Protective Effect of 18β-Glycyrrhetinic Acid against Triptolide-Induced Hepatotoxicity in Rats

Subchronic toxicity evaluation of Huobahuagen extract and plasma metabolic profiling analysis combined with conventional pathology methods

Huobahua, namely, Tripterygium hypoglaucum (Levl.) Hutch, known as a traditional Chinese herbal medicine, especially its underground parts, has been widely developed into several Tripterygium agents for the treatment of rheumatoid arthritis and other autoimmune diseases. It has sparked wide public concern about its safety, such as multi-organ toxicity. However, the toxic characteristics and damage mechanism of Huobahuagen extract (HBHGE) remain unclear. In the present study, subchronic oral toxicity study of HBHGE (10.0 g crude drug/kg/day for 12 weeks) was performed in male rats. Hematological, serum biochemical, and histopathological parameters, urinalysis, and plasma metabolic profiling were assessed. The single-dose subchronic toxicity results related to HBHGE exhibited obvious toxicity to the testis and epididymis of male rats. Furthermore, plasma metabolomics analysis suggested that a series of metabolic disorders were induced by oral administration of HBHGE, mainly focusing on amino acid (glutamate, phenylalanine, and tryptophan) metabolisms, pyrimidine metabolism, glutathione metabolism, and steroid hormone biosynthesis. Moreover, it appeared that serum testosterone in male rats treated with HBHGE for 12 weeks, decreased significantly, and was susceptible to the toxic effects of HBHGE. Taken together, conventional pathology and plasma metabolomics for preliminarily exploring subchronic toxicity and underlying mechanism can provide useful information about the reduction of toxic risks from HBHGE and new insights into the development of detoxification preparations.

Glycyrrhetinic acid ameliorates diosbulbin B-induced hepatotoxicity in mice by modulating metabolic activation of diosbulbin B

Exposure to diosbulbin B (DBB), the primary component of the herbal medicine Dioscorea bulbifera L. (DB), can cause liver injury in humans and experimental animals. A previous study found DBB-induced hepatotoxicity was initiated by CYP3A4-mediated metabolic activation and subsequent formation of adducts with cellular proteins. The herbal medicine licorice (Glycyrrhiza glabra L.) is frequently combined with DB used in numerous Chinese medicinal formulas in an effort to protect against DB-elicited hepatotoxicity. Importantly, glycyrrhetinic acid (GA), the major bioactive ingredient in licorice, inhibits CYP3A4 activity. The study aimed to investigate the protection of GA against DBB-induced hepatotoxicity and the underlying mechanism. Biochemical and histopathological analysis showed GA alleviated DBB-induced liver injury in a dose-dependent manner. In vitro metabolism assay with mouse liver microsomes (MLMs) indicated that GA decreased the generation of metabolic activation-derived pyrrole-glutathione (GSH) conjugates from DBB. Toxicokinetic studies demonstrated that GA increased maximal serum concentration (Cmax ) and area under the serum-time curve (AUC) of DBB in mice. In addition, GA attenuated hepatic GSH depletion caused by DBB. Further mechanistic studies showed that GA reduced the production of DBB-derived pyrroline-protein adducts in a dose-dependent manner. In conclusion, our findings demonstrated that GA exerted protective effect against DBB-induced hepatotoxicity, mainly correlated with suppressing the metabolic activation of DBB. Therefore, the development of a standardized combination of DBB with GA may protect patients from DBB-induced hepatotoxicity.

18-α-glycyrrhetinic acid alleviates oxidative damage in periodontal tissue by modulating the interaction of Cx43 and JNK/NF-κB pathways

