-nitrophenol formed from 4-nitrophenyl-β-D-glucopyranoside hydrolysis.

RESULTS

DSS induction did not alter AUC_0-t and C_max of Rb1, which, however, were doubled together with elevated AUC_0-t of the metabolites, in particular Rd and CK, in GP group. GP influenced the microbial composition and showed a prebiotic-like effect. Accordingly, GP treatment could partially restore the β-glucosidase activity which was reduced by DSS induction. The presence of GP resulted in quicker microbial metabolism of Rb1 and higher Rd formation in first 8 h of incubation, while the impact on F2 and CK formation/conversion became obvious after 8 h. More interestingly, GP slightly stimulated Caco-2 cell growth and facilitated Rb1 transport across the Caco-2 monolayer in both directions, increasing the P_app of Rb1 from 10^-7 cm/s to 10^-6 cm/s.

CONCLUSIONS

GP alleviated DSS-induced colitis-like symptoms and enhanced the systemic exposure of Rb1 through enhancing microbial deglycosylation and intestinal epithelial absorption of Rb1. These findings further demonstrated the important role of gut microbiota in the multifaceted action of polysaccharides in the holistic actions of traditional decoction of TCMs.

Simultaneous quantification six active compounds in rat plasma by UPLC-MS/MS and its application to a pharmacokinetic study of Pien-Tze-Huang

Pien-Tze-Huang (PZH) is a popular traditional Chinese medicine (TCM) formula in China, but its pharmacokinetics has not been investigated yet. To better study the pharmacokinetic behaviors of PZH, an optimal ultra-performance liquid chromatography with triple quadrupole mass spectrometry (UPLC-MS/MS) method was developed for rapid quantification of six compounds (notoginsenoside R1, ginsenosides Re, Rg1, Rb1, Rd, and muscone) in rat plasma after oral administration of PZH. All analytes were extracted by protein precipitation with acetonitrile and separated on a Waters Acquity Cortecs C18 column within 3.9min, and detected by multiple-reaction monitoring in positive ion mode. This proposed method exhibited good linearity (r≥0.9932) with a lower quantification limits of 0.558-1.566ng/mL for all analytes. The intra- and inter-day precisions were within 8.24%, and the accuracy was within -10.05 to 9.87% for each analyte. The extraction recovery for each analyte ranged from 80.02 to 96.12%. This UPLC-MS/MS method was successfully applied to the pharmacokinetic study for PZH in rats.

Comparative Analysis of the Rats' Gut Microbiota Composition in Animals with Different Ginsenosides Metabolizing Activity

Following oral intake of Panax ginseng, major ginsenosides are metabolized to deglycosylated ginsenosides by gut microbiota before absorption into the blood. As the composition of gut microbiota varies between individuals, metabolic activities are significantly different. We selected 6 rats with low efficiency metabolism (LEM) and 6 rats with high efficiency metabolism (HEM) from 60 rats following oral administration of Panax ginseng extract, and analyzed their gut microbiota composition using Illumina HiSeq sequencing of the 16S rRNA gene. The components of gut microbiota between the LEM and HEM groups were significantly different. Between the 2 groups, S24-7, Alcaligenaceae, and Erysipelotrichaceae occupied most OTUs of the HEM group, which was notably higher than the LEM group. Furthermore, we isolated Bifidobacterium animalis GM1 that could convert the ginsenoside Rb1 to Rd. The result implies that these specific intestinal bacteria may dominate the metabolism of Panax ginseng.

The octanol/water distribution coefficients of ardipusilloside-I and its metabolites, and their permeation characteristics across Caco-2 cell monolayer

Background

Ardipusilloside-I (ADS-I) is a triterpenoid saponin extracted from Chinese medicinal herb Ardisiapusill A. DC. Previous studies have demonstrated the potent anti-tumor activities of ADS-I both in vitro and in vivo, and its main metabolites (M1 and M2) from human intestinal bacteria. However, the physicochemical properties and intestinal permeation rate of ADS-I and its metabolites are not understood. In this study, the octanol/water distribution coefficients (logP) of ADS-I and metabolites were investigated using standard shake flask technique, and their permeability properties was investigated across Caco-2 cells monolayer.

