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Myocardial ischemia/reperfusion injury (MIRI) is the major cause of myocardial cell damage in acute myocardial infarction, and its treatment remains a clinical challenge. Ginsenoside Rb1 showed protective effects on the cardiovascular system; however, the underlying mechanism remains largely unclear. Effects of Ginsenoside Rb1 on rat MIRI-induced myocardial infarct size were evaluated through TTC staining. TUNEL assay and flow cytometry analysis were employed to estimate cell apoptosis. Apoptosis, autophagy and PI3K/Akt/mTOR pathway-related proteins were estimated via western blot. Expression of Beclin1 in myocardial tissues were examined by immunohistochemical analysis. Expression levels of IL-1 β , TNF- α and IL-6 were tested by enzyme-linked immunosorbent assay (ELISA). Here, we found that Ginsenoside Rb1 treatment not only alleviated MIRI in rats but also protected H9C2 cells against hypoxia/reoxygenation induced damage. Ginsenoside Rb1 abolished the MIRI-induced activation of autophagy. Meanwhile, we found that treatment of 3-MA (autophagy inhibitor) could enhance the protective effects of Ginsenoside Rb1 on H9C2 cells during H/R. Moreover, Ginsenoside Rb1 treatment resulted in the activation of the PI3K/Akt/mTOR pathway, and treatment of LY294002 (PI3K/Akt pathway repressor) abolished the protective effects of Ginsenoside Rb1 on myocardial in vitro and in vivo. Our results suggest that Ginsenoside Rb1 functions as a protector against MIRI by repressing cardiomyocyte autophagy through the PI3K/Akt/mTOR signaling pathway. [ABSTRACT FROM AUTHOR]

Background The total flavonoids from ethanol extract of the aerial part of Ziziphora clinopodioides Lam. (Lamlaceae) (Xintahua) showed protective activities against rat acute myocardial ischemia in rats. This study aims to isolate acacetin, a flavonoid, from the aerial part of Z. clinopodioides, to develop an HPLC method for its detection, and to evaluate its protective effects on neonatal rat cardiomyocytes. Methods Sephadex LH-20 silicagel and pillar layer chromatography silica gel were applied for the isolation and purification of acacetin and its structure was elucidated on the basis of ¹H and 13C NMR spectroscopy. The content of acacetin in Z.clinopodioides collected from three different origins was determined by HPLC. The neonatal rat cardiomyocytes were isolated and cultured in vitro to establish a hypoxia/reoxygenation injury model. The viability of cardiomyocytes was measured by the MTT method. Changes of malondialdehyde (MDA) content in the medium were also determined. Results The acacetin content in various batches of Z. clinopodioides ranged from 45.50 to 47.41 µg/g. Acacetin of 25, 10, 5 µg/mL significantly decreased the MDA content in a model of hypoxia/reoxygenation injury (P < 0.001, P < 0.001 and P = 0.033, respectively). Conclusions Acacetin protects neonatal cardiomyocytes from the damage induced by hypoxia/reoxygenation stress through reduction of lipid peroxidation and enhancement of the antioxidant activity. [ABSTRACT FROM AUTHOR]