Nowadays, the incidence of acute myocardial infarction (AMI) remains a significant contributor to global mortality rates. As such, timely and effective myocardial reperfusion therapy can effectively improve acute ischemic myocardial injury and reduce myocardial infarction area in patients with AMI [1]. However, reperfusion of ischemic myocardial tissue can result in additional damage to both the cardiac tissue and local vascular network within the reperfusion zone, which is referred to as ischemia–reperfusion (I/R) damage. I/R injury can result in a variety of cellular demise in the myocardium, encompassing autophagy, apoptosis, pyroptosis, necrosis, and ferroptosis [2,3]. According to previous reports, necrosis, and apoptosis are primarily responsible for myocardial cell damage during the acute phase of reperfusion injury. As the duration of reperfusion injury increases, ferroptosis assumes a crucial role in long-term heart dysfunction induced by I/R.

Ferroptosis is an emerging iron-dependent cascade reaction involving lipid peroxidation–driven cell death. Reactive oxygen species (ROS), reactive lipid substances (RLS), and reactive nitrogen species (RNS), engage with polyunsaturated fatty acids (PUFAs) in plasma and organelle membranes, creating lipid peroxides that initiate lipid peroxidation. Ferroptosis primarily arises from the oxidation of lipids [4,5]. Acyl-CoA synthetase long-chain family member 4 (ACSL4) catalyzes lipid biosynthesis containing PUFAs, leading to a buildup of byproducts from lipid peroxidation, culminating in the development of ferroptosis [6]. A number of diseases are associated with RLS derived from lipid peroxidation, including malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), which are linked to heart disease, cancer, liver disease, diabetes, and neurological disorders. Cells possess endogenous antioxidant defense systems capable of regulating cellular redox balance. The Nuclear factor erythroid-2-related factor 2 (Nrf2), as the primary regulator of antioxidant reactions, plays a pivotal role in governing subsequent target genes, thereby facilitating the prevention and correction of cellular redox imbalances. Initiators of ferroptosis, RSL-3 and elastin, trigger the ferritin cascade by blocking glutathione peroxidase 4 (GPX4) and the cysteine/glutamate transporter system xC/xCT, in that order. It has been confirmed that GPX4 and solute carrier family 7 member 11 (SLC7A11, a cystine-glutamate antiporter, also referred to as xCT) are both downstream targets of Nrf2 [7].

Isoliquiritigenin (ISL), found in licorice, is an isoflavone compound recognized for its anti-inflammatory, anticancer, antioxidant, and other properties. According to our previous study, ISL can activate the Nrf2/heme oxygenase 1 (HO-1) signaling pathway, alleviate oxidative stress damage induced by acute myocardial ischemia, inhibit myocardial inflammatory response, and protect cardiac function [8]. Cai et al. [2] indicated that the prolonged myocardial I/R time significantly contributed to ferroptosis in the pathological progression of myocardial damage. Therefore, reducing ferroptosis in myocardial cells is an effective treatment for alleviating myocardial I/R damage. Tang et al. [9] reported that ISL inhibited lipid peroxidation and Fe2+ accumulation in lipopolysaccharide (LPS)-induced HK2 cells, reduced ferroptosis, and alleviated LPS-induced acute kidney injury. However, the impact of ISL on long-term I/R injury in heart and its fundamental mechanism has not yet been reported. We hypothesized that ISL regulates the Nrf2/GPX4 pathway in cardiomyocytes to reduce ferroptosis and lipid peroxidation. To verify this hypothesis, we simulated a model of cardiac I/R damage through in vitro and in vivo experiments, examined ISL's impact on long-term cardiac I/R injury, and further identified the fundamental mechanism.