18β-glycyrrhetinic acid improves high-intensity exercise performance by promoting glucose-dependent energy production and inhibiting oxidative stress in mice

Enhancing Cardioprotection Through Neutrophil-Mediated Delivery of 18β-Glycyrrhetinic Acid in Myocardial Ischemia/Reperfusion Injury

Myocardial ischemia/reperfusion injury (MI/RI) generates reactive oxygen species (ROS) and initiates inflammatory responses. Traditional therapies targeting specific cytokines or ROS often prove inadequate. An innovative drug delivery system (DDS) is developed using neutrophil decoys (NDs) that encapsulate 18β-glycyrrhetinic acid (GA) within a hydrolyzable oxalate polymer (HOP) and neutrophil membrane vesicles (NMVs). These NDs are responsive to hydrogen peroxide (H2O2), enabling controlled GA release. Additionally, NDs adsorb inflammatory factors, thereby reducing inflammation. They exhibit enhanced adhesion to inflamed endothelial cells (ECs) and improved penetration. Once internalized by cardiomyocytes through clathrin-mediated endocytosis, NDs protect against ROS-induced damage and inhibit HMGB1 translocation. In vivo studies show that NDs preferentially accumulate in injured myocardium, reducing infarct size, mitigating adverse remodeling, and enhancing cardiac function, all while maintaining favorable biosafety profiles. This neutrophil-based system offers a promising targeted therapy for MI/RI by addressing both inflammation and ROS, holding potential for future clinical applications.

18β-glycyrrhetinic acid ameliorates bleomycin-induced idiopathic pulmonary fibrosis via inhibiting TGF-β1/JAK2/STAT3 signaling axis

Idiopathic pulmonary fibrosis (IPF) is a debilitating and progressive lung disease with an unknown cause that has few treatment options. 18β-Glycyrrhetinic acid (18β-GA) is the main bioactive component in licorice, exhibiting anti-inflammatory and antioxidant effects, while also holding certain application value in the metabolism and regulation of steroids. In this study, we demonstrated that 18β-GA effectively alleviates bleomycin (BLM)-induced IPF by inhibiting the TGF-β1/JAK2/STAT3 signaling axis. In vivo experiments demonstrate that 18β-GA significantly attenuates pulmonary fibrosis progression by reducing lung inflammation, improving lung function, and decreasing collagen deposition. In vitro experiments reveal that 18β-GA inhibits the activation and migration of TGF-β1-induced fibroblasts. Furthermore, it regulates the expression of vimentin, N-cadherin and E-cadherin proteins, thereby inhibiting TGF-β1-induced epithelial-mesenchymal transition (EMT) in lung alveolar epithelial cells. Mechanistically, 18β-GA ameliorates pulmonary fibrosis by modulating the TGF-β1/JAK2/STAT3 signaling pathway in activated fibroblasts. Taken together, our findings demonstrate the potential and underlying mechanisms of 18β-GA in ameliorating IPF, emphasizing its potential as a novel therapeutic drug for the treatment of this devastating disease.

One-Step Organic Synthesis of 18β-Glycyrrhetinic Acid-Anthraquinone Ester Products: Exploration of Antibacterial Activity and Structure-Activity Relationship, Toxicity Evaluation in Zebrafish

To combine the activity characteristics of 18β-glycyrrhetinic acid (18β-GA) and anthraquinone compounds (rhein and emodin), reduce toxicity, and explore the structure-activity relationship (SAR) of anthraquinones, 18β-GA-anthraquinone ester compounds were synthesized by one-step organic synthesis. The products were separated and purified by HPLC and characterized by NMR and EI-MS. It was finally determined as di-18β-GA-3-rhein ester (1, New), GA dimer (2, known), 18β-GA-3-emodin ester (3, known), and di-18β-GA-1-emodin ester (4, new). The MIC of three reactants and four products against Escherichia coli and Staphylococcus aureus were detected in vitro. Its developmental toxicity and cardiotoxicity were assessed using zebrafish embryos. The experimental results showed that rhein had the best antibacterial activity against Staphylococcus aureus with MIC50 of 2.4 mM, and it was speculated that -COOH, -OH, and intramolecular hydrogen bonds in anthraquinone compounds would enhance the antibacterial effect, while the presence of-CH3 might weaken the antibacterial activity. Product 1 increased the hatching rate and survival rate of zebrafish embryos and reduced the malformation rate and cardiomyocyte apoptosis. This experiment lays the foundation for further studying the SAR of anthraquinones and providing new drug candidates.

