Profiling the metabolism of astragaloside IV by ultra performance liquid chromatography coupled with quadrupole/time-of-flight mass spectrometry

Identification and Characterization of the Chemical Constituents of Qianlie Shule Capsules by UPLC-Q-Orbitrap-MS/MS

BACKGROUND

The Qianlie Shule capsule is a classical Chinese medicine compound preparation frequently used in therapeutic settings to alleviate astringent pain in the urethra, prostatic hypertrophy, and chronic prostatitis or urinary frequency. However, a comprehensive analysis of the chemical composition of Qianlie Shule capsules has not been reported.

OBJECTIVE

To establish a quick and effective analytical method based on hybrid quadrupole-orbitrap mass spectrometry ultrahigh-performance liquid chromatography (UPLC-Q-Orbitrap-MS/MS) for the identification and characterization of chemical components in Qianlie Shule capsules.

METHOD

Using ultrahigh-performance liquid chromatography with hybrid quadrupole-orbitrap mass spectrometry and data post-processing, the samples of Qianlie Shule capsules were examined. First, the whole extract of the Qianlie Shule capsules was separated using a UPLC machine, and the fragmentation data were collected in both positive and negative ion mode. The target molecule is then quickly identified by comparing the fragmentation information of the neutral loss (NLs) and characteristic fragments (CFs) reported in the literature.

RESULTS

A total of 145 chemical components were identified. It includes flavonoids, triterpenoids, phenylpropanoids, organic acids, alkaloids, phenylethanoids, iridoids, and anthraquinones.

CONCLUSIONS

This study is a method for the rapid qualitative analysis of the chemical composition of Qianlie Shule capsules, which provides a method for the rapid, sensitive, and high-throughput identification of the prescription components of Chinese medicine.

HIGHLIGHTS

Systematic identification of the chemical composition of QLSL capsules provides a theoretical basis for studying the substance basis of QLSL capsules and the improvement of the quality control level.

Investigation of the Metabolism of Astragaloside IV in a Puromycin-Damaged Rat Model by UPLC-Q-TOF-MS/MS Analysis

Astragaloside IV (AS-IV) has been shown to provide renal protection in various kidney injury models. However, the metabolic profile variation of AS-IV in pathological models in vivo is not well established. This study aims to explore the metabolic pathway of AS-IV in vivo in the classical puromycin aminonucleoside (PAN)-induced kidney injury in a rat model. Twelve Wistar rats were randomly divided into the AS-IV (CA) and the PAN+AS-IV (PA) treatment groups. PAN was injected by a single tail intravenous (i. v.) injection at 5 mg/100 g body weight, and AS-IV was administered intragastrically (i. g.) at 40 mg/kg for 10 days. Fecal samples of these rats were collected, and metabolites of AS-IV were detected by ultra-performance liquid chromatography coupled with quadrupole/time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS) to explore the AS-IV metabolic pathway. The metabolic differences between the AS-IV and PAN+AS-IV groups were compared. A total of 25 metabolites were detected, and deglycosylation, deoxygenation, and methyl oxidation were found to be the main metabolic pathways of AS-IV in vivo. The abundance of most of these metabolites in the PAN+AS-IV group was lower than that in the AS-IV treatment group, and differences for seven of them were statistically significant. Our study indicates that AS-IV metabolism is affected in the PAN-induced kidney injury rat model.

Metabolic profiling of Qi-Yu-San-Long decoction in rat feces by ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry combined with a post-targeted screening strategy

Research into traditional Chinese medicine metabolism in feces is one of the key avenues to understanding the fate of traditional Chinese medicines in vivo. In this study, we used ultraperformance liquid chromatography-quadrupole time-of-flight MS in combination with a post-targeted screening strategy to identify the prototype components and metabolites in rat feces after oral administration. Based on our group's previous research, the component database of Qi-Yu-San-Long decoction (QYSLD) was established. Prototype components were screened from the fecal samples based on summarized chromatographic and MS behaviors. According to the chemical structure characteristics of related compounds, the possible metabolic pathways were inferred, and the metabolites related to QYSLD were predicted. We extracted ion chromatograms by predicting the m/z values of metabolite excimer ions and identified related metabolites based on their retention time and fragmentation behavior. A total of 93 QYSLD-related xenobiotics were confirmed or tentatively identified in rat fecal samples, and the results indicated that the main metabolic pathways of QYSLD were hydrolysis, deglycosylation, oxidation, reduction, decarboxylation, methylation and acetylation. This study presents a rapid method for identifying the prototype components and metabolites, and offers valuable insights into the biotransformation profiling of QYSLD in rat feces.

