ß-keto amyrin isolated from Cryptostegia grandiflora R. br. inhibits inflammation caused by Daboia russellii viper venom: Direct binding of ß-keto amyrin to phospholipase A2.

The search for mechanism-based anti-inflammatory therapies is of fundamental importance to avoid undesired off-target effects. Phospholipase A2 (PLA2) activity is a potential molecular target for anti-inflammatory drugs because it fuels arachidonic acid needed to synthesize inflammation mediators, such as prostaglandins. Herein, we aim to investigate the molecular mechanism by which ß-keto amyrin isolated from a methanolic extract of Cryptostegia grandiflora R. Br. Leaves can inhibit inflammation caused by Daboia russellii viper (DR) venom that mainly contains PLA2. We found that ß-keto amyrin neutralizes DR venom-induced paw-edema in a mouse model. Molecular docking of PLA2 with ß-keto amyrin complex resulted in a higher binding energy score of -8.86 kcal/mol and an inhibition constant of 611.7 nM. Diclofenac had a binding energy of -7.04 kcal/mol and an IC50 value of 620 nM, which predicts a poorer binding interaction than ß-keto amyrin. The higher conformational stability of ß-keto amyrin interaction compared to diclofenac is confirmed by molecular dynamics simulation. ß-keto amyrin isolated from C. grandiflora inhibits the PLA2 activity contained in Daboia russellii viper venom. The anti-inflammatory property of ß-keto amyrin is due to its direct binding into the active site of PLA2, thus inhibiting its enzyme activity.

Phytochemical profiling, antioxidant, cytotoxic, and anti-inflammatory activities of Plectranthus rugosus extract and fractions: in vitro, in vivo, and in silico approaches.

BACKGROUND: Inflammation is a key biological reaction that comprises a complex network of signals that both initiate and stop the inflammation process. PURPOSE: This study targets to evaluate the anti-inflammatory potential of the leaves of the Plectranthus rugosus (P. rugosus) plant involving both in vitro and in vivo measures. The current available drugs exhibit serious side effects. Traditional medicines impart an essential role in drug development. P. rugosus is a plant used in traditional medicine of Tropical Africa, China, and Australia to treat various diseases. METHODS: Lipopolysaccharide (LPS), an endotoxin, kindles macrophages to discharge huge quantities of pro-inflammatory cytokines like TNF-α and IL-6. So, clampdown of macrophage stimulation may have a beneficial potential to treat various inflammatory disorders. The leaves of the P. rugosus are used for swelling purpose by local population; however, its use as an anti-inflammatory agent and associated disorders has no scientific evidence. RESULTS: The extracts of the plant Plectranthus rugosus ethanolic extract (PREE), Plectranthus rugosus ethyl acetate extract (PREAF), and the compound isolated (oleanolic acid) suppress the pro-inflammatory cytokines (IL-6 and TNF-α) and nitric oxide (NO), confirming its importance in traditional medicine. CONCLUSION: The pro-inflammatory cytokines are inhibited by P. rugosus extracts, as well as an isolated compound oleanolic acid without compromising cell viability.

The Effect and Mechanism of Oleanolic Acid in the Treatment of Metabolic Syndrome and Related Cardiovascular Diseases.

Metabolic syndromes (MetS) and related cardiovascular diseases (CVDs) pose a serious threat to human health. MetS are metabolic disorders characterized by obesity, dyslipidemia, and hypertension, which increase the risk of CVDs' initiation and development. Although there are many availabile drugs for treating MetS and related CVDs, some side effects also occur. Considering the low-level side effects, many natural products have been tried to treat MetS and CVDs. A five-cyclic triterpenoid natural product, oleanolic acid (OA), has been reported to have many pharmacologic actions such as anti-hypertension, anti-hyperlipidemia, and liver protection. OA has specific advantages in the treatment of MetS and CVDs. OA achieves therapeutic effects through a variety of pathways, attracting great interest and playing a vital role in the treatment of MetS and CVDs. Consequently, in this article, we aim to review the pharmacological actions and potential mechanisms of OA in treating MetS and related CVDs.

The therapeutic effects of saikosaponins on depression through the modulation of neuroplasticity: From molecular mechanisms to potential clinical applications.