Objective: Periodontitis is a common chronic inflammatory disease in which oxidative stress is one of the key pathogenic factors. Connexin43 (Cx43) is the most critical and widely distributed connexin isoform. When the organism undergoes a severe and sustained stress response, Cx43-mediated gap junctions (GJs) are believed to underlie the biology of tissue injury exacerbation and amplification. Notably, 18-α-glycyrrhetinic acid (GA) is a classical pharmacological inhibitor of GJs and has antioxidant potential. However, the regulatory role of GA in the redox signaling of periodontal tissues and the potential mechanisms of Cx43 in the pathogenesis of periodontitis remain uncertain. Methods: In this study, we evaluated the effects and mechanisms of GA in alleviating oxidative damage of periodontal tissues and cells by constructing an H2O2-induced oxidative stress model in human periodontal ligament cells (hPDLCs) and a periodontitis model in rats. Results: Cellular experiments showed that GA effectively attenuated H2O2-induced oxidative damage in hPDLCs by inhibiting the expression and function of Cx43. In addition, pretreatment of hPDLCs with either GA or SP600125 (a JNK inhibitor) inhibited the Cx43/JNK/NF-κB pathway, restored cell viability, and reduced apoptosis. Animal experiment results showed that GA intervention reduced alveolar bone resorption and periodontal tissue destruction, inhibited osteoclast differentiation, improved mitochondrial structural abnormalities and dysfunction in periodontal tissue, and decreased oxidative stress levels and apoptosis in rats with periodontitis. Conclusion: Overall, our findings suggest that the Cx43/JNK/NF-κB pathway may play a vital role to promote periodontitis progression, while GA reduces oxidative stress and apoptosis by inhibiting the interaction of Cx43 and JNK/NF-κB pathways, thus alleviating oxidative damage in the periodontal tissues.

Pharmacological Features of 18β-Glycyrrhetinic Acid: A Pentacyclic Triterpenoid of Therapeutic Potential

Glycyrrhiza glabra L. (belonging to the family Leguminosae), commonly known as Licorice, is a popular medicinal plant that has been used in traditional medicine worldwide for its ethnopharmacological efficacy in treating several ailments. Natural herbal substances with strong biological activity have recently received much attention. The main metabolite of glycyrrhizic acid is 18β-glycyrrhetinic acid (18βGA), a pentacyclic triterpene. A major active plant component derived from licorice root, 18βGA has sparked a lot of attention due to its pharmacological properties. The current review thoroughly examines the literature on 18βGA, a major active plant component obtained from Glycyrrhiza glabra L. The current work provides insight into the pharmacological activities of 18βGA and the potential mechanisms of action involved. The plant contains a variety of phytoconstituents such as 18βGA, which has a variety of biological effects including antiasthmatic, hepatoprotective, anticancer, nephroprotective, antidiabetic, antileishmanial, antiviral, antibacterial, antipsoriasis, antiosteoporosis, antiepileptic, antiarrhythmic, and anti-inflammatory, and is also useful in the management of pulmonary arterial hypertension, antipsychotic-induced hyperprolactinemia, and cerebral ischemia. This review examines research on the pharmacological characteristics of 18βGA throughout recent decades to demonstrate its therapeutic potential and any gaps that may exist, presenting possibilities for future drug research and development.

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.

The Effect of Triptolide Combined With Crocin on Arthritis in Mice: From Side Effect Attenuation to Therapy

Clinical use of triptolide (TP) is restricted due to severe toxicity. This study assessed the protective effect of crocin (CR) as a natural antioxidant against TP-induced toxicity in bovine collagen type II-induced arthritis (CIA) in mice. The mice in the CIA model group showed macroscopic signs of severe arthritis. The anti-arthritis effects in the control, TP + CR, and TP groups were evaluated through assessment of foot volume, arthritis score, and proinflammatory cytokines, and collagen antibody assay. Crocin reduced TP-induced toxicity, as evidenced by evaluation of survival rate, body weight, visceral index, hepatic and renal functions, histopathologic analyses, and antioxidant enzyme activities. Transcriptome sequencing resulted in identification of 76 differentially expressed genes (DEGs) associated with hepatotoxicity between the TP and TP + CR groups. Of these, Three DEGs (Cyp1a2,Gsta4, and Gstp1) were validated using quantitative real-time PCR analysis. In conclusion, CR protected CIA mice from TP-induced toxicity through modulation of the cytochrome P450 and glutathione metabolism pathways.