Results

The logP of ADS-I, M1 and M2 was −0.01, 0.95 ± 0.04, 1.57 ± 0.11, respectively. The P_app values of ADS-I, M1 and M2 (in 10 μmol/L) across Caco-2 cell monolayers from the apical (AP) to basolateral (BL) direction were 1.88 ± 0.21 × 10⁻⁶ cm·s⁻¹, 4.30 ± 0.43 × 10⁻⁶ cm·s⁻¹, 4.74 ± 0.47 × 10⁻⁶ cm·s⁻¹, respectively.

Conclusion

Our data indicated that ADS-I has the poorer intestinal absorption than its metabolites (M1 and M2) in these experimental systems, suggesting that the metabolites of ADS-I may be the predominant products absorbed by the intestine when ADS-I is administered orally.

Antidepressant-like effects of ginsenosides: A comparison of ginsenoside Rb3 and its four deglycosylated derivatives, Rg3, Rh2, compound K, and 20(S)-protopanaxadiol in mice models of despair

Ginsenoside Rb3 has been proved to have antidepressant-like effects, which possesses 1 xylose and 3 glucose moieties with 20(S)-protopanaxadiol (PPD) as the aglycone. However, it is commonly accepted that orally ingested ginsenosides can be deglycosylated or partially deglycosylated into active derivatives by the intestinal bacteria. To identify potential antidepressant drug candidates, we compared the antidepressant-like activities between ginsenoside Rb3 and its four deglycosylated derivatives, Rg3, Rh2, compound K (C-K), and PPD. Effects of acute (1-day), short chronic (7-days), and longer chronic treatments (14-days) with these ginsenosides (50 and 100mg/kg, p.o.) on the behavioral changes in the forced swim test (FST), tail suspension test (TST) and open field test were investigated. Serum corticosterone and adrenocorticotropic hormone (ACTH) levels and mouse brain monoamine neurotransmitters 5-HT, NA and DA levels were measured using commercially available competitive enzyme-linked immunosorbent assay (ELISA) kits. Interestingly, C-K showed antidepressant-like activities similar to that of Rb3, and Rg3 displayed antidepressant-like effects at lower dosage and faster time, indicating it has better effects than Rb3, whereas Rh2 and PPD failed to show any effect. Our results also showed, unlike the positive control fluoxetine, Rb3, Rg3 and C-K significantly increased the NA levels in the brain regions of mice exposed to FST but did not affect the 5-HT and DA levels. Moreover, treatment with Rg3 could reverse swim stress-induced increased levels of serum ACTH and corticosterone. These results suggest that C-K and Rg3 are the active deglycosylated derivatives, especially the latter compound, which is more potent than Rb3 and exerts antidepressant-like effects by regulating NA, ACTH and corticosterone levels.

Protective effects of ginseng on neurological disorders

Ginseng (Order: Apiales, Family: Araliaceae, Genus: Panax) has been used as a traditional herbal medicine for over 2000 years, and is recorded to have antianxiety, antidepressant and cognition enhancing properties. The protective effects of ginseng on neurological disorders are discussed in this review. Ginseng species and ginsenosides, and their intestinal metabolism and bioavailability are briefly introduced. This is followed by molecular mechanisms of effects of ginseng on the brain, including glutamatergic transmission, monoamine transmission, estrogen signaling, nitric oxide (NO) production, the Keap1/Nrf2 adaptive cellular stress pathway, neuronal survival, apoptosis, neural stem cells and neuroregeneration, microglia, astrocytes, oligodendrocytes and cerebral microvessels. The molecular mechanisms of the neuroprotective effects of ginseng in Alzheimer’s disease (AD) including β-amyloid (Aβ) formation, tau hyperphosphorylation and oxidative stress, major depression, stroke, Parkinson’s disease and multiple sclerosis are presented. It is hoped that this discussion will stimulate more studies on the use of ginseng in neurological disorders.

