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    Please use this identifier to cite or link to this item: https://ir.csmu.edu.tw:8080/ir/handle/310902500/21896


    Title: é•·æ™‚間煮沸豬肉汁中主要IQ型致突變物的鑑定及可能參與形成的化學成份之研究
    Authors: æž—明陽
    Contributors: ä¸­å±±é†«å­¸å¤§å­¸:醫研所;李輝
    Date: 1993-05
    Issue Date: 2021-11-15T03:33:12Z (UTC)
    Abstract: è±¬è‚‰æ±ç¶“過長時間(12小時)的迴流煮沸(102°C)後，用二氯甲烷萃取的鹼層物在老鼠肝臟酵素S9的存在下，會對沙門氏菌TA98 產生致突變性，更進一步將豬肉汁的鹼層萃取物以藍棉萃取役， 再以半製備型及分析型高效液相層析儀純化收集，並利用菌種特異性及酸性亞硝酸鈉測試加以確認為IQ型致突變物。最後將純化致突變物的紫線吸收光譜再配合質譜分析確定分別為MeIQx、IQ及MeIQ。估計每克豬肉汁中約含有4.1 微克的MeIQx，3.7微克的IQ及12 微克的MeIQ，而所含MeIQx、IQ及MeIQ分別相當於全部致突變性的19.0%、27.3%及34.3% ，然而豬肉汁中也含有其它致突變物如問DEMeIQx(致突變性約佔9.4%)等，但因含量太少而只能以高效液相層析的滯留時間來判別。
    至於將豬肉汁中可能產生致突變物的前軀物，如glucose、ribose 、alanine、creatinine及Maillard反應物等分別添加入豬肉汁模式系統中分析其對豬肉汁形成致突變物的影響，結果顯示glucose、alanine、creatinine及ribose等能增強
    豬肉汁模式系統之致突變力2.7-6.7 倍，Maillard反應物中的2-methylthiophene、3-methylpyridine、2,3-dimethylpraxine及tetra-hydrothiophen-3-one等能促進1.2-2.9倍致突變物之形成，而imidazole和2-acetylpyrrole反而各抑制豬肉汁模式系統之致突變力為0.2 和0.3 倍，因此我們推測這些會促進豬肉汁模式系統致突變力的化合物很可能參與豬肉汁模式系統形
    成致突變物的過程。進一步將對豬肉汁模式系統之致突變力最為增強的兩種Maillard反應物一tetrahydrothiophen-3-one和2,3-dimethylpyrzine分別添加入豬肉汁模式系統中探討其最佳反應條件，結果添加2.5 mmol 的tetrahydrothiophen-3-one 在pH5.0 狀態下煮沸20 小時能產生最高致突變性。而添加2.5 mmol的2,3-dimethylpyrzine在pH 6.0 下煮沸12小時則是2,3-dimethylpyrzine的最佳反應條件。而在以高效液相層析儀分析所促進形成的主要致突變物亦皆為豬肉汁模式系統中的主要IQ 型致突變物。同時我們也在添加tetrahydrothiophen-3-one或2,3-dimethylpyrzie的豬肉汁模式系統中，以氣相層析儀分析其反映過程中Maillard反應物的耗用量，發現和致突變物的生成有明顯相關性。因此我們推測此兩類化合物可能是參與豬肉汁模式系統形成致突變物的前軀物。
    最後，我們再以Maillard反應物/醛類/肌酸酐的簡單的模式系統探討Jagerstad et d .(l983a) 及Nyhammar (1986) 所提之可能形成IQ型致突變物路徑的可能性，結果在2methylpyridine / acetylformaldehyde / creatinine的模式系統中找到每克肌酸酐產生64微克的IQ，因此證實其路徑，不過醛類在此模式系統的角色，仍待進一步的研究。

    The boiled pork juice was refluxed at 102°C for 12 hr and then basic extracts of the mixture was found to be mutagenic toward Salmonella typhimurium TA98 with S9 mix.The mutagenic fractions were purified by blue cotton extraction and high performance liquid chromatography (HPLC). The HPLC fractionation followed by mutagenicity testing yielded mutagenicity profiles with peaks in areas where the heterocyclic amines standards appeared. The mutagenic fractions were collected and confirmed by the comparison of UV absorption spectra，strain specificity, and acid nitrie treatment. Finally, mutagens were identified as MeIQx, IQ and MeIQ by mass spectrometry(MS). One gram of boiled pork juice was estimated to contain 4.1 ng of MeIQx, 3.7 ng IQ , and 1.2 ng of MeIQ, which accounted for 19.0%, 27.3% and 34.3%, respectively, of the total mutagenicity. The remaining mutagenic fraction might be DiMeIQx isomer which will be further confirmed by MS.
    The possible mutagenic precursors in boiled pork extracts, such as glucose,ribose, alanine, creatinine, and some Maillard reaction products. They were added to boiled pork juice model system seperately to examine the effect of these compounds on the mutagen formation in boiled pork extracts. The results showed that the addition of glucose, alanine, creatinine, and ribose to the boiled pork juice enhanced 2.7-6.7 folds mutagenicity of boiled pork extracts. The four Maillard reaction products, 2-methylthiophene,
    3-methylpyridine, 2，3-dimethylpyrazine, and tetrahydrothiophen-3-one, also increased the formation of mutagens about 1.2-2.9 folds. However, imidazole and 2-acetylpyrrole significantly inhibited the mutagenicity of boiled pork extracts (0.2 and 0.3 folds). Thus, we suggested that glucose, ribose, alanine, creatinine, 2-methylthiophene, 3-methylpyridine, 2,3-dimethylpyrazine, and tetrahydrothiophen-3-one could be the possible chemical componets which participated the mutagen formation in the boiled pork juice model system.
    Then, two active Maillard reaction products, tetrahydrothiophen-3-one and 2,3-dirnethylpyrazine, were added to boiled pork juice and estimated the optimal reaction conditions to enhance the mutagenicity. Data showed that 2.5 mmol tetrahydrothiophen-3-one was added to boiled pork juice boiled for 20 hr at pH 5.0 had the
    most highly mutagenicity. However, 2.5 mmol 2,3-dimethylpyrazine boiled for 12 hr at pH 6.0 was the optimal condition for 2,3-dimethylpyrazine. The HPLC mutagenic profiles of basic extracts of the addition of Maillard reaction products were similar to that of boiled pork extracts. We also evaluated the correlation of the variation of tetrahydrothiophen-3-one and 2,3-dimethylpyrazine in boiled pork juice models during the boiling period with their mutagenicity. Our data showed that the residue of tetrahydrothiophen-3-one and 2,3-dimethylpyrazine during the boiling period were significantly correlated to their mutagenicity, respectively (r=-0.83, p<0.02; r=-O.85， p<O.O1).
    These findings suggested that tetraydrothiophen-3-one and 2,3-dimethylpyrazine could participate the chemical pathway of the mutagens formation in boiled pork juice model systems.
    Furthermore, the possible pathway of IQ-type mutagen formation proposed by Jagerstad group was studied using a Maillard reaction product / aldehyde / creatinine model. The preliminary data showed the 2-methylpyridine / acetylformaldehyde / creatinine model can produce IQ mutagen indeed. But the optimal reaction conditions
    and the role of aldehyde in this model system for mutagens formation will be investigated in future.
    URI: https://ir.csmu.edu.tw:8080/handle/310902500/21896
    Appears in Collections:[醫學研究所] 博碩士論文

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