Transforming growth factor (TGF) is a cytokine with numerous functions that regulates and takes part in a variety of biological and pathological events in the heart. Saljic et al. (2022), Gu and Liang, (2023), Liang et al. (2022), Ren et al. (2023), Alex et al. (2023), Dong et al. (2023). To protect the heart, the TGF-β signaling system controls apoptosis, autophagy, and antifibrotic activities (Deng et al., 2019; Shen et al., 2020a; Liang et al., 2022). Of these, the most in-depth studies have been conducted on the effects of TGF-β1 on myocardial fibrosis (Garlapati et al., 2023).

In rats with myocardial infarction induced by ligation of coronary arteries, Pan et al. (2011) found that SCU prevented the multiplication of cardiac fibroblasts (CFs) and the production of collagen, ultimately reducing interstitial fibrosis by decreasing the expression of FN1 and TGF-β1. It is inferred that SCU may exert its effect on improving the impaired cardiac function in infarcted rats through the TGF-β1 signal pathway. In a different series of Ang II-induced myocardial fibrosis experiments in rats, it was discovered that SCU not only prevented Ang II-induced CFs’ growth and production of collagen as well as downregulated their expression of FN1 and TGF-β1, but also prevented the phosphorylation of both ERK1/2 and p38-MAPK. By controlling the TGF-β1/MAPK signal system, SCU can prevent the formation and progression of cardiac fibrosis. In a study on doxorubicin (DOX)-induced chronic cardiotoxicity, Sun et al. (2023) discovered that SCU inhibited TGF-β1 protein expression and increased pSmad2 levels, reducing the accumulation of collagen and the area of heart fibrosis. Thus, SCU can exert cardioprotective effects through the TGF-β1/Smad2 pathway. In conclusion, SCU can exhibit beneficial effects on the circulatory system by acting on both the traditional and non-classical signal pathways of TGF-β1 (Figure 1).

The PI3K/AKT/mTOR signal system is a crucial mechanism for controlling cell growth, proliferation, migration, and death and can be crucial for controlling lipid and glucose metabolism (Suber et al., 2018; Senoo et al., 2021; Xiao et al., 2022; Sun et al., 2023). The development of heart-related illnesses is significantly influenced by abnormalities in lipid and glucose metabolism, which are separate risk factors for the cardiovascular system. The PI3K/AKT signal pathway is the primary target of drugs being developed and approved for type II diabetes treatment (Aierken et al., 2022; Fan et al., 2023b). The PI3K/AKT signal system, a key component of the insulin route, controls liver glycogen production, gluconeogenesis, and lipid synthesis to control both glucose balance and lipid synthesis (Huang et al., 2018b; Petersen and Shulman, 2018).

In the cytotoxicity experiment, Zhou et al. discovered that SCU increased the expression of p-AKT, p-mTOR, and p62 while down-regulating the expression of Beclin 1 and LC3-II. This resulted in a reduction in the rate of cell death and a restoration of cell viability (Zhou et al., 2022b). In this work, it was shown that SCU might protect cells by inhibiting the autophagy process via the PI3K/AKT signal pathway. In a different study, Fan et al. (2017) discovered that SCU increased the expression of the proteins Nrf2, HO-1, PI3K, AKT, and NQO1 in rat livers with non-alcoholic fatty liver disease to reduce oxidative damage and enhance lipid metabolism. It was deduced that PI3K/AKT phosphorylation and consequent Nrf2 transfer were necessary for SCU’s anti-hyperlipidemic action. Xu et al. (2021) found in diabetic cardiomyopathy (DCM) mice, SCU improved cardiac function by preventing the decline of p-AKT and increasing the subsequent Nrf2 translocation with HO-1 protein expression in diabetic mouse cardiomyocytes. It can be inferred that the PI3K/AKT/mTOR signal pathway played a role in how protective SCU was for cardiomyocytes. Fu et al. (2019) found in an apoptosis-inducing assay in human aortic endothelial cells that SCU increased the cell viability of post-injury human aortic endothelial cells by elevating the levels of PI3K, P-AKT, and P-FOXO3A and that PI3K inhibitors could attenuate this promotion.