Characterization of oxygenated metabolites of ginsenoside Rb1 in plasma and urine of rat

Oxygenated metabolites have been suggested as the major circulating metabolites of ginsenosides. In the current study, 10 oxygenated metabolites of ginsenoside Rb1 in plasma and urine of rat following iv dose were characterized by comparison with chemically synthesized authentic compounds as quinquenoside L16 (M1 and M2), notoginsenoside A (M3), ginsenoside V (M4 and M7), epoxyginsenoside Rb1 (M5 and M9), notoginsenoside K (M6), and notoginsenoside C (M8 and M10), 9 of which were detected as in vivo metabolites for the first time. After oral administration of ginsenoside Rb1, M3, M4, and M7 were observed as major circulating metabolites and presented in the bloodstream of rat for 24 h. Characterization of the exact chemical structures of these circulating metabolites could contribute greatly to our understanding of chemical exposure of ginsenosides after consumption of ginseng products and provide valuable information for explaining multiple bioactivities of ginseng products.

Structural identification of neopanaxadiol metabolites in rats by ultraperformance liquid chromatography/quadrupole-time-of-flight mass spectrometry

RATIONALE

Neopanaxadiol (NPD) is one of the major ginsenosides in Panax ginseng C. A. Meyer (Araliaceae) that has been suggested to be a drug candidate against Alzheimer's disease. However, few data are available regarding its metabolism in rats.

METHODS

In this study, a method of ultraperformance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC/QTOFMS) was developed to identify major metabolites of NPD in the stomach, intestine, urine and feces of rats, with the aim of determining the main metabolic pathways of NPD in rats after oral administration.

RESULTS

UPLC/QTOFMS revealed two metabolites in the stomach of rats, one metabolite in the intestine and two metabolites in feces. One metabolite, named M2, was isolated and purified from rats feces, which was identified as (20S,22S)-dammar-22,25-epoxy-3β,12β,20-triol based on extensive NMR spectroscopy and mass spectrometry data. The main metabolites of NPD in rats were the products of epoxidation, dehydrogenation and hydroxylation. NPD was predominantly metabolized by 20,22-double-bond epoxidation and rearrangement to yield an expoxidation product (M2).

CONCLUSIONS

Based on the profiles of the metabolites, possible metabolic pathways of NPD in rats were proposed for the first time. This study provides new and available information on the metabolism of NPD, which is indispensable for further research on metabolic pathways of dammarane ginsengenins in vivo.

Tissue distribution and excretion of herbal components after intravenous administration of a Chinese medicine (Shengmai injection) in rat

Shengmai injection, consisting of Panax ginseng, Radix ophiopogonis and Schisandra chinensis, is a widely used Chinese medicine for the treatment of various cardiovascular diseases. In this study, tissue distribution and excretion of its multiple active components including protopanaxatriol-type (Ppt-type) ginsenosides (ginsenoside Rg1, Re, Rf and Rg2), protopanaxadiol-type (Ppd-type) ginsenosides (ginsenoside Rb1, Rd and Rc), ophiopogonin (ophiopogonin D), and lignan (schisandrin, schisandrol B and schizandrin B) in rat after single intravenous administration of Shengmai injection were reported. Ppt-type ginsenosides exhibited quick and wide distribution from blood into tissues and were eliminated rapidly through biliary, urinary and fecal excretions. Ppd-type ginsenosides Rb1, Rd and Rc distributed quickly from blood to all tissues but exhibited slow elimination by biliary and urinary excretions. Ophiopogonin D was excreted into bile with no urinary and fecal excretion, indicating its elimination in the form of secondary metabolites. Schisandrin, schisandrol B and schizandrin B was found to distribute quickly from blood into most tissues and had accumulation in these tissues. Very low biliary, urinary and fecal excretion implied that lignan was mainly excreted in the form of their metabolites. This study produced a first hand in vivo tissue distribution and dynamic profiles of the active components of Shengmai injection, providing valuable information for drug development and clinical application of Shengmai injection.

