According to our previous study, fisetin (3,3’,4’,7-tetrahydroxyflavone), a bioactive phytochemical (flavonol), reportedly showed cardioprotection against ischemia-reperfusion injury (IRI) by reducing oxidative stress and inhibiting glycogen synthase kinase 3β (GSK3β) [1]. GSK3β is said to exert a non-mitochondrial mediated cardioprotection; therefore, distinct mechanisms of GSK3β on the regulatory effect of mitochondria need to be addressed. The two distinct mitochondrial subpopulations in the heart, namely interfibrillar mitochondria (IFM) and subsarcolemmal mitochondria (SSM), respond differently to disease states. The current study aimed to understand the effect of fisetin on the subpopulation-specific preservation of IFM and SSM while rendering cardioprotection against ischemia reperfusion (I/R). Rats were pre-treated with fisetin (20 mg/kg) intraperitoneally, and IRI was induced using Langendorff isolated heart perfusion technique. Hemodynamic parameters were recorded, and the cardiac injury was assessed using infarct size (IS), lactate dehydrogenase (LDH), and creatine kinase (CK) levels. Subpopulation-specific mitochondrial preservation was evaluated by electron transport chain (ETC), catalase, superoxide dismutase (SOD), and glutathione (GSH) activities. The bioavailability of fisetin in IFM and SSM was measured using the fluorescence method. The ability of fisetin to bind directly to the mitochondrial complex-1 and activating it through donating electrons to FMN was studied using molecular docking studies and further validated by in vitro rotenone sensitivity assay. Cardioprotective effects exhibited by fisetin were mainly mediated through IFM preservation. Mitochondrial bioavailability of fisetin is more in IFM than SSM in both ex vivo and in vitro conditions. Fisetin increased mitochondrial ATP production in I/R insult hearts by activating ETC complex 1. Inhibition of complex 1 prevents the ATP-producing capacity of fisetin. Our results provide evidence that fisetin plays a protective role in myocardial IRI, possibly by preserving the functional activities of IFM.

根据我们之前的研究，据报道，一种具有生物活性的植物化学物质（黄酮醇）非瑟酮（3,3',4',7-四羟基黄酮）通过减少氧化应激和抑制糖原合酶激酶 3β 对缺血再灌注损伤（IRI）具有心脏保护作用。 GSK3β) [1]。据说 GSK3β 发挥非线粒体介导的心脏保护作用；因此，需要解决 GSK3β 对线粒体调节作用的不同机制。心脏中两种不同的线粒体亚群，即原纤维间线粒体 (IFM) 和肌膜下线粒体 (SSM)，对疾病状态的反应不同。目前的研究旨在了解非瑟酮对 IFM 和 SSM 亚群特异性保存的影响，同时提供对缺血再灌注 (I/R) 的心脏保护作用。用非瑟酮（20 mg/kg）腹膜内预处理大鼠，并使用 Langendorff 离体心脏灌注技术诱导 IRI。记录血流动力学参数，并使用梗死面积 (IS)、乳酸脱氢酶 (LDH) 和肌酸激酶 (CK) 水平评估心脏损伤。通过电子传递链 (ETC)、过氧化氢酶、超氧化物歧化酶 (SOD) 和谷胱甘肽 (GSH) 活性评估亚群特异性线粒体保存。使用荧光法测量 IFM 和 SSM 中非瑟酮的生物利用度。使用分子对接研究研究了非瑟酮直接与线粒体复合物-1 结合并通过向 FMN 捐赠电子来激活它的能力，并通过体外鱼藤酮敏感性测定进一步验证。非瑟酮表现出的心脏保护作用主要通过 IFM 保存介导。在离体和体外条件下，非瑟酮的线粒体生物利用度在 IFM 中高于 SSM。Fisetin 通过激活 ETC 复合物 1 增加 I/R 损伤心脏中线粒体 ATP 的产生。复合物 1 的抑制阻止了 fisetin 的 ATP 生产能力。我们的研究结果提供了非瑟酮在心肌 IRI 中发挥保护作用的证据，可能是通过保留 IFM 的功能活动。