Numerous inflammatory processes are mediated by the NLRP3 inflammasome (NLRP3), which is activated by mTOR signal (Dai et al., 2019; Yang et al., 2019; Marín-Aguilar et al., 2020; Ye et al., 2020; Chen et al., 2021). Xu et al. (2020) found that SCU exerted a role in inhibiting NLRP3 activation and thus attenuating the inflammatory response by increasing AKT phosphorylation and inhibiting mTORC1 activity in experiments in which acute myocardial I/R injury induced H9c2 damage. Furthermore, this study found that SCU-mediated inhibition of mTORC1 and activation of NLRP3 could be abolished by gene silencing of AKT by siRNA. In conclusion, SCU has the ability to protect the cardiovascular system by activating the PI3K/AKT/mTOR signal pathway (Figure 2).

Regarding redox homeostasis, DNA repair, iron homeostasis, cell proliferation, and other processes, nuclear factor erythroid 2-related factor 2 (Nrf2) is among the most active activators of transcription in the Cap ‘n ‘Collar family. One of the most vital cellular routes is the Nrf2/Keap/ARE signal pathway. This mechanism reduces oxidative stress and eliminates excess ROS to maintain redox equilibrium in vivo (Chen, 2022).

By promoting the expression of Nrf2, NQO-1, and HO-1 and suppressing the expression of Keap1 mRNA in the hearts of diabetic mice, Huo et al.'s research in a mouse model of type 2 diabetes revealed that SCU plays an essential part in reducing oxidative damage and the severity of type 2 diabetes-induced cardiac complications (Huo et al., 2021). SCU significantly elevated the expression of the proteins Nrf2 and HO-1 and reduced oxidative damage in mice with STZ-induced DCM, according to Xu et al.'s findings (Xu et al., 2021). It suggests that SCU may exert cardioprotective effects against diabetic injury through the Nrf2/Keap/ARE signal pathway. Fan et al. (2017) in an experiment to induce hyperlipidaemia in rats, found that SCU attenuated oxidative damage by increasing the expression of Nrf2, HO-1, PI3K, and AKT proteins, thereby improving serum and liver lipid metabolism levels. This suggests that through the Nrf2/Keap/ARE signal pathway, SCU can contribute to improved lipid metabolism and anti-hyperlipidemia (Figure 3).

NOTCH signal is an event that regulates differentiation, proliferation, and apoptosis through cell-to-cell interactions. In the growth, maturation, and restoration of the heart, NOTCH signal is crucial (Zhou et al., 2022a).

Zhou et al. (2014) found in an experimental model of myocardial fibrosis in rats that SCU inhibited the development of myocardial fibrosis by reversing the induction of increased a smooth muscle actin expression and decreased CD31, Notch1, Jagged1, and Hes1 expression. It suggests that SCU can exert cardioprotective effects against myocardial fibrosis through the NOTCH pathway (Figure 4).

In recent years, the eNOS/cGMP/PKG signal pathway has been considered an important target for therapies such as regulating blood pressure, attenuating IR injury, and delaying heart failure (Anwar et al., 2017; Kolijn et al., 2021; Park et al., 2022). Additionally, the eNOS/cGMP/PKG signal route is crucial for controlling blood pressure and vascular endothelial function (Zhang et al., 2023).

Li et al. (2015) found in an experimental model of myocardial ischemia-reperfusion (MIR)in rats that SCU was able to exert an anti-MIR injury effect by increasing the levels of p-VASP Ser239 in rat cardiac tissue and serum. p-VASP Ser239 is a marker of PKG activation. Therefore, the protective effect of SCU against MIR injury is related to the PKG pathway. They also performed human cardiac microvascular endothelial cells injury experiments. It was discovered that SCU might have a positive impact on hypoxia reoxygenation (HR)-injured endothelial cells by reversing the decrease in PKG-I, PKG-I phosphorylation, and PKG-I mRNA after HR injury and, concurrently, raising p-VASP Ser239 and the ratio of p-VASP Ser239 to total VASP. Chen et al. (2015) found that SCU exerted endothelium-dependent relaxation and attenuated endothelial damage by increasing pVASP protein levels in HR-induced endothelial dysfunction in isolated rat CA. This experiment demonstrated that SCU can perform vascular endothelial protection through the PKG pathway. In conclusion, SCU can protect the cardiovascular system by activating the eNOS/cGMP/PKG signal pathway (Figure 5).

