口服馬兜鈴酸對小鼠肝腎 CYP1A1、CYP1A2 和 NQO1 蛋白表現量變化之分析

Abstract

馬兜鈴酸 (aristolochic acid, 簡稱AA) 為馬兜鈴屬植物中，所萃取出能引發腎毒性的主要成分，與馬兜鈴酸腎病變 (Aristolochic acid nephropathy) 亦稱中草藥腎病變 (Chinese herb nephropathy) 有其關聯性。在in vivo的實驗中發現有 AAⅠ-DNA 加成物的形成，這種加成物可能與細胞毒性 (cytotoxicity) 有所關聯。因此推測馬兜鈴酸可能藉由還原代謝機制，使馬兜鈴酸之代謝物與 DNA 形成 AA-DNA 加成物。參與前述活化反應的酵素可能包括細胞色素P450中的 CYP1A1和 CYP 1A2、NADPH：CYP reductases 和 cytosolic nitroreductases 中的 NAD(P)H：quinone oxidoreducyase (NQO1) 。為了更進一步釐清這些酵素在前述所提及的代謝過程中之角色，我們對餵食純品馬兜鈴酸或單方馬兜鈴粉末與複方馬兜鈴粉末 (補肺阿膠湯) 小鼠的肝、腎 CYP1A1、CYP1A2 和 NQO1 酵素的表現量進行分析。我們的觀察結果顯示，餵食馬兜鈴酸之小鼠，其肝或腎之 CYP1A1、CYP1A2 或 NQO1 酵素表現量並無隨著馬兜鈴酸劑量增加而有明顯的變化，且與馬兜鈴酸誘發之細胞毒性無相關性。

Aristolochic acids (AA), naturally occurring nephrotoxins extracted from plants of the Aristolochiaceae family, have been associated with aristolochic acid nephropathy, which is also known as Chinese herbs nephropathy. AAⅠ-DNA adduct formation, likely to be correlated with AAs cytotoxicity, has been observed from in vivo studies. It has been suggested that AA needs reductive metabolic activation to be able to react with DNA to form AA-DNA adducts. Several enzymes, including CYP450 isozymes such as CYP1A1, CYP1A2, NADPH：CYP reductases, and cytosolic nitroreductases, for example, the NAD(P)H dehydrogenase, quinone 1 (NQO1), have all been proposed to be participated in the aforementioned activation pathway. To further clarify the roles of these enzymes in the activation process, we analyzed the expression levels of CYP1A1, CYP1A2, and NQO1 in liver and kidney of the experimental animals treated with either aristolochic acid mixture or grounded Aristolochia contorta or bu-fei-a-jiau-tang powder . Our results indicated that there is no significant changes in the expression levels of CYP1A1, CYP1A2, and NQO1 in the livers and kidneys of mice treated with varying doses of aristolochic acid, and is not correlated with the observed nephropathy.