Ginsenoside Rg3 improves microcystin-induced cardiotoxicity through the miR-128-3p/MDM4 axis

Microcystin (MC) is the byproduct of cyanobacteria metabolism that is associated with oxidative stress and heart damage. This study aimed to investigate the effect of ginsenoside Rg3 on MC-induced cardiotoxicity. A mouse model of myocardial infarction was constructed by oral MC administration. H9C2 cells were used for in vitro analysis. Cellular oxidative stress, apoptosis, and the relationship between miR-128-3p and double minute 4 protein (MDM4) were analyzed. MiR-128-3p expression was upregulated in vitro and in vivo after MC treatment, which was downregulated after Rg3 treatment. Left ventricular ejection fraction (LVEF) and left ventricular systolic pressure (LVSP) were increased and left ventricular end-diastolic pressure (LVEDP) was decreased after Rg3 treatment. Moreover, Rg3 alleviated MC-induced pathological changes and apoptosis in myocardial tissues. Meanwhile, Rg3 treatment decreased the lactate dehydrogenase (LDH) and malondialdehyde (MDA) levels and inhabited cell apoptosis and oxidative stress in MC-treated myocardial cells. MiR-128-3p overexpression attenuated the protective effect of Rg3 on MC-induced cardiotoxicity. MiR-128-3p negatively regulated MDM4 expression. This study revealed that Rg3 alleviated MC-induced cardiotoxicity through the miR-128-3p/MDM4 axis, which emphasized the potential of Rg3 as a therapeutic agent for MC-induced cardiotoxicity, and miR-128-3p as a target for the Rg3 therapy.

Protective Effects of Epigallocatechin-3-gallate (EGCG) against the Jellyfish Nemopilema nomurai Envenoming

Jellyfish stings are the most common marine animal injuries worldwide, with approximately 150 million envenomation cases annually, and the victims may suffer from severe pain, itching, swelling, inflammation, arrhythmias, cardiac failure, or even death. Consequently, identification of effective first aid reagents for jellyfish envenoming is urgently needed. Here, we found that the polyphenol epigallocatechin-3-gallate (EGCG) markedly antagonized the hemolytic toxicity, proteolytic activity, and cardiomyocyte toxicity of the jellyfish Nemopilema nomurai venom in vitro and could prevent and treat systemic envenoming caused by N. nomurai venom in vivo. Moreover, EGCG is a natural plant active ingredient and widely used as a food additive without toxic side effects. Hence, we suppose that EGCG might be an effective antagonist against systemic envenoming induced by jellyfish venom.

Gastrodin protects against high glucose-induced cardiomyocyte toxicity via GSK-3β-mediated nuclear translocation of Nrf2

Diabetic cardiomyopathy (DCM) is one of the major complications of diabetes that causes mortality and morbidity in diabetic patients. Gastrodin (GSTD) is a bioactive phenolic glucoside component of an ancient Chinese herb Tianma (Gastrodia elata Bl.), which is widely used for cardiovascular and cerebrovascular diseases by ancient Chinese. Up to now, whether GSTD has a beneficial effect on DCM is unclear. Therefore, this study aimed to investigate the effect of GSTD on high glucose-induced injury in H9c2 rat cardiomyocytes and HL-1 mouse cardiomyocytes, and its underlying mechanisms. High glucose (33 mM) treatment caused cardiomyocyte toxicity, oxidative stress and apoptosis in both H9c2 and HL-1 cells. Under both normal (5.5 mM glucose) and high glucose conditions, GSTD showed protective effect against high glucose-induced cytotoxicity and promoted the nuclear translocation of Nrf2 in a concentration and time-dependent manner in H9c2 and HL-1 cells. Knockdown of Nrf2 expression using siRNA specifically targeting Nrf2 attenuated the protective effect of GSTD. Furthermore, GSTD promoted the nuclear translocation of Nrf2 via activating glycogen synthase kinse-3β (GSK-3β) signaling pathway. 4-benzyl, 2-methyl, 1, 2, 4-thiadiazolidine, 3, 5 dione (TDZD-8), an inhibitor of GSK-3β, inhibited the nuclear translocation of Nrf2 induced by GSTD, and attenuated the protective effect of GSTD as Nrf2 knockdown did. In summary, GSTD could protect against high glucose-induced cardiomyocyte toxicity via GSK-3β-mediated nuclear translocation of Nrf2.