Betulinic acid attenuates liver fibrosis by inducing autophagy via the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway

Drug Delivery Systems of Betulin and Its Derivatives: An Overview

Natural origin products are regarded as promising for the development of new therapeutic therapies with improved effectiveness, biocompatibility, reduced side effects, and low cost of production. Betulin (BE) is very promising due to its wide range of pharmacological activities, including its anticancer, antioxidant, and antimicrobial properties. However, despite advancements in the use of triterpenes for clinical purposes, there are still some obstacles that hinder their full potential, such as their hydrophobicity, low solubility, and poor bioavailability. To address these concerns, new BE derivatives have been synthesized. Moreover, drug delivery systems have emerged as a promising solution to overcome the barriers faced in the clinical application of natural products. The aim of this manuscript is to summarize the recent achievements in the field of delivery systems of BE and its derivatives. This review also presents the BE derivatives mostly considered for medical applications. The electronic databases of scientific publications were searched for the most interesting achievements in the last ten years. Thus far, it is mostly nanoparticles (NPs) that have been considered for the delivery of betulin and its derivatives, including organic NPs (e.g., micelles, conjugates, liposomes, cyclodextrins, protein NPs), inorganic NPs (carbon nanotubes, gold NPs, silver), and complex/hybrid and miscellaneous nanoparticulate systems. However, there are also examples of microparticles, gel-based systems, suspensions, emulsions, and scaffolds, which seem promising for the delivery of BE and its derivatives.

Research Progress on Application of Inonotus obliquus in Diabetic Kidney Disease

Diabetic kidney disease (DKD) is one of the prime causes of end-stage renal disease. At present, the treatment of DKD is mainly confined to inhibiting the renin-angiotensin-aldosterone system, but the therapeutic effects is not satisfactory. As a kind of very rare and precious medicinal fungi, Inonotus obliquus has a very high medicinal value. Due to its special hypoglycemic and pharmacological effect, researchers currently have attached great importance to it. In this paper, the biological activities, pharmacological effects and application status in the treatment of DKD-related diseases of Inonotus obliquus and the latest progress of metabolites isolated from it in DKD were summarized, thus providing detailed insights and basic understanding of the potential application prospects in DKD.

Discovery, structural optimization, and anti-tumor bioactivity evaluations of betulinic acid derivatives as a new type of RORγ antagonists

Betulinic acid (BA) is a natural pentacyclic triterpenoid that has a wide range of biological and pharmacological effects. Here, computational methods such as pharmacophore screening and reverse docking were used to predict the potential target for BA. Retinoic acid receptor-related orphan receptor gamma (RORγ) was confirmed as its target by several molecular assays as well as crystal complex structure determination. RORγ has been the focus of metabolic regulation, but its potential role in cancer treatment has only recently come to the fore. In this study, rationale optimization of BA was performed and several new derivatives were generated. Among them, the compound 22 showed stronger binding affinity with RORγ (K_D = 180 nM), good anti-proliferative activity against cancer cell lines, and potent anti-tumor efficacy with a TGI value of 71.6% (at a dose of 15 mg/kg) in the HPAF-II pancreatic cancer xenograft model. Further RNA-seq analysis and cellular validation experiments supported that RORγ antagonism was closely related to the antitumor activity of BA and 22, resulting in suppression of the RAS/MAPK and AKT/mTORC1 pathway and inducing caspase-dependent apoptosis in pancreatic cancer cells. RORγ was highly expressed in cancer cells and tissues and positively correlated with the poor prognosis of cancer patients. These results suggest that BA derivatives are potential RORγ antagonists worthy of further exploration.

