De-An Guo

Shanghai Institutes for Biological Sciences, Shanghai, Shanghai Shi, China

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Publications (217)475.85 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Microbial transformation of 20(R)-panaxadiol by the fungus Rhizopus chinensis CICC 3043 yielded seven metabolites. Their structures were elucidated on the basis of extensive spectroscopic analyses. R. chinensis could catalyze hydroxylation and further dehydrogenation at C-24 of 20(R)-panaxadiol, as well as hydroxylation at C-7, C-15, C-16, and C-29. Three of these compounds at 10μM could moderately inhibit growth of HepG2 human hepatocellular carcinoma cells with an inhibition rate of about 40%. Three compounds (also at 10μM) showed approximately 30% inhibition on NF-κB transcriptional activity in SW480 human colon carcinoma cells stably transfected with NF-κB luciferase reporter and induced by LPS.
    Phytochemistry 06/2014; · 3.05 Impact Factor
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    ABSTRACT: Ergostanes are major bioactive constituents of the medicinal mushroom Antrodia camphorata. These tetracyclic triterpenoids usually occur as 25R/S epimeric pairs, which renders their chromatographic separation difficult. In this study, we used analytical supercritical-fluid chromatography (SFC) to separate seven pairs of 25R/S-ergostanes from A. camphorata. The (R)- and (S)-forms for each of the seven pairs could be well resolved (Rs>1.3) on a Chiralcel OJ-H column (4.6×250mm, 5μm, chiral), eluted by 10% MeOH in CO2 at 2mL/min with a back pressure of 120bar and a column temperature of 40°C. Particularly, this chiral-SFC method could rapidly and efficiently separate low-polarity epimers like antcin A and antcin B, which were very difficult for RP-HPLC. A 3-min preparative-scale method was established to purify (25S)- and (25R)-antcin A for the first time. However, OJ-H column suffered from peak overlapping of different pairs of ergostanes. We found that Princeton 2-ethylpyridine column (2-EP, 4.6×250mm, 3μm, achiral) could effectively separate different pairs, although the resolutions for 25-R/S forms of each epimeric pair were not as good as OJ-H column. Meanwhile, all the (25S)-forms showed stronger retentions than the corresponding (25R)-epimers on the 2-EP column. These results demonstrated different selectivity of chiral- and achiral-SFC in separating 25R/S-ergostane epimers. Aside from high separation efficiency, SFC also showed advantage over HPLC in short analysis time and low consumption of organic solvents. Finally, both OJ-H and 2-EP columns were used on analytical SFC to separate 25R/S-ergostanes in an extract of A. camphorata.
    Journal of chromatography. A. 06/2014;
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    ABSTRACT: Seven hexahydrobenzophenanthridine-type alkaloids, Ambiguanine A-G, along with eight known alkaloids, were isolated from tubers of Corydalis ambigua var. amurensis. Their structures were elucidated based on extensive spectroscopic analyses, with absolute configurations determined by CD experiments.
    Phytochemistry 06/2014; · 3.05 Impact Factor
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    ABSTRACT: Glycycoumarin is a major bioactive coumarin of licorice (Glycyrrhiza uralensis), one of the most popular herbal medicines worldwide. In this work, the metabolism of glycycoumarin in rats was investigated. After oral administration of 40mg/kg glycycoumarin, 4 and 10 metabolites were respectively detected in rats plasma and urine samples by liquid chromatography coupled with mass spectrometry (LC/MS). These metabolites were tentatively characterized by analyzing their tandem mass spectra and high-resolution mass spectra, and the structures of glucuronides were confirmed by β-glucuronidase hydrolysis. Glycycoumarin mainly undertakes hydroxylation and glucuronidation metabolism, accompanied by hydrogenation and dehydrogenation as minor reactions. Two hydroxylated metabolites, 4''-hydroxyl glycycoumarin and 5''-hydroxyl glycycoumarin, were obtained by microbial transformation of Syncephalastrum racemosum AS 3.264, and their structures were fully identified by 1D and 2D NMR. Both metabolites are new compounds. Furthermore, they were proved to be catalyzed by P450 enzymes by rat liver microsomes incubation experiments. Finally, a metabolic pathway of glycycoumarin in rats was proposed. This is the first systematic study on metabolites identification of glycycoumarin.