The PINK1/Parkin signal pathway is closely related to “mitophagy" (Wang et al., 2021a). An important part of the metabolism of heart energy is played by mitochondria. However, too much ROS generation brought on by mitochondrial malfunction destroys cardiomyocytes and causes a number of cardiovascular disorders. The injured mitochondria in this situation need to be removed. Mitophagy is crucial for preserving heart homeostasis. Cardiac homeostasis is inseparable from mitochondrial autophagy, which is inseparable from the PINK1/Parkin signal pathway.

Xi et al. (2021) found in human umbilical vein endothelial cells (HUVECs) injury experiments that SCU reduced the expression of P62 and apoptotic proteins Cyt. C, cleaved caspase3 by elevating the High glucose-induced reduced levels of PINK1. Meanwhile, SCU promoted the expression of PINK1, Parkin, and Mitofusin2. Thus, SCU exerts a cell viability-enhancing and vascular endothelial protective effect on HUVECs by activating autophagy and attenuating apoptotic pathways. This study confirmed that SCU exerts a protective effect on vascular endothelium through the PINK1/Parkin signal pathway (Figure 6).

The JAK/STAT signal pathways involve biological functions such as cell apoptosis, cell cycle, and stem cell homeostasis. The JAK2/STAT3 pathway is one of the JAK/STAT pathways (Verhoeven et al., 2020; Xin et al., 2020). Previous studies have demonstrated that the JAK2/STAT3 pathway can potentially alleviate oxidative stress, apoptosis, and other mechanisms that contribute to mitigating myocardial IR injury (Mahdiani et al., 2022).

Wang et al. (2016) found that SCU increased the expression of Bcl2, VEGF, MMP2, MMP9, and SOD, attenuated the expression of Bax and caspase-3 and the level of MDA through the JAK/STAT3 signal pathway and exerted cardioprotective effects in the experiments on I/R-injured H9c2 (Figure 7).

In the cardiovascular system, calcium signal is central to cardiac physiology and is closely related to the contraction and diastole of cardiac tissue and endovascular myocytes (Nattel et al., 2020; Chen et al., 2022b). Dysregulated calcium signals can lead to abnormal blood pressure, cardiac hypertrophy, heart failure, and other diseases. (Beckendorf et al., 2018; Basu et al., 2019; Luczak et al., 2020).

Earlier, Pan and others found that SCU exerted endothelium-independent vasorelaxation by inhibiting extracellular calcium inward flow in isolated rat aortas in experiments in which noradrenaline bitartrate induced aortic constriction in rats and that this effect was independent of vdcs (Pan et al., 2008). Subsequently, Pan et al. (2010) found that SCU exerted its anti-cardiac hypertrophic influence by inhibiting the increase of intracellular calcium and calcineurin and inhibiting the expression of calcineurin in experiments with phenylephrine-induced hypertrophy of neonatal rat cardiomyocytes, and a model of pressure overload-induced cardiac hypertrophy in mice. In further AB mouse experiments, SCU inhibited phosphorylated CaMKII that was elevated after AB treatment. However, phosphorylated CaMKII is the active form of CaMKII. Thus, the team demonstrated, by means of a progressive research approach, that SCU can exert significant anti-cardiac hypertrophic effects by inhibiting the Ca²⁺-ediated CaMKII signal pathway (Figure 8).

The classical TLR4/MyD88/NF-κB signal route is involved in activating processes such as inflammatory responses, oxidative stress, and immune regulation in the organism (Shen et al., 2020b; Guo et al., 2021; Liu et al., 2022). In the cardiac system, the TLR4/Myd88/NF-κB pathway has a regulatory role in hypertension and a protective effect on the heart (Kim et al., 2020; Yang et al., 2020). By reducing oxidative stress, inflammation, and apoptosis, the TLR4/NF-κB signal pathway may reduce hyperglycemia and diabetes-induced cardiomyopathy (Yao et al., 2021).