Identification of chemical components and rat serum metabolites in Danggui Buxue decoction based on UPLC-Q-TOF-MS, the UNIFI platform and molecular networks

Danggui Buxue Decoction (DBD), consisting of Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao (Huangqi, HQ) and Angelica sinensis (Oliv.) Diels (Danggui, DG), is a traditional Chinese medicine (TCM) formula with the function of tonifying Qi and promoting blood. In this study, ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was used to comprehensively identify the chemical constituents in DBD and those entering into the rat serum after gastric perfusion. A combination of the UNIFI platform and Global Natural Product Social molecular networking (GNPS) was used to analyze the chemical composition of DBD. As a result, 207 compounds were unambiguously or tentatively identified including 60 flavonoids, 38 saponins, 35 organic acids, 26 phthalides, 12 phenylpropanoids, 11 amino acids and 25 others. Furthermore, a total of 80 compounds, including 29 prototype components and 51 exogenous metabolites, were detected in the serum of rats. Phase I reactions (oxidation, reduction, and hydration), phase II reactions (methylation, sulfation, and glucuronidation), and their combinations were the main metabolic pathways of DBD. The results provided fundamental information for further studying the pharmacological mechanisms of DBD, as well as its quality control research.

Using UPLC-LTQ-Orbitrap-MS and HPLC-CAD to Identify Impurities in Cycloastragenol, Which Is a Pre-Clinical Candidate for COPD

Chronic obstructive pulmonary disease (COPD) is a highly prevalent disease that has become the third leading cause of death worldwide. Cycloastragenol (CAG), which is the genuine sapogenin of the main active triterpene saponins in Astragali radix, is a bioavailable pre-clinical candidate for chronic obstructive pulmonary disease (COPD), and it was investigated in our previous study. In order to progress medical research, it was first efficiently produced on a 2.5-kg scale via Smith degradation from astragaloside IV (AS-IV). Simultaneously, since the impurity profiling of a drug is critical for performing CMC documentation in pre-clinical development, a study on impurities was carried out. As these structures do not contain chromophores and possess weak UV absorption characteristics, HPLC-CAD and UPLC-LTQ-Orbitrap-MS were employed to carry out the quality control of the impurities. Then, column chromatography (CC), preparative thin-layer chromatography (PTLC), and crystallization led to the identification of 15 impurities from CAG API. Among these impurities, compounds 1, 4, 9, 10, 14, and 15 were elucidated via spectroscopic analysis, and 2-3, 5-8, and 11-13 were putatively identified. Interestingly, the new compounds 9 and 14 were rare 10, 19-secocycloartane triterpenoids that displayed certain anti-inflammatory activities against LPS-induced lymphocyte cells and CSE-induced MLE-12 cells. Additionally, a plausible structural transformation pathway of the degradation compounds from CAG or AS IV was proposed. The information obtained will provide a material basis to carry out the quality control and clinical safety assurance of API and related prescriptions. Reasonable guidance will also be provided regarding the compounds with weak UV absorption characteristics.

Astragaloside IV, as a potential anticancer agent

Cancer is a global intractable disease, and its morbidity and mortality are increasing year by year in developing countries. Surgery and chemotherapy are often used to treat cancer, but they result in unsatisfactory outcomes, such as severe side effects and drug resistance. With the accelerated modernization of traditional Chinese medicine (TCM), an increasing body of evidence has shown that several TCM components have significant anticancer activities. Astragaloside IV (AS-IV) is considered the main active ingredient of the dried root of Astragalus membranaceus. AS-IV exhibits various pharmacological effects, such as anti-inflammatory, hypoglycemic, antifibrotic, and anticancer activities. AS-IV possesses a wide range of activities, such as the modulation of reactive oxygen species-scavenging enzyme activities, participation in cell cycle arrest, induction of apoptosis and autophagy, and suppression of cancer cell proliferation, invasiveness, and metastasis. These effects are involved in the inhibition of different malignant tumors, such as lung, liver, breast, and gastric cancers. This article reviews the bioavailability, anticancer activity, and mechanism of AS-IV and provides suggestions for further research of this TCM.

