以基因轉殖線蟲為模式探討具有抗阿茲海默症潛力之植物成分

阿茲海默症(Alzheimer’s disease, AD)為一種漸進式的神經退化性疾病，患者會有記憶力喪失，認知功能障礙，行為能力退化。AD患者在腦部主要有兩個病理特徵，包括：細胞外的類澱粉胜肽(β-amyloid peptide) 沉積及細胞內tau蛋白過磷酸化所引起的神經纖維糾結 (neurofibrillary tangles, NFT)。秀麗隱桿線蟲(Caenorhabditis elegans)為一種小型非寄生性的土壤線蟲，目前已被廣泛用於發展生物學，基因體學以及神經生物學的研究。AD基因轉殖線蟲CL4176帶有人類Aβ1-42基因，能藉由升溫於體璧肌肉細胞內生成Aβ，並伴隨快速麻痺現象的產生。此外，在CL4176中也能觀察到AD患者體內ROS含量增加之現象。因此CL4176為一個合適的體內試驗模式。本研究目的在於以AD基因轉殖線蟲CL4176為模式，篩選出具有抗阿茲海默症潛力之植物成分，如EGb761、sesamol、tetrahydrocurcumin (THC)、gallic acid以及蓮子心甲醇萃物之正丁醇區分層，並探討其可能作用機制。首先發現EGb761 (100 ppm)、sesamol (10 ppm)、蓮子心甲醇萃物之正丁醇第五及第七區分層 (Nn-M-B V及 Nn-M-B VII, 100 ppm) 能延緩線蟲CL4176升溫後之麻痺現象。Sesamol以及Nn-M-B VII皆能促進熱休克蛋白 Hsp 16, Hsp 40 及 Hsp 70的表現量。由Western blot 的結果顯示sesamol、Nn-M-B V 以及 Nn-M-B VII 能抑制CL4176體內Aβ的聚集。此外EGb761及sesamol 能提升CL4176體內catalase活性，並降低ROS含量。因此本研究推測 sesamol以及 Nn-M-B VII 能藉由活化線蟲體內熱休克蛋白(HSPs)及抑制Aβ聚集，而達延緩線蟲麻痺之功效。另外EGb 761, sesamol能活化catalase活性，並降低線蟲體內ROS含量，故可藉由降低線蟲體內氧化壓力而延緩線蟲之麻痺現象。本研究結果顯示EGb 761、sesamol、Nn-M-B V 以及 Nn-M-B VII皆具有預防及治療AD之潛力。

關鍵字

阿茲海默症；類澱粉胜肽AD基因轉殖線蟲CL4176 ； sesamol ； gallic acid ； tetrahydrocurcumin ；蓮子心

並列摘要

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that leads to cognitive, memory and behavioural impairments. AD patients have two neuropathological characteristics in brain: extracellular accumulation of β amyloid peptide (Aβ) and the formation of intracellular neurofibrillary tangles (NTF) of hyperphosphorylated tau protein. Caenorhabditis elegans is a small, free-living soil nematode. It is widely employed in the studies of developmental biology, genetics and neurobiology. The AD transgenic C. elegans CL4176 which carry the human gene for Aβ1-42 have intracellular amyloid formation in body-wall muscle cells, and can develop concomitant rapid paralysis by temperature up-shift. Moreover, CL4176 exhibits increased levels of reactive oxygen species (ROS) and protein carbonyl content, similar to those observed in AD patients. Thus, this transgenic C. elegans CL4176 is a suitable in vivo model for AD research. The aim of this study is to screen out the potential anti-AD activity compounds, including EGb761, sesamol, tetrahydrocurcumin (THC), gallic acid, n-butanol fraction of 70% methanol extract of embryo of Nelumbo nucifera Gaertn. Seed (Nn-M-B) by AD transgenic C. elegans model CL4176 and to study the possible mechanisms for their efficacy. First, we found that EGb761 100 ppm, sesamol 10 ppm, Nn-M-B V and Nn-M-B VII 100 ppm could delay the paralysis in CL4176 after temperature up-shift. Furthermore, sesamol and Nn-M-B VII increased the expression of Hsp16, Hsp40 and Hsp70. and inhibited Aβ aggregation in CL4176 by Western blot. We also found that EGb761, sesamol could increase the activity of catalase, and reduced the level of ROS in CL4176. These finding suggest that EGb 761, sesamol, Nn-M-B V and Nn-M-B VII delay the paralysis in CL4176, possibly by inducing HSPs expression and inhibiting Aβ aggregation. Furthermore, EGb 761, sesamol increase the activity of catalase and reduce the level of ROS in CL4176. These results suggest that EGb761, sesamol, Nn-M-B V and Nn-M-B VII have potential for prevention and treatment of AD.

並列關鍵字

β amyloid peptide ； AD transgenic C. elegans CL4176 ； sesamol ； gallic acid ； tetrahydrocurcumin ； Nelumbo nucifera Gaertn. Seed

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以基因轉殖線蟲為模式探討具有抗阿茲海默症潛力之植物成分

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