A new free radical scavenger, resorcimoline, prevents ischaemia/reperfusion injury in the heart

Abstract Introduction Ischaemic heart disease remains the leading cause of death worldwide. Early coronary revascularisation is the most important treatment. Recent findings have revealed that reactive oxygen species (ROS) can lead to tissue damage following coronary artery revascularisation, known as ischaemia-reperfusion injury. In this study, we focused on resorcimoline, a new free radical scavenger that was generated during the synthesis of dimethylresveratrol and dimethylpiceatannol. Last year, we reported the scavenging activity in vitro against multiple ROS, confirmed by the electron spin resonance spectrometry (Ref. 1). Purpose This study aimed to assess the potential of resorcimoline as a novel therapeutic treatment for reducing the degree of infarction caused by myocardial ischaemia, by eliminating ROS generated during myocardial ischaemia-reperfusion. Methods Nine-to-eleven-week-old male Wistar rats were subjected to acute myocardial ischaemia induced by ligation of the left anterior descending coronary artery for 30 minutes, followed by reperfusion for 24 hours. Rats received intravenous injections of resorcimoline at 6 mg/kg before coronary ligation or saline as a control (n = 9 vs. n = 8). The heart sections were double-stained with Evans blue 1% and triphenyltetrazolium chloride 1% to assess infarct area and area-at-risk. For immunohistochemical study, the other ischaemia/reperfusion models were treated with resorcimoline and saline (n = 7 vs. n = 7) as above, and the middle parts of the hearts were embedded in optimal cutting temperature compound and quickly frozen. In the H＆E-stained section, the infarct border zone was defined as a 2-mm band surrounding the necrosis area. Troponin I levels in serum were measured using ELISA. Primary cultured cardiomyocytes were treated with 10 μM angiotensin II for 3.5 hours and then exposed to resorcimoline for 30 minutes at an increasing dosage. A cellular ROS assay kit was used to assess the levels of ROS in the cardiomyocytes and the number of cells was counted with DAPI stain using an image processing software. Results Infarct size in resorcimoline-treated animals was significantly smaller than in control animals (41.8±19.4% vs. 60.8±12.9%, p=0.03, Fig. 1A) and area-at-risk was not significantly different (58.0±27.8% vs. 51.9±18.5%, p=0.61). Apoptotic cells in the border zone were significantly reduced in resorcimoline-treated animals (32.0±11.7% vs. 55.1±16.9%, p=0.01, Fig. 1B). Troponin I levels in resorcimoline-treated animals were significantly lower than in control animals (4524±3596 vs. 7856±4653, p=0.04, Fig. 1C). resorcimoline significantly reduced angiotensin II-induced ROS in cardiomyocytes in a concentration-dependent manner (Fig. 2A,B). Conclusion This novel compound, resorcimoline, can reduce infarct size induced by coronary ischaemia-reperfusion injury by reducing the ROS damage to myocardiocytes in the border zone and cellular ROS levels in cardiomyocytes.