Chen Chia-Nan, Huang Hsin-Hsiu, Wu Chia-Li, Lin Coney P C, Hsu John T A, Hsieh Hsing-Pang, Chuang Shuang-En, Lai Gi-Ming
Divsion of Cancer Research, National Health Research Institutes (NHRI), Taipei 114, Taiwan, ROC.
Cancer Lett. 2007 Feb 8;246(1-2):237-52. doi: 10.1016/j.canlet.2006.03.004. Epub 2006 May 11.
Isocostunolide is a sesquiterpene lactone isolated from the roots of Inula helenium. Its chemical structure was determined by NMR and FAB-MS spectra. No biological activities of this compound have yet been reported. In this study, we found isocostunolide could effectively induce cytotoxicity in three cancer cell lines (A2058, HT-29, and HepG2), with an IC(50) of 3.2, 5.0, and 2.0 micro g/mL, respectively. DNA flow cytometric analysis indicated that isocostunolide actively induced apoptosis of cancer cells accompanied by a marked loss of G0/G1 phase cells. To address the mechanism of the apoptotic effect of isocostunolide, we analyzed the induction of apoptosis-related proteins in A2058. The levels of pro-caspase-8, Bid, pro-caspase-3, and poly(ADP-ribose) polymerase (PARP) decreased. However, the level of Fas was increased markedly in a dose-dependent manner. Furthermore, this compound markedly induced a depolarization of mitochondrial membranes to facilitate cytochrome c release into cytosol. The findings suggest that isocostunolide may activate a mitochondria-mediated apoptosis pathway. To address this, we found that isocostunolide-induced loss of mitochondrial membrane potential occurred via modulation of the Bcl-2 family proteins. The production of intracellular reactive oxygen species (ROS) in A2058 was not elicited. In summary, for the first time, we have isolated and characterized isocostunolide from I. helenium. This compound induces apoptosis through a mitochondria-dependent pathway in A2058 cells.
异土木香内酯是一种从土木香根部分离得到的倍半萜内酯。其化学结构通过核磁共振（NMR）和快原子轰击质谱（FAB-MS）光谱确定。该化合物的生物活性尚未见报道。在本研究中，我们发现异土木香内酯能有效诱导三种癌细胞系（A2058、HT - 29和HepG2）产生细胞毒性，其半数抑制浓度（IC50）分别为3.2、5.0和2.0μg/mL。DNA流式细胞术分析表明，异土木香内酯可积极诱导癌细胞凋亡，同时伴有G0/G1期细胞显著减少。为探究异土木香内酯凋亡效应的机制，我们分析了A2058细胞中凋亡相关蛋白的诱导情况。前半胱天冬酶 - 8、Bid、前半胱天冬酶 - 3和聚（ADP - 核糖）聚合酶（PARP）的水平降低。然而，Fas水平呈剂量依赖性显著升高。此外，该化合物显著诱导线粒体膜去极化，促进细胞色素c释放到细胞质中。这些发现表明异土木香内酯可能激活线粒体介导的凋亡途径。为证实这一点，我们发现异土木香内酯诱导的线粒体膜电位丧失是通过调节Bcl - 2家族蛋白发生的。A2058细胞中未引发细胞内活性氧（ROS）的产生。总之，我们首次从土木香中分离并鉴定了异土木香内酯。该化合物通过线粒体依赖性途径诱导A2058细胞凋亡。