Depression is a major global health issue that urgently requires innovative and precise treatment options. In this context, saikosaponin has emerged as a promising candidate, offering a variety of therapeutic benefits that may be effective in combating depression. This review delves into the multifaceted potential of saikosaponins in alleviating depressive symptoms. We summarized the effects of saikosaponins on structural and functional neuroplasticity, elaborated the regulatory mechanism of saikosaponins in modulating key factors that affect neuroplasticity, such as inflammation, the hypothalamic-pituitary-adrenal (HPA) axis, oxidative stress, and the brain-gut axis. Moreover, this paper highlights existing gaps in current researches and outlines directions for future studies. A detailed plan is provided for the future clinical application of saikosaponins, advocating for more targeted researches to speed up its transition from preclinical trials to clinical practice.

Oleanolic acid alleviates obesity-induced skeletal muscle atrophy via the PI3K/Akt signaling pathway.

Oleanolic acid (OA) is a pentacyclic triterpene with reported protective effects against various diseases, including diabetes, hepatitis, and different cancers. However, the effects of OA on obesity-induced muscle atrophy remain largely unknown. This study investigated the effects of OA on skeletal muscle production and proliferation of C2C12 cells. We report that OA significantly increased skeletal muscle mass and improved glucose intolerance and insulin resistance. OA inhibited dexamethasone (Dex)-induced muscle atrophy in C2C12 myoblasts by regulating the PI3K/Akt signaling pathway. In addition, it also inhibited expression of MuRF1 and Atrogin1 genes in skeletal muscle of obese mice suffering from muscle atrophy, and increased the activation of PI3K and Akt, thereby promoting protein synthesis, and eventually alleviating muscle atrophy. Taken together, these findings suggest OA may have potential for the prevention and treatment of muscle atrophy.

Integrating network pharmacology and animal experimental validation to investigate the action mechanism of oleanolic acid in obesity.

BACKGROUND: Obesity, a condition associated with the development of widespread cardiovascular disease, metabolic disorders, and other health complications, has emerged as a significant global health issue. Oleanolic acid (OA), a pentacyclic triterpenoid compound that is widely distributed in various natural plants, has demonstrated potential anti-inflammatory and anti-atherosclerotic properties. However, the mechanism by which OA fights obesity has not been well studied. METHOD: Network pharmacology was utilized to search for potential targets and pathways of OA against obesity. Molecular docking and molecular dynamics simulations were utilized to validate the interaction of OA with core targets, and an animal model of obesity induced by high-fat eating was then employed to confirm the most central of these targets. RESULTS: The network pharmacology study thoroughly examined 42 important OA targets for the treatment of obesity. The key biological processes (BP), cellular components (CC), and molecular functions (MF) of OA for anti-obesity were identified using GO enrichment analysis, including intracellular receptor signaling, intracellular steroid hormone receptor signaling, chromatin, nucleoplasm, receptor complex, endoplasmic reticulum membrane, and RNA polymerase II transcription Factor Activity. The KEGG/DAVID database enrichment study found that metabolic pathways, PPAR signaling pathways, cancer pathways/PPAR signaling pathways, insulin resistance, and ovarian steroidogenesis all play essential roles in the treatment of obesity and OA. The protein-protein interaction (PPI) network was used to screen nine main targets: PPARG, PPARA, MAPK3, NR3C1, PTGS2, CYP19A1, CNR1, HSD11B1, and AGTR1. Using molecular docking technology, the possible binding mechanism and degree of binding between OA and each important target were validated, demonstrating that OA has a good binding potential with each target. The molecular dynamics simulation's Root Mean Square Deviation (RMSD), and Radius of Gyration (Rg) further demonstrated that OA has strong binding stability with each target. Additional animal studies confirmed the significance of the core target PPARG and the core pathway PPAR signaling pathway in OA anti-obesity. CONCLUSION: Overall, our study utilized a multifaceted approach to investigate the value and mechanisms of OA in treating obesity, thereby providing a novel foundation for the identification and development of natural drug treatments.

A Synergistic Combination of Oleanolic Acid and Apatinib to Enhance Antitumor Effect on Liver Cancer Cells and Protect against Hepatic Injury.

