Taipei Medical University Institutional Repository:Item 987654321/4328
English  |  正體中文  |  简体中文  |  Items with full text/Total items : 45069/58245 (77%)
Visitors : 2369141      Online Users : 167
RC Version 7.0 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
Scope Tips:
  • please add "double quotation mark" for query phrases to get precise results
  • please goto advance search for comprehansive author search
  • Adv. Search
    HomeLoginUploadHelpAboutAdminister Goto mobile version
    Please use this identifier to cite or link to this item: http://libir.tmu.edu.tw/handle/987654321/4328


    Title: 葉綠素衍生物對誘發型DNA損傷之保護效應
    Preventive Effects of Chlorophyll Derivatives on Induced-type DNA Damage
    Authors: 許青雲
    Ching-Yun Hsu
    Contributors: 藥學系(博士班)
    Keywords: 葉綠素
    脫鎂脫植醇葉綠素
    脫鎂醇葉綠素
    黃麴毒素
    Chlorophyll
    Pheophorbide
    Chlorophyllide
    Aflatoxin
    Date: 2009
    Issue Date: 2009-08-31 14:17:37 (UTC+8)
    Abstract: 葉綠素是植物體中含量最多最廣泛的色素。因此本研究主要探討四種葉綠素的水萃取物,包括脫植醇葉綠素 a 與b、脫鎂脫植醇葉綠素a 與b,對於淋巴球細胞中DNA氧化損傷的抗氧化作用;以及對於黃麴毒素所誘導肝細胞DNA損傷後的抗基因突變作用。第一部分,將淋巴球細胞分別與四種葉綠素衍生物5~50µM共同培養後,再將其暴露在10 、 50µM的過氧化氫使其誘導氧化傷害。利用單細胞膠體電泳法(彗星分析)觀察DNA氧化斷裂的情形,以及氧化代謝產物8-OHdG。結果顯示:四種葉綠素衍生物對10 µM的過氧化氫誘導淋巴球細胞氧化傷害都具有保護的作用;但是在50 µM的過氧化氫的誘導下,脫鎂脫植醇葉綠素a 與b對淋巴球細胞氧化傷害仍有保護的效果。第二部份,將小鼠肝臟細胞株分別暴露在四種葉綠素衍生物5~50µM共同培養後,再給與5、10 ng/mL黃麴毒素誘導肝細胞的DNA損傷。利用ELISA 測量黃麴毒素與DNA結合的產物結果顯示:四種葉綠素衍生物對於黃麴毒素誘導肝細胞的DNA損傷都具有保護的作用,推測葉綠素的結構具有捕捉分子的能力,可螯合黃麴毒素進而減少黃麴毒素對肝細胞基因的損傷。此外,在排除分子捕捉能力的研究中發現,脫鎂脫植醇葉綠素a 與b對於肝細胞DNA的損傷仍具有保護的效果,且可以調節肝細胞中麩胱甘肽轉硫酶的活性,進而增加肝臟中對黃麴毒素的解毒功能。

    Chlorophylls (Chls) are the most abundant natural plant pigments. Four chlorophyll derivatives, including chlorophyllide a and b (Chlide a and b) and pheophorbide a and b (Pho a and b), were investigated for their in vitro antioxidative capacities and anticytotoxicity properties to the cell DNA damage. First, the antioxidative effects of four chlorophyll derivatives on hydrogen peroxide (H2O2)-induced strand breaks and oxidative damage were evaluated in human lymphocyte. Lymphocytes exposed to H2O2 at a concentration of 10 and 50µM revealed an increased frequency of DNA single-strand breaks (ssbs; as measured by the comet assay) and also the level of oxidized nucleoside (as measured by 8-hydroxy-2-deoxyguanosine; 8-OHdG). All Chls reduced the level of DNA ssbs and 8-OHdG within human lymphocytes following exposure to 10µM H2O2. Only Pho a and b were able to decrease DNA ssbs and 8-OHdG following treatment of lymphocytes with 50µM H2O2, in a concentration-dependent fashion. It was demonstrated herein that Pho a and b, were more antioxidative than others. We applied DPPH free-radical scavenge assays in vitro, and also got similar results. Pho a and b were higher ability on scavenging capacities than others. In the second part, the inhibitory effects of four chlorophyll derivatives on aflatoxin B1 (AFB1)-DNA adduct formation, and on the modulation of hepatic glutathione S-transferase (GST) were evaluated in murine hepatoma (Hepa-1) cells. Enzyme-linked immunosorbent assay (ELISA) showed that pretreatment with Chlide or Pho significantly reduced the formation of AFB1-DNA adducts, and that Pho was the most potent inhibitor. However, wash-out prior to adding AFB1 totally eliminated inhibition by Childe and partially eliminated inhibition by Pho, indicating that the inhibitory effect of Chlide, and to some extent Pho, was mediated through direct trapping of AFB1. Furthermore, spectrophotometric analysis showed that Pho treatment could increase GST activity in Hepa-1 cells. These observations indicate that the chlorophyll derivatives studied may attenuate AFB1-induced DNA damage in the Hepa-1 cell by direct trapping of AFB1. Pho provided additional protection not only by direct trapping, but also by increasing GST activity against hepatic AFB1 metabolites.
    We conclude that water extract Chls are able to enhance cells’ ability to resist H2O2-induced oxidative damage and (AFB1)-DNA adduct formation, especially for Pho a and b.
    Data Type: thesis
    Appears in Collections:[School of Pharmacy] Dissertation/Thesis

    Files in This Item:

    File Description SizeFormat
    tmu-98-D001089006-1.pdf6935KbAdobe PDF2570View/Open


    All items in TMUIR are protected by copyright, with all rights reserved.


    著作權聲明 Copyright Notice
    • 本平台之數位內容為臺北醫學大學所收錄之機構典藏,包含體系內各式學術著作及學術產出。秉持開放取用的精神,提供使用者進行資料檢索、下載與取用,惟仍請適度、合理地於合法範圍內使用本平台之內容,以尊重著作權人之權益。商業上之利用,請先取得著作權人之授權。

      The digital content on this platform is part of the Taipei Medical University Institutional Repository, featuring various academic works and outputs from the institution. It offers free access to academic research and public education for non-commercial use. Please use the content appropriately and within legal boundaries to respect copyright owners' rights. For commercial use, please obtain prior authorization from the copyright owner.

    • 瀏覽或使用本平台,視同使用者已完全接受並瞭解聲明中所有規範、中華民國相關法規、一切國際網路規定及使用慣例,並不得為任何不法目的使用TMUIR。

      By utilising the platform, users are deemed to have fully accepted and understood all the regulations set out in the statement, relevant laws of the Republic of China, all international internet regulations, and usage conventions. Furthermore, users must not use TMUIR for any illegal purposes.

    • 本平台盡力防止侵害著作權人之權益。若發現本平台之數位內容有侵害著作權人權益情事者,煩請權利人通知本平台維護人員([email protected]),將立即採取移除該數位著作等補救措施。

      TMUIR is made to protect the interests of copyright owners. If you believe that any material on the website infringes copyright, please contact our staff([email protected]). We will remove the work from the repository.

    Back to Top
    DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - Feedback