In this study, we investigated the cardioprotective mechanisms of action of DT-010, a novel danshensutetramethylpyrazine conjugate. DT-010 significantly preserved cell viability and suppressed cell apoptosis in H9c2 cells injured by tert-butylhydroperoxide (t-BHP), iodoacetic acid (IAA) and hypoxia-reoxygenation. In addition, DT-010 pre-treatment reduced the intracellular level of free radicals including superoxide anion (·O 2 ), hydroxyl radical (·OH) and peroxynitrite anion (ONOO ) after t-BHP exposure. Moreover, DT-010 up-regulated the protein expression of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) and nuclear factor-E2-related factor 2 (Nrf2) as well as mitochondrial transcription factor A (Tfam) and heme oxygenase-1 (HO-1) in H9c2 cells. DT-010 also triggered Nrf2 nuclear translocation. In a rat myocardial ischemia-reperfusion model, DT-010 significantly alleviated myocardial infarction. The results indicated that DT-010 may be a promising candidate for the treatment of cardiovascular diseases, particularly myocardial ischemia and reperfusion injury.Key words Danshensu derivative; oxidative stress; apoptosis; myocardial ischemia reperfusion injury; peroxisome proliferator-activated receptor gamma coactivator 1 alpha/nuclear factor-E2-related factor 2/heme oxygenase-1 (PGC-1α/Nrf2/HO-1) pathway Myocardial ischemia is a primary cause of sudden death worldwide. Myocardial ischemia results from a decreased blood flow to the heart, preventing the heart from receiving adequate supply of energy. The reduced blood flow is usually caused by a partial or complete blockade of the arteries. Traditional treatments focus on restoring blood supply, such as by pass-graft surgery, dilation of coronary artery and coronary thrombolysis, and etc. 1) Although restoration of blood flow to the ischemic heart tissues is important, it is not adequate because myocardial ischemic damage is progressively developed following reperfusion due to an over-production of a large number of biospecies. 2,3) Compelling evidence demonstrated that free radicals generated during ischemia and reperfusion play pivotal roles in myocardial apoptosis. Free radical scavengers can effectively inhibit myocardial apoptosis. The previous studies have demonstrated that agents that combine anti-thrombolytic and anti-oxidative activities showed promising therapeutic efficacy in the treatment of myocardial ischemia. 4,5) In China, many traditional herbs have been used to prevent and treat myocardial ischemia. Among them are Salvia miltiorrhiza (Danshen) and Ligusticum wallichii (Chuanxiong). As the major active ingredients, (3-(3,4-dihydroxyphenyl) lactic acid) (Danshensu, DSS, Fig. 1) isolated from Danshen and tetramethylpyrazine (TMP, Fig. 1) isolated from Chuanxiong have a variety of biological activities. They lyse blood clot, dilate coronary arteries, inhibit platelet aggregation, scavenge free radicals, improve microcirculation and have anti-inflammatory properties. 6,7) Both of them are widely used in clinic for treatm...

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Myocardial ischemia/reperfusion injury (MIRI) is an inevitable and unsolved clinical problem in the treatment of ischemic heart diseases. Compound DT-010 is a novel danshensu/tetramethylpyrazine derivative and was examined as a candidate for treating MIRI. In the present study, MTT, lactate dehydrogenase assay and Hoechst staining data indicated that DT-010 attenuated tert-butylhydroperoxide (t-BHP)-induced oxidative damage by increasing cell survival, reducing cell damage and decreasing apoptosis in H9c2 cardiomyocytes. Autophagy was assessed by western blotting for microtubule-associated protein 1A/1B-light chain 3 (LC3-II and LC3-I) expression, acridine orange and monodansylcadaverine staining for autophagosome formation and the monomeric red fluorescent protein-green fluorescent protein-LC3 assay for autophagic flow. t-BHP-induced cell damage was aggravated by the autophagy agonist rapamycin and alleviated by the autophagy blocker hydroxy-chloroquine, suggesting that autophagy was involved in t-BHP-induced cardiomyocyte injury. DT-010 pretreatment significantly prevented t-BHP-induced cell damage, which was partially but significantly abolished by rapamycin and significantly improved by hydroxy-chloroquine treatment. DT-010 treatment inhibited t-BHP-induced autophagy in H9c2 cells, reduced phosphorylation of 5'-AMP-activated protein kinase (AMPK) and promoted the phosphorylation of mTOR and unc-51 like autophagy activating kinase 1 (Ulk1). To conclude, DT-010 can serve as a potential candidate for myocardial ischemia-reperfusion injury therapy. The cardioprotective effects of DT-010 could be partially attributed to its inhibition of autophagy via the AMPK-mTOR-Ulk1 signaling pathway.

In this work, we explored the protective effect of DT-018, a danshensu and tetramethylpyrazine conjugate, on mitochondrial injury induced by tert-butylhydroperoxide (t-BHP) and its possible mechanisms of action. DT-018 effectively quenched intracellular and mitochondrial reactive oxygen species (ROS), preserved the mitochondrial function, restored the intracellular level of ATP and augmented mitochondrial membrane potential (Δψm) while suppressed mitochondrial swelling in isolated myocardial mitochondria. DT-018 increased the expression of MEF2D and PGC-1α as well as Nrf2 and Tfam in H9c2 cells. Transfection of MEF2D-siRNA and PGC-1α-siRNA down-regulated the protein expression of PGC-1α and partially abolished the cardioprotection of DT-018 in t-BHP injured cells. For the in vivo studies, administration of DT-018 significantly alleviated infarct area induced by ischemia and reperfusion injury. These observations demonstrated that the cardioprotective effect of DT-018 is mediated, at least in part, by preservation of mitochondrial integrity through up-regulation of MEF2D/PGC-1α pathway.