Natural compounds against nonalcoholic fatty liver disease: A review on the involvement of the LKB1/AMPK signaling pathway

Although various therapeutic approaches are used to manage nonalcoholic fatty liver disease (NAFLD), the best approach to NAFLD management is unclear. NAFLD is a liver disorder associated with obesity, metabolic syndrome, and diabetes mellitus. NAFLD progression can lead to cirrhosis and end-stage liver disease. Hepatic kinase B1 (LKB1) is an upstream kinase of 5'-adenosine monophosphate-activated protein kinase (AMPK), a crucial regulator in hepatic lipid metabolism. Activation of LKB1/AMPK inhibits fatty acid synthesis, increases mitochondrial β-oxidation, decreases the expression of genes encoding lipogenic enzymes, improves nonalcoholic steatohepatitis, and suppresses NAFLD progression. One potential opening for new and safe chemicals that can tackle the NAFLD pathogenesis through the LKB1-AMPK pathway includes natural bioactive compounds. Accordingly, we summarized in vitro and in vivo studies regarding the effect of natural bioactive compounds such as a few members of the polyphenols, terpenoids, alkaloids, and some natural extracts on NAFLD through the LKB1/AMPK signaling pathway. This manuscript may shed light on the way to finding a new therapeutic agent for NAFLD management.

Advances in the study of the vascular protective effects and molecular mechanisms of hawthorn (Crataegus anamesa Sarg.) extracts in cardiovascular diseases

Hawthorn belongs to the rose family and is a type of functional food. It contains various chemicals, including flavonoids, terpenoids, and organic acid compounds. This study aimed to review the vascular protective effects and molecular mechanisms of hawthorn and its extracts on cardiovascular diseases (CVDs). Hawthorn has a wide range of biological functions. Evidence suggests that the active components of HE reduce oxidative stress and inflammation, regulate lipid levels to prevent lipid accumulation, and inhibit free cholesterol accumulation in macrophages and foam cell formation. Additionally, hawthorn extract (HE) can protect vascular endothelial function, regulate endothelial dysfunction, and promote vascular endothelial relaxation. It has also been reported that the effective components of hawthorn can prevent age-related endothelial dysfunction, increase cellular calcium levels, cause antiplatelet aggregation, and promote antithrombosis. In clinical trials, HE has been proved to reduce the adverse effects of CVDs on blood lipids, blood pressure, left ventricular ejection fraction, heart rate, and exercise tolerance. Previous studies have pointed to the benefits of hawthorn and its extracts in treating atherosclerosis and other vascular diseases. Therefore, as both medicine and food, hawthorn can be used as a new drug source for treating cardiovascular diseases.

Recent Advances Regarding the Molecular Mechanisms of Triterpenic Acids: A Review (Part II)

Triterpenic acids are a widespread class of phytocompounds which have been found to possess valuable therapeutic properties such as anticancer, anti-inflammatory, hepatoprotective, cardioprotective, antidiabetic, neuroprotective, lipolytic, antiviral, and antiparasitic effects. They are a subclass of triterpenes bearing a characteristic lipophilic structure that imprints unfavorable in vivo properties which subsequently limit their applications. The early investigation of the mechanism of action (MOA) of a drug candidate can provide valuable information regarding the possible side effects and drug interactions that may occur after administration. The current paper aimed to summarize the most recent (last 5 years) studies regarding the MOA of betulinic acid, boswellic acid, glycyrrhetinic acid, madecassic acid, moronic acid, and pomolic acid in order to provide scientists with updated and accessible material on the topic that could contribute to the development of future studies; the paper stands as the sequel of our previously published paper regarding the MOA of triterpenic acids with therapeutic value. The recent literature published on the topic has highlighted the role of triterpenic acids in several signaling pathways including PI3/AKT/mTOR, TNF-alpha/NF-kappa B, JNK-p38, HIF-α/AMPK, and Grb2/Sos/Ras/MAPK, which trigger their various biological activities.

