Taipei Medical University Institutional Repository:Item 987654321/3831
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    Title: Antioxidant and nitric oxide production inhibitory activities of galacturonyl hydroxamic acid
    Authors: 侯文琪
    Liu YH;Lin SY;Lee CC;Hou WC
    Contributors: 生藥學研究所
    Date: 2008
    Issue Date: 2009-08-25 12:25:43 (UTC+8)
    Abstract: The self-prepared pectin hydroxamic acid has been reported to have antioxidant activities [Yang, S. S., Cheng, K. D., Lin, Y. S., Liu, Y. W., & Hou, W. C. (2004). Pectin hydroxamic acids exhibit antioxidant activities in vitro. Journal of Agricultural and Food Chemistry, 52, 4270–4273]. In this study, the galacturonic acid (GalA), the monomer unit of the pectin polymer, was esterified with acidic methanol (1 N HCl) at 4 °C with gentle stirring for 5 days to get galacturonic acid methyl ester which was further reacted with alkaline hydroxylamine to get galacturonyl hydroxamic acid (GalA–NHOH). The GalA–NHOH was used to test the antioxidant and antiradical activities in the comparison with GalA. The scavenging activities of GalA–NHOH against DPPH radicals (half-inhibition concentration, IC50, was 82 μM), hydroxyl radicals detected by electron spin resonance (IC50 was 0.227 nM in the comparison with Trolox of 0.433 μM), superoxide radicals (IC50 was 830 μM) were determined. The protection activities of GalA–NHOH against hydroxyl radicals-mediated calf thymus DNA damages, linoleic acid peroxidation and peroxynitrite-mediated dihydrorhodamine 123 oxidations were also investigated. It was found that the GalA–NHOH exhibited dose-dependently antioxidant activity and few or none was found in GalA. The GalA–NHOH was used to evaluate the suppressed activity of nitric oxide (NO) productions of RAW264.7 cells in the presence of lipopolysaccharide (LPS, 100 ng/ml) as inducers. It was found that GalA–NHOH (0.02–0.1 mg/ml) could dose-dependently suppress the NO productions (expressed as nitrite concentrations) in RAW264.7 cells without significant cytotoxicity.

    Keywords: Antioxidant activity; Electron spin resonance (ESR); Galacturonylhydroxamic acid (GalA–NHOH); Nitric oxide; RAW264.7 cells
    Relation: Food Chemistry.(109):159-166.
    Data Type: article
    Appears in Collections:[Graduate Institute of Pharmacognosy Science] Periodical Article

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