Liquiritin from Radix Glycyrrhizae Protects Cardiac Mitochondria from Hypoxia/Reoxygenation Damage

Mechanistic investigation of the ameliorative effect of liquiritin on hypoxia/reoxygenation‑induced cardiomyocyte injury based on network pharmacology and in vitro validation

Liquiritin (LIQ) is a flavonoid known for its cardioprotective properties, extracted from Glycyrrhiza uralensis Fisch. The purpose of the present study was to investigate the protective mechanism of LIQ against hypoxia/reoxygenation (H/R) injury through in vitro experiments, with the goal of enhancing its pharmacological effects. Initially, network pharmacology was employed to explore the targets and mechanisms of LIQ. Subsequently, an in vitro H/R model was established using H9c2 cells. Potential targets for LIQ and myocardial ischemia-reperfusion injury (MIRI) were identified through online databases. The STRING, Cytoscape and DAVID databases were used to extract intersecting targets and mechanisms. In vitro experiments were conducted to validate these findings, assessing cardiac enzymes, oxidative stress indicators, mitochondrial fluorescence, apoptotic fluorescence, inflammation and related protein expression. The network pharmacological analysis revealed that the protective effects of LIQ on MIRI involve oxidative stress, inflammation and apoptosis. The results of in vitro experimental validation demonstrated that LIQ significantly reduced the activities of lactated dehydrogenase and creatine kinase isoenzyme-MB (P<0.05 or 0.01), as well as the level of malondialdehyde (P<0.01). It also inhibited the production of reactive oxygen species (P<0.01), the release of inflammatory factors (P<0.05 or 0.01) and apoptosis (P<0.01). By contrast, the LIQ pre-treatment group exhibited a significant increase in mitochondrial membrane potential level (P<0.05 or 0.01) and the activities of antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase (P<0.05 or 0.01). Furthermore, LIQ reduced the protein expressions of TNF-α receptor type 1 (TNFR1) and MMP9, along with the level of NF-κB phosphorylation (P<0.05 or 0.01). In conclusion, LIQ mitigated H/R-induced cardiomyocyte injury through mechanisms that may involve antioxidants, anti-apoptotic effects, protection against mitochondrial damage and suppression of inflammatory levels. These effects are achieved via inhibition of the TNFR1/NF-κB/MMP9 pathway.

Jingfang Granule mitigates Coxsackievirus B3-induced myocardial damage by modulating mucolipin 1 expression

ETHNOPHARMACOLOGICAL RELEVANCE

Jingfang Granules (JFG) originate from the traditional herbal formula Jingfang Baidu powder. It has the effects of inducing sweating and dispelling wind. It is a classic medication used for treating external pathogenic factors and viral diseases. However, the therapeutic mechanism of JFG for viral myocarditis needs further clarification.

AIM OF THE STUDY

This study aimed to explore the therapeutic efficacy of JFG on coxsackievirus B3-induced viral myocarditis (VMC), along with the elucidation of its underlying mechanisms.

MATERIALS AND METHODS

C57 BL/6JNifdc mice were divided randomly into several groups: control, model, Jingfang Granule groups (0.23, 0.46, and 0.69 g/20g, respectively), and a positive group (oseltamivir, 19.33 mg/kg). Following the establishment of the VMC model, the mice underwent an 8 -week treatment regimen. Pathological alterations in cardiac tissues and inflammatory protein expression were monitored. Differential gene analysis was conducted utilizing transcriptomic techniques. The differential gene mucolipin 1 (Mcoln1) was knocked down by transfection with siRNA in H9C2 cell, and investigative techniques such as immunoblotting, qRT-PCR, immunofluorescence, JC-1 staining, reactive oxygen species (ROS) detection, and mitochondrial stress testing were employed to examine its mechanism of action.