Ameliorative Effects of Malonyl Ginsenoside from Panax ginseng on Glucose-Lipid Metabolism and Insulin Resistance via IRS1/PI3K/Akt and AMPK Signaling Pathways in Type 2 Diabetic Mice

Our previous study has revealed that malonyl-ginsenosides from Panax ginseng (PG-MGR) play a crucial role in the treatment of T2DM. However, its potential mechanism was still unclear. In this study, we investigated the anti-diabetic mechanisms of action of PG-MGR in high fat diet-fed (HFD) and streptozotocin-induced diabetic mice and determined the main constituents of PG-MGR responsible for its anti-diabetic effects. Our results showed that 16 malonyl ginsenosides were identified in PG-MGR by HPLC-ESI-MS/MS. PG-MGR treatment significantly reduced fasting blood glucose (FBG), triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels and improved insulin resistance and glucose tolerance. Simultaneously, PG-MGR treatment improved liver injury by decreasing aspartate aminotransferase (AST) and alanine aminotransferase (ALT) expression. Furthermore, Western blot analysis demonstrated that the protein expression levels of p-PI3K/PI3K, p-AKT/AKT, p-AMPK/AMPK, p-ACC/ACC and GLUT4 in liver and skeletal muscle were significantly up-regulated after PG-MGR treatment, and the protein expression levels of p-IRS-1/IRS-1, Fas and SREBP-1c were significantly reduced. These findings revealed that PG-MGR has the potential to improve glucose and lipid metabolism and insulin resistance by activating the IRS-1/PI3K/AKT and AMPK signal pathways.

Network pharmacology analysis and experimental validation to explore the mechanism of Bushao Tiaozhi capsule (BSTZC) on hyperlipidemia

Bushao Tiaozhi Capsule (BSTZC) is a novel drug in China that is used in clinical practice and has significant therapeutic effects on hyperlipidemia (HLP). In our previous study, BSTZC has a good regulatory effect on lipid metabolism of HLP rats. However, its bioactive compounds, potential targets, and underlying mechanism remain largely unclear. We extracted the active ingredients and targets in BSTZC from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) and literature mining. Subsequently, core ingredients, potential targets, and signaling pathways were determined through bioinformatics analysis, including constructed Drug-Ingredient-Gene symbols-Disease (D-I-G-D), protein–protein interaction (PPI), the Gene Ontology (GO), and the Kyoto Encyclopedia of Genes and Genomes (KEGG). Finally, the reliability of the core targets was evaluated using in vivo studies. A total of 36 bioactive ingredients and 209 gene targets were identified in BSTZC. The network analysis revealed that quercetin, kaempferol, wogonin, isorhamnetin, baicalein and luteolin may be the core ingredients. The 26 core targets of BSTZC, including IL-6, TNF, VEGFA, and CASP3, were considered potential therapeutic targets. Furthermore, GO and KEGG analyses indicated that the treatment of HLP by BSTZC might be related to lipopolysaccharide, oxidative stress, inflammatory response and cell proliferation, differentiation and apoptosis. The pathway analysis showed enrichment for different pathways like MAPK signaling pathway, AGE-RAGE signaling pathway in diabetic, IL-17 signaling pathway and TNF signaling pathway. In this study, network pharmacology analysis, and experiment verification were combined, and revealed that BSTZC may regulate key inflammatory markers and apoptosis for ameliorating HLP.

Potential Roles and Key Mechanisms of Hawthorn Extract against Various Liver Diseases

The genus Crataegus (hawthorn), a flowering shrub or tree, is a member of the Rosaceae family and consists of approximately 280 species that have been primarily cultivated in East Asia, North America, and Europe. Consumption of hawthorn preparations has been chiefly associated with pharmacological benefits for cardiovascular diseases, including congestive heart failure and angina pectoris. Treatment with hawthorn extracts can be related to improvements in the complex pathogenesis of various hepatic and cardiovascular disorders. In this regard, the present review described that the presence of hawthorn extracts ameliorated hepatic injury, lipid accumulation, inflammation, fibrosis, and cancer in an abundance of experimental models. Hawthorn extracts might have these promising activities, largely by enhancing the hepatic antioxidant system. In addition, several mechanisms, including AMP-activated protein kinase (AMPK) signaling and apoptosis, are responsible for the role of hawthorn extracts in repairing the dysfunction of injured hepatocytes. Specifically, hawthorn possesses a wide range of biological actions relevant to the treatment of toxic hepatitis, alcoholic liver disease, non-alcoholic fatty liver disease, and hepatocellular carcinoma. Accordingly, hawthorn extracts can be developed as a major source of therapeutic agents for liver diseases.