    Journal of pharmaceutical and biomedical analysis. 06/2014; 98C:287-295.
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    ABSTRACT: Three new cardenolides (1-3) were isolated from the 90% ethanolic extract of the bark of a wild-type Calotropis gigantea. Their structures were determined by using NMR spectra and LC-MS analysis. Their inhibitory activities were evaluated against non-small cell lung carcinoma (A549) and human cervix epithelial adenocarcinoma (HeLa) cell lines. Compounds 1 and 3 exhibited strong inhibitory effect on two cancer cell lines.
    Natural product research 04/2014; · 1.01 Impact Factor
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    ABSTRACT: Five new oleanane and ursane type triterpenes, namely uncarinic acids F-J (1-5), together with six known triterpenic acids (6-11) were isolated from the stems and hooks of Uncaria rhynchophylla. Structure elucidation of 1-5 was based on the integrated analyses of high-resolution MS data, 1-D ((1)H NMR, (13)C NMR, DEPT) and 2-D (HSQC, HMBC, ROESY) NMR spectra. Compounds 4, 10, and 11 exhibited weak inhibitory effects on LPS-induced NO production in RAW264.7 cells (with IC50 1.48, 7.01, and 1.89μM, respectively) with dexamethasone (IC50 0.04μM) and quercetin (IC50 0.86μM) as the positive controls. 19-OH substituted oleanane triterpenic acids (1, 2, 5, 8) were prone to eliminate CH2O3, whereas those ursane-type encompassing 19-OH (3, 6, 7, 9, 4) were featured by preferred cleavage of H2O while performing the negative collision-induced MS/MS fragmentation on an LTQ/Orbitrap mass spectrometer.
    Fitoterapia 04/2014; · 2.23 Impact Factor
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    ABSTRACT: Over the past 30 years, China has significantly improved the drug development environment by establishing a series of policies for the regulation of new drug approval. The regulatory system for new drug evaluation and registration in China was gradually developed in accordance with international standards. The approval and registration of TCM in China became as strict as those of chemical drugs and biological products. In this review, TCM-based new drug discovery and development are introduced according to the TCM classification of nine categories.
    Chinese Journal of Natural Medicines 04/2014; 12(4):241-50.
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    ABSTRACT: Negative ESI-QIT-MS of several subtypes of flavonoid O-glycosides is known to produce deprotonated molecular ions which undergo homolytic fragmentation at the glycosidic bond upon collision-induced dissociation (CID). However, these subtypes have never been simultaneously compared under unified MS conditions. The (-)-ESI-MS(n) fragmentations of 69 flavonoid O-glycosides, involving eight subtypes, were analyzed using a quadrupole ion-trap mass spectrometer with collision energies varying from 18-44%. Factors influencing the homolytic glycosidic bond fragmentation, such as collision energy, hydroxylation of aglycone, and glycosylation pattern, were comprehensively studied. Under the unified CID-QIT-MS(2) conditions, the precursor deprotonated molecular ions [M-H](-) for 3-O-glycosyl, 3,7-di-O-glycosyl and 3,6,7-tri-O-glycosyl flavonols experienced homolytic fragmentation at the glycosidic bond and generated the radical aglycone ion [Y0 -H](-•) . This gas-phase CID fragmentation behavior was not observed for the other subtypes. A general trend was found that hydroxyl substitution at C-6, glycosylation at C-6/C-7, and acetylation of the saccharide moiety remarkably suppressed this fragmentation. In addition, flavonol 3-O-diglycosides (disaccharides) possessing a 1 → 2 glycosidic bond generated more abundant [Y0 -H](-•) product ions than those with a 1 → 3 or 1 → 6 bond. The terminal sugar triggered the homolytic fragmentation in the order Rha > Xyl > Glc. Moreover, new counterexamples were found for previously reported fragmentation rules. The low-energy CID homolytic fragmentation was diagnostic for structural identification of flavonol 3-O-glycosides. We have summarized key factors affecting this fragmentation. The results could be useful for rapid characterization of flavonoid O-glycosides in complicated herbal extracts. Copyright © 2014 John Wiley & Sons, Ltd.