In a rat model of hypertension, Chen et al. (2013) discovered that SCU could have tissue-protective and antihypertensive effects by upregulating Mcl1 and downregulating inflammatory and apoptotic factors like TLR4, NF-κB, p65, TNF-α, IL-1β, IL-18, Bax, and cleaved-caspase-3 p17. In addition, Huo and others found that SCU inhibited the increase of cardiac inflammatory markers in diabetic mice, such as TLR4, MyD88, NF-κB, and IL-6, through the TLR4/MyD88/NF-κB signal pathway, as well as inhibited the increase in the protein distribution of NF-κB and TNF-α and the decrease in the protein distribution of IKKβ in the diabetic cardiac immunohistochemical sections in their experiments on the type 2 diabetes mellitus model (Huo et al., 2021). SCU reduces the heart damage caused by type 2 diabetes by activating this signal route. The above studies demonstrated that SCU acts on the TLR4/MyD88/NF-κB signal pathway to exert antihypertensive and antidiabetic effects (Figure 9).

The cGAS-STING signal pathway was originally recognized for its role in immune defense due to its immune recognition of cytoplasmic DNA (Zhang et al., 2020b). As an emerging hot pathway in recent years, it can have a considerable impact on the cardiovascular system (Wang et al., 2020; Oduro et al., 2022; Luo et al., 2023). Some of these studies have found that the cGAS-STING signal pathway may be a critical therapeutic target for improving the prognosis of myocardial infarction and ischaemic reperfusion injury (Rech et al., 2022; Lv et al., 2023).

Li et al. (2023b). found that intraperitoneal injection of SCU attenuated I/R-induced apoptosis of cardiomyocytes in mice while improving I/R-induced diminished cardiac function in an in vivo experiment in mice with cardiac I/R injury. Moreover, SCU reduced the expression of cGAS, STING, and cleaved caspase3 in I/R injury-induced cardiac tissues while increasing the Bcl2/Bax ratio. This experiment suggests that the effect of SCU in improving cardiac function in mice may be related to the cGAS-STING signal pathway. Then, in an in vitro experiment of H/R-induced H9c2 cell injury, Li et al. found that H/R led to apoptosis of H9c2 cells while increasing the expression levels of cGAS, STING, and cleaved caspase3 and decreasing the Bcl2/Bax ratio. This phenomenon can be reversed by SCU and cGAS inhibitors. Thus, this study suggests that SCU inhibits myocardial apoptosis induced by activation of the cGAS-STING signal pathway, thereby exerting a cardioprotective effect.

Atherosclerosis, diabetic cardiomyopathy, myocardial infarction, and myocardial ischemia-reperfusion injury are only a few examples of cardiovascular illnesses influenced by inflammatory reactions (Chistiakov et al., 2017; Fredman and MacNamara, 2021; Goswami et al., 2021; Avagimyan et al., 2022). As the population ages and living standards improve, physiopathological factors such as aging, hyperglycemia, and hyperlipidemia exacerbate the development of an inflammatory response in the cardiovascular system, ultimately leading to heart failure (Chistiakov et al., 2017; Goldfine and Shoelson, 2017; Adamo et al., 2020). To prevent and treat CVD, it is crucial to effectively reduce the inflammatory response. According to a few studies, SCU has cardioprotective properties by reducing inflammatory reactions.