Research progress on the antitumor effects of astragaloside IV

One of the most important and effective components of Astragalus membranaceus is astragaloside IV (AS-IV), which can exert anti-tumor effects through various pathways. For instance, AS-IV exerts an anti-tumor effect by acting at the cellular level, regulating the phenotype switch of tumor-associated macrophages, or inhibiting the development of tumor cells. Furthermore, AS-IV inhibits tumor cell progression by enhancing its sensitivity to antitumor drugs or reversing the drug resistance of tumor cells. This article reviews the different mechanisms of AS-IV inhibition of epithelial-mesenchymal transition (EMT), migration, proliferation, and invasion of tumor cells, inducing apoptosis and improving the sensitivity of anti-tumor drugs. This review summarizes recent progress in the current research into AS-IV anti-tumor effect and provides insight on the next anti-tumor research of AS-IV.

Yu-Ping-Feng Formula Ameliorates Alveolar-Capillary Barrier Injury Induced by Exhausted-Exercise via Regulation of Cytoskeleton

Background: Yu-ping-feng powder (YPF) is a compound traditional Chinese medicine extensively used in China for respiratory diseases. However, the role of YPF in alveolar-capillary barrier dysfunction remains unknown. This study aimed to explore the effect and potential mechanism of YPF on alveolar-capillary barrier injury induced by exhausted exercise.

Methods: Male Sprague–Dawley rats were used to establish an exhausted-exercise model by using a motorized rodent treadmill. YPF at doses of 2.18 g/kg was administrated by gavage before exercise training for 10 consecutive days. Food intake-weight/body weight, blood gas analysis, lung water percent content, BALF protein concentration, morphological observation, quantitative proteomics, real-time PCR, and Western blot were performed. A rat pulmonary microvascular endothelial cell line (PMVEC) subjected to hypoxia was applied for assessing the related mechanism.

Results: YPF attenuated the decrease of food intake weight/body weight, improved lung swelling and hemorrhage, alleviated the increase of lung water percent content and BALF protein concentration, and inhibited the impairment of lung morphology. In addition, YPF increased the expression of claudin 3, claudin 18, occludin, VE-cadherin, and β-catenin, attenuated the epithelial and endothelial hyperpermeability in vivo and/or in vitro, and the stress fiber formation in PMVECs after hypoxia. Quantitative proteomics discovered that the effect of YPF implicated the Siah2-ubiquitin-proteasomal pathway, Gng12-PAK1-MLCK, and RhoA/ROCK, which was further confirmed by Western blot. Data are available via ProteomeXchange with identifier PXD032737.

Conclusion: YPF ameliorated alveolar-capillary barrier injury induced by exhausted exercise, which is accounted for at least partly by the regulation of cytoskeleton.

Surface-Enhanced Raman Spectroscopy Analysis of Astragalus Saponins and Identification of Metabolites After Oral Administration in Rats by Ultrahigh-Performance Liquid Chromatography/Quadrupole Time-of-Flight Mass Spectrometry Analysis