    Rapid Communications in Mass Spectrometry 02/2014; 28(4):385-95. · 2.51 Impact Factor
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    ABSTRACT: The chemical composition of Drynaria fortunei, a traditional Chinese herbal medicine, is very complicated. In order to separate these chemicals to obtain their structural information, an orthogonal sample enrichment procedure was established. The ethyl acetate extract of D. fortunei was pre-separated by Sephadex LH-20 × polyamide columns to yield 15 fractions. These fractions were analyzed successively using a reversed-phase Agilent Zorbax SB-C18 column, coupled with diode array detection and electrospray ionization tandem mass spectrometry. The method reduced co-elution and enriched minor compounds on the basis of their chemical features. A total of 369 compounds were detected by LC/MSn, compared to less than 50 compounds without pre-separation. The pretreatment facilitated the analytical separation of flavonoids, proanthocyanidins, triterpenoids, phenolic acids, and lignans in D. fortunei, and allowed a comprehensive chemical profiling of these constituents. This method could be applied to other multicomponent herbal extracts.
    Planta Medica 02/2014; · 2.35 Impact Factor
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    ABSTRACT: Minor phenolic compounds in licorice (Glycyrrhiza uralensis) have recently been proved for diverse bioactivities and favorable bioavailability, indicating that they may play an important role in the therapeutic effects or herb-drug interactions of licorice. However, so far, their abundance in licorice remains unknown. In this study, a reliable solid-phase extraction coupled with a high-performance liquid chromatography and diode array detection method was established to determine the minor phenolic compounds in licorice. The analytes were enriched by a three-step solid-phase extraction method, and then separated on a YMC ODS-A column by gradient elution. Five coumarins and flavonoids were identified by electrospray ionization tandem mass spectrometry, and then quantified using high-performance liquid chromatography and diode array detection. The amounts of glycycoumarin, dehydroglyasperin C, glycyrol, licoflavonol, and glycyrin in G. uralensis were 0.81 ± 0.28, 1.25 ± 0.59, 0.20 ± 0.08, 0.12 ± 0.04, and 0.17 ± 0.08 mg/g, respectively. Abundances of these compounds in other Glycyrrhiza species (G. glabra, G. inflata, and G. yunnanesis) were remarkably lower than G. uralensis.
    Planta Medica 02/2014; · 2.35 Impact Factor
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    ABSTRACT: Two new cucurbitane triterpenoids, 7β-hydroxycucurbitacin F-25-O-acetate (1) and 2β,3β,20(S),26,27-pentahydroxy-16α,23(S)-epoxycucurbita-5,24-dien-11-one (2) along with eleven known cucurbitane triterpenoids (3-13, resp.) were isolated from the rhizomes of Hemsleya amabilis Diels. The chemical structures of the new isolated compounds were elucidated unambiguously by spectroscopic data analysis. The cytotoxic activities of the isolated cucurbitane triterpenoids were evaluated against the HeLa human cancer cell lines. Hemslein A (5), the main ingredient of Hemsleya amabilis, exhibited the significant cytotoxicity with IC50 value of 0.389 μM.
    Fitoterapia 01/2014; · 2.23 Impact Factor
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    ABSTRACT: Cycloastragenol (CA) is the genuine sapogenin of astragaloside IV (ASI). This study focuses on the preparation of CA from ASI. Five hydrolysis methods were compared including H2SO4 hydrolysis, HCl hydrolysis, two-phase acid hydrolysis, mild acid hydrolysis, and Smith degradation. Seven hydrolysis products were purified, and five of them were identified as new compounds. The results indicated that Smith degradation was the most effective approach to prepare CA. In contrast, mild acid hydrolysis produced CA at a low yield, accompanied with the artificial sapogenin astragenol. The other three acid hydrolysis methods mainly produced astragenol. Furthermore, the reaction conditions for Smith degradation were optimized as follows: ASI was dissolved in 60% MeOH-H2O solution, oxidized with 5 equiv. NaIO4 for 12h, followed by reduction with 3 equiv. NaBH4 for 4h, and finally acidified with 1M H2SO4 at pH2 for 24h. Under the optimal conditions, CA could be prepared from ASI at a yield of 84.4%.
