厚葉石斑木葉子抽出物對基因轉殖秀麗隱桿線蟲β-類澱粉蛋白生成之影響

Abstract

阿茲海默症 (Alzheimer's disease) 的主要病理特徵為β-類澱粉蛋白 (β-Amyloid, Aβ) 過量累積於患者腦部，不正常的Aβ聚集導致神經細胞凋亡。秀麗隱桿線蟲 (Caenorhabditis elegans) 為一種便利且能表現有機體複雜性之模式生物，因此本研究之目的為利用轉殖人類Aβ基因之秀麗隱桿線蟲CL4176及CL2120作為模式生物，評估厚葉石斑木 (Rhaphiolepis umbellata var. integerrima) 葉子乙醇抽出物及四個可溶部對基因轉殖線蟲麻痺率、體內羰基化蛋白質含量及Aβ生成之影響。 研究結果顯示乙醇抽出物及正己烷可溶部可減少基因轉殖線蟲CL4176麻痺率，效果較正對照組咖啡因佳，證實厚葉石斑木乙醇抽出物及正己烷可溶部可有效抑制線蟲體內Aβ之毒性。線蟲體內蛋白質羰基化分析則顯示，乙酸乙酯可溶部、正丁醇可溶部及高濃度正己烷可溶部能降低CL4176線蟲及CL2120線蟲體內羰基化蛋白質含量。基因轉殖線蟲CL2120的Aβ沉積數量分析顯示，正己烷可溶部隨著濃度增加，可以減少線蟲頭部之Aβ沉積數量。正己烷可溶部可減少CL4176線蟲及CL2120線蟲體內Aβ單體與寡聚體的生成量，且效果優於正對照組Epigallocatechin-3-gallate (EGCG)。綜合試驗結果顯示，厚葉石斑木葉子抽出物之正己烷可溶部，可以抑制基因轉殖線蟲體內Aβ的生成與毒性。

The major symptom of Alzheimer's disease (AD) pathology is the accumulation of β-amyloid (Aβ) in the AD patients’ brain; Aβ aggregation may lead to neuronal cell death. Caenorhabditis elegans is a convenient animal model to express organismal complexity. Thus, the purposes of this study is to use human Aβ gene tranginic C. elegans CL4176 and CL2120 to evaluate the effect of leaf extract and four soluble fractions from Rhaphiolepis umbellata var. integerrima on paralyze rate, carbonylated proteins content and Aβ expression in transgenic C. elegans. Results showed that the ethanolic extract and n-hexane soluble fraction reduced Aβ –induced paralysis in transgenic C. elegans CL4176, and its activity was much better than that of positive control, caffeine. It proved that the ethanolic extract and n-hexane soluble fraction from R. umbellata var. integerrima could inhibit Aβ toxicity in C. elegans. The analysis of carbonylated proteins showed that ethyl acetate soluble fraction, n-butanol soluble fraction, and higher concentration of n-hexane soluble fraction reduced carbonylated proteins in C. elegans CL4176 and CL2120. The analysis of Aβ deposits in transgenic C. elegans CL2120 revealed that n-hexane soluble fraction reduced Aβ deposits with the increasing concentration. Effect of n-hexane soluble fraction on decreasing Aβ monomers and Aβ oligomers in C. elegans CL4176 and CL2120 was superior than that of positive control, epigallocatechin-3-gallate (EGCG). According to these results, n-hxexane soluble fraction from R. umbellata var. integerrima could reduce Aβ expression and inhibit Aβ toxicity in transgenic C. elegans.