Natural-Product-Mediated Autophagy in the Treatment of Various Liver Diseases

Autophagy is essential for the maintenance of hepatic homeostasis, and autophagic malfunction has been linked to the pathogenesis of substantial liver diseases. As a popular source of drug discovery, natural products have been used for centuries to effectively prevent the progression of various liver diseases. Emerging evidence has suggested that autophagy regulation is a critical mechanism underlying the therapeutic effects of these natural products. In this review, relevant studies are retrieved from scientific databases published between 2011 and 2022, and a novel scoring system was established to critically evaluate the completeness and scientific significance of the reviewed literature. We observed that numerous natural products were suggested to regulate autophagic flux. Depending on the therapeutic or pathogenic role autophagy plays in different liver diseases, autophagy-regulative natural products exhibit different therapeutic effects. According to our novel scoring system, in a considerable amount of the involved studies, convincing and reasonable evidence to elucidate the regulatory effects and underlying mechanisms of natural-product-mediated autophagy regulation was missing and needed further illustration. We highlight that autophagy-regulative natural products are valuable drug candidates with promising prospects for the treatment of liver diseases and deserve more attention in the future.

23-hydroxybetulinic acid reduces tumorigenesis, metastasis and immunosuppression in a mouse model of hepatocellular carcinoma via disruption of the MAPK signaling pathway

Hepatocellular carcinoma (HCC) shows recurrence and lung metastasis even after treatment. 23-hydroxybetulinic acid (23-HBA), a major active constituent of Pulsatilla chinensis, exhibits potent antitumor activities. We herein investigate the biological effect of 23-HBA on metastasis and immunosuppression in a mouse model of HCC. Microarray-based gene expression profiling was employed to identify the target genes of 23-HBA in the treatment of HCC. The effect of 23-HBA on the progression of HCC was evaluated by in-vitro cell function measurements along with in-vivo xenograft implantation, lung metastasis and CD11b+Gr1+ staining experiments. The potential mechanism involving target signaling pathway was investigated by western blot analysis. Bioinformatics analysis revealed that matrix metalloproteinase 2 (MMP2) was a key target gene mediated by 23-HBA in HCC, whereas Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis demonstrated that MMP2 mainly affects the development and metastasis of HCC. 23-HBA significantly reduced cell malignant functions in vitro while delaying the HCC growth and metastasis in vivo. In addition, the number of myeloid-derived suppressor cells was shown to be reduced following administration of 23-HBA in mice. Mechanistic analysis indicated that these effects of 23-HBA during HCC were involved with the mitogen-activated protein kinase (MAPK) signaling pathway inactivation and resulted in decreased phosphorylation of both mitogen-activated protein kinases 1/2 and extracellular signal-regulated kinase 1/2. Our study reveals that 23-HBA acts as a tumor suppressor agent and suppresses HCC tumorigenesis, metastasis and immunosuppression via blockade of the MAPK signaling pathway, suggesting that 23-HBA may serve as a promising drug target to treat HCC.

Preparation of Betulinic Acid Galactosylated Chitosan Nanoparticles and Their Effect on Liver Fibrosis

Aim

Liver fibrosis is mainly characterized by the formation of fibrous scars. Galactosylated chitosan (GC) has gained increasing attention as a liver-targeted drug carrier in recent years. The present study aimed to investigate the availability of betulinic acid-loaded GC nanoparticles (BA-GC-NPs) for liver protection. Covalently-conjugated galactose, recognized by asialoglycoprotein receptors exclusively expressed in hepatocytes, was employed to target the liver.

Materials and Methods

Galactose was coupled to chitosan by chemical covalent binding. BA-GC-NPs were synthesized by wrapping BA into NPs via ion-crosslinking method. The potential advantage of BA-GC-NP as a liver-targeting agent in the treatment of liver fibrosis has been demonstrated in vivo and in vitro.

Results

BA-GC-NPs with diameters <200 nm were manufactured in a virtually spherical core-shell arrangement, and BA was released consistently and continuously for 96 h, as assessed by an in vitro release assay. According to the safety evaluation, BA-GC-NPs demonstrated good biocompatibility at the cellular level and did not generate any inflammatory reaction in mice. Importantly, BA-GC-NPs showed an inherent liver-targeting potential in the uptake behavioral studies in cells and bioimaging tests in vivo. Efficacy tests revealed that administering BA-GC-NPs in a mouse model of liver fibrosis reduced the degree of liver injury in mice.

Conclusion

The findings showed that BA-GC-NPs form a safe and effective anti-hepatic fibrosis medication delivery strategy.

