Carpenedo R, Carlà V, Moneti G, Chiarugi A, Moroni F
Department of Preclinical and Clinical Pharmacology, University of Florence, Italy.
Anal Biochem. 1997 Jan 1;244(1):74-9. doi: 10.1006/abio.1996.9854.
Oxindole, a putative tryptophan metabolite able to cause profound sedation when administered in relatively low doses to mammals, has been identified and measured in the brains of mice, rats, and guinea pigs using HPLC and GC/MS with a quadrupole ion trap and a collision-induced dissociation mass spectrometer. The identification and measurement of the compound required a protein precipitation step with HClO4, extraction into chloroform, an HPLC separation on a reverse-phase column, and detection by UV or coulometry. The definitive identification of the oxindole peak was obtained with a Saturn 4D GC/MS quadrupole ion trap operated under GC/MS, GC/MS/MS, and GC/MS/MS/MS modes. The HPLC methods we used had a low interassay variability, easily allowing the identification and measurement of the compound in 1 g of tissue. The oxindole concentrations in rat brain, blood, liver, and kidney were each approximately 100 pmol/g wt. Interestingly, the content of oxindole in the guinea pig brain was found to be significantly lower than that in the mouse and rat brains, possibly reflecting a lower dietary intake of tryptophan in the guinea pigs.
氧化吲哚是一种假定的色氨酸代谢产物，当以相对低剂量给哺乳动物施用时能够引起深度镇静。已使用配备四极杆离子阱和碰撞诱导解离质谱仪的高效液相色谱（HPLC）和气相色谱-质谱联用（GC/MS）技术，在小鼠、大鼠和豚鼠的大脑中鉴定并测量了氧化吲哚。该化合物的鉴定和测量需要用高氯酸进行蛋白质沉淀步骤，用氯仿萃取，在反相柱上进行HPLC分离，并用紫外或库仑法检测。氧化吲哚峰的最终鉴定是通过在气相色谱-质谱联用（GC/MS）、气相色谱-串联质谱联用（GC/MS/MS）和气相色谱-串联串联质谱联用（GC/MS/MS/MS）模式下操作的Saturn 4D GC/MS四极杆离子阱获得的。我们使用的HPLC方法具有较低的批间变异性，能够轻松地在1克组织中鉴定和测量该化合物。大鼠脑、血液、肝脏和肾脏中的氧化吲哚浓度均约为100 pmol/g体重。有趣的是，发现豚鼠脑中氧化吲哚的含量明显低于小鼠和大鼠脑，这可能反映了豚鼠饮食中色氨酸的摄入量较低。