18β-glycyrrhetinic acid alleviates radiation-induced skin injury by activating the Nrf2/HO-1 signaling pathway

Radiation-induced skin injury is a common side effect of radiotherapy, but there are few therapeutic drugs available for prevention or treatment. In this study, we demonstrate that 18β-Glycyrrhetinic acid (18β-GA), a bioactive component derived from Glycyrrhiza glabra, substantially reduces the accumulation of reactive oxygen species (ROS) and inhibits apoptosis in HaCaT cells after ionizing radiation (IR), thereby mitigating radiation-induced skin injury. Mechanistically, 18β-GA promotes the nuclear import of Nrf2, leading to activation of the Nrf2/HO-1 signaling pathway in response to IR. Importantly, Nrf2 silencing increases cell apoptosis and reverse the protective effect of 18β-GA on radiation-induced skin injury. Furthermore, 18β-GA preserves skin tissue structure after irradiation, inhibits inflammatory cell infiltration, and alleviates radiation dermatitis. In conclusion, our results suggest that 18β-GA reduces intracellular ROS production and apoptosis by activating the Nrf2/HO-1 signaling pathway, leading to amelioration of radiation dermatitis.

18β-glycyrrhetinic acid suppresses Lewis lung cancer growth through protecting immune cells from ferroptosis

PURPOSE

18β-glycyrrhetinic acid (GA), the main metabolite of glycyrrhizic acid extracted from the root of licorice, has been reported to possess anti-cancer and immunomodulatory activity, but the mechanisms are not well understood. Recent studies have shown that ferroptosis of immune cells is involved in tumor-associated immune suppression. The purpose of this study was to investigate whether the enhanced immune response via inhibiting immune cell ferroptosis contributed to the anticancer effect of 18β-GA.

METHODS

Lewis Lung carcinoma mouse model and Murine CD8 + T cell culture model were used to examine the changes of immune response and ferroptosis of immune cells.

RESULTS

We found that 18β-GA was effective against lung cancer accompanied by enhanced activation of tumor-infiltrating CD8+ T cells in Lewis Lung carcinoma mouse model. Furthermore, we demonstrated that the boosted immune response by GA was attributed to its ability to inhibit arachidonic acid (AA)-mediated CD8+ T ferroptosis via suppressing CD36 expression.

CONCLUSION

The findings of the present study unraveled a novel mechanism underlying the anti-cancer and immunomodulatory activity of 18β-GA and support that 18β-GA holds potential to be used as an immune enhancer for lung cancer prevention or treatment.

18β-Glycyrrhetinic Acid Ameliorates Neuroinflammation Linked Depressive Behavior Instigated by Chronic Unpredictable Mild Stress via Triggering BDNF/TrkB Signaling Pathway in Rats