Ginsenoside Rb1 Attenuates Triptolide-Induced Cytotoxicity in HL-7702 Cells via the Activation of Keap1/Nrf2/ARE Pathway

Triptolide (TP) is the major bioactive compound extracted from Tripterygium wilfordii Hook F. It exerts anti-inflammatory, antirheumatic, antineoplastic, and neuroprotective effects. However, the severe hepatotoxicity induced by TP limits its clinical application. Ginsenoside Rb1 has been reported to possess potential hepatoprotective effects, but its mechanism has not been fully investigated. This study was aimed at investigating the effect of ginsenoside Rb1 against TP-induced cytotoxicity in HL-7702 cells, as well as the underlying mechanism. The results revealed that ginsenoside Rb1 effectively reversed TP-induced cytotoxicity in HL-7702 cells. Apoptosis induced by TP was suppressed by ginsenoside Rb1 via inhibition of death receptor-mediated apoptotic pathway and mitochondrial-dependent apoptotic pathway. Pretreatment with ginsenoside Rb1 significantly reduced Bax/Bcl-2 ratio and down-regulated the expression of Fas, cleaved poly ADP-ribose polymerase (PARP), cleaved caspase-3, and -9. Furthermore, ginsenoside Rb1 reversed TP-induced cell cycle arrest in HL-7702 cells at S and G2/M phase, via upregulation of the expressions of cyclin-dependent kinase 2 (CDK2), cyclin E, cyclin A, and downregulation of the expressions of p53, p21, and p-p53. Ginsenoside Rb1 increased glutathione (GSH) and superoxide dismutase (SOD) levels, but decreased the reactive oxygen species (ROS) and malondialdehyde (MDA) levels. Pretreatment with ginsenoside Rb1 enhanced the expression levels of nuclear factor-erythroid 2-related factor 2 (Nrf2), total Nrf2, NAD(P)H: quinone oxidoreductases-1 (NQO-1), heme oxygenase-1 (HO-1), and Kelch-like ECH-associated protein 1 (Keap1)/Nrf2 complex. Therefore, ginsenoside Rb1 effectively alleviates TP-induced cytotoxicity in HL-7702 cells through activation of the Keap1/Nrf2/ARE antioxidant pathway.

Tripterygium hypoglaucum (Lévl.) Hutch and Its Main Bioactive Components: Recent Advances in Pharmacological Activity, Pharmacokinetics and Potential Toxicity

Tripterygium hypoglaucum (Lévl.) Hutch (THH) is believed to play an important role in health care and disease treatment according to traditional Chinese medicine. Moreover, it is also the representative of medicine with both significant efficacy and potential toxicity. This characteristic causes THH hard for embracing and fearing. In order to verify its prospect for clinic, a wide variety of studies were carried out in the most recent years. However, there has not been any review about THH yet. Therefore, this review summarized its characteristic of components, pharmacological effect, pharmacokinetics and toxicity to comprehensively shed light on the potential clinical application. More than 120 secondary metabolites including terpenoids, alkaloids, glycosides, sugars, organic acids, oleanolic acid, polysaccharides and other components were found in THH based on phytochemical research. All these components might be the pharmacological bases for immunosuppression, anti-inflammatory and anti-tumour effect. In addition, recent studies found that THH and its bioactive compounds also demonstrated remarkable effect on obesity, insulin resistance, fertility and infection of virus. The main mechanism seemed to be closely related to regulation the balance of immune, inflammation, apoptosis and so on in various disease. Furthermore, the study of pharmacokinetics revealed quick elimination of the main component triptolide. The feature of celastrol was also investigated by several models. Finally, the side effect of THH was thought to be the key for its limitation in clinical application. A series of reports indicated that multiple organs or systems including liver, kidney and genital system were involved in the toxicity. Its potential serious problem in liver was paid specific attention in recent years. In summary, considering the significant effect and potential toxicity of THH as well as its components, the combined medication to inhibit the toxicity, maintain effect might be a promising method for clinical conversion. Modern advanced technology such as structure optimization might be another way to reach the efficacy and safety. Thus, THH is still a crucial plant which remains for further investigation.

