豆腐乳對低密度脂蛋白氧化，大腸癌細胞增生以及4-NQO對腸道上表皮細胞基因毒性之抑制作用

Abstract

本研究即針對豆腐乳之製程，於 37oC下進行發酵製備豆腐乳，以水及甲醇製備萃取物，各別分析延緩低密度脂蛋白 (low density lipoprotein, LDL) 氧化之活以及抑制結腸癌細胞株 Caco-2 和 HT-29 增生與其抗 4-nitroquinoline-N-oxide (4NQO) 誘導腸道細胞株 Int-407 毒性之效果。此外，並藉由分段式預反應探討豆腐乳萃取物抗細胞毒性之機制。結果顯示，無論是豆腐乳塊或豆米麴均具有抗氧化活性、抗癌細胞增生以及抑制 4NQO 誘導細胞之損傷等生理活性。豆腐乳塊及豆米麴水萃取物具抗 LDL 氧化效果且隨發酵時間增加而上升，此外胺基態氮含量也具相同趨勢。其甲醇萃取物具於抑制結腸癌細胞株 Caco-2 和 HT-29 增生與其抗 4NQO 誘導腸道細胞株Int-407毒性試驗方面皆具有抑制效果且隨發酵時間增加效果亦隨之上升，進一步探討抗 4NQO 所引起細胞毒性之機制，顯示其活性來自於使 4NQO 不活化 (Descytotoxic effect)、修飾細胞之機能阻斷 4NQO 之傷害 (Blocking effect)以及修補受損 DNA (Bioanticytotoxic effect) 等作用。

In the present study, the enzyme-ripened sufu was prepared by fermentation at 37℃ for 16 days. The water and methanol extracts of the sufu were prepared. Water extracts of the prepared sufu for 16 days were examined for their amino nitrogen contents and inhibitory effect on low density lipoprotein (LDL) oxidation. Besides the effect of methanol extracts against the proliferation of colon cancer cells, Caco-2 and HT-29, as well as on the cytotoxic and genotoxicity induced by 4-nitroquinoline-N-oxide (4NQO) on Int-407 were detected. It was found that the water extracts of sufu or rice-soybean koji granule showed inhibitory effect on LDL oxidation. This effect increased as the fermentation period were extended and corresponded with time increase content of amino nitrogen. On the other hand, the methanol extracts of sufu and rice-soybean koji granule reduced the proliferation of Caco-2 and HT-29 cells at the cytotoxicity and genotoxicity of 4NQO toward Int-407. The methanol extracts of sufu and rice-soybean koji granule reduced the proliferation of Caco-2 and HT-29 cells. Besides, they showed inhibitory effect on 4NQO-induced cytotoxicity. These effects enhanced as the fermentation period extended. Futher study revealed that the methanol exracts might exert the anticytotoxicity through adjusting the function of Int-407 (blocking effect), repairing the 4NQO damaged cell (bioanticytoxic effect) and interacting directly with 4NQO (descytotoxic effect).