1,3-diene probes for detection of triplet carbonyls in biological systems
1,3-diene probes for detection of triplet carbonyls in biological systems
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DOI：
10.1021/tx700074n
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发表时间：
2007-08-01
影响因子：
4.1
通讯作者：
Bechara, Etelvino J. H.
中科院分区：
文献类型：
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作者：
Velosa, Adriana C.;Baader, Wilhelm J.;Bechara, Etelvino J. H.
在多不饱和脂肪酸、氨基酸和β-二羰基代谢物的氧化降解过程中形成电子激发的三重态羰基。由于它们的长寿命和高烷氧基自由基样反应性，三重态羰基可能在生物系统中引发有害反应。在这里，我们研究了共轭二烯，特别是2，4-hexadienoate（山梨酸酯）和它的烷基酯，对三重态丙酮化学（四甲基-1，2-二氧杂环丁烷的热交换）或酶促（辣根过氧化物酶催化异丁醛的有氧氧化）产生的猝灭性能。三重态丙酮猝灭速率接近扩散控制（k（q）= 10（8）-10（9）M-1 s（-1）），并伴有二烯顺反异构化。在已知产生活性氧的经典系统中，没有一种二烯显示抗氧化活性：超氧阴离子自由基、羟基自由基、烷氧基和烷基过氧自由基或单线态氧。广泛用于研究脂质过氧化反应的模型系统的实验表明，山梨酸盐可以抑制由酶促形成的三重态二苯甲酮诱导的线粒体肿胀，并淬灭用铁和抗坏血酸盐挑战的微粒体制剂的化学发光。总之，我们的数据表明，共轭二烯可用作氧化应激过程中生物系统中形成的三重态羰基的特异性猝灭剂。此外，他们认为山梨酸酯的众所周知的食品防腐性能可能是由于其三重态羰基淬灭活性。
Electronically excited triplet carbonyls are formed during the oxidative degradation of polyunsaturated fatty acids, amino acids, and beta-dicarbonyl metabolites. Due to their long lifetime and high alkoxyl radical-like reactivity, triplet carbonyls may initiate deleterious reactions in biological systems. Here we study the quenching properties of conjugated dienes, specifically 2,4-hexadienoate (sorbate) and its alkyl ester, on triplet acetone generated chemically (thermolysis of tetramethyl-1,2-dioxetane) or enzymatically (horseradish peroxidase-catalyzed aerobic oxidation of isobutanal). Triplet acetone quenching rates were near diffusion control (k(q) = 10(8)-10(9) M-1 s(-1)) and accompanied by diene cistrans isomerization. None of the dienes displays antioxidant activity in classical systems known to generate reactive oxygen species: superoxide anion radical, hydroxyl radical, alkoxyl and alkylperoxyl radicals, or singlet oxygen. Experiments with model systems used widely to study lipid peroxidation showed that sorbate can inhibit mitochondrial swelling induced by enzymically formed triplet benzophenone and quench the chemiluminescence of microsome preparations challenged with iron and ascorbate. Altogether, our data indicate that conjugated dienes can be used as specific quenchers of triplet carbonyls formed in biological systems during oxidative stress. Moreover, they suggest that the well-known food preservative properties of sorbate may be due to its triplet carbonyl quenching activity.