    Fitoterapia 01/2014; · 2.23 Impact Factor
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    ABSTRACT: At least 289 saponins have been isolated from the Panax genus to the end of 2012. P. ginseng, P. quinquefolius, and P. notoginseng were mostly studied, and protopanaxadiol (PPD), protopanaxatriol (PPT), octillol (OT), and oleanolic acid (OA) type saponins are the four most common subtypes.
    Phytochemistry 01/2014; · 3.05 Impact Factor
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    ABSTRACT: Using activity-guided fractionation, phenolic amides (such as trans-N-caffeoyltyramine) were confirmed as main components from Cortex Lycii responsible for NF-κB inhibition. Fatty acids were identified as the major plant constituent responsible for the PPARγ activation.
    Journal of ethnopharmacology 01/2014; · 2.32 Impact Factor
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    ABSTRACT: Seven hexahydrobenzophenanthridine type alkaloids, along with eight known alkaloids, were isolated and identified from tubers of Corydalis ambigua var. amurensis. Their absolute configurations were determined by CD experiments.
    Phytochemistry 01/2014; · 3.05 Impact Factor
  • Journal of Pharmaceutical and Biomedical Analysis. 01/2014; 98:287–295.
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    ABSTRACT: The roots of Glycyrrhiza yunnanensis Cheng f. et L. K. Dai ex P. C. Li are used as licorice in traditional medicine of Southwest China. Triterpene saponins are the major chemical constituents. In this study, one new oleanane-type triterpenoid, glyyunnansapogenin I (I), seven new triterpene saponins, yunganosides E3 (II), L (III), M (IV), N1 (V), O (VI), P (VII) and N2 (VIII), together with four known saponins (IX-XII) were isolated from the roots of G. yunnanensis by preparative chromatography. Their structures were identified by spectroscopic analysis including NMR and HR-MS. Based on (-)-ESI-MS/MS fragmentation behaviors of these reference standards, an LC/MS/MS method using neutral loss scan and precursor ion scan on a triple quadrupole mass spectrometer was established to rapidly and comprehensively analyze triterpene saponins in G. yunnanensis. Combined with high-accuracy qTOF mass spectrometry analysis, a total of 50 saponins were detected, and their structures were identified or tentatively characterized. This is the first systematic study on triterpene saponins in G. yunnanensis.
    Journal of pharmaceutical and biomedical analysis 11/2013; 90C:15-26. · 2.45 Impact Factor
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    ABSTRACT: Licorice has been shown to affect the activities of several cytochrome P450 enzymes. This study aims to identify the key constituents in licorice which may affect these activities. Bioactivity assay was combined with metabolic profiling to identify these compounds in several complex licorice extracts. Firstly, the inhibition potencies of 40 pure licorice compounds were tested using an liquid chromatography/tandem mass spectrometry cocktail method. Significant inhibitors of human P450 isozymes 1A2, 2C9, 2C19, 2D6, and 3A4 were then selected for examination of their structural features by molecular docking to determine their molecular interaction with several P450 isozymes. Based on the present in vitro inhibition findings, along with our previous in vivo metabolic studies and the prevalence of individual compounds in licorice extract, we identified several licorice constituents, viz., liquiritigenin, isoliquiritigenin, together with seven isoprenylated flavonoids and arylcoumarins, which could be key components responsible for the herb-drug interaction between cytochrome P450 and licorice. In addition, hydrophilic flavonoid glycosides and saponins may be converted into these P450 inhibitors in vivo. These studies represent a comprehensive examination of the potential effects of licorice components on the metabolic activities of P450 enzymes.