Astragalus mongholicus Bunge (Fabaceae) is an ancient Chinese herbal medicine, and Astragalus saponins are the main active components, which have a wide range of biological activities, such as immunomodulation, antioxidation, and neuroprotection. In this study, silver nanoparticles obtained by sodium borohydride reduction were used as the enhanced substrate to detect astragaloside I (1), astragaloside II (2), astragaloside III (3), astragaloside IV (4), isoastragaloside I (5), and isoastragaloside II (6) in the phloem, xylem, and cork by surface-enhanced Raman spectroscopy (SERS). In the SERS spectrum of Astragalus slices, the characteristic peaks were observed at 562, 671, 732, 801, 836, 950, 1,026, 1,391, and 1,584 cm⁻¹, among which 950 cm⁻¹ and 1,391 cm⁻¹ were strong SERS signals. Subsequently, the metabolites of the six kinds of Astragalus saponins were identified by UPLC/ESI/Q-TOF-MS. Totally, 80, 89, and 90 metabolites were identified in rat plasma, urine, and feces, respectively. The metabolism of saponins mainly involves dehydration, deacetylation, dihydroxylation, dexylose reaction, deglycosylation, methylation, deacetylation, and glycol dehydration. Ten metabolites (1-M2, 1-M11, 2-M3, 2-M12, 3-M14, 4-M9, 5-M2, 5-M17, 6-M3, and 6-M12) were identified by comparison with reference standards. Interestingly, Astragalus saponins 1, 2, 5, and 6 were deacetylated to form astragaloside IV (4), which has been reported to have good pharmacological neuroprotective, liver protective, anticancer, and antidiabetic effects. Six kinds of active Astragalus saponins from different parts of Astragalus mongholicus were identified by SERS spectroscopy. Six kinds of active Astragalus saponins from different parts of Astragalus mongholicus were identified by SERS spectrum, and the metabolites were characterized by UPLC/ESI/Q-TOF-MS, which not only provided a new method for the identification of traditional Chinese medicine but also provided a theoretical basis for the study of the pharmacodynamic substance basis of Astragalus mongholicus saponins.

Quantification by LC-MS/MS of astragaloside IV and isoflavones in Astragali radix can be more accurate by using standard addition

INTRODUCTION

Astragali radix (AR), the root of Astragalus, is an important medical herb widely used in traditional Chinese medicine. Bioactive components include isoflavones and a unique class of triterpenoid saponins (named astragalosides).

OBJECTIVES

Accurate measurement of bioactive components, especially astragaloside IV, is necessary for confirming AR authenticity, quality control and future medical research.

METHODOLOGY

Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) is a suitable technique but suffers from ion suppression effects due to sample matrix. This can be corrected by using isotopic labelled internal standards, but these are not available for many phytochemicals. We explored the use of standard addition to circumvent this issue.

RESULTS

LC-MS/MS and liquid chromatography coupled with ultraviolet (LC-UV) detection provided linear calibration curves (R² > 0.99). LC-MS/MS provided superior selectivity and detection limits below 10 ng/mL, which was 2-3 magnitudes lower than LC-UV detection. Precision and accuracy were overall improved by using LC-MS/MS with diluted sample extracts, resulting in an inter series coefficient of variation (CV) of 12% or less and mean recovery estimates in the 85-115% range. LC-MS/MS quantification by standard addition resulted in significantly higher concentrations of astragaloside IV measured in the samples. Concentrations calculated by standard addition were unaffected by large variation in signal response caused by matrix effects, independent of variation in slope of the standard addition curves.

CONCLUSION

Sample dilution was helpful but not sufficient for reducing effects of ion suppression. We have shown that LC-MS/MS quantification by standard addition can be a powerful approach for accurate measurement of phytochemicals in the absence of isotopic labelled internal standards.

Screening and characterization of aldose reductase inhibitors from Traditional Chinese medicine based on ultrafiltration-liquid chromatography mass spectrometry and in silico molecular docking

ETHNOPHARMACOLOGICAL RELEVANCE

Shenqi Jiangtang granule (SJG) is an ancient Chinese herbal formula used for treatment of Diabetes mellitus and its complications.

AIM OF THE STUDY

To establish an integrated approach for discovery of effective Aldose reductase inhibitors (ARIs) from SJG.

MATERIALS AND METHODS

An integrated approach combining ultrafiltration-liquid chromatography-mass spectrometry (UF-LC-MS) with in silico molecular docking was established for development of ARIs. AR enzyme was separated from the rabbit's crystalline lens. The inhibitory activities of these compounds were detected by UV spectrophotometry with DL-glyceraldehyde as a substrate. Furthermore, molecular docking was used to understand the binding mechanism of these screened compounds interacting with AR.

RESULTS

After optimization of AR reaction system and ultrafiltration incubation system, 17 active ingredients were screened from SJG by UF-LC-MS technique. Among these potential AR inhibitors, ginsenoside Rd exhibited the strongest activity with IC₅₀ value of 45.77 μM. Three of them, calycosin, gomisin J and schisandrin A were demonstrated to be potential inhibitors for the first time, with IC₅₀ at 447.34 μM, 181.73 μM, and 429.00 μM, respectively. Most of the active compounds exhibited competitive inhibition against AR. The docking scores of saponins were higher than that of lignans, which was consistent with the verification results.

