Mitoapocynin is a triphenylphosphonium conjugated derivative of apocynin that specifically locates to the mitochondria. It has been developed as a mitochondrially targeted therapeutic antioxidant. We attempted to attenuate the mitochondrial ROS induced in H9c2 cardiac myoblast cells treated with norepinephrine. Mitoapocynin was a poor quencher of total ROS as detected by the fluoroprobe DCFH-DA. Using mitochondrial superoxide specific probe MitoSoxRed, we found that 5–10 µM mitoapocynin itself induces superoxide over and above that is generated by the norepinephrine treatment. A supposedly control molecule to mitoapocynin, the synthetic compound PhC11TPP, having the triphenylphosphonium group and a benzene moiety with C11 aliphatic chain spacer was also found to be a robust inducer of mitochondrial ROS. Subsequent assays with several cell lines viz., NIH3T3, HEK293, Neuro2A, MCF-7 and H9c2, showed that prolonged exposure to mitoapocynin induces cell death by apoptosis that can be partially prevented by the general antioxidant N-acetyl cysteine. Analyses of mitochondrial electron transport complexes by Blue Native Polyacrylamide gel electrophoresis showed that both mitoapocynin and PhC11TPP disrupt the mitochondrial Complex I and V, and in addition, PhC11TPP also damages the Complex IV. Our data thus highlights the limitations of the therapeutic use of mitoapocynin as an antioxidant.
Mitoapocynin是一种与
三苯基膦(triphenylphOSphonium)结合的apocynin衍
生物,专门定位于线粒体。它被开发为一种靶向线粒体的治疗性
抗氧化剂。我们试图减轻在H9c2心肌母细胞中由
去甲肾上腺素诱导的线粒体活性氧(ROS)。通过荧光探针DCFH-
DA检测,发现Mitoapocynin对总ROS的淬灭效果较差。使用特定于线粒体超氧化物的探针MitOSoxRed,我们发现5–10 µM的Mitoapocynin自身就会诱导超氧化物的产生,超过了
去甲肾上腺素处理所产生的量。一个被认为是Mitoapocynin对照分子的合成化合物PhC11
TPP,具有
三苯基膦基团和带有C11脂肪链间隔的苯基,也被发现是强烈的线粒体ROS诱导剂。随后对几种
细胞系(如NIH3T3、HEK293、Neuro2A、MCF-7和H9c2)的实验表明,长时间接触Mitoapocynin会通过凋亡诱导
细胞死亡,而这一过程可以通过通用
抗氧化剂N-乙酰半胱
氨酸部分阻止。通过蓝色原位聚
丙烯酰胺凝胶电泳分析线粒体电子传递复合物显示,Mitoapocynin和PhC11
TPP都干扰了线粒体的复合体I和V,此外,PhC11
TPP还损害了复合体IV。因此,我们的数据强调了Mitoapocynin作为
抗氧化剂的治疗用途的局限性。