Anti-inflammatory and Pro-apoptotic Effects of 18beta-Glycyrrhetinic Acid In Vitro and In Vivo Models of Rheumatoid Arthritis

18β-Glycyrrhetinic acid (18β-GA), an active component from Glycyrrhiza glabra L. root (licorice), has been demonstrated to be able to protect against inflammatory response and reduce methotrexate (MTX)-derived toxicity. This study was therefore designed to test the therapeutic possibility of 18β-GA on rheumatoid arthritis (RA) and to explore the underlying mechanism. LPS or TNF-α-induced inflammatory cell models and collagen-induced arthritis (CIA) animal models were applied in this study. Real-time quantitative PCR (RT-qPCR) was used to measure the mRNA levels of various cytokines and FOXO family members. The protein levels of molecules in the MAPK/NF-κB signaling pathway were analyzed using western blot. The cell proliferation assay and colony-forming assay were used to test the influence of 18β-GA on cell viability. The cell apoptosis assay and cell cycle assay were performed to detect the effect of 18β-GA on cell proliferative capacity by using flow cytometry. Hematoxylin and eosin (H&E) staining was performed to evaluate pathological changes after drug administration. The enzyme-linked immunosorbent assay (ELISA) was carried out for the detection of cytokines in serum. In vitro, we found that 18β-GA decreased the mRNA levels of IL-1β, IL-6, and COX-2 by inhibiting the MAPK/NF-κB signaling pathway in MH7A and RAW264.7 cell lines. Moreover, 18β-GA was able to suppress cell viability, trigger cell apoptosis, and G1 phase cell cycle arrest in our in vitro studies. 18β-GA dramatically enhanced the mRNA level of FOXO3 in both TNF-α- and LPS-induced inflammation models in vitro. Interestingly, after analyzing GEO datasets, we found that the FOXO3 gene was significantly decreased in the RA synovial tissue as compared to healthy donors in multiple microarray studies. In vivo, 18β-GA exhibited a promising therapeutic effect in a collagen-induced arthritis mouse model by alleviating joint pathological changes and declining serum levels of TNF-α, IL-1β, and IL-6. Finally, we observed that 18β-GA administration could mitigate liver damage caused by collagen or MTX. Collectively, the current study demonstrates for the first time that 18β-GA can inhibit inflammation and proliferation of synovial cells, and the underlying mechanism may be associated with its inhibition of MAPK/NF-κB signaling and promotion of FOXO3 signaling. Therefore, 18β-GA is expected to be a new drug candidate for RA therapy.

Administration of glycyrrhetinic acid reinforces therapeutic effects of mesenchymal stem cell-derived exosome against acute liver ischemia-reperfusion injury

Recent studies have shown that mesenchymal stem cell‐derived exosome could attenuate ischaemia‐reperfusion (I/R) injury by suppressing inflammatory response in the liver. Glycyrrhetinic acid was also shown to be capable of repressing the TLR4 signalling pathway. However, it remains to be explored as whether the combined administration of mesenchyma stem cell (MSC)‐derived exosome and glycyrrhetinic acid (GA) could increase their therapeutic effects on I/R injury. Western blot was performed to evaluate the expression of proteins associated with inflammatory response in THP‐1 cells and I/R rat models treated under different conditions. Flow cytometry was carried out to analyse the proportions of different subtypes of peripheral blood cells in I/R rats. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured to assess the liver injury in I/R rats. Combined treatment with MSC‐derived exosome and GA effectively maintained the expression of key proteins involved in inflammatory response in LPS stimulated THP‐1 cells and THP‐1 cells treated under hypoxia conditions. In the established of I/R rat models, GA administration reinforced the therapeutic efficiency of MSC‐derived exosomes by maintaining the proportion of different subgroups of peripheral blood cells, decreasing the concentration of ALT and AST, and restoring the expression of dysregulated proteins associated with inflammation. Our results demonstrated that treatment with exosomes derived from mesenchymal stem cells (MSCs) attenuated liver I/R injury, while the pre‐treatment with GA may further promote the therapeutic effect of mesenchymal stem cell‐derived exosome against acute liver ischaemia‐reperfusion injury.