Liquid chromatographic study of two structural isomeric pentacyclic triterpenes on reversed-phase stationary phase with hydroxypropyl-β-cyclodextrin as mobile phase additive

Retention behavior of two structural isomeric pentacyclic triterpenic acids, maslinic acid and corosolic acid, was investigated by reverse phase high performance liquid chromatography (HPLC) with hydroxypropyl-β-cyclodextrin (HP-β-CD) as mobile phase additive. Inclusion complexation of maslinic acid, corosolic acid with hydroxypropyl-β-cyclodextrin was evaluated under different concentration of hydroxypropyl-β-cyclodextrin. Apparent formation constant (K_m) between methanol and hydroxypropyl-β-cyclodextrin was determined to be 13.82 L mol^-1 under 25 °C using UV-spectrophotometry. Two retention models were employed individually for evaluation of inclusion complexation between the two pentacyclic triterpenic acids and hydroxypropyl-β-cyclodextrin. It was found that a higher apparent formation constant (K_f) for corosolic acid and hydroxypropyl-β-cyclodextrin was obtained, 19115 L mol^-1, indicating that a greater affinity of hydroxypropyl-β-cyclodextrin with corosolic acid was produced compared with that of maslinic acid, 11775 L mol^-1, in the selected mobile phase, and stoichiometric ratio for both of inclusion complex was found to be 1:1. Thermodynamic analysis showed that a negative standard enthalpy change (ΔH) and an entropy change (ΔS*) for analyte transfer were obtained, where ΔH of maslinic acid and corosolic acid was found to be -10.188 kJ mol^-1 and -10.650 kJ mol^-1, ΔS* of two compounds was -2.092 and -2.180, respectively, indicating that transfer of structural isomers from mobile phase to stationary phase was enthalpically driven. Meanwhile, positive values were obtained for standard enthalpy change and standard entropy change, 136 kJ mol^-1 and 274 kJ mol^-1 and 536 J mol^-1 K^-1and 1004 J mol^-1 K^-1, for inclusion complexation between maslinic acid, corosolic acid and hydroxypropyl-β-cyclodextrin, while negative values were obtained for Gibbs free energy during formation of inclusion complex, -160 kJ mol^-1 and -299 kJ mol^-1, indicating a spontaneous inclusion reaction happened.

Lagerstroemia speciosa (L.) Pers., ethanolic leaves extract attenuates dapsone-induced liver inflammation in rats

Drug-induced liver injury is a common cause of acute liver failure. Dapsone is increasingly used in combination with rifampicin for the treatment of leprosy and also for several dermatological disorders. Clinically, abnormal liver function and focal bile duct destruction were reported after dapsone therapy. Lagerstroemia speciosa Pers., commonly known as Banaba has been traditionally used to treat various ailments including diabetes and obesity due to its antioxidant and anti-inflammatory efficacies. This study investigated the hepatoprotective effect of ethanolic banaba leaves extract (EBLE) against dapsone-induced hepatotoxicity in rats. Dapsone (30 mg/kg, i.p.) was administered twice daily for 30 days. In separate groups, rats were post-treated orally with EBLE (250 and 500 mg/kg) and silymarin (100 mg/kg) once daily for 30 days after dapsone administration. The marker enzymes of hepatotoxicity, oxidative stress markers, inflammatory markers and histopathology of liver were done. HPTLC analysis confirmed the presence of 12.87 µg of corosolic acid per mg of EBLE. Dapsone administration-induced significant (p < 0.001) elevation of marker enzymes of hepatotoxicity in serum. This treatment also increased lipid peroxidation (p < 0.001) and pro-inflammatory markers (tumor necrosis factor-alpha, transforming growth factor-beta, and nuclear factor kappa-B) expressions (p < 0.001) and decreased antioxidants (p < 0.001) such superoxide dismutase, catalase and glutathione in the liver tissue. All these abnormalities were significantly (p < 0.001) mitigated after EBLE (500 mg/kg) and silymarin post-treatments. The results of this study suggest that silymarin and EBLE can be used for dapsone-induced hepatotoxicity.

