Mingcang Chen

Metabolism and Pharmacokinetics of Mangiferin in Conventional Rats, Pseudo-Germ-Free Rats, and Streptozotocin-Induced Diabetic Rats

To clarify the role of the intestinal flora in the absorption and metabolism of mangiferin and to elucidate its metabolic fate and pharmacokinetic profile in diabetic rats, a systematic and comparative investigation of the metabolism and pharmacokinetics of mangiferin in conventional rats, pseudo-germ-free rats, and streptozotocin (STZ)-induced diabetic rats was conducted. Forty-eight metabolites of mangiferin were detected and identified in the urine, plasma, and feces after oral administration (400 mg/kg). Mangiferin underwent extensive metabolism in conventional rats and diabetic rats, but the diabetic rats exhibited a greater number of metabolites compared with that of conventional rats. When the intestinal flora were inhibited, deglycosylation of mangiferin and sequential biotransformations would not occur. Pharmacokinetic studies indicated a 2.79- and 2.35-fold increase in the plasma maximum concentration and the area under the concentration-time curve from 0 to 24 h of mangiferin in diabetic rats compared with those for conventional rats, whereas no significant differences were observed between conventional rats and pseudo-germ-free rats. Further real-time quantitative reverse transcription-polymerase chain reaction results indicated that the multidrug resistance (mdr) 1a level in the ileum increased, whereas its level in the duodenum and the mdr1b mRNA levels in the duodenum, jejunum, and ileum decreased in diabetic rats compared with those in conventional rats. With regard to the pseudo-germ-free rats, up-regulated mdr1a mRNA levels and down-regulated mdr1b mRNA levels in the small intestines were observed. The diabetic status induced increased UDP-glucuronosyltransferase (UGT) 1A3, UGT1A8, UGT2B8, and sulfotransferase (SULT) 1A1 mRNA levels and decreased catechol-O-methyltransferase (COMT), UGT2B6, UGT2B12, and SULT1C1 mRNA levels. These results might partially explain the different pharmacokinetic and metabolic disposition of mangiferin among conventional and model rats.

Analysis and detection of the chemical constituents of Radix Polygalae and their metabolites in rats after oral administration by ultra high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry

Radix Polygalae (RP), the dried root of Polygala tenuifolia Willd., is a well-known traditional Chinese medicine to mediate sedative, antipsychotic, cognitive improving, neuroprotective, and anti-inflammatory therapeutic effects on the central nervous system. In this work, ultra high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UHPLC/ESI-Q-TOF-MS/MS) was established for the separation and characterization of the chemical constituents in Radix Polygalae and their metabolites in rat plasma and urine after oral administration. Samples were separated on an Agilent Zorbax Eclipse Plus-C18 column (100mm×2.1mm, 1.8μm) with 0.1% formic acid aqueous solution and acetonitrile as the mobile phase under gradient conditions. Overall, 50 compounds were characterized from the RP, 9 of which are to our knowledge reported for the first time. In vivo, 10 components and 2 metabolites were observed in rat plasma, and 27 components and 7 metabolites were detected in rat urine. The results from this work improve our understanding on the chemical constituents of RP and their metabolic profiling.

Systematic screening and characterization of the major bioactive components of Poria cocos and their metabolites in rats by LC-ESI-MSn

Poria cocos is a well-known medicinal plant widely used in China and other East Asian countries owing to its various therapeutic effects. However, the bioactive constituents responsible for the pharmacological effects of Poria cocos and their metabolites in vivo are still unclear to date. The aim of the present study was to develop a practical method based on the combined use of the liquid chromatography coupled with electrospray ionization multistage tandem mass spectrometry (LC-ESI-MS(n) ) for the comprehensive and systematic separation and characterization of the bioactive constituents of Poria cocos extract and their metabolites in rats. Based on the proposed strategy, a total of 34 compounds were characterized from the extract of Poria cocos. Among them, eight were unambiguously identified by comparing their retention times and mass spectra with those of reference standards, and 26 were tentatively identified on the basis of their MS(n) fragmentation behaviors and molecular weight information from literatures. In vivo, seven compounds were successfully detected in rat urine whereas one was found in rat plasma. This study proposed a series of potential bioactive components and provided helpful chemical information for further research on the action mechanism of traditional Chinese medicine.

Structural elucidation and protective role of a polysaccharide from Sargassum fusiforme on ameliorating learning and memory deficiencies in mice.