RESULTS

JFG significantly mitigates the pathological damage observed in the cardiac tissues of CVB3-induced VMC mice and attenuates the expression of inflammatory genes. Subsequently, differentially expressed genes are identified through transcriptomic analysis and validated via PCR. Among these, the upregulation of Mcoln1 promotes autophagy, facilitating the clearance of damaged mitochondria and excessive ROS. This has been substantiated through in vitro experiments. Excessive ROS precipitates a reduction in mitochondrial membrane potential, instigating cell apoptosis. In accordance with TUNEL staining results, JFG acts to inhibit cell apoptosis. To ascertain whether Mcoln1 is a crucial target for JFG in treating VMC, Mcoln1 was suppressed in H9C2 cells. The suppression of Mcoln1 hinders the elevation in autophagy levels post-JFG treatment, obstructs the enhancement of mitochondrial function, and impedes the clearance of ROS. Furthermore, the inhibitory effect of JFG on cell apoptosis is attenuated.

CONCLUSION

The research findings indicate that JFG has a protective effect on CVB3-induced H9C2 cell injury. JFG may exert its effects in VMC treatment by enhancing autophagy to suppress cell apoptosis through the mitochondrial pathway, thereby counteracting cell damage.

Liquiritin inhibits MRGPRX2-mediated pseudo-allergy through the PI3K/AKT and PLCγ signaling pathways

Liquiritin is a natural flavone with a variety of pharmacological effects derived from the medicinal food homology plant Glycyrrhiza uralensis Fisch. As a kind of lethal allergic reactions, pseudo-allergic reactions (PARs) arise from the Mas-related G protein coupled receptor X2 (MRGPRX2)-triggered fast degranulation of mast cells (MCs). In the current work, the anti-pseudo-allergy action and potential mechanisms of liquiritin were explored in vivo and in vitro. Liquiritin suppressed the calcium influx and degranulation elicited by Compound 48/80 (C48/80) in mouse peritoneal mast cells (MPMCs). In mice, liquiritin also inhibited the C48/80-elicited hind paw extravasation, as well as the elevations in TNF-α and histamine levels. Molecular docking combined with detection of HEK293T cells expressing human MRGPRX2 showed that liquiritin was a potential MRGPRX2 antagonist and inhibited PARs through the PI3K/AKT and PLCγ signaling pathways downstream of MRGPRX2. The present work opens a new avenue for the PARs management.

Liquiritin Attenuates Pathological Cardiac Hypertrophy by Activating the PKA/LKB1/AMPK Pathway

Background: Liquiritin (LQ) is one of the main flavonoids extracted from the roots of Glycyrrhiza spp., which are widely used in traditional Chinese medicine. Studies in both cellular and animal disease models have shown that LQ attenuates or prevents oxidative stress, inflammation, and apoptosis. However, the potential therapeutic effects of LQ on pressure overload-induced cardiac hypertrophy have not been so far explored. Therefore, we investigated the cardioprotective role of LQ and its underlying mechanisms in the aortic banding (AB)-induced cardiac hypertrophy mouse model.

Methods and Results: Starting 3 days after AB surgery, LQ (80 mg/kg/day) was administered daily over 4 weeks. Echocardiography and pressure-volume loop analysis indicated that LQ treatment markedly improved hypertrophy-related cardiac dysfunction. Moreover, hematoxylin and eosin, picrosirius red, and TUNEL staining showed that LQ significantly inhibited cardiomyocyte hypertrophy, interstitial fibrosis, and apoptosis. Western blot assays further showed that LQ activated LKB1/AMPKα2/ACC signaling and inhibited mTORC1 phosphorylation in cardiomyocytes. Notably, LQ treatment failed to prevent cardiac dysfunction, hypertrophy, and fibrosis in AMPKα2 knockout (AMPKα2^−/−) mice. However, LQ still induced LKB1 phosphorylation in AMPKα2^−/− mouse hearts. In vitro experiments further demonstrated that LQ inhibited Ang II-induced hypertrophy in neonatal rat cardiomyocytes (NRCMs) by increasing cAMP levels and PKA activity. Supporting the central involvement of the cAMP/PKA/LKB1/AMPKα2 signaling pathway in the cardioprotective effects of LQ, inhibition of Ang II-induced hypertrophy and induction of LKB1 and AMPKα phosphorylation were no longer observed after inhibiting PKA activity.

Conclusion: This study revealed that LQ alleviates pressure overload-induced cardiac hypertrophy in vivo and inhibits Ang II-induced cardiomyocyte hypertrophy in vitro via activating cAMP/PKA/LKB1/AMPKα2 signaling. These findings suggest that LQ might be a valuable adjunct to therapeutic approaches for treating pathological cardiac remodeling.