Duc Manh Hoang

Chosun University, Gwangju, Gwangju, South Korea

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Publications (6)9.16 Total impact

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    ABSTRACT: Protein tyrosine phosphatase 1B (PTP1B), a negative regulator of insulin signaling, has served as a potential drug target for the treatment of type 2 diabetes. The MeOH extracts of twenty-nine medicinal plants, traditionally used in Vietnam as anti-diabetes agents, were investigated for PTP1B inhibitory activity in vitro. The results indicated that, most materials showed moderate to strong inhibitory activity with IC50 values ranging from 3.4 μg/mL to 35.1 μg/mL; meanwhile, eleven extracts (37.9%) could demonstrate PTP1B activity with IC50 values less than 15.5 μg/mL; sixteen extracts (55.2%) could demonstrate PTP1B activity with IC50 values ranging from 15.5 μg/mL to 35.1 μg/mL. The study may provide a proof, at least in a part, for the ethno-medical use in diabetes disease of these plants.
    Natural Product Sciences 11/2010; 16(4):239-244.
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    ABSTRACT: Bioassay-guided fractionation of the chloroform-soluble fraction of Morus bombycis, using an in vitro PTP1B inhibitory assay led to the identification of three 2-arylbenzofurans, albafuran A (1), mulberrofuran W (2) and mulberrofuran D (6), along with three chalcone-derived Diels-Alder products, kuwanon J (3), kuwanon R (4), and kuwanon V (5). Compounds 1-6 showed remarkable inhibitory activity against PTP1B with IC(50) values ranging from 2.7 to 13.8 microM. Inhibition kinetics were analyzed by Lineweaver-Burk plots, which suggested that compounds 1-6 inhibited PTP1B in a mixed-type manner. The present results indicate that the respective lipophilic and hydroxyl groups of 2-arylbenzofurans and chalcone-derived Diels-Alder products play an important role in inhibition of PTP1B.
    Bioorganic & medicinal chemistry letters 12/2009; 19(23):6759-61. · 2.65 Impact Factor
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    ABSTRACT: Gynostemma pentaphyllum (Thunb.) tea was used in Vietnamese folk medicine as anti-diabetic agent. This study was aimed to investigate the inhibitory activities of fractions and constituents isolated from Gynostemma pentaphyllum on protein tyrosine phosphatase 1B (PTP1B) since it has been proposed as a treatment therapy for type 2 diabetes and obesity. The 70% EtOH extract, CHCl3 fraction, EtOAc fraction, BuOH fraction, and seven isolated dammarane triterpenes were evaluated for their inhibitory activity in protein phosphatase enzymes (PTP1B and VHR). CHCl3-soluble fraction showed a dose-dependent inhibitory activity of the PTP1B enzyme with the IC50 value of 30.5 microg/mL. Among seven tested compounds, compounds 6 showed the most potent PTP1B inhibitory activity with IC50 value of 5.3+/-0.4 microM compared to a range 15.7-28.5 microM for the other six compounds. The inhibition mode of 6 was competitive toward p-NPP with a K(i) value of 2.8 microM. These study results suggested that the PTP1B inhibitory activity of these dammaranes may enable this plant to play an important role in the treatment of diabetes.
    Journal of ethnopharmacology 05/2009; 124(2):240-5. · 2.32 Impact Factor
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    ABSTRACT: An EtOAc-soluble partition of the MeOH extract of a branch of Tetracera scandens (Dilleniaceae family) was subjected to a glucose-uptake assay, which led to the isolation and identification of five isoflavones of previously known structure namely, genistein (1), its derivatives 3',5'-diprenylgenistein (2), 6,8-diprenylgenistein (3), derrone (4) and alpinumisoflavone (5). Of these, compounds 2--5 exhibited significant glucose-uptake activity in basal and insulin-stimulated L6 myotubes. The findings from adenosine monophosphate-activated kinase (AMPK) activation and glucose transport protein4 (GLUT4) and GLUT1 over-expression revealed certain characteristics of compounds 2--5. These compounds inhibited protein tyrosine phosphatase 1B (PTP1B) activities with IC50 values ranging from 20.63 +/- 0.17 to 37.52 +/- 0.31 microM. No muscle cell toxicity was reported with compounds 3--5, while compounds 1 and 2 reduced muscle cell viability with IC50 values of 34.27 +/- 0.35 and 18.69 +/- 0.19 microM, respectively. It was concluded that T. scandens and its constituents exerted highly desirable activities on type 2 diabetes mellitus treatment since they significantly stimulated the uptake of glucose, AMPK phosphorylation, GLUT4 and GLUT1 mRNA expressions and PTP1B inhibition in L6 myotubes.
    Biological & Pharmaceutical Bulletin 04/2009; 32(3):504-8. · 1.85 Impact Factor
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    ABSTRACT: Bioassay-guided fractionation of an EtOAc-soluble extract of the stem bark of Erythrina addisoniae (Leguminosae), using an in vitro PTP1B inhibitory assay, resulted in the isolation of three new (1-3) and three known (4-6) 2-arylbenzofuran derivatives. The new compounds were identified as 2-[2',4'-dihydroxy-3'-(3-methylbut-2-enyl)phenyl]-6-hydroxybenzofuran (1), 2-[2'-methoxy-4'-hydroxy-5'-(3-methylbut-2-enyl)phenyl]-6-hydroxybenzofuran (2), and 2-(2'-methoxy-4'-hydroxyphenyl)-5-(3-methylbut-2-enyl)-6-hydroxybenzofuran (3). The new 2-arylbenzofurans 1-3 inhibited PTP1B activity with IC(50) values ranging from 13.6+/-1.1 to 17.5+/-1.2 microM in vitro assay. On the basis of the data obtained, 2-arylbenzofurans with prenyl group may be considered as a new class of PTP1B inhibitors.
    Bioorganic & Medicinal Chemistry Letters 08/2007; 17(14):3868-71. · 2.34 Impact Factor
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
    ChemInform 01/2007; 38(46).