Girón-Calle Julio, Alaiz Manuel, Millán Francisco, Ruiz-Gutiérrez Valentina, Vioque Eduardo
Instituto de la Grasa, Consejo Superior de Investigaciones Científicas, Avenida Padre García Tejero 4, 41012 Sevilla, Spain.
J Agric Food Chem. 2002 Oct 9;50(21):6194-8. doi: 10.1021/jf025681r.
The lipid peroxidation product malondialdehyde is mostly bound to proteins in foods as an N-2-propenal derivative that is released as N-epsilon-(2-propenal)lysine by digestive enzymes. N-2-Propenals have been identified as the major forms of malondialdehyde in urine. To determine whether available lysine can be released from the N-2-propenals of lysine in vivo, two preparations containing N-epsilon-(2-propenal)lysine and N-alpha-(2-propenal)lysine or N,N'-di-(2-propenal)lysine were synthesized using radioactively labeled lysine and were administered to rats by gastric intubation and intraperitoneal injection. Both preparations were absorbed from the digestive tract, although not as efficiently as free lysine, but most of the radioactivity was excreted in urine. The radioactive label was also readily excreted after intraperitoneal injection. It is concluded that the N-2-propenals of lysine are fairly stable in vivo, so that, although they are absorbed from the gut, most of the absorbed material is not metabolized and is readily excreted as nonavailable lysine.
脂质过氧化产物丙二醛在食物中大多以N - 2 - 丙烯醛衍生物的形式与蛋白质结合，消化酶可将其释放为N - ε -（2 - 丙烯醛）赖氨酸。已确定N - 2 - 丙烯醛是尿液中丙二醛的主要形式。为了确定体内赖氨酸的N - 2 - 丙烯醛形式是否能释放出可利用的赖氨酸，使用放射性标记的赖氨酸合成了两种分别含有N - ε -（2 - 丙烯醛）赖氨酸、N - α -（2 - 丙烯醛）赖氨酸或N，N'-二 -（2 - 丙烯醛）赖氨酸的制剂，并通过胃插管和腹腔注射给予大鼠。两种制剂均从消化道吸收，尽管吸收效率不如游离赖氨酸，但大部分放射性物质经尿液排出。放射性标记物在腹腔注射后也很容易排出。结论是赖氨酸的N - 2 - 丙烯醛在体内相当稳定，因此，尽管它们从肠道吸收，但大部分吸收的物质未被代谢，而是作为不可利用的赖氨酸很容易排出。