BACKGROUND: As a pentacyclic triterpenoid, OA (oleanolic acid) has exhibited antiinflammatory, immunomodulatory and antitumor effects. VEGFR-2 (vascular endothelial cells receptor-2) tyrosine kinase activity could be inhibited by apatinib, a small-molecule antiangiogenic agent. OBJECTIVE: Thus, this study sought to investigate the mechanism underlying the synergistic antitumor activity of combined OA and apatinib patent. METHODS: Through CCK8 (Cell counting kit 8 assay), flow cytometric and western blotting techniques, we conducted in vitro studies on apatinib and OA effects on cell proliferation and apoptosis in H22 cell line. H22 tumor-burdened mice model was established in vivo, while the related signaling pathways were studied via pathological examination, western blotting and qPCR (quantitative polymerase chain reaction). RESULTS: Growth of H22 cells in vitro and in vivo could be inhibited effectively by apatinib and OA. Thus, OA repaired liver function and inhibited oxidative stress induced by apatinib. CONCLUSION: OA can treat apatinib induced liver injury in H22 Tumor-burdened mice by enhancing the suppresssive effect of apatinib on the growth of tumor.

Molecular mechanism of α-Hederin in tumor progression.

α-Hederin is a monosaccharide pentacyclic triterpene saponin compound derived from the Chinese herb, Pulsatilla. It has garnered considerable attention for its anti-tumor, anti-inflammatory, and spasmolytic pharmacological activities. Given the rising incidence of cancer and the pronounced adverse reactions associated with chemotherapy drugs-which profoundly impact the quality of life for cancer patients-there is an immediate need for safe and effective antitumor agents. Traditional drugs and their anticancer effects have become a focal point of research in recent years. Studies indicate that α-Hederin can hinder tumor cell proliferation and impede the advancement of various cancers, including breast, lung, colorectal, and liver cancers. The principal mechanism behind its anti-tumor activity involves inhibiting tumor cell proliferation, facilitating tumor cell apoptosis, and arresting the cell cycle process. Current evidence suggests that α-Hederin can exert its anti-tumor properties through diverse mechanisms, positioning it as a promising agent in anti-tumor therapy. However, a comprehensive literature search revealed a gap in the comprehensive understanding of α-Hederin. This paper aims to review the available literature on the anti-tumor mechanisms of α-Hederin, hoping to provide valuable insights for the clinical treatment of malignant tumors and the innovation of novel anti-tumor medications.

Oleanolic acid derivative alleviates cardiac fibrosis through inhibiting PTP1B activity and regulating AMPK/TGF-ß/Smads pathway.

Cardiac fibrosis (CF) in response to persistent exogenous stimuli or myocardial injury results in cardiovascular diseases (CVDs). Protein tyrosine phosphatase 1B (PTP1B) can promote collagen deposition through regulating AMPK/TGF-ß/Smads signaling pathway, and PTP1B knockout improves cardiac dysfunction against overload-induced heart failure. Oleanolic acid (OA) has been proven to be an inhibitor of PTP1B, and its anti-cardiac remodeling effects have been validated in different mouse models. To improve the bioactivity of OA and to clarify whether OA derivatives with stronger inhibition of PTP1B activity have greater prevention of cardiac remodeling than OA, four new OA derivatives were synthesized and among them, we found that compound B had better effects than OA in inhibiting cardiac fibrosis both in vivo in the isoproterenol (ISO)-induced mouse cardiac fibrosis and in vitro in the TGF-ß/ISO-induced 3T3 cells. Combining with the results of molecular docking, surface plasmon resonance and PTP1B activity assay, we reported that OA and compound B directly bound to PTP1B and inhibited its activity, and that compound B showed comparable binding capability but stronger inhibitory effect on PTP1B activity than OA. Moreover, compound B presented much greater effects on AMPK activation and TGF-ß/Smads inhibition than OA. Taken together, OA derivative compound B more significantly alleviated cardiac fibrosis than OA through much greater inhibition of PTP1B activity and thus much stronger regulation of AMPK/TGF-ß/Smads signaling pathway.

Integrative transcriptome and single-cell sequencing technology analysis of the potential therapeutic benefits of oleanolic acid in liver injury and liver cancer.

