Ikpa Nsisong, Forman Rachel, Garchow Kendra, Sukowski Ernest, Peterson Darryl R
Departments of 1Physiology and Biophysics and 2Medicine, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL.
Am J Ther. 2015 Jul-Aug;22(4):e97-e106. doi: 10.1097/MJT.0000000000000246.
Treatment for ischemic stroke involves a thrombolytic agent to re-establish blood flow in the brain. However, delayed reperfusion may cause injury to brain capillaries. Previous studies indicate that the antioxidant gamma-L-glutamyl-L-cysteine (γ-Glu-Cys) contributes to reducing reperfusion injury to the cerebral vasculature in rats, when administered intravascularly. To determine the stability of γ-Glu-Cys in blood, the peptide was incubated in rat serum in vitro, and its degradation was quantified by high-pressure liquid chromatography. The half-time (t1/2) for degradation of γ-Glu-Cys was 11 ± 1 minute (mean ± SD, n = 3). A similar pattern of degradation was observed when γ-Glu-Cys was incubated in the presence of human plasma (t1/2 = 17 ± 8 minutes, n = 3). In a second series of experiments, degradation of an analog (γ-Glu-D-Cys) was tested in rat serum and found to be more stable than the native molecule. The initial velocity for degradation of γ-Glu-D-Cys (0.12 ± 0.02 mM/min; mean ± SD, n = 3) was significantly (P = 0.006) less than that of γ-Glu-Cys (0.22 ± 0.03 mM/min; mean ± SD, n = 3). Furthermore, an in vitro assay indicated that the analog has as an oxidative capacity that equals that of the original peptide in the presence of rat serum and human plasma. Finally, both peptides were found to be similarly effective in preventing lysis of intact cells using in vitro assays. These studies show that γ-Glu-Cys remains intact in blood for several minutes, and the analog γ-Glu-D-Cys may be a more stable, but similarly effective antioxidant.
缺血性中风的治疗涉及使用溶栓剂来重新建立脑部的血流。然而，延迟再灌注可能会导致脑毛细血管损伤。先前的研究表明，抗氧化剂γ-L-谷氨酰-L-半胱氨酸（γ-Glu-Cys）经血管内给药时，有助于减轻大鼠脑血管的再灌注损伤。为了确定γ-Glu-Cys在血液中的稳定性，将该肽在大鼠血清中进行体外孵育，并通过高压液相色谱法对其降解情况进行定量。γ-Glu-Cys降解的半衰期（t1/2）为11±1分钟（平均值±标准差，n = 3）。当γ-Glu-Cys在人血浆存在的情况下孵育时，观察到了类似的降解模式（t1/2 = 17±8分钟，n = 3）。在第二系列实验中，对一种类似物（γ-Glu-D-Cys）在大鼠血清中的降解情况进行了测试，发现它比天然分子更稳定。γ-Glu-D-Cys降解的初始速度（0.12±0.02 mM/分钟；平均值±标准差，n = 3）显著低于γ-Glu-Cys（0.22±0.03 mM/分钟；平均值±标准差），n = 3，P = 0.006）。此外，一项体外试验表明，在大鼠血清和人血浆存在的情况下，该类似物具有与原始肽相当的氧化能力。最后，通过体外试验发现，这两种肽在防止完整细胞裂解方面同样有效。这些研究表明，γ-Glu-Cys在血液中能保持完整数分钟，类似物γ-Glu-D-Cys可能是一种更稳定但同样有效的抗氧化剂。