Bioconversion of ginsenosides in the american ginseng ( xī yáng shēn) extraction residue by fermentation with lingzhi ( líng zhī, ganoderma lucidum)

Ginseng ( Rén Shēn) has been widely employed in functional foods and traditional medicines in many Asian countries. Owing to the high consumer demand of ginseng products, a large amount of ginseng residue is generated after extraction of ginseng. However, the ginseng residue still contains many bioactive compounds such as ginsenosides. The objective of this research was to convert ginsenosides in American ginseng ( Xī Yáng Shēn) extraction residue (AmR) by fermentation with lingzhi ( Líng Zhī, Ganoderma lucidum) and the fermentation products will be used for further hypoglycemic activity research. Thus, this study was primarily focused on the ginsenosides that have been reported to possess hypoglycemic activity. In this study, the changes in seven ginsenoside [Rg1, Re, Rb1, Rc, Rg3(S), compound K (CK), and Rh2(S)] in the products as affected by fermentation were investigated. Our results showed that the levels of ginsenosides, namely, Rg1, Rg3(S), and CK increased, while the other ginsenosides (Re, Rb1, and Rc) decreased during the fermentation process.

Transformation of ginsenosides from notoginseng by artificial gastric juice can increase cytotoxicity toward cancer cells

Multicomponent metabolic profile of notoginseng saponins in artificial gastric juice was qualitatively and quantitatively investigated, showing that ginsenosides were transformed via multiple pathways including deglycosylation, dehydration, hydration, and oxygenation. A total of 83 metabolites was identified by using UPLC-Q-TOF-MS, among which 16 new dammarane glycosides were further characterized by comparing with synthesized authentic compounds. Transformation time-course of notoginseng saponins in artificial gastric juice was quantitatively measured for the first time, showing rapid degradation of primary ginsenosides and concomitant formation of deglycosylation, hydration, and dehydration products. It was further demonstrated that the resultant metabolites exhibited enhanced cytotoxicity toward cancer cells. The extensive metabolism of ginsenosides within a transit time span in stomach, together with the formation of metabolites with diversified chemical structures possessing enhanced biological activities, indicated an important role of transformation in gastric juice in the systematic effects of ginsenosides.

Biotransformation of ginsenoside Rb1 via the gypenoside pathway by human gut bacteria

Background

Bacterial conversion of ginsenosides is crucial for the health-promoting effects of ginsenosides. Previous studies on the biotransformation of ginsenoside Rb1 (Rb1) by gut bacteria have focused on the ginsenoside Rd (Rd) pathway (Rb1 → Rd → ginsenoside F2 (F2) → compound K (Cpd K)). This study aims to examine the gypenoside pathway in human gut bacteria in vitro.

Methods

The metabolic pathways of ginsenoside Rb1 and its metabolites ginsenoside Rd and gypenoside XVII in human gut bacteria were investigated by incubating the compounds anaerobically with pooled or individual gut bacteria samples from healthy volunteers. Ginsenoside Rb1, the metabolites generated by human gut bacteria, and degraded products in simulated gastric fluid (SGF) were qualitatively analyzed using an LC/MSD Trap system in the negative ion mode and quantitatively determined by HPLC-UV analysis.

Results

When incubated anaerobically with pooled gut bacteria, Rb1 generated five metabolites, namely Rd, F2, Cpd K, and the rare gypenosides XVII (G-XVII) and LXXV (G-LXXV). The gypenoside pathway (Rb1 → G-XVII → G-LXXV → Cpd K) was rapid, intermediate, and minor, and finally converted Rb1 to Cpd K via G-XVII → F2 (major)/G-LXXV (minor). Both the Rd and gypenoside pathways exhibited great inter-individual variations in age-and sex-independent manners (P > 0.05). Rb1 was highly acid-labile and degraded rapidly to form F2, ginsenoside Rg3, ginsenoside Rh2, and Cpd K, but did not generate the gypenosides in SGF. The formation of the gypenosides might be explained by the involvement of a gut bacteria-mediated enzymatic process.

Conclusions

Rb1 was metabolized to G-XVII, F2 (major) or G-LXXL (minor), and finally Cpd K by human gut bacteria in vitro.