BACKGROUND: Oleanolic acid has important hepatoprotective effects and inhibits liver tissue carcinogenesis. The aim of this study was to investigate the mechanism of action of oleanolic acid in inhibiting liver injury and liver cancer. METHOD: In this study, we applied differential gene analysis and gene enrichment analysis to identify the targets of oleanolic acid for the treatment of liver injury. And this study also applied Cibersort and GSVA methods to investigate the targets of oleanolic acid in liver injury. Based on oleanolic acid targets, we explored the major targets and further explored the role of the major targets in liver cancer. This study used the oncoPredict and the TIDE algorithm to predict the effect of oleanolic acid on drug resistance. Finally, the binding effect of oleanolic acid to relevant targets was explored using molecular docking techniques. RESULT: In this study, oleanolic acid was found to inhibit liver injury and promote liver regeneration mainly by promoting elevated expression of HMOX1. Oleanolic acid can inhibit oxidative stress and promotes Ferroptosis in liver injury. In liver cancer, we identified that the main target of oleanolic acid is HMOX1 and HDAC1. And we determined that HMOX1 promotes Ferroptosis in liver cancer. This reduced the sensitivity of liver cancer to targeted therapies and immunotherapy. Molecular docking showed high binding of oleanolic acid to HDAC1 and HMOX1. CONCLUSIONS: Oleanolic acid is an antioxidant by promoting high expression of HMOX1 and promotes the development of Ferroptosis in liver cancer and liver injury.

Advances in the anti-tumor potential of hederagenin and its analogs.

Hederagenin is a pentacyclic triterpenoid that is widely distributed as the main pharmaceutical ingredient in various medicinal plants. Similarly as other pentacyclic triterpenoids, hederagenin has various pharmacological effects such as anti-tumor, anti-inflammatory, anti-depressant, and anti-viral activities. In particular, the anti-tumor activity of hederagenin indicates its potential for development into highly effective chemotherapeutic agents. Studies revealed that hederagenin effectively suppresses the growth of various tumor cell lines in vitro and interacts with several molecular targets that play essential roles in various cellular signaling pathways. The compound suppresses transformation, inhibits proliferation, and induces apoptosis in tumor cells. In this review, we highlight research progress on the source, pharmacokinetics, pharmacological activity, and mechanism of action of hederagenin and the anti-tumor activity of its analogs by integrating and analyzing relevant domestic and international studies and providing a basis for their further development and application.

Potentials of Terpenoids as Inhibitors of Multiple Plasmodium falciparum Protein Drug Targets.

PURPOSE: The resistance of parasite to readily affordable antimalarial drugs, the high cost of currently potent drugs, and the resistance of vector mosquitoes to insecticides threaten the possibility of malaria eradication in malaria endemic areas. Due to the fact that quinine and artemisinin were isolated from plants sources, researchers have been encouraged to search for new antimalarials from medicinal plants. This is especially the case in Africa where a large percentage of the population depends on medicinal plant to treat malaria and other ailments. METHOD: In this study, we evaluated previously characterized Plasmodium-cidal compounds obtained from the African flora to identify their likely biochemical targets, for an insight into their possible antimalarial chemotherapy. Molecular docking study was first conducted, after which remarkable compounds were submitted for molecular dynamic (MD) simulations studies. RESULTS: From a total of 38 Plasmodium-cidal compounds docked with confirmed Plasmodium falciparum protein drug targets [plasmepsin II (PMII), histo-aspartic protein (HAP) and falcipain-2 (FP)], two pentacyclic triterpene, cucurbitacin B and 3 beta-O-acetyl oleanolic acid showed high binding affinity relative to artesunate. This implies their capacity to inhibit the three selected P. falciparum target proteins, and consequently, antimalarial potential. From the MD simulations studies and binding free energy outcomes, results confirmed that the two compounds are stable in complex with the selected antimalarial targets; they also showed excellent binding affinities during the 100 ns simulation. CONCLUSION: These results showed that cucurbitacin B and 3 beta-O-acetyl oleanolic acid are potent antimalarials and should be considered for further studies.

Effects of oleanolic acid and ursolic acid on depression-like behaviors induced by maternal separation in mice.

Oleanolic acid (OA) and ursolic acid (UA) are structural isomeric triterpenoids. Both triterpenoids have been reported to be able to improve depression. However, no studies have compared their effects in the same system. Whether OA or UA could ameliorate depression-like behaviors in maternal separation (MS)-induced depression-like model was investigated. MS model is a well-accepted mouse model that can reflect the phenotype and pathogenesis of depression. Depression is a mental illness caused by neuroinflammation or changes in neuroplasticity in certain brain regions, such as the prefrontal cortex and hippocampus. Depression-like behaviors were measured using splash test or forced swimming test. In addition, anxiety-like behaviors were also measured using the open field test or elevated plus-maze test. MS-treated female mice showed greater depression-like behaviors than male mice, and that OA improved several depression-like behaviors, whereas UA only relieved anxiety-like behavior of MS-treated mice. Microglial activation, expression levels of TNF-α, and mRNA levels of IDO1 were increased in the hippocampi of MS-treated female mice. However, OA and UA treatments attenuated such increases. In addition, expression levels of synaptophysin and PSD-95 were decreased in the hippocampi of MS-treated female mice. These decreased expression levels of synaptophysin were reversed by both OA and UA treatments, although decreased PSD-95 expression levels were only reversed by OA treatment. Our findings suggest that MS cause depression-like behaviors through female-specific neuroinflammation, changes of tryptophan metabolism, and alterations of synaptic plasticity. Our findings also suggest that OA could reverse MS-induced depression-like behaviors more effectively than UA.