A fucoidan, Sargassum fusiforme polysaccharide 65 (SFPS65) A, was isolated from a brown alga (S. fusiforme). SFPS65A had an estimated molecular weight of 90kDa and showed αD(20) -74.3288 (c 0.05, H2O). SFPS65A is composed of fucose, galactose, xylose, glucose, glucuronic acid, and mannose in the ratio of 19.23:9.58:6.64:1:6.52:2.57. The structural features of SFPS65A were investigated using composition analysis, methylation analysis, infrared spectrum, nuclear magnetic resonance spectroscopy, and electrospray ionization quadruple time-of-flight tandem mass spectroscopy. Results showed that SFPS65A has a main chain composed of →3)-β-l-Fucp-(1→3,4)-β-l-Fucp-(1→3,4)-β-l-Fucp-(1→ and connected with →3,4)-α-d-GlcAp-(1→, →4)-β-d-Xylp-(1→, →4)-α-d-Galp-(1→, →3,6)-α-d-Manp-(1→ alternately. The branches at O-3 of the fucosyl residue and O-3 of the hexosyl residues may include sulfate, →4)-β-l-Fucp-(1→, β-d-Xylp-(1→, and β-d-Xylp-(1→. SFPS65A exhibited an activity on Alzheimers disease in vivo in the pharmacological experiments by increasing the cognitive abilities of scopolamine-, ethanol-, and sodium nitrite-treated mice against memory deficits.

HPLC‐Q‐TOF‐MS/MS for analysis of major chemical constituents of Yinchen–Zhizi herb pair extract

The Yinchen-Zhizi herb pair (YZHP) consists of Herba Artemisiae Scopariae (Yinchen in Chinese) and Fructus Gardeniae (Zhizi in Chinese), and is mainly used to treat icteric hepatitis, itching skin and eczema. However, the bioactive constituents responsible for the pharmacological effects of YZHP are still unclear to date. In this work, a rapid and sensitive method was established to comprehensively study the constituents in YZHP extract by HPLC-Q-TOF MS/MS. The analysis was performed on an HPLC system equipped with an Agilent poroshell 120 EC-C18 column (100 × 2.1 mm, 2.7 mm) working in a gradient elution program coupled to quadrupole-time-of-flight mass spectrometry operating in the negative ion mode. As a result, a total of 46 compounds including 17 from Herba Artemisiae Scopariae and 36 from Fructus Gardeniae were detected and tentatively identified in YZHP extract by comparing the retention time and mass spectrometry and retrieving the reference literature. More importantly, a series of constituents, such as many iridoid glycosides, were reported for the first time in this formula. The HPLC-Q-TOF MS/MS method was developed and utilized successfully to identify the major constituents in YZHP extract and would be helpful for further metabolism and pharmacology research on YZHP.

Structural investigation and immunological activity of a heteropolysaccharide from Sargassum fusiforme

A heteropolysaccharide was isolated from the brown alga, Sargassum fusiforme. The heteropolysaccharide was estimated to have a molecular weight of 11kDa and showed [α]D(20) -62.2420 (c 0.05, H2O). SFPS65-B comprised galactose, glucose, mannose, fucose, and galacturonic acid at a ratio of 3.04:1:1.15:2.82:6.51. Its structural features were investigated using composition analysis, methylation analysis, IR, NMR spectroscopy, and ESI-Q-TOF MS spectroscopy. Results showed that SFPS65-B contained the backbone of →4)-α-GalAp-(1→4)-α-Hexp-(1→4)-α-GalAp-(1→4)-α-Fucp-(1→4)-α-GalAp-(1→. The sulfated unit and terminal fucose residues were attached onto the backbone through the O-2 of some galactose residues. Results also showed that SFPS65-B had a good effect on thymus and spleen indices at a dose of 100mg/kg upon immunosuppression in cyclophosphamide-treated mice.

Fragmentation patterns study of iridoid glycosides in Fructus Gardeniae by HPLC‐Q/TOF‐MS/MS

Iridoid glycosides (IGs), the major constituents in Fructus Gardeniae, have demonstrated various pharmacological activities, but there is no systematic chemical profile of IGs in Fructus Gardeniae in the published literature until now. Therefore, it is imperative that a rapid and sensitive high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (HPLC-Q/TOF-MS/MS) method is established for comprehensive characterization of IGs in Fructus Gardeniae. Firstly, the fragmentation patterns of six known IGs were investigated and proposed and further concluded the diagnostic fragment ions and characteristic fragmentation pathways. Then, based on the summarized fragmentation patterns and the known compounds in the literatures, the other IGs in Fructus Gardeniae were identified successively. As a result, a total of 20 IGs were identified, of which three pairs of epimers were structurally characterized and differentiated. More importantly, one compound, the isoshanzhiside methyl ester, was tentatively identified as a new compound. The results of this study demonstrate the superiority of HPLC-MS with a high-resolution mass spectrometer for the rapid and sensitive structural elucidation of the multiple groups of constituents in Fructus Gardeniae.