    The AAPS Journal 11/2013; · 4.39 Impact Factor
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    ABSTRACT: Licorice (Gancao) is derived from the dried roots and rhizomes of Glycyrrhiza species (Leguminosae) and appears as a component herb in about 60% of traditional Chinese medicine (TCM) prescriptions. Modern pharmacological studies have shown that flavonoids are one class of the major components responsible for the bioactivities of licorice. Ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/QTOF MS) has proven to be a powerful tool for rapid profiling and identification of natural products in complex herbal medicines. A UPLC/QTOF MS method was established for the first time for profiling and structural characterization of the phenolic compounds (most of them flavonoids) in licorice. The combined use of data-independent acquisition (MS(E) ) and data-dependent acquisition (DDA) was illustrated. Fifteen flavonoid reference compounds were used to explore the fragmentation pathways. Compound identification was based upon the exact mass, general fragmentation behaviors, retention times, UV absorption, and the related botanical biogenesis. As a result, a total of 51 compounds were characterized, three of which were reported for the first time. The LC/MS analysis for each injection took less than 9 min. The developed method is fast, accurate and reliable due to its high resolution and high efficiency characteristics as a result of combining both UPLC separation and QTOF exact mass measurement. Copyright © 2013 John Wiley & Sons, Ltd.
    Rapid Communications in Mass Spectrometry 11/2013; 27(21):2297-2309. · 2.51 Impact Factor
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    ABSTRACT: The quality control of Da-Fu-Fang (DFF), referring to the traditional Chinese medicine (TCM) preparations comprising more than 10 TCMs, is challenging due to their extreme chemical complexity. In this study, a strategy is proposed for the holistic quality control of DFFs based on HPLC/qTOF-MS-oriented characteristic components data set (CCDS) and chemometric analysis. Niuhuang Shangqing pill (NHSQP), composed of 19 TCMs, is used to illustrate this strategy. The fingerprint profiling of NHSQP by HPLC/qTOF-MS resulted in the characterization of 190 compounds, comprising 47 unambiguously identified by reference standard comparison. A CCDS containing 60 characteristic components was constructed by analyzing the MS spectral differentiation of the crude drugs, a laboratory-made NHSQP powder, and negative control preparations. With the established CCDS, it was possible to simultaneously monitor 16 out of the 19 drugs involved in NHSQP. Subsequently, 26 NHSQP samples from different vendors were evaluated by the qualitative and semi-quantitative analyses of their LC/MS fingerprint data. The 60 characteristic components were detected in all of the NHSQP samples, which demonstrated their authenticity. When compared with the standard sample No. 3, however, 15 of the NHSQP samples exhibited inferior quality. Samples No. 21 and No. 13 differed significantly based on a PCA score plot, and the components responsible for the differentiation were confirmed to originate from different TCMs. This strategy is a powerful and easy method to implement and provides a potential approach to establishing the holistic quality control of complex TCM preparations.
    Journal of pharmaceutical and biomedical analysis 11/2013; 89C:130-141. · 2.45 Impact Factor

Publication Stats

2k Citations
475.85 Total Impact Points

Institutions

  • 2006–2014
    • Shanghai Institutes for Biological Sciences
      Shanghai, Shanghai Shi, China
  • 2002–2014
    • Peking University
      • • School of Pharmaceutical Sciences
      • • Modern Research Center for Traditional Chinese Medicine
      Peping, Beijing, China
  • 2008–2013
    • China Pharmaceutical University
      Nan-ching-hsü, Jiangxi Sheng, China
    • Chinese Academy of Sciences
      • Research Center for Modernization of Traditional Chinese Medicine
      Peping, Beijing, China
    • Shanghai University of Traditional Chinese Medicine
      • Department of Chinese Materia Medica
      Shanghai, Shanghai Shi, China
    • Shenyang Pharmaceutical University
      • School of Traditional Chinese Materia Medica
      Feng-t’ien, Liaoning, China
    • Dalian Medical University
      Lü-ta-shih, Liaoning, China
  • 2006–2013
    • Northeast Institute of Geography and Agroecology
      • Research Center for Modernization of Traditional Chinese Medicine
      Beijing, Beijing Shi, China
  • 2012
    • China Academy of Traditional Chinese Medicine
      Peping, Beijing, China
  • 2007–2012
    • Peking University Health Science Center
      Peping, Beijing, China
    • National Institute for the Control of Pharmaceutical and Biological Products
      Peping, Beijing, China