ANTIOXIDANT POTENTIAL OF ANAEROBIC HUMAN PLASMA - ROLE OF SERUM-ALBUMIN AND THIOLS AS SCAVENGERS OF CARBON RADICALS
ANTIOXIDANT POTENTIAL OF ANAEROBIC HUMAN PLASMA - ROLE OF SERUM-ALBUMIN AND THIOLS AS SCAVENGERS OF CARBON RADICALS
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DOI：
10.1006/abbi.1994.1297
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发表时间：
1994-07-01
影响因子：
3.9
通讯作者：
MINETTI, M
中科院分区：
文献类型：
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作者：
SORIANI, M;PIETRAFORTE, D;MINETTI, M
细胞外液含有低分子量抗氧化剂，积极参与防御活性氧。这些化合物的抗氧化活性很大程度上归因于它们捕获氧自由基的能力。鲜为人知的是细胞外抗氧化剂清除碳中心自由基（C-自由基）的能力。这些自由基可能参与缺氧/缺氧条件下的损伤以及缺血/再灌注损伤。我们研究了一些血浆抗氧化剂在厌氧条件下对偶氮化合物 2,2'-偶氮双(2-脒基丙烷)盐酸盐 (AAP) 产生的水溶性 C-自由基的反应性。等离子体中的AAP C-自由基被自旋陷阱3,5-二溴-4-亚硝基苯磺酸(DBNBS)捕获并产生DBNBS自由基。通过抑制 DBNBS 自由基的强度来评估尿酸盐、半胱氨酸、谷胱甘肽、天然氨基酸和血清白蛋白的清除特性。抗坏血酸和维生素E的抗氧化活性是通过自由基的形成直接测量的。尿酸盐、维生素 E 和非 SH 氨基酸无效，抗坏血酸是 AAP C 自由基的较差清除剂。不同的是，半胱氨酸和谷胱甘肽 (0.1-1.0 mM) 是 AAP C 自由基的有效清除剂，重要的是，可以保护血浆抗坏血酸在有氧或厌氧条件下免受氧化。我们的数据表明，有氧血浆中的抗坏血酸可以减少维生素E自由基，并且氧化的抗坏血酸可以通过硫醇抗氧化循环进行回收。低分子量抗氧化剂仅部分地解释了 C-自由基的血浆清除活性。血浆强烈降低了 DBNBS 自由基的强度，透析后，其活性降低了约 10%。血清白蛋白显示出与透析血浆相当的抗氧化活性。血清白蛋白的半胱氨酸残基也是 C-自由基的有效清除剂，硫醇烷基化后蛋白质清除活性降低了约 20%。这些结果表明血浆中总还原硫醇浓度的升高可以提高其在缺氧/缺氧条件下的抗氧化活性。这可能特别有用，因为其他重要的抗氧化机制（例如尿酸盐、抗坏血酸盐和维生素 E）似乎效率低下。 (C) 1994 年学术出版社
Extracellular fluids contain low-molecular-weight antioxidants that are actively involved in the defense against reactive oxygen species. The antioxidant activity of these compounds is largely due to their ability to trap oxygen radicals. Less known is the ability of extracellular antioxidants to scavenge carbon-centered free radicals (C-radicals). These radicals can be involved in the damage under hypoxic/anoxic conditions as well as in ischemia/reperfusion injury. We studied the reactivity of some plasma antioxidants toward a water-soluble C-radical generated by the azocompound 2,2'-azobis(2-amidinopropane) hydrochloride (AAP) under anaerobic conditions. The AAP C-radical in plasma was trapped by the spin trap 3,5-dibromo-4-nitrosobenzene-sulfonic acid (DBNBS) and produced a DBNBS radical. The scavenging properties of urate, cysteine, glutathione, natural amino acids, and serum albumin were assessed by the inhibition of the intensity of DBNBS radical. The antioxidant activity of ascorbate and that of vitamin E was measured directly by the formation of their free radicals. Urate, vitamin E and non-SH amino acids were ineffective and ascorbate was a poor scavenger of AAP C-radical. At variance, cysteine and glutathione (0.1-1.0 mM) were effective scavengers of AAP C-radicals and, importantly, protected plasma ascorbate from oxidation under both aerobic or anaerobic conditions. Our data show that ascorbate in aerobic plasma can reduce vitamin E radical and the oxidized ascorbate may be recycled by a thiol antioxidant cycle. Low-molecular-weight antioxidants accounted only partially for plasma scavenging activity of C-radicals. Plasma strongly reduced the intensity of DBNBS radical and, after dialysis, its activity was reduced by similar to 10%. Serum albumin showed an antioxidant activity comparable to dialyzed plasma. Also the cysteine residue of serum albumin was an efficient scavenger of C-radicals as shown by similar to 20% decrease in the protein scavenging activity after thiol alkylation. These results suggest that elevation in the concentration of total reduced thiols in plasma may improve its antioxidant activity under hypoxic/anoxic conditions. This may be particularly useful since other important antioxidant mechanisms such as urate, ascorbate, and vitamin E appear to be inefficient. (C) 1994 Academic Press, Inc.