Ameliorative effect of betulinic acid against zearalenone exposure triggers testicular dysfunction and oxidative stress in mice via p38/ERK MAPK inhibition and Nrf2-mediated antioxidant defense activation

Zearalenone (ZEA) is a nonsteroidal estrogenic mycotoxin, which mainly contaminates grains and has estrogen-like effects on the reproductive system. Betulinic acid (BA), a natural lupane-type pentacyclic triterpene, has anti-oxidative and anti-inflammatory properties. This study aimed to investigate whether BA alleviates ZEA-induced testicular damage and explore the possible mechanism. Here, BA ameliorated testicular damage by mitigating the disordered arrangement of seminiferous tubules, the exfoliation of lumen cells, and the increase of cell apoptosis caused by ZEA. Meanwhile, BA alleviated ZEA-triggered testicular damage by restoring hormone levels and sperm motility, and reconstructing the blood-testis-barrier. Moreover, BA alleviated ZEA-exposed testicular oxidative stress by activating Nrf2 pathway. Furthermore, BA moderated ZEA-evoked testicular inflammation by inhibiting p38/ERK MAPK pathway. Overall, our results revealed that BA has a therapeutic protective effect on ZEA-induced testicular injury and oxidative stress via p38/ERK MAPK inhibition and Nrf2-mediated antioxidant defense activation, which provides a viable alternative to alleviate ZEA-induced male reproductive toxicology.

Betulinic acid-nucleoside hybrid prevents acute alcohol -induced liver damage by promoting anti-oxidative stress and autophagy

Alcoholic abuse is one of the most serious causes of liver diseases worldwide. Although detailed molecular pathogenesis of alcohol-induced liver damages remains elusive with intensive debates, it has been widely recognized that hepatic damage caused by free radicals generated from alcohol metabolism is one of the most critical factors for alcohol-induced liver diseases. Betulinic acid is a potent antioxidant with additional known pharmacological safety characteristics and minimal toxicity. However, poor solubility limited its usage. In this study, we assessed the efficacy of BAN, a betulinic acid and nucleoside hybrid with good water solubility, in reversing acute liver damages using an established alcohol overdose animal model. The results indicated that BAN is an extremely promising therapeutic agent against acute alcohol-induced liver damage. BAN effectively protects liver from alcohol damage by reducing serum ALT level by up to 47%, as well as liver oxidative stress indicated by significantly increased SOD, CAT, and GSH-Px levels. Moreover, hepatic FXR activation and a corresponding downstream anti-oxidative stress transcriptional cascade including Nrf2, HO-1, and NOQ1 induce the protective role of BAN. On the other hand, BAN administration also leads to increase cellular autophagy response, as indicated by the key ATG protein activation. We concluded that BAN, comparing with Betulinic acid, prevents acute alcohol-induced liver damages more effectively, with the dual mechanisms of neutralizing oxidative stress and promoting autophagy.

Suppression of endoplasmic reticulum stress-associated pathways and hepatocyte apoptosis participates in the attenuation of betulinic acid on alcohol-provoked liver injury in mice

BA protects against alcohol-induced liver damage through the alleviation of oxidative stress and suppression of ERS-induced apoptosis.

The Potential Application of Chinese Medicine in Liver Diseases: A New Opportunity

Liver diseases have been a common challenge for people all over the world, which threatens the quality of life and safety of hundreds of millions of patients. China is a major country with liver diseases. Metabolic associated fatty liver disease, hepatitis B virus and alcoholic liver disease are the three most common liver diseases in our country, and the number of patients with liver cancer is increasing. Therefore, finding effective drugs to treat liver disease has become an urgent task. Chinese medicine (CM) has the advantages of low cost, high safety, and various biological activities, which is an important factor for the prevention and treatment of liver diseases. This review systematically summarizes the potential of CM in the treatment of liver diseases, showing that CM can alleviate liver diseases by regulating lipid metabolism, bile acid metabolism, immune function, and gut microbiota, as well as exerting anti-liver injury, anti-oxidation, and anti-hepatitis virus effects. Among them, Keap1/Nrf2, TGF-β/SMADS, p38 MAPK, NF-κB/IκBα, NF-κB-NLRP3, PI3K/Akt, TLR4-MyD88-NF-κB and IL-6/STAT3 signaling pathways are mainly involved. In conclusion, CM is very likely to be a potential candidate for liver disease treatment based on modern phytochemistry, pharmacology, and genomeproteomics, which needs more clinical trials to further clarify its importance in the treatment of liver diseases.

