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Publications (8)12.81 Total impact

  • Y-Z Tang, Y-H Liu, J-X Chen
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    ABSTRACT: Due to the rapid onset of resistance to most antibacterial drugs, research efforts are focusing on new classes of antibacterials with different mechanisms of action from clinically used antibacterials. Pleuromutilin derivatives have received more and more scientific attention for their unique mechanism of action. Two pleuromutilin derivatives, tiamulin and valnemulin have been successfully developed as antibiotics for veterinary use. Retapamulin, another pleuromutilin derivative has been approved for use in humans in April 2007 by Food and Drug Administration (FDA). It has been shown that there is rarely cross-resistance between pleuromutilin derivatives and other antimicrobial agents, and the development of resistance bacterial is still low. This review will demonstrate mechanism of action of pleuromutilin derivatives and reveal the structure-activity relationship (SAR) of pleuromutilin derivatives. Additionally, the pleuromutilin antibacterial derivative agents in the market, such as tiamulin, valnemulin and retapamulin, will be discussed. It is proposed that new antibacterial agents might be developed from pleuromutilin derivatives in the future.
    Mini Reviews in Medicinal Chemistry 10/2011; 12(1):53-61. DOI:10.2174/138955712798868968 · 3.19 Impact Factor
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    ABSTRACT: This study was conducted to investigate the effects of apple polyphenol extract (APE) against influenza virus in mice loaded with restraint stress. The high-performance liquid chromatography (HPLC) fingerprint of APE was recorded, and the percentage composition of polyphenols was determined as 81.7%. Our results showed that restraint stress significantly promoted the mortality and duration of complications of mice infected with the H1N1 virus. However, oral administration of APE (100 and 200 mg/kg) improved the survival rates and prolonged living time of stressed mice infected with influenza virus in a dose-dependent manner. APE was further found to significantly improve the number of immunocytes, ratio of CD4 helper cells, secretion of IL-2, and capabilities of natural killer (NK) cytotoxicity (LU10/spleen) in spleens of restraint-stressed mice. In addition, APE also significantly decreased the level of lipid peroxidation and increased oxygen radical absorbance capacity (ORAC) in splenocytes. These results indicated that the protective effects of APE on mice infected with influenza virus were related to the alleviation of stress-induced impairment of immune functions and its antioxidant property might contribute to the immune recovery.
    Journal of Agricultural and Food Chemistry 03/2011; 59(8):3730-7. DOI:10.1021/jf104982y · 3.11 Impact Factor
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    ABSTRACT: To study the chemical constituents of the full plant of Lobelia chinensis. The compounds were isolated and purified using several column chromatographic methods. Their structures were elucidated based on their physicochemical properties and spectral data. Twelve compounds were isolated from L. chinensis. Their structures were elucidated as 6,7-dimethoxycoumarin (1), fraxinol (2), 5-hydroxy-7-methoxycoumarin (3), tomentin (4), 3'-hydroxygenkwanin (5), apigenin (6), quercetin (7), luteolin (8), linarin (9), luteolin 3',4'-dimethylether-7-O-beta-D-glucoside (10), isoferulic acid (11), and ethyl ros-marinate (12), respectively. Compounds 1 -5 and 10 -12 are isolated from this plant for the first time.
    Zhong yao cai = Zhongyaocai = Journal of Chinese medicinal materials 11/2010; 33(11):1721-4.
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    ABSTRACT: A pair of new enantiomeric neolignans, ethyl 3-[(2R,3S)-2-(4-hydroxy-3-methoxyphenyl)-3-(hydroxymethyl)-7-methoxy-2,3-dihydro-1-benzofuran-5-yl] propanoate (+) (1) and ethyl 3-[(2S,3R)-2-(4-hydroxy-3-methoxyphenyl)-3-(hydroxymethyl)-7-methoxy-2,3-dihydro-1-benzofuran-5-yl] propanoate (-) (1), together with a pair of known enantiomeric neolignans (+) (2) and (-) (2), as well as five known lignans (3-7) were isolated from the ethanol extract of Lobelia chinensis. Their structures were elucidated on the basis of extensive spectroscopic analyses, including 1D and 2D NMR, HR-ESI-MS and CD spectra.
