Structural requirements for optimized delivery, inhibition of oxidative stress, and antiapoptotic activity of targeted nitroxides
Structural requirements for optimized delivery, inhibition of oxidative stress, and antiapoptotic activity of targeted nitroxides
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DOI：
10.1124/jpet.106.114769
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发表时间：
2007-03-01
影响因子：
3.5
通讯作者：
Kagan, Valerian E.
中科院分区：
文献类型：
--
作者：
Jiang, Jianfei;Kurnikov, Igor;Kagan, Valerian E.
抑制线粒体产生活性氧是对抗退行性疾病典型的内在凋亡的一种有前途的策略。稳定的氮氧自由基如4-羟基-2，2，6，6-四甲基哌啶-1-氧基（TEMPOL）及其类似物结合了联合收割机的几个重要特征，包括可重复性、呼吸复合物的电子接受、超氧化物歧化酶模拟和自由基清除。虽然在抗氧化保护方面是成功的，但它们的有效浓度对于成功的体内应用来说太高。最近（J Am Chem Soc 127：12460，2005），我们报道了与短杆菌肽S（GS）的五个残基片段共价缀合的4-氨基2，2，6，6-四甲基-1-哌啶基氧基被整合到线粒体中并阻断放线菌素D（ActD）诱导的超氧化物生成和细胞凋亡。使用ActD诱导的小鼠胚胎细胞凋亡的模型，我们筛选了一个库的氮氧化物，探讨其抗氧化/抗凋亡特性和化学组成和三维（3D）结构之间的结构-活性关系。高疏水性和有效的线粒体整合是必要的，但不足以高抗凋亡/抗氧化活性的氮氧共轭物。通过设计构象预组织的肽基氮氧化物缀合物和表征其3D结构实验（圆二色谱和NMR）和理论（分子动力学），我们建立了β-转角/β-折叠二级结构的存在是必要的所需的活动。在模型脂质膜中的Monte Carlo模拟证实，在半GS类似物中D-Phe-Pro反转的保守确保了氮氧部分在线粒体膜界面处的特定定位，并使其保护作用最大化。这些新的见解氮氧自由基-肽和-肽电子等排体缀合物的结构-活性关系的开发新的机制为基础的治疗有效的药物。
Suppression of mitochondrial production of reactive oxygen species is a promising strategy against intrinsic apoptosis typical of degenerative diseases. Stable nitroxide radicals such as 4-hydroxy-2,2,6,6-tetramethyl piperidine-1-oxyl (TEMPOL) and its analogs combine several important features, including recycleability, electron acceptance from respiratory complexes, superoxide dismutase mimicry, and radical scavenging. Although successful in antioxidant protection, their effective concentrations are too high for successful in vivo applications. Recently (J Am Chem Soc 127: 12460, 2005), we reported that 4-amino 2,2,6,6-tetramethyl-1-piperidinyloxy, covalently conjugated to a five-residue segment of gramicidin S (GS), was integrated into mitochondria and blocked actinomycin D (ActD)-induced superoxide generation and apoptosis. Using a model of ActD-induced apoptosis in mouse embryonic cells, we screened a library of nitroxides to explore structure-activity relationships between their antioxidant/antiapoptotic properties and chemical composition and three-dimensional (3D) structure. High hydrophobicity and effective mitochondrial integration are necessary but not sufficient for high antiapoptotic/antioxidant activity of a nitroxide conjugate. By designing conformationally preorganized peptidyl nitroxide conjugates and characterizing their 3D structure experimentally (circular dichroism and NMR) and theoretically (molecular dynamics), we established that the presence of the beta-turn/beta-sheet secondary structure is essential for the desired activity. Monte Carlo simulations in model lipid membranes confirmed that the conservation of the D-Phe-Pro reverse turn in hemi-GS analogs ensures the specific positioning of the nitroxide moiety at the mitochondrial membrane interface and maximizes their protective effects. These new insights into the structure-activity relationships of nitroxide-peptide and -peptide isostere conjugates are instrumental for development of new mechanism-based therapeutically effective agents.