CONCLUSION

The results indicated that TCM formula with clinical efficacy was indeed hopeful source for screening active ingredients, and the combination of UF-LC-MS and in silico molecular docking was a universal and promising approach for development of effective enzyme inhibitors.

Comprehensive investigation of mechanism and effective ingredients of Fangji Huangqi Tang by serum pharmacochemistry and network pharmacology

Fangji Huangqi Tang (FHT), has been reported to show effects on nephrotic syndrome, but its mechanism of action and bioactive components have not yet been determined. In this study, a method using UPLC-HRMS/MS was established for the detection and identification of the chemical constituents and metabolites absorbed into the blood. Absorbed components in serum were then used for the network pharmacology analysis to deduce the mechanism and effective components. A total of 86 compounds were identified or tentatively characterized. Based on the same instrumental conditions, 85 compounds were found in rat serum after oral administration of FHT, including 22 prototypes and 63 metabolites. Network pharmacology analysis showed that absorbed components, such as (3R)-2',3',4',7-tetrahydroxyisoflavan, astrapterocarpan, cycloastragenol, 7,2'-dihydroxy-3',4'-dimethoxyisoflavan, astragaloside IV, astrapterocarpan glucoside and glycyrrhetinic acid, could be responsible for the pharmacological activity of nephrotic syndrome by regulating the VEGF signaling pathway, focal adhesion and MAPK signaling pathway. Furthermore, the pathway-target network showed that the MAPK1, AKT2 and CDC42 were involved in the signal pathways above. This study provides a scientific basis for the mechanism and effective ingredients of FHT.

A Systematic Review of Phytochemistry, Pharmacology and Pharmacokinetics on Astragali Radix: Implications for Astragali Radix as a Personalized Medicine

Astragali radix (AR) is one of the most widely used traditional Chinese herbal medicines. Modern pharmacological studies and clinical practices indicate that AR possesses various biological functions, including potent immunomodulation, antioxidant, anti-inflammation and antitumor activities. To date, more than 200 chemical constituents have been isolated and identified from AR. Among them, isoflavonoids, saponins and polysaccharides are the three main types of beneficial compounds responsible for its pharmacological activities and therapeutic efficacy. After ingestion of AR, the metabolism and biotransformation of the bioactive compounds were extensive in vivo. The isoflavonoids and saponins and their metabolites are the major type of constituents absorbed in plasma. The bioavailability barrier (BB), which is mainly composed of efflux transporters and conjugating enzymes, is expected to have a significant impact on the bioavailability of AR. This review summarizes studies on the phytochemistry, pharmacology and pharmacokinetics on AR. Additionally, the use of AR as a personalized medicine based on the BB is also discussed, which may provide beneficial information to achieve a better and more accurate therapeutic response of AR in clinical practice.

Determination of a astragaloside IV derivative LS-102 in plasma by ultra-performance liquid chromatography-tandem mass spectrometry in dog plasma and its application in a pharmacokinetic study

BACKGROUND

Astragalosidic acid (LS-102) is a new water-soluble derivative of astragaloside IV - a major effective component isolated from the Chinese herb Astragali Radix. Our previous study showed that LS-102 exhibited potent cardiovascular activity.

PURPOSE

The objective of this study was to investigate the pharmacokinetic properties of LS-102 after single-dose, oral administration in beagle dogs by developing and validating an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method.

