McGirr L G, Hadley M, Draper H H
J Biol Chem. 1985 Dec 15;260(29):15427-31.
Although orally administered malondialdehyde (MDA), a reactive hepatotoxic and mutagenic product of lipid peroxidation, is extensively metabolized to CO2, a portion is excreted in the urine in acid labile "bound" forms. Since much of the MDA in the diet is apparently bound to protein, the metabolism of protein-bound MDA was investigated. MDA was reacted with serum albumin and fed to rats. A urinary metabolite was detected which was shown to be identical to a metabolite of the lysine-MDA enaminal N epsilon-(2-propenal)lysine. After isolation by ion exchange and high performance liquid chromatography the metabolite was identified using high field nuclear magnetic resonance spectroscopy and fast atom bombardment-mass spectroscopy as N alpha-acetyl-epsilon-(2-propenal)lysine. This compound also was a major urinary metabolite of the Na enol salt of MDA administered by stomach intubation, and was excreted in increased amounts by rats fed a diet containing a highly peroxidizable oil (cod liver oil). It was also detected in the urine of fasted animals after injection with NaMDA, indicating that it is formed as a product of lipid peroxidation in vivo as well as of peroxidation of dietary lipids.
尽管口服的丙二醛（MDA），一种脂质过氧化反应产生的具有肝毒性和致突变性的产物，会大量代谢为二氧化碳，但仍有一部分以酸不稳定的“结合”形式经尿液排出。由于饮食中的大部分MDA显然与蛋白质结合，因此对蛋白质结合型MDA的代谢进行了研究。将MDA与血清白蛋白反应后喂给大鼠。检测到一种尿液代谢产物，结果表明它与赖氨酸 - MDA烯胺Nε-(2 - 丙烯醛)赖氨酸的一种代谢产物相同。通过离子交换和高效液相色谱分离后，利用高场核磁共振光谱和快原子轰击质谱法将该代谢产物鉴定为Nα - 乙酰基 - ε-(2 - 丙烯醛)赖氨酸。这种化合物也是经胃插管给予的MDA烯醇钠盐的主要尿液代谢产物，并且在喂食含有高度可过氧化油（鱼肝油）的日粮的大鼠中，其排泄量会增加。在注射NaMDA后，禁食动物的尿液中也检测到了该化合物，这表明它是体内脂质过氧化以及膳食脂质过氧化的产物。