Evidence shows that inflammatory responses may encompass the onset of severe depressive illness. Traditionally used licorice contains 18β-glycyrrhetinic acid (18βGA), which has been demonstrated to reduce inflammation and oxidative stress. This study investigates the antidepressant effects of 18βGA and the underlying mechanism in rats exposed to chronic unpredictable mild stress (CUMS). Wistar rats were exposed to CUMS for 36 consecutive days to establish depression. 18βGA (10, 20, and 50 mg/kg) or fluoxetine was given once daily (from day 30 to day 36). Thereafter, behavior parameters (sucrose preference test, forced-swimming test, open-field test, body weight), pro-inflammatory cytokines, neurotransmitters, adrenocorticotropic hormone (ACTH), corticosterone (CORT), and liver biomarkers were studied. Immunohistochemistry and western blot analyses were conducted to investigate the protein's expression. 18βGA (20 and 50 mg/kg) treatment increased sucrose intake, locomotion in the open-field test, decreased immobility time in the forced swim test, and improved body weight in CUMS-exposed rats. The therapy of 18βGA dramatically declined cytokines, ACTH and CORT and improved 5HT and norepinephrine in CUMS rats. Furthermore, BDNF and TrkB proteins were down-regulated in CUMS group, which was increased to varying degrees by 18βGA at doses of 20 and 50 mg/kg. Therefore, 18βGA ameliorates depressive-like behavior persuaded by chronic unpredictable mild stress, decreases neuroinflammation, liver biomarkers, stress hormones, and improves body weight, brain neurotransmitter concentration via activating on BDNF/TrkB signaling pathway in both PFC and hippocampus in rats.

Trilobatin, a Naturally Occurring Food Additive, Ameliorates Exhaustive Exercise-Induced Fatigue in Mice: Involvement of Nrf2/ARE/Ferroptosis Signaling Pathway

Nrf2-mediated oxidative stress is a promising target of exhaustive exercise-induced fatigue (EEIF). Trilobatin (TLB) is a naturally occurring food additive with antioxidant effect and Nrf2 activation potency. The present study aimed to investigate the effect of TLB on EEIF and elucidate its underlying mechanism. Our results showed that TLB exerted potent anti-EEIF effect, as reflected by the rope climbing test and exhaustive swimming test. Moreover, TLB also effectively reduced the levels of lactate, creatine kinase, and blood urea nitrogen, and increased liver glycogen and skeletal muscle glycogen in mice after EEIF insult. Additionally, TLB also balanced the redox status as evidenced by decreasing the generation of reactive oxygen species and improving the antioxidant enzyme activities including superoxide dismutase, catalase, and glutathione peroxidase, as well as the level of glutathione both in the tissue of muscle and myocardium. Furthermore, TLB promoted nuclear factor erythroid 2-related factor 2 (Nrf2) from the cytoplasm to the nucleus, and upregulated its downstream antioxidant response element (ARE) including quinone oxidoreductase-1 and heme oxygenase-1. Intriguingly, TLB also upregulated the GPx4 protein expression and reduced iron overload in mice after EEIF insult. Encouragingly, the beneficial effect of TLB on EEIF-induced oxidative stress and ferroptosis were substantially abolished in Nrf2-deficient mice. In conclusion, our findings demonstrate, for the first time, that TLB alleviates EEIF-induced oxidative stress through mediating Nrf2/ARE/ferroptosis axis.

A Comparative Study on Relieving Exercise-Induced Fatigue by Inhalation of Different Citrus Essential Oils

Citrus essential oils (CEOs) possess physiological functions due to diverse aroma components. However, evidence for the effects of CEOs on exercise performance and exercise-induced fatigue is limited. The CEOs with discrepancies in components may exert different effects on the amelioration of exercise-induced fatigue. In this study, sweet orange (Citrus sinensis L.) essential oil (SEO), lemon (Citrus limon Osbeck) essential oil (LEO), and bergamot (Citrus bergamia Risso and Poit) essential oil (BEO) were chosen to explore the effect on amelioration of exercise-induced fatigue. Our results demonstrated that SEO and LEO increased the swimming time by 276% and 46.5%, while BEO did not. Moreover, the three CEOs exerted varying effects on mitigating exercise-induced fatigue via inhibiting oxidative stress, protecting muscle injury, and promoting glucose-dependent energy supply. Accordingly, BEO showed the best efficiency. Moreover, the GC-MS and Pearson correlation analysis of BEO showed that the contents of the major components, such as (±)-limonene (32.9%), linalyl butyrate (17.8%), and linalool (7.7%), were significantly positively correlated with relieving exercise-induced fatigue.