The aim of this study was to investigate the cytotoxic and apoptotic effects of Nephelium ramboutan-ake (pulasan) rind in selected human cancer cell lines. The crude ethanol extract and fractions (ethyl acetate and aqueous) of N. ramboutan-ake inhibited the growth of HT-29, HCT-116, MDA-MB-231, Ca Ski cells according to MTT assays. The N. ramboutan-ake aqueous fraction (NRAF) was found to exert the greatest cytotoxic effect against HT-29 in a dose-dependent manner. Evidence of apoptotic cell death was revealed by features such as chromatin condensation, nuclear fragmentation and apoptotic body formation. The result from a TUNEL assay strongly suggested that NRAF brings about DNA fragmentation in HT-29 cells. Phosphatidylserine (PS) externalization on the outer leaflet of plasma membranes was detected with annexin V-FITC/PI binding, confirming the early stage of apoptosis. The mitochondrial permeability transition is an important step in the induction of cellular apoptosis, and the results clearly suggested that NRAF led to collapse of mitochondrial transmembrane potential in HT-29 cells. This attenuation of mitochondrial membrane potential (Δψm) was accompanied by increased production of ROS and depletion of GSH, an increase of Bax protein expression, and induced-activation of caspase-3/7 and caspase-9. These combined results suggest that NRAF induces mitochondrial-mediated apoptosis.
本研究的目的是调查Nephelium RAmboutan-ake(pulasan)果皮对选定人类癌
细胞系的细胞毒性和凋亡效应。根据M
TT实验,N. RAmboutan-ake的粗
乙醇提取物及其分馏(
乙酸乙酯和
水相)抑制了HT-29、HCT-116、
MDA-MB-231和Ca Ski细胞的生长。研究发现,N. RAmboutan-ake
水相分馏(NRAF)对HT-29细胞产生了剂量依赖性的最大细胞毒性效应。通过染色质浓缩、细胞核碎裂和凋亡小体形成等特征显示出凋亡
细胞死亡的证据。TUNEL实验结果强烈表明NRAF导致HT-29细胞的DNA碎裂。在外膜上检测到
磷脂酰丝氨酸(PS)的外翻,通过annexin V-FITC/
PI结合确认了凋亡的早期阶段。线粒体通透性转变是诱导细胞凋亡的一个重要步骤,结果明显表明NRAF导致HT-29细胞中线粒体跨膜电位的崩溃。这种线粒体膜电位(Δψm)的减弱伴随着活性氧(ROS)的增加和
谷胱甘肽(GSH)的耗竭、Bax蛋白表达的增加,以及caspase-3/7和caspase-9的激活。这些结合的结果表明,NRAF诱导了线粒体介导的凋亡。