Analysis of Multiple Constituents in Cong‐Ming‐Tang, a Chinese Herbal Formula for the Treatment of Amnesia, by High‐performance Liquid Chromatography with Quadrupole Time‐of‐flight Mass Spectrometry

INTRODUCTION Cong-Ming-Tang (CMT), named smart-soup in English, is a well-known traditional Chinese medicine formula for the treatment of amnesia in China. However, the isolation, purification and identification procedures of the major bioactive constituents in CMT are difficult and time consuming. OBJECTIVE To establish a rapid and sensitive high-performance liquid chromatography/electrospray ionisation with quadrupole time-of-flight tandem mass spectrometry (HPLC-QTOF/MS/MS) method that could be applied to rapidly separate and identify the major bioactive constituents in CMT. METHODS Methanolic extract of CMT was used for HPLC-QTOF/MS/MS analysis. Separation was performed on an Agilent Poroshell 120 EC- C18 column (2.7 ×100 mm .i.d., 2.7 µm) with 0.1% formic acid aqueous solution and acetonitrile as the mobile phase under gradient conditions. Both positive and negative ion modes were employed. RESULTS This analytical tool allowed the identification of 55 compounds from CMT formulae by comparing their retention times and MS spectra with those of authentic compounds or literature data in both positive and negative ion modes, including 4 xanthone C-glycosides, 4 sucrose esters, 11 oligosaccharide multi-esters,15 triterpene saponins, 15 triterpene acids, 2 lignans and 4 phenylpropanoids. Onjisaponin MF was tentatively elucidated as a new triterpene saponin based on the summarised fragmentation rules. CONCLUSION HPLC-QTOF/MS/MS provides a new powerful approach to identify the major chemical constituents in CMT rapidly and accurately. This study proposed a series of potential bioactive components without preparative isolation from the crude extract of CMT and indicated that the HPLC-QTOF/MS/MS method also can be a promising tool for the analysis of other traditional Chinese medicines.

Metabolite Identification of Myricetin in Rats Using HPLC Coupled with ESI-MS

Myricetin, a naturally occurring flavonol, shows multifarious pharmacological activities, e.g., antidiabetic, antioxidant, anti-inflammatory, antitumor, and liver protection effects. In order to obtain an understanding of the myricetin’s metabolism in vivo, a rapid and sensitive method by high-performance liquid chromatography coupled with electrospray-ionization mass spectrometry (HPLC-MSn) techniques was employed to investigate the biotransformation in rats after oral administration of myricetin. Recognition and structural exposition of the metabolites were operated by comparing the changes in molecular mass (ΔM) and MSn spectra with the parent drug. As a result, the parent compound and seven metabolites were found in rat plasma, urine, and feces. In addition, besides 3,5-dihydroxyphenylacetic acid (M1) and 3,4,5-trihydroxyphenylacetic acid (M2), five other compounds were first discovered in the metabolite research of myricetin. These results indicated that, besides ring-fission, there were methylate (M3, M4, M5) and glucuronide (M6, M7) biotransformations of myricetin occurring in vivo.

Systematic and comprehensive strategy for metabolite profiling in bioanalysis using software-assisted HPLC-Q-TOF: magnoflorine as an example

AbstractMetabolite profiling plays a crucial role in drug discovery and development, and HPLC–Q-TOF has evolved into a powerful and effective high-resolution analytical tool for metabolite detection. However, traditional empirical identification is laborious and incomplete. This paper presents a systematic and comprehensive strategy for elucidating metabolite structures using software-assisted HPLC-Q-TOF that takes full advantage of data acquisition, data processing, and data mining technologies, especially for high-throughput metabolite screening. This strategy has been successfully applied in the study of magnoflorine metabolism based on our previous report of its poor bioavailability and drug–drug interactions. In this report, 23 metabolites of magnoflorine were tentatively identified with detailed fragmentation pathways in rat biological samples (urine, feces, plasma, and various organs) after i.p. or i.g. administration, and for most of these metabolites, the metabolic sites were determined. The phase I biotransformations of magnoflorine (M1-M7, M10-M14) consist of demethylation, dehydrogenation, hydroxylation, methylene to ketone transformation, N-ring opening, and dehydroxylation. The phase II biotransformations (M8, M9, and M15-M23) consist of methylation, acetylation, glucuronidation, and N-acetylcysteine conjugation. The results indicate that the extensive metabolism and wide tissue distribution of magnoflorine and its metabolites may partly contribute to its poor bioavailability and drug–drug interaction, and i.p. administration should thus be a suitable approach for isolating magnoflorine metabolites. In summary, this strategy could provide an efficient, rapid, and reliable method for the structural characterization of drug metabolites and may be applicable for general Q-TOF users. Graphical abstractᅟ