Effect of betulinic acid administration on TLR-9/NF-κB /IL-18 levels in experimental liver injury

Background/aim

Acetaminophen (APAP), used in the composition of thousands of preparations, is the most commonly used analgesic and antipyretic drug. The present study aimed to investigate the potential protective effects of the betulinic acid (BA) treatment through an APAP-induced hepatotoxicity rat model, using inflammatory, biochemical, and histopathological parameters.

Materials and methods

The study consisted of four groups: control group, APAP group, BA group, and APAP+BA group. Experimental studies continued for fifteen days. Serum samples were analysed for glucose, total cholesterol (TChol), triglyceride (TG), low density lipoprotein (LDL), high density lipoprotein (HDL), aspartate amino transferase (AST), malondialdehyde (MDA), toll-like receptor-9 (TLR-9), nuclear factor kappa B (NF-κB), and interleukin-18 (IL-18).

Results

TLR9, IL-18, NF-κB, and MDA levels increased significantly in liver injury groups. These increases considerably decreased by the BA treatment. All groups showed immunopositivity for 8-hydroxy-2’–deoxyguanosine (8-OHdG) and interleukin (IL-1β) in the hepatocytes, inflammatory cells, and epithelial cells of bile ducts.

Conclusion

BA can be used as an effective agent in the prevention and treatment of acute liver diseases due to its inhibitory properties in multiple pathways and its potent antioxidant effects.

Betulinic Acid Ameliorates the Severity of Acute Pancreatitis via Inhibition of the NF-κB Signaling Pathway in Mice

Acute pancreatitis (AP) is an inflammatory disorder, involving acinar cell death and the release of inflammatory cytokines. Currently, there are limited effective therapeutic agents for AP. Betulinic acid (BA) is a pentacyclic triterpenoid extracted from Betula platyphylla that has been shown to have anti-inflammatory effects. In this study, we aimed to investigate the effects of BA on AP and elucidate the potential underlying mechanisms. AP was induced in mice through six intraperitoneal injections of cerulein. After the last cerulein injection, the mice were sacrificed. Our results revealed that pre- and post-treatment with BA significantly reduced the severity of pancreatitis, as evidenced by a decrease in histological damage in the pancreas and lung, serum amylase and lipase activity and pancreatic myeloperoxidase activity. Furthermore, BA pretreatment reduced proinflammatory cytokine production, augmentation of chemokines, and infiltration of macrophages and neutrophils in the pancreas of AP mice. In addition, mice that were pretreated with BA showed a reduction in Iκ-Bα degradation and nuclear factor-kappa B (NF-κB) binding activity in the pancreas. Moreover, BA reduced the production of proinflammatory cytokines and NF-κB activation in pancreatic acinar cells (PACs). These findings suggest that BA may have prophylactic and therapeutic effects on AP via inhibition of the NF-κB signaling pathway.

Acankoreagenin and acankoreosides, a family of lupane triterpenoids with anti-inflammatory properties: an overview

Acankoreagenin (ACK, also known as acankoreanogenin and HLEDA) and impressic acid are two lupane-type triterpenes that can be isolated from various Acanthopanax and Schefflera species. They efficiently block activation of the NF-κB signaling pathway and the release of proinflammatory cytokines and/or the action of inflammation mediators (HMGB1, iNOS, and NO). These effects are the basis for the antiviral and anticancer activities reported with these pentacyclic compounds or their various glycoside derivatives. More than 15 acankoreosides (Ack-A to -O, and -R) and a few other mono- and bidesmosidic saponins (acantrifoside A and acangraciliside S) derive from the ACK aglycone. Compounds like Ack-A and -B are remarkable anti-inflammatory agents, inhibiting cytokine release from activated macrophages. Despite their effectiveness, ACK and impressic acid are far much less known and studied than the structurally related compounds betulinic acid and 23-hydroxybetulinic acid (anemosapogenin). The structural differences (notably the R/S stereoisomerism of the 3-hydroxyl group) and functional similarities of these compounds are discussed. The complete series of acankoreosides is presented for the first time. These natural products deserve further attention as anti-inflammatory agents, and ACK is recommended as a template for the design of new anticancer and antiviral drugs.