Identification of 20(S)-protopanaxatriol metabolites in rats by ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry and nuclear magnetic resonance spectroscopy

20(S)-Protopanaxatriol (PPT), one of the aglycones of ginsenosides, has been shown to exert cardioprotective effects against myocardial ischemic injury. However, studies on PPT metabolism have rarely been reported. This study is the first to investigate the in vivo metabolism of PPT following oral administration by ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC-Q/TOF-MS) and nuclear magnetic resonance (NMR) spectroscopy. The structures of the metabolites were identified based on the characteristics of their MS data, MS(2) data, and chromatographic retention times. A total of 22 metabolites, including 17 phase I and 5 phase II metabolites, were found and tentatively identified by comparing their mass spectrometry profiles with those of PPT. Two new monooxygenation metabolites, (20S,24S)-epoxy-dammarane-3,6,12,25-tetraol and (20S,24R)-epoxy-dammarane-3,6,12,25-tetraol, were chemicallly synthesized and unambiguously characterized according to the NMR spectroscopic data. The metabolic pathways of PPT were proposed accordingly for the first time. Results revealed that oxidation of (1) double bonds at Δ((24,25)) to form 24,25-epoxides, followed by rearrangement to yield 20,24-oxide forms; and (2) vinyl-methyl at C-26/27 to form corresponding carboxylic acid were the predominant metabolic pathways. Phase II metabolic pathways were proven for the first time to consist of glucuronidation and cysteine conjugation. This study provides valuable and new information on the metabolism of PPT, which is indispensable for understanding the safety and efficacy of PPT, as well as its corresponding ginsenosides.

Biotransformation of ginsenoside Rd in the ginseng extraction residue by fermentation with lingzhi (Ganoderma lucidum)

Ginseng and lingzhi (Ganoderma lucidum) both are valuable traditional Chinese medicines and have been extensively utilised in functional foods and traditional medicines in many Asian countries. However, massive quantity of ginseng residue is produced after extraction of ginseng which still contains a lot of bioactive compounds such as ginsenosides. The goal of this study was to reuse the American ginseng extraction residue as the fermentation medium of G. lucidum to produce bioactive ginsenoside enriched biotransformation products. The changes of ginsenosides in the fermentation products were analysed during fermentation. Our results showed that after 30 days of fermentation, ginsenoside Rg1, Rd, and compound K (CK) significantly increased, especially Rd, while other ginsenosides (Re, Rb1 and Rc) decreased during fermentation. Ginsenoside Rd is the major ginsenoside in the final fermentation product. Furthermore, the biotransformation of ginsenosides was the major reaction in this fermentation process.

Intestinal bacterial transformation - a nonnegligible part of Chinese medicine research

Intestinal bacteria play an essential part in the metabolism of the constituents of herbal drugs, and a lot of investigations have been done to unveil their functions and mechanisms in modification of these constituents and their effect. This review provides a progressive description of intestinal bacterial transformation with respect to properties, reactions, correlation with the effect of herbal drugs, research interests, and methodology. In addition, the problems encountered during the investigation are addressed and perspectives are proposed.

Metabolism of ginseng and its interactions with drugs

Ginseng is an herbal medicine used worldwide. It is reported to have a wide range of pharmacological activities because of a diversified group of steroidal saponins called ginsenosides. Compared to extensive pharmacological studies of ginseng, the pharmacokinetics, especially the metabolism of this herb, has received less attention. In this article we review the known pharmacokinetic data on ginseng. Understanding ginseng's pharmacokinetics may reduce the potential for interactions in patients who use both ginseng and prescription medications. In addition, bioavailability after taking ginseng orally is low, and the metabolites of ginsenosides produced by gut microbiota may be biologically active. One ginseng metabolite, Compound K, and its potential for cancer chemoprevention is also discussed. An active ginseng metabolite may differ in distribution and clearance from its parent compound, and the parent compound and its metabolite may be bioactive by similar or different mechanisms. Thus, further investigation of ginseng metabolites is needed for predicting the therapeutic outcome with ginseng.

Bioactivity enhancement of herbal supplements by intestinal microbiota focusing on ginsenosides

Intestinal microbiota contribute to diverse mammalian processes including the metabolic functions of drugs. It is a potential new territory for drug targeting, especially for dietary herbal products. Because most herbal medicines are orally administered, the chemical profile and corresponding bioactivities of herbal medicines may be altered by intestinal microbiota. Ginseng is one of the most commonly used herbs and it is an attractive natural product to study its effect in the body. In this review, after briefly introducing the interactions of herbal products and gut microbiota, we discuss the microbiota-mediated metabolism of ginsenosides in ginseng and red ginseng. In particular, the major metabolite compound K and its pharmacological advances are described including anticancer, antidiabetic and anti-inflammatory effects. In summary, the intestinal microbiota may play an important role in mediating the metabolism bioactivity of herbal medicines.