SIRT1/Nrf2/NF-κB Signaling Mediates Anti-Inflammatory and Anti-Apoptotic Activities of Oleanolic Acid in a Mouse Model of Acute Hepatorenal Damage.

Background and objectives: Oleanolic acid (OA) is a penta-cyclic triterpene with diverse bioactivities such as anticarcinogenic, antiviral, antimicrobial, hepatoprotective, anti-atherosclerotic, hypolipidemic, and gastroprotective. However, its effects on hepatorenal damage remain unclear. The protective activity of OA, separated from Viscum schimperi (Loranthaceae), against TAA (thioacetamide)-produced acute hepatic and renal damage was explored. Materials and Methods: Mice were treated with OA for 7 days before TAA (200 mg/kg, i.p.). Serum indices of hepatorenal injury, pathological lesions, molecular biological indexes, and inflammatory/apoptotic genes were estimated. Results: The tissues of both organs were greatly affected by the TAA injection. That was evident through increased serum markers of hepato-renal injury as well as remarkable histopathological lesions. TAA-induced injury was associated with oxidative and inflammatory responses in both organs as there was an elevation of oxidative stress parameters (4-HNE (4-hydroxy-nonenal), MDA (malondialdehyde), NOx (nitric oxide)), decline of antioxidants (reduced glutathione (GSH), superoxide dismutase (SOD), and total antioxidant capacity (TAC)), and an increase in the gene expression/level of inflammatory mediators (interleukins (1ß&6)). The inflammatory response was linked to a significant activation of NF-κB (nuclear-factor kappa-B)/TNF-α (tumor-necrosis factor-alpha) signaling. The inflammatory response in both organs was accompanied by apoptotic changes, including a rise in the gene expression and level of apoptotic parameters (caspase-3 and Bax) along with a decline in Bcl-2 (anti-apoptotic parameter) gene expression and level. These pathogenic events were found to be closely related to the suppression of the antioxidant signaling pathway, Nrf2 (nuclear-factor erythroid 2-related factor-2)/SIRT1 (sirtuin-1)/HO-1 (heme-oxygenase 1). On the other hand, OA significantly ameliorated TAA-induced injury in both organs. On the other hand, OA counterpoised the inflammatory response as it ameliorated NF-κB/TNF-α signaling and cytokine release. OA enhanced Nrf2/SIRT1/HO-1 signaling and counteracted apoptotic damage. Conclusions: OA showed anti-inflammation and antiapoptotic capacities that effectively suppressed TAA-induced acute hepatorenal damage.

Pharmacological properties and derivatives of saikosaponins-a review of recent studies.

OBJECTIVES: Saikosaponins (SSs) constitute a class of medicinal monomers characterised by a triterpene tricyclic structure. Despite their potential therapeutic effects for various pathological conditions, the underlying mechanisms of their actions have not been systematically analysed. Here, we mainly review the important anti-inflammatory, anticancer, and antiviral mechanisms underlying SS actions. METHODS: Information from multiple scientific databases, such as PubMed, the Web of Science, and Google Scholar, was collected between 2018 and 2023. The search term used was saikosaponin. KEY FINDINGS: Numerous studies have shown that Saikosaponin A exerts anti-inflammatory effects by modulating cytokine and reactive oxygen species (ROS) production and lipid metabolism. Moreover, saikosaponin D exerts antitumor effects by inhibiting cell proliferation and inducing apoptosis and autophagy, and the antiviral mechanisms of SSs, especially against SARS-CoV-2, have been partially revealed. Interestingly, an increasing body of experimental evidence suggests that SSs show the potential for use as anti-addiction, anxiolytic, and antidepressant treatments, and therefore, the related molecular mechanisms warrant further study. CONCLUSIONS: An increasing amount of data have indicated diverse SS pharmacological properties, indicating crucial clues for future studies and the production of novel saikosaponin-based anti-inflammatory, efficacious anticancer, and anti-novel-coronavirus agents with improved efficacy and reduced toxicity.