Ethyl Acetate Fraction of Dicliptera chinensis (L.) Juss. Ameliorates Liver Fibrosis by Inducing Autophagy via PI3K/AKT/mTOR/p70S6K Signaling Pathway

OBJECTIVE

To investigate the molecular mechanism underlying the anti-hepatic fibrosis activity of ethyl acetate fraction Dicliptera chinensis (L.) Juss. (EDC) in human hepatic stellate cells (HSCs) in vitro and in a carbon tetrachloride (CCl₄)-induced hepatic fibrosis mouse model in vivo.

METHODS

For in vitro study, HSCs were pre-treated with platelet-derived growth factor (10 ng/mL) for 2 h to ensure activation and treated with EDC for 24 h and 48 h, respectively. The effect of EDC on HSCs was assessed using cell counting kit-8 assay, EdU staining, transmission electron microscopy, immunofluorescence staining, and Western blot, respectively. For in vivo experiments, mice were intraperitoneally injected with CCl₄ (2 ° L/g, adjusted to a 25% concentration in olive oil), 3 times per week for 6 weeks, to develop a hepatic fibrosis model. Forty 8-week-old male C57BL/6 mice were divided into 4 groups using a random number table (n=10), including control, model, positive control and EDC treatment groups. Mice in the EDC and colchicine groups were intragastrically administered EDC (0.5 g/kg) or colchicine (0.2 mg/kg) once per day for 6 weeks. Mice in the control and model groups received an equal volume of saline. Biochemical assays and histological examinations were used to assess liver damage. Protein expression levels of α -smooth muscle actin (α -SMA) and microtubule-associated protein light chain 3B (LC3B) were measured by Western blot.

RESULTS

EDC reduced pathological damage associated with liver fibrosis, downregulated the expression of α -SMA and upregulated the expression of LC3B (P<0.05), both in HSCs and the CCl₄-induced liver fibrosis mouse model. The intervention of bafilomycin A1 and rapamycin in HSCs strongly supported the notion that inhibition of autophagy enhanced α -SMA protein expression levels (P<0.01). The results also found that the levels of phosphoinositide (PI3K), p-PI3K, AKT, p-AKT, mammalian target of rapamycin (mTOR), p-mTOR, and p-p70S6K all decreased after EDC treatment (P<0.05).

CONCLUSIONS

EDC has anti-hepatic fibrosis activity by inducing autophagy and might be a potential drug to be further developed for human liver fibrosis therapy.

Astragali Radix Contributes to the Inhibition of Liver Fibrosis via High-Mobility Group Box 1-Mediated Inflammatory Signaling Pathway

Astragali Radix (AR), the dried root of Astragali Radix membranaceus (Fisch.) Bge. or Astragali Radix membranaceus (Fisch.) Bge. var. mongholicus (Bge) Hsiao, is a commonly used traditional Chinese medicine for the treatment of liver diseases. This study aimed to comprehensively evaluate the pharmacological action and explore the potential mechanism of AR on liver fibrosis. Rats were administered with carbon tetrachloride for eight weeks, followed by oral treatment with AR for six weeks. The efficacy was confirmed by measuring liver function and liver fibrosis levels. The underlying mechanisms were explored by detecting the expression of related proteins. AR significantly decreased the serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), collagen IV (COL-IV), hyaluronic acid (HA), laminin (LN), and precollagen type III (PCIII). In addition, AR inhibited the deposition of collagen and the activation of hepatic stellate cells. Those data strongly demonstrated that AR alleviated liver fibrosis by CCl₄. In order to illustrate the potential inflammatory, the mRNA levels of IL-6, TNF-α, and IL-1β were detected. Subsequently, immunohistochemistry analysis was performed to further verify the expression of type I collagen. Finally, the expression of key proteins in the inflammatory signaling pathway was detected. AR significantly reduced the expression of high-mobility group box 1 (HMGB1), TLR4, Myd88, RAGE, and NF-κ B p65 genes and proteins. In addition, western blotting showed AR decreased the protein expression of RAGE, p-MEK1/2, p-ERK1/2, and p-c-Jun. Taken together, our data reveal that AR significantly inhibits liver fibrosis by intervening in the HMGB1-mediated inflammatory signaling pathway and secretion signaling pathway. This study will provide valuable references for the in-depth research and development of Astragali Radix against liver fibrosis.