Corosolic acid ameliorates non-alcoholic steatohepatitis induced by high-fat diet and carbon tetrachloride by regulating TGF-β1/Smad2, NF-κB, and AMPK signaling pathways

Hawthorn (Crataegus pinnatifida Bunge. var. major) is an edible and medicinal fruit that is very common in food and traditional Chinese medicine. Corosolic acid (CA), a pentacyclic triterpenoid, which is an active component of hawthorn (Crataegus pinnatifida Bunge. var. major), has been exhibiting various pharmacological activities such as antidiabetic, antibacterial, anticancer, antiinflammatory, and antioxidant effects. The study aimed to evaluate the effect of CA on non-alcoholic steatohepatitis (NASH) in mice induced by 60 kcal% high-fat diet (HFD) and carbon tetrachloride (CCl₄ ). CA lowered liver index and serum AST, ALT, TG, and TC levels compared to those in the model group. Histological analyses of the liver tissues of mice treated with CA revealed significantly decreased number of lipid droplets and alleviated inflammation and fibrosis. CA inhibited the transcripts of pro-fibrogenic markers (including α-SMA, collagen I, and TIMP-1) and the levels of pro-inflammatory cytokines (including TNF-α, IL-1β, caspase-1, and IL-6) associated with hepatic fibrosis, and NF-κB translocation and TGF-β1/Smad2 and AMPK pathways. In addition, CA reduced lipid accumulation via the regulation of AMPK and NF-κB activation in FFA-induced steatotic HepG2 cells. CA also decreased α-SMA, collagen I expressions, and Smad2 phosphorylation, which were reduced by TGF-β1 treatment in LX2 cells. Our results suggested that CA ameliorated NASH through regulating TGF-β1/Smad2, NF-κB, and AMPK signaling pathways, and CA could be developed as a potential health functional food or therapeutic agent for NASH patients.

The anti-inflammatory and analgesic activities of the ethyl acetate extract of Viburnum taitoense Hayata

ETHNOPHARMACOLOGICAL RELEVANCE

Viburnum taitoense Hayata has been used as folk medicine by the minority people in Southwestern China for a long history, especially in Guangxi Zhuang Autonomous Region. The minority in Guangxi including Zhuang, Miao and Yao people use the ethanol extract of V. taitoense Hayata to treat the fracture, kill the pain of rheumatism because of its definite therapeutic effects.

AIM OF THE STUDY

So far, the scientific investigation of V. taitoense Hayata is done very little. Here, we first prepared the ethyl acetate extract of V. taitoense (EEVt), secondly measured the contents of phenols, flavonoids, and terpenoids in EEVt, and thirdly, the anti-inflammatory and analgesic activities of EEVt were investigated by invitro model of RAW 264.7 cells and invivo models of inflammation and pain in rats and mice.

MATERIALS AND METHODS

The contents of phenols, flavonoids, and terpenoids in EEVt were determined by UV spectrophotometry, respectively. The anti-inflammatory effect of EEVt (5, 25, 50, 100, and 200 μg/mL) in vitro was tested by determining its inhibitory effect on the nitric oxide production of RAW264.7 cells activated by lipopolysaccharide (LPS). The anti-inflammatory and analgesic effects of EEVt in vivo were investigated in the following experimental rats and mice models: carrageenan-induced paw edema, corton-oil-induced ear edema, acetic acid writhing test, and formalin pain test.

RESULTS

The contents of total phenolic, total flavonoids, and total triterpenoids in V. taitoense were measured to be 3.46 ± 0.04%, 2.38 ± 0.04%, and 14.96 ± 0.17%, respectively. In vitro test showed that EEVt at different tested dosages (5, 25, 50, 100, and 200 μg/mL) had no significant toxicity to RAW264.7 macrophages. At dosages of 37.5 and 75 μg/mL of EEVt significant inhibitory (p < 0.001) on the productions of nitric oxide (NO). High dosage (200 μg/mL) of EEVt displayed highly significant inhibitory (p < 0.001) on the productions of proinflammatory cytokines IL-6, IL-1β, and TNF-α from the LPS-induced RAW264.7 macrophages. EEVt showed obvious anti-inflammatory activity at different time points after carrageenan injection (p < 0.05) in vivo test, and its anti-inflammatory activity reached the strongest 4 h. Similarly, through the ear swelling test, EEVt (200 mg/kg) showed significant (p < 0.05) anti-inflammatory activity. Besides, formalin and acetic acid writhing experiments also showed that EEVt has significant (p < 0.05) analgesic activity.

CONCLUSION

EEVt was confirmed to be definite anti-inflammatory and analgesic effects, and the phytochemicals of EEVt was disclosed to be rich in triterpenoids, which was worthy to be further investigated.

Nuciferine Inhibited the Differentiation and