Oleanolic acid inhibits mercury chloride induced-liver ferroptosis by regulating ROS/iron overload.

Mercury chloride can cause severe liver injury, which involves multiple mechanisms. Ferroptosis plays an important role in regulating the development and progression of liver pathology. Oleanolic acid (OA), a triterpenoid compound widely exists in fruits, has liver protective properties. In this study, we investigated the role of ferroptosis in mercury chloride-induced liver injury and the intervention effect of OA, and clarified the potential mechanism. We found that mercury chloride-induced oxidative stress in liver tissues and cells, leading to lipid peroxidation and iron overload, thereby reducing the expression levels of GPX4 and SLC7A11, and increasing the expression level of TRF1, OA pretreatment improved the changes of GPX4, SLC7A11 and TRF1 induced by mercury chloride, which were related to its inhibition of oxidative stress. Furthermore, We pretreated cells with OA, VC, and Fer-1, respectively and found that VC pretreatment reduced oxidative stress and significantly reversed the gene and protein expressions of GPX4, SLC7A11, and TRF1 in mercury chloride-exposed cells (P < 0.05, vs. HgCl2 group), however, the protein expression level of GPX4 in OA pre-treatment group was lower than that in VC pre-treatment group (P < 0.05). Fer-1 pretreatment decreased the level of iron ions in cells, increased the gene and protein expression levels of GPX4 and SLC7A11, and decreased the gene and protein expression levels of TRF1 (P < 0.05, vs. HgCl2 group), however, the protein expression levels of GPX4 and SLC7A11 in OA pre-treatment group were lower than those in Fer-1 pre-treatment group (P < 0.05). Moreover, vivo experiments also demonstrated that pre-treatment with OA, VC, and Fer-1 reversed the changes in gene expression levels of Nrf2 and SOD1, and protein expression of GPX4 induced by mercury chloride (P < 0.05, vs. HgCl2 group), meanwhile, the difference was not statistically significant among OA, VC, and Fer-1 pretreatment. The improvement effect of OA pretreatment on the change in TFR1 protein expression caused by mercury chloride was similar to that of Fer-1 and VC, however, the intervention effect of OA on SLC7A11 protein expression was not as good as Fer-1 and VC pre-treatment. To sum up, all these results suggest that ferroptosis is involved in mercury chloride-induced liver injury, OA pretreatment alleviated mercury chloride-induced ferroptosis by inhibiting ROS production and iron ion overload, and then alleviate the liver injury.

A Point Mutation at C151 of Keap1 of Mice Abrogates NRF2 Signaling, Cytoprotection in Vitro, and Hepatoprotection in Vivo by Bardoxolone Methyl (CDDO-Me).

Bardoxolone methyl (CDDO-Me) is an oleanane triterpenoid in late-stage clinical development for the treatment of patients with diabetic kidney disease. Preclinical studies in rodents demonstrate the efficacy of triterpenoids against carcinogenesis and other diseases, including renal ischemia-reperfusion injury, hyperoxia-induced acute lung injury, and immune hepatitis. Genetic disruption of Nrf2 abrogates protection by triterpenoids, suggesting that induction of the NRF2 pathway may drive this protection. Herein, we examined the effect of a point mutation (C151S) in KEAP1, a repressor of NRF2 signaling, at cysteine 151 in mouse embryo fibroblasts and mouse liver. Induction of target gene transcripts and enzyme activity by CDDO-Me was lost in C151S mutant fibroblasts compared with wild-type. Protection against menadione toxicity was also nullified in the mutant fibroblasts. In mouse liver, CDDO-Me evoked the nuclear translocation of NRF2, followed by increased transcript and activity levels of a prototypic target gene, Nqo1, in wild-type, but not C151S mutant, mice. To test the role of KEAP1 Cys151 in governing the broader pharmacodynamic action of CDDO-Me, wild-type and C151S mutant mice were challenged with concanavalin A to induce immune hepatitis. Strong protection was seen in wild-type but not C151S mutant mice. RNA-seq analysis of mouse liver from wild-type, C151S mutant, and Nrf2-knockout mice revealed a vigorous response of the NRF2 transcriptome in wild-type, but in neither C151S mutant nor Nrf2-knockout, mice. Activation of "off-target" pathways by CDDO were not observed. These data highlight the singular importance of the KEAP1 cysteine 151 sensor for activation of NRF2 signaling by CDDO-Me. SIGNIFICANCE STATEMENT: KEAP1 serves as a key sensor for induction of the cytoprotective signaling pathway driven by the transcription factor NRF2. Mutation of a single cysteine (C151) in KEAP1 abrogates the induction of NRF2 signaling and its downstream cytoprotective actions in vitro and in vivo by bardoxolone methyl (CDDO-Me), a drug in late-stage clinical development. Further, at these bioeffective concentrations/doses, activation of "off-target" pathways by CDDO-Me are not observed, highlighting the singular importance of NRF2 in its mode of action.