20(S)-protopanaxadiol, an active ginseng metabolite, exhibits strong antidepressant-like effects in animal tests

Ginseng has been used for mood adjustment in traditional Chinese medicine for thousands of years. Our previous study has shown that, total ginsenosides, the major pharmacologically functional ingredients of ginseng, possess antidepressant activity. In the present study, we hypothesized that an intestinal metabolite of ginseng, 20(S)-protopanaxadiol (code name S111), as a post metabolism compound (PMC) of ingested ginsenosides, may be responsible for the antidepressant activity of ginseng. To test this hypothesis, antidepressant-like activity of orally given S111 was measured in animal tests including tail suspension test, forced swimming test and rat olfactory bulbectomy depression model. In all those tests, S111 demonstrated antidepressant-like activity as potent as fluoxetine. S111 treated bulbectomy animals had higher levels of monoamine neurotransmitters in the brain and in vitro reuptake assay showed that S111 had a mild inhibitory effect. Furthermore, S111 but not fluoxetine significantly reduced brain oxidative stress and down-regulated serum corticosterone concentration in bulbectomy animals. No disturbance to central nervous system (CNS) normal functions were found in S111 treated animals. These results suggest that the ginseng active metabolite S111 is a potential antidepressant. Since the monoamine reuptake activity of this compound is rather weak, it remains to be investigated whether its antidepressant-like effect is by mechanisms that are different from current antidepressants. Furthermore, this study has demonstrated that post metabolism compounds (PMCs) of herb medicines such as S111 may be a novel source for drug discovery from medicinal herbs.

Microsomal cytochrome p450-mediated metabolism of protopanaxatriol ginsenosides: metabolite profile, reaction phenotyping, and structure-metabolism relationship

Although the biotransformation of ginsenosides in the gastrointestinal tract has been extensively studied, much less is known about hepatic cytochrome P450 (P450)-catalyzed metabolism. The major aims of this study were to clarify the metabolic pathway and P450 isoforms involved and to explore the structure-metabolism relationship of protopanaxatriol (PPT)-type ginsenosides in hepatic microsomes. Efficient depletion of ginsenoside Rh1, Rg2, Rf, and PPT was found, whereas the elimination of Re and Rg1, characterized by a glucose substitution at the C20 hydroxy group, was negligible in microsomal incubation systems. Based on high-performance liquid chromatography hybrid ion trap and time-of-flight mass spectrometry analysis, the oxygenation metabolism on the C20 aliphatic branch chain was identified as the predominant metabolic pathway of PPT ginsenosides in both human and rat hepatic microsomes. By a comparison with authentic standards, the C24-25 double bond was identified as one of the oxygenation sites to produce the metabolites of C20-24 epoxide (ocotillol-type ginsenosides). Both chemical inhibition and human recombinant P450 isoform assays indicated that CYP3A4 was the predominant isozyme responsible for the oxygenation metabolism of PPT ginsenosides. Enzyme kinetic evaluations in rat and human hepatic microsomes and human recombinant CYP3A4 isozyme incubation systems showed generally consistent results in that the intrinsic clearance ranked as Rf ≤ Rg2 < Rh1 < PPT, closely correlating with logP values and the number of glycosyl substitutions. Results obtained from this study suggest that CYP3A4-catalyzed oxygenation metabolism plays an important role in the hepatic disposition of ginsenosides and that glycosyl substitution, especially at the C20 hydroxy group, determines their intrinsic clearances by CYP3A4.

Biotransformation of ginsenosides Rb1, Rg3 and Rh2 in rat gastrointestinal tracts

BACKGROUND

Ginsenosides such as Rb1, Rg3 and Rh2 are major bioactive components of Panax ginseng. This in vivo study investigates the metabolic pathways of ginsenosides Rb1, Rg3 and Rh2 orally administered to rats.