Research progress of natural compounds in anti-liver fibrosis by affecting autophagy of hepatic stellate cells

Chronic liver diseases caused by various pathogenesis are marked by inflammatory infiltration and wound healing reaction, while their normal regeneration ability is impaired. The unbalance between the generation and the degradation of extracellular matrix (ECM) leads to collagen accumulation and develops into liver fibrosis. Inflammation, oxidative stress, and autophagy interact closely in the pathogenesis of hepatic fibrosis. Reactive Oxygen Species (ROS) can not only stimulate Kupffer cells to release massive inflammatory factors, but induce autophagy. However, the latter may suppress inflammatory reaction by inhibiting proinflammatory complex formation directly, and removing damaged organelles or pathogenic microorganism indirectly. At present, effective anti-fibrosis drugs are still lacking. Previous studies have found various natural compounds enabled liver protection through anti-inflammatory, antioxidant, and other mechanisms. In recent years, autophagy, a vital life activity, has been found to be involved in the mechanism of liver fibrosis. As a new target, developing anti-liver fibrosis drugs that regulate the activity of autophagy is very promising. In this review, we summarize the latest studies about natural compounds in the treatment of liver fibrosis by regulating autophagy.

Hypoxia induces the activation of hepatic stellate cells through the PVT1-miR-152-ATG14 signaling pathway

Increasing studies have indicated that hypoxia serves as a pivotal microenvironmental factor that facilitates activation of hepatic stellate cells (HSCs). However, the mechanism by which hypoxia activates HSCs is not clear. Here, we demonstrated that plasmacytoma variant translocation 1 (PVT1) and autophagy were overexpressed in liver fibrotic specimens. In primary mouse HSCs, both PVT1 and autophagy were induced by hypoxia. Further study showed that hypoxia-induced autophagy depended on expression of PVT1 and miR-152 in HSCs. Luciferase reporter assay indicated that autophagy-related gene 14 (ATG14) was a direct target of miR-152. In addition, inhibition of autophagy by 3-methyladenine and Beclin-1 siRNA impeded activation of HSCs cultured in 1% O₂. Taken together, autophagy induction via the PVT1-miR-152-ATG14 signaling pathway contributes to activation of HSCs under hypoxia condition.

Betulinic Acid Enhances the Viability of Random-Pattern Skin Flaps by Activating Autophagy

Random-pattern skin flap replantation is commonly used to repair skin defects during plastic and reconstructive surgery. However, flap necrosis due to ischemia and ischemia-reperfusion injury limits clinical applications. Betulinic acid, a plant-derived pentacyclic triterpene, may facilitate flap survival. In the present study, the effects of betulinic acid on flap survival and the underlying mechanisms were assessed. Fifty-four mice with a dorsal random flap model were randomly divided into the control, betulinic acid group, and the betulinic acid + 3-methyladenine group. These groups were treated with dimethyl sulfoxide, betulinic acid, and betulinic acid plus 3-methyladenine, respectively. Flap tissues were acquired on postoperative day 7 to assess angiogenesis, apoptosis, oxidative stress, and autophagy. Betulinic acid promoted survival of the skin flap area, reduced tissue edema, and enhanced the number of microvessels. It also enhanced angiogenesis, attenuated apoptosis, alleviated oxidative stress, and activated autophagy. However, its effects on flap viability and angiogenesis, apoptosis, and oxidative stress were reversed by the autophagy inhibitor 3-methyladenine. Our findings reveal that betulinic acid improves survival of random-pattern skin flaps by promoting angiogenesis, dampening apoptosis, and alleviating oxidative stress, which mediates activation of autophagy.