AMP-activated protein kinase-farnesoid X receptor pathway contributes to oleanolic acid-induced liver injury.

Natural pentacyclic triterpenoid oleanolic acid (OA) is used as an over-the-counter drug for acute and chronic hepatitis. However, clinical use of OA-containing herbal medicines has been reported to cause cholestasis, and the specific mechanism is unknown. The purpose of this study was to explore how OA causes cholestatic liver injury via the AMP-activated protein kinase (AMPK)-farnesoid X receptor (FXR) pathway. In animal experiments, it was found that OA treatment activated AMPK and decreased FXR and bile acid efflux transport proteins expression. When intervened with the specific inhibitor Compound C (CC), it was observed that AMPK activation was inhibited, the reduction of FXR and bile acid efflux transport protein expression was effectively alleviated, serum biochemical indicators were significantly reduced, and liver pathological damage brought about by OA was effectively ameliorated. In addition, OA was found to downregulate the expression of FXR and bile acid efflux transport proteins by activating the ERK1/2-LKB1-AMPK pathway in cellular experiments. The ERK1/2 inhibitor U0126 was used to pretreat primary hepatocytes, and this drastically reduced the phosphorylation levels of LKB1 and AMPK. The inhibition effects of OA on FXR and bile acid efflux transport proteins were also effectively alleviated after pretreatment with CC. In addition, OA-induced downregulation of FXR gene and protein expression levels was significantly prevented after silencing AMPKα1 expression in AML12 cells. Our study demonstrated that OA inhibited FXR and bile acid efflux transporters through the activation of AMPK, thus leading to cholestatic liver injury.

Network pharmacology study of the mechanism underlying the therapeutic effect of Zhujing pill and its main component oleanolic acid against diabetic retinopathy.

Diabetic retinopathy (DR) is the leading cause of blindness in the working population worldwide, with few effective drugs available for its treatment in the early stages. The Zhujing pill (ZJP) is well-established to enhance the early symptoms of DR, but the mechanism underlying its therapeutic effect remains unclear. In the present study, we used systems biology and multidirectional pharmacology to screen the main active ingredients of ZJP and retrieved DrugBank and Genecards databases to obtain 'drug-disease' common targets. Using bioinformatics analysis, we obtained the core targets, and potential mechanisms of action of ZJP and its main components for the treatment of DR. Molecular docking was used to predict the binding sites and the binding affinity of the main active ingredients to the core targets. The predicted mechanism was verified in animal experiments. We found that the main active ingredient of ZJP was oleanolic acid, and 63 common 'drug-disease' targets were identified. Topological analysis and cluster analysis based on the protein-protein interaction network of the Metascape database screened the core targets as PRKCA, etc. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that these core targets were significantly enriched in the pro-angiogenic pathway of the VEGF signaling pathway. Molecular docking and surface plasmon resonance revealed that ZJP and its main active component, oleanolic acid had the highest binding affinity with PKC-α, the core target of the VEGF signaling pathway. Animal experiments validated that ZJP and oleanolic acid could improve DR.

Oleanolic acid and ursolic acid: therapeutic potential in neurodegenerative diseases, neuropsychiatric diseases and other brain disorders.

Brain disorders such as neurodegenerative diseases and neuropsychiatric diseases have become serious threatens to human health and quality of life. Oleanolic acid (OA) and ursolic acid (UA) are pentacyclic triterpenoid isomers widely distributed in various plant foods and Chinese herbal medicines. Accumulating evidence indicates that OA and UA exhibit neuroprotective effects on multiple brain disorders. Therefore, this paper reviews researches of OA and UA on neurodegenerative diseases, neuropsychiatric diseases and other brain disorders including ischemic stroke, epilepsy, etc, as well as the potential underlying molecular mechanisms.