METHODS

High performance liquid chromatography-mass spectrometry (LC-MS) and tandem mass spectrometry (MS-MS) techniques, particularly liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS), were used to identify the metabolites.

RESULTS

Six metabolites of Rb1, six metabolites of Rg3 and three metabolites of Rh2 were detected in the feces samples of the rats. Rh2 was a metabolite of Rb1 and Rg3, whereas Rg3 was a metabolite of Rb1. Some metabolites such as protopanaxadiol and monooxygenated protopanaxadiol are metabolites of all three ginsenosides.

CONCLUSION

Oxygenation and deglycosylation are two major metabolic pathways of the ginsenosides in rat gastrointestinal tracts.

Characterization of metabolism and in vitro permeability study of notoginsenoside R1 from Radix notoginseng

As a main and characteristic constituent in Radix notoginseng, the fate of notoginsenoside R1 (NGR1) in human is largely unknown. The present study investigated, for the first time, NGR1 metabolism by human intestinal bacteria and liver subcellular fractions, and permeability properties of NGR1 and resultant metabolites on a Caco-2 model. Samples were qualitatively analyzed using HPLC-MS/MS and quantitatively determined using HPLC-UV. When incubated with pooled human intestinal bacteria anaerobically, NGR1 showed biphasic elimination: an insignificant decrease in the first 8 h followed by a rapid elimination during 8-48 h. Four metabolites, three unambiguously identified as ginsenosides Rg1, F1 and 20(S)-protopanaxatriol formed via stepwise deglycosylation, and one tentatively assigned as a dehydrogenated protopanaxatriol with transformation occurring at the tetracyclic triterpenoid skeleton, were produced sequentially. Rg1 and F1 were formed transiently at low apparent velocities, while 20(S)-protopanaxatriol was the major metabolite with a formation rate close to the rate of NGR1 elimination and a low elimination rate. NGR1 remained intact in human liver S9 or microsomes over 1 h. Transport study of NGR1 and its metabolites revealed an ascending permeability order with stepwise deglycosylation. Taken together, the results revealed a determinant role of intestinal bacteria in the overall disposition and potential bioactivity of NGR1 in human.

Simultaneous determination of three major bioactive saponins of Panax notoginseng using liquid chromatography-tandem mass spectrometry and a pharmacokinetic study

BACKGROUND

Panax notoginseng saponins (PNS), the main active components of Radix Notoginseng, has been used for treating atherosclerosis, cerebral infarction, and cerebral ischemia. Ginsenosides Rg1, ginsenoside Rb1, and notoginsenoside R1 are the main contributors of biological activities, determination of these three saponins is very important for the in vivo evaluation of PNS. The present study aims to develop a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantification of ginsenosides Rg1, ginsenoside Rb1, and notoginsenoside R1. The use of this method was exemplified in pharmacokinetic study of beagle dog plasma after oral administration of PNS.

METHODS

Liquid chromatography-tandem mass spectrometry (LC/MS/MS) method was combined with solid-phase extraction (SPE). This setup was used to determine simultaneously the three major PNS (ginsenoside Rg1, ginsenoside Rb1, and notoginsenoside R1) in beagle dog plasma. Tandem mass spectrometry was performed using electrospray ionization in the positive ion mode.

RESULTS

The lower limits of quantification were 0.5 ng/mL for notoginsenoside R1, 0.82 ng/mL for ginsenoside Rg1, and 1.10 ng/mL for ginsenoside Rb1. The calibration curves for the three saponins were linear over the concentration ranges 2.64-264 ng/mL (r2 = 0.9967, P = 0.003), 3.6-360 ng/mL (r2 = 0.9941, P = 0.004), and 18.7-1870 ng/mL (r2 = 0.9912, P = 0.004) for notoginsenoside R1, ginsenoside Rg1, and ginsenoside Rb1, respectively. Within these concentration ranges, the relative standard deviation (RSD) of intra- and interday assays for the three PNS from beagle dog plasma samples were less than 12%.

CONCLUSIONS

This LC/MS/MS method in combination with SPE is useful in the pharmacokinetic study of PNS, such as the simultaneous determination of saponins in beagle dog plasma after oral administration.