    Natural product communications 10/2010; 5(10):1627-30. · 0.92 Impact Factor
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    ABSTRACT: A method based on accelerated solvent extraction combined with rapid-resolution LC-MS for efficient extraction, rapid separation, online identification and accurate determination of the saikosaponins (SSs) in Radix bupleuri (RB) was developed. The RB samples were extracted by accelerated solvent extraction using 70% aqueous ethanol v/v as solvent, at a temperature of 120 degrees C and pressure of 100 bar, with 10 min of static extraction time and three extraction cycles. Rapid-resolution LC separation was performed by using a C(18) column at gradient elution of water (containing 0.5% formic acid) and acetonitrile, and the major constituents were well separated within 20 min. A TOF-MS and an IT-MS were used for online identification of the major constituents, and 27 SSs were identified or tentatively identified. Five major bioactive SSs (SSa, SSc, SSd, 6''-O-acetyl-SSa and 6''-O-acetyl-SSd) with obvious peak areas and good resolution were chosen as benchmark substances, and a triple quadrupole MS operating in multiple-reaction monitoring mode was used for their quantitative analysis. A total of 16 RB samples from different regions of China were analyzed. The results indicated that the method was rapid, efficient, accurate and suitable for use in the quality control of RB.
    Journal of Separation Science 07/2010; 33(13):1933-45. DOI:10.1002/jssc.201000100 · 2.59 Impact Factor
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    ABSTRACT: A new prenylcoumarin, 5-methoxyl-4,2'-epoxy-3-(4', 5'-dihydroxyphenyl)-linear pyranocoumarin (1), and a new flavonoid, 3-acetyl-3,5,4'-trihydroxy-7-methoxylflavone (2), were isolated from the roots of Ficus hirta. Their structures were elucidated by spectroscopic methods including 1D-, 2D- NMR and HR-ESI-MS.
    Natural product research 04/2010; 24(7):621-5. DOI:10.1080/14786410902847377 · 1.23 Impact Factor
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    ABSTRACT: Infections with influenza A viruses are still a major threat to humans and several animal species. The occurrence of highly pathogenic avian influenza viruses capable of infecting and killing humans highlights the urgency for a new and efficient strategy for the treatment of diseases caused by the virus. Andrographolide and its derivatives have been widely used for treating respiratory infections in China for decades. We have recently synthesized new andrographolide derivatives and found that some of the compounds including 14-alpha-lipoyl andrographolide (AL-1) have significant activity against bacterial infections with an unique mechanism of action. We report here the antiviral activity of AL-1 and other andrographolide drugs. AL-1 showed significant activity against influenza A viruses including the H5N1 avian influenza virus. The administration of AL-1 by oral gavage to mice infected with avian influenza A/Chicken/Guangdong /96 (H9N2), A/Duck/Guangdong/99 (H5N1), and human influenza A/PR/8/34 (H1N1) viruses greatly reduced the death rate, prolonged life, inhibited lung consolidation, and reduced viral titers in the lung. The most effective dosage of AL-1 in these studies ranged from 100 to 200 mg/kg/d, when administered twice daily for 7 d beginning 24 h before viral exposure. The LD(50) of AL-1 was 1243 mg/kg/d. AL-1 was effective against avian influenza A (H9N2 and H5N1) and human influenza A H1N1 viruses in vitro, with the 50% effective concentrations ranging from 7.2 to 15.2 microM and the selective indexes ranging from 51 to 109. Significant inhibition of viral adsorption onto red blood cells with minimum inhibitory concentrations ranging from 5.3 to 16.8 mM suggested that AL-1 was capable of directly interfering with viral hemagglutinin to block binding to cellular receptors. With potent antiviral activity and a potentially new mechanism of action, AL-1 may warrant further evaluation as a possible therapy for influenza.
    Biological & Pharmaceutical Bulletin 09/2009; 32(8):1385-91. DOI:10.1248/bpb.32.1385 · 1.78 Impact Factor