18 beta-glycyrrhetinic acid ameliorates the cognitive functions and decreases the recurrence rate of pituitary adenomas patients

Pituitary adenomas, the most common tumors of all intracranial neoplasms, may cause either symptoms of mass effect or symptoms of hormone abnormal production. Besides physical damages, patients with pituitary adenomas always suffer from cognitive impairments, mainly in memory and executive functions. 18 beta-glycyrrhetinic acid (GA) has been found to exhibit anti-tumor effects in rat pituitary adenoma-derived cells. The aim of this paper was to investigate the effect of GA in postoperative clinical application. In this study, we recruited 647 patients with pituitary adenoma and 135 patients who dropped out were excluded from analysis. Thus, altogether 512 patients with pituitary adenoma completed the study, of whom 268 were treated with GA, and 244 were treated with placebo. Cognitive assessments, eyesight, tumor size, and hormone secretion levels were examined before and after surgery in both groups. All patients underwent surgeries by single-nostril transsphenoidal approach for their first-time medical treatment. Hormone secretion levels were measured by blood samples and Magnetic resonance imaging (MRI) was used for examining the status of tumor excision. Compared with placebo group, the scores in orientation, language (expression), memory (recall), practice, abstract thinking, and MiniMental State Examination (MMSE) were significantly improved (p < 0.05) in GA treated group after one month of surgery. After six months, there was still a significant increase in abstract thinking scores. Moreover, GA did not impact the overall survival percentage of patients enrolled during our five-year follow-up, but significantly reduced the recurrence rate than that of the placebo group. GA significantly improved the cognitive functions at the early stage after surgery and had a long-termed efficacy on abstract thinking. Notably, GA inhibited the five-year recurrence rate of the recruited pituitary adenomas patients.

Protective effects of silymarin on triptolide-induced acute hepatotoxicity in rats

Silymarin has been used in the treatment of a number of liver diseases for a long time, but its efficacy in preventing triptolide induced acute hepatotoxicity has not been reported previously. The present study aimed to assess the protective effect of silymarin against triptolide (TP)-induced hepatotoxicity in rats. Rats were orally administrated with silymarin (50, 100 and 200 mg/kg) for 7 days and received intraperitoneal TP (2 mg/kg) on the day 8. Hepatic injuries were comprehensively evaluated in terms of serum parameters, morphological changes, oxidative damage, inflammation and apoptosis. The results demonstrated that TP-induced increases in serum parameters, including alanine transaminase, aspartate aminotransferase, alkaline phosphatase, total cholesterol and γ-glutamyl transpeptidase, which were determined using a biochemical analyzer, and histopathological alterations and hepatocyte apoptosis as determined by hematoxylin and eosin and TUNEL staining, respectively, were prevented by silymarin pretreatment in a dose-dependent manner. TP-induced depletions in the activity of the antioxidant enzymes superoxide dismutase, glutathione peroxidase, glutathione S-transferase and catalase, and glutathione levels, were also significantly reversed by silymarin, as determined using specific kits. Additionally, silymarin dose-dependently exhibited inhibitory effects on malonaldehyde content in the liver. The production of proinflammatory cytokines was investigated using ELISA kits, and the results demonstrated that silymarin dose-dependently inhibited the production of tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-10 and IL-1β in the liver. To determine the mechanism of silymarin, western blot analysis was performed to investigate the protein expression of phosphorylated (p)-p38 and p-c-Jun N-terminal kinase (JNK) of the TNF-α induced inflammatory response and apoptotic pathways. Silymarin significantly blocked p38 and JNK phosphorylation and activation. Additionally, the expression of the proapoptotic proteins cytochrome c, cleaved caspase-3 and Bcl-2-associated X was also reduced following treatment with silymarin, as determined by ELISA, western blotting and immunohistochemistry, respectively. In conclusion, silymarin was demonstrated to dose-dependently protect rat liver from TP-induced acute hepatotoxicity, with the high dose (200 mg/kg) achieving a superior effect. This protective effect may be associated with the improvement of antioxidant and anti-inflammatory status, as well as the prevention of hepatocyte apoptosis. Therefore, silymarin may have the potential to be applied clinically to prevent TP-induced acute hepatotoxicity.