Cálgaro-Helena Anaísa F, Devienne Karina F, Rodrigues Tiago, Dorta Daniel J, Raddi Maria Stella G, Vilegas Wagner, Uyemura Sérgio A, Santos Antonio C, Curti Carlos
Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Brazil.
Chem Biol Interact. 2006 Jun 10;161(2):155-64. doi: 10.1016/j.cbi.2006.04.006. Epub 2006 Apr 28.
Isolated mitochondria may undergo uncoupling, and in presence of Ca(2+) at different conditions, a mitochondrial permeability transition (MPT) linked to protein thiol oxidation, and demonstrated by CsA-sensitive mitochondrial swelling; these processes may cause cell death either by necrosis or by apoptosis. Isocoumarins isolated from the Brazilian plant Paepalanthus bromelioides (Eriocaulaceae) paepalantine (9,10-dihydroxy-5,7-dimethoxy-1H-naptho(2,3c)pyran-1-one), 8,8'-paepalantine dimer, and vioxanthin were assayed at 1-50 microM on isolated rat liver mitochondria, for respiration, MPT, protein thiol oxidation, and interaction with the mitochondrial membrane using 1,6-diphenyl-1,3,5-hexatriene (DPH). The isocoumarins did not significantly affect state 3 respiration of succinate-energized mitochondria; they did however, stimulate 4 respiration, indicating mitochondrial uncoupling. Induction of MPT and protein thiol oxidation were assessed in succinate-energized mitochondria exposed to 10 microM Ca(2+); inhibition of these processes was assessed in non-energized organelles in the presence of 300 microM t-butyl hydroperoxide plus 500 microM Ca(2+). Only paepalantine was an effective MPT/protein thiol oxidation inducer, also releasing cytochrome c from mitochondria; the protein thiol oxidation, unlike mitochondrial swelling, was neither inhibited by CsA nor dependent on the presence of Ca(2+). Vioxanthin was an effective inhibitor of MPT/protein thiol oxidation. All isocoumarins inserted deeply into the mitochondrial membrane, but only paepalantine dimer and vioxantin decreased the membrane's fluidity. A direct reaction with mitochondrial membrane protein thiols, involving an oxidation of these groups, is proposed to account for MPT induction by paepalantine, while a restriction of oxidation of these same thiol groups imposed by the decrease of membrane fluidity, is proposed to account for MPT inhibition by vioxanthin.
分离出的线粒体可能会发生解偶联，并且在不同条件下存在Ca(2+)时，会发生与蛋白质硫醇氧化相关的线粒体通透性转换（MPT），并通过环孢素A敏感的线粒体肿胀来证明；这些过程可能通过坏死或凋亡导致细胞死亡。从巴西植物凤梨科的Paepalanthus bromelioides中分离出的异香豆素，如paepalantine（9,10 - 二羟基 - 5,7 - 二甲氧基 - 1H - 萘并(2,3c)吡喃 - 1 - 酮）、8,8'-paepalantine二聚体和紫黄质，在1 - 50 microM浓度下对分离出的大鼠肝脏线粒体进行了检测，以研究呼吸作用、MPT、蛋白质硫醇氧化以及使用1,6 - 二苯基 - 1,3,5 - 己三烯（DPH）与线粒体膜的相互作用。这些异香豆素对琥珀酸供能的线粒体的状态3呼吸没有显著影响；然而，它们确实刺激了状态4呼吸，表明线粒体发生了解偶联。在暴露于10 microM Ca(2+)的琥珀酸供能的线粒体中评估MPT和蛋白质硫醇氧化的诱导情况；在存在300 microM叔丁基过氧化氢加500 microM Ca(2+)的情况下，在非供能细胞器中评估这些过程的抑制情况。只有paepalantine是一种有效的MPT/蛋白质硫醇氧化诱导剂，还能从线粒体中释放细胞色素c；蛋白质硫醇氧化与线粒体肿胀不同，既不受环孢素A抑制，也不依赖于Ca(2+)的存在。紫黄质是MPT/蛋白质硫醇氧化的有效抑制剂所有异香豆素都能深入插入线粒体膜，但只有paepalantine二聚体和紫黄质降低了膜的流动性。有人提出，paepalantine诱导MPT是由于与线粒体膜蛋白质硫醇发生直接反应，涉及这些基团的氧化，而紫黄质抑制MPT是由于膜流动性降低对这些相同硫醇基团氧化的限制。