METHOD AND RESULT

The chromatographic separation was performed on a Acquity HSS C₁₈ column (100 mm × 2.1 mm, 1.8 µm) by a gradient elution using a mobile phase consisting of water and acetonitrile at a flow rate of 0.35 ml/min. The analytes were detected with a triple quadrupole tandem mass spectrometry in multiple reaction monitoring mode. Method validation revealed a wide linearity over the range of 2.0-10,000 ng/ml together with satisfactory intra- and inter-day precision, accuracy, and recovery. Stability testing showed that LS-102 spiked into dog plasma was stable for 4 h at room temperature, for up to 2 weeks at -80 °C, and during three freeze-thaw cycles. The method was effectively and successfully applied to the pharmacokinetics of LS-102 after oral administration (5, 10 and 20 mg/kg) to beagle dogs. Peak plasma concentrations are attained within approximately 2 h after oral administration with a half-life ranging from 1.55 h to 4.49 h. The plasma concentration-time curve of LS-102 after oral administration presents the phenomenon of a double-peak absorption phase. The peak concentration and area under the concentration-time curve of LS-102 seemed to increase with the increasing doses proportionally, that suggesting linear pharmacokinetics in dogs. Meanwhile, the doxorubicin (Dox)-injured H9c2 cell model was prepared by incubating the cells in 1 µM Dox for 24 h. MTT assay and LDH release measurement showed that LS-102 protected against Dox-induced cardiomyocyte death.

CONCLUSION

The obtained results may help to guide the further pre-clinical research of LS-102 as a potentially novel cardioprotective agent.

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.

Identification of metabolites of liquiritin in rats by UHPLC-Q-TOF-MS/MS: metabolic profiling and pathway comparisonin vitroandin vivo

Liquiritin (LQ), the main bioactive constituent of licorice, is a common flavoring and sweetening agent in food products and has a wide range of pharmacological properties, including antidepressant-like, neuroprotective, anti-cancer and anti-inflammatory properties. This study investigated the metabolic pathways of LQ in vitro (rat liver microsomes) and in vivo (rat model) using ultra high-performance liquid chromatography coupled with hybrid triple quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS). Moreover, supplementary tools such as key product ions (KPIs) were employed to search for and identify compounds. As a result, 56 in vivo metabolites and 15 in vitro metabolites were structurally characterized. Oxidation, reduction, hydrolysis, methylation, acetylation, and sulfate and glucuronide conjugation were determined to be the major metabolic pathways of LQ, and there were differences in LQ metabolism in vitro and in vivo. In addition, the in vitro and in vivo metabolic pathways were compared in this study.

Liquiritin (LQ), the main bioactive constituent of licorice, is a common flavoring and sweetening agent in food products and has a wide range of pharmacological properties, including antidepressant-like, neuroprotective and anti-cancer properties.

Evaluation and Comparison of the Inhibition Effect of Astragaloside IV and Aglycone Cycloastragenol on Various UDP-Glucuronosyltransferase (UGT) Isoforms

As one of the main active ingredients from Radix Astragali (RA), orally dosed astragaloside IV (AST) is easily transformed to sapogenin-cycloastragenol (CAG) by deglycosylation in the gastrointestinal tract. Because the potential adverse effects of AST and CAG remain unclear, the present study in this article was carried out to investigate the inhibition effects of AST and CAG on UDP-glucuronosyltransferases (UGTs) to explore potential clinical toxicity. An in vitro UGTs incubation mixture was employed to study the inhibition of AST and CAG towards UGT isoforms. Concentrations of 100 μM for each compound were used to initially screen the inhibitory efficiency. Deglycosylation of AST to CAG could strongly increase the inhibitory effects towards almost all of the tested UGT isoforms, with an IC₅₀ of 0.84 μM and 11.28 μM for UGT1A8 and UGT2B7, respectively. Ulteriorly, the inhibition type and kinetics of CAG towards UGT1A8 and UGT2B7 were evaluated depending on the initial screening results. Data fitting using Dixon and Lineweaver-Burk plots demonstrated that CAG competitively inhibited UGT1A8 and noncompetitively inhibited UGT2B7. From the second plot drawn with the slopes from the Lineweaver-Burk plot versus the concentrations of CAG, the inhibition constant (Ki) was calculated to be 0.034 μM and 20.98 μM for the inhibition of UGT1A8 and UGT2B7, respectively. Based on the [I]/Ki standard ([I]/Ki < 0.1, low possibility; 1 > [I]/Ki > 0.1, medium possibility; [I]/Ki > 1, high possibility), it was successfully predicted here that an in vivo herb-drug interaction between AST/CAG and drugs mainly undergoing UGT1A8- or UGT2B7-catalyzed metabolism might occur when the plasma concentration of CAG is above 0.034 μM and 20.98 μM, respectively.