Huo et al. (2021) found that SCU could attenuate cardiac histopathological changes by decreasing high fat diet/streptozotocin (HFD/STZ)-induced upregulation of TLR4, Myd88, NF-κB, IL- 6, and TNF-α and by increasing HFD/STZ-induced downregulation of IkBβ mRNA expression in a mouse model of type 2 diabetes mellitus. It suggests that SCU may exert cardioprotective effects by reducing cellular damage by inhibiting inflammatory responses. In another study, SCU could exert an inhibitory effect on the activation of NLRP3 through activation of AKT and inhibition of mTORC1, which in turn exerted a cardioprotective effect (Xu et al., 2020). In addition, Huang et al. found in isoproterenol (ISO)-induced myocardial infarction in rats that SCU could play a role in attenuating cardiac injury by decreasing the expression of myocardial inflammatory cytokines, such as gelatinase-associated lipid transport protein, NF-κB, IL-1β, and IL-6, in neutrophils induced by ISO(Huang et al., 2018a). In other cases, Xu et al. (2021) found in streptozotocin (STZ)-induced DCM in small mice that SCU attenuated myocardial damage in diabetic mice by inhibiting the activation of NLRP3, the release of proinflammatory cytokines, and the nuclear translocation of NF-κB. In summary, SCU can exert cardioprotective effects by suppressing the inflammatory response.

Cardiovascular illnesses like hypertension, atherosclerosis, and other ischemic heart diseases are influenced by oxidative stress (Guzik and Touyz, 2017; Kibel et al., 2020). Moreover, excessive oxidative stress accelerates the rate of cardiovascular system aging as the body ages (Kibel et al., 2020). Oxidative stress is also inextricably linked to hyperlipidemia, diabetes, and metabolism-related cardiac complications (Zhang et al., 2020a; Fuller et al., 2020; Tao et al., 2021). Therefore, modulation of oxidative stress is essential to mitigate CVD. Some studies have found that SCU can exert cardiovascular protection through antioxidant responses (Table 1).

Apoptosis, also known as programmed cell death, can mediate many cardiac pathologies such as heart failure, myocardial infarction, ischaemia-reperfusion injury, diabetic cardiomyopathy, and vascular endothelial injury (Cheng et al., 2020; Li et al., 2021; Liao et al., 2022; Liu et al., 2023). Promoting apoptosis exacerbates CVD, whereas limiting apoptosis exerts a cardioprotective effect. Recent research has revealed that SCU affects the apoptotic process, which could lead to the development of novel therapies for the treatment of connected diseases (Table 2).

Endothelial cells make up the vascular endothelium. The regulation of vasodilatory tone and angiogenesis are two functions that endothelial cells do (Alvandi and Bischoff, 2021; Trimm and Red-Horse, 2023). As a result, endothelial function plays a key role in the development of numerous illnesses, including hypertension, atherosclerosis, and myocardial infarction (Dikalova et al., 2020; Luo et al., 2022; Fan et al., 2023a). Some studies have found that SCU can protect vascular endothelial cells through different mechanisms and thereby exert cardiovascular protection (Table 3).

Prolonged stress overload or noxious stimuli induce changes in the heart, such as cardiomyocyte hypertrophy and interstitial fibrosis, which macroscopically manifest as cardiac hypertrophy. Although cardiac hypertrophy is a physiological and pathological adaptive response, continued pathological stimulation can cause cardiac remodeling, leading to arrhythmias and heart failure (Marian et al., 2020; Fan et al., 2023a). Recent investigations have revealed that SCU has anti-myocardial hypertrophic and fibrotic properties (Table 4).

Hyperglycaemia and hyperlipidemia are independent risk factors for CVD. The microvascular, macrovascular, and myocardial tissues of the human body will be harmed by long-term hyperglycemia, which will also hasten the development of cardiovascular disorders such as atherosclerosis, acute myocardial infarction, diabetic cardiomyopathy, and heart failure (Withaar et al., 2021; Paolisso et al., 2022; Rampin et al., 2022; Wei et al., 2022; Li et al., 2023a). Atherosclerosis is known to be facilitated by hyperlipidemia. However, it has been discovered recently that serum lipids can directly harm cardiac tissues by inducing oxidative stress, inflammatory reactions, and other processes that result in ventricular dysfunction and electrophysiological alterations (Castillo et al., 2018; Choi et al., 2021; Mohammadi-Shemirani et al., 2022). Therefore, reducing blood lipids and glucose levels is crucial to preventing the onset of cardiovascular illnesses. Numerous research conducted recently have supported the regulating effects of SCU on cholesterol and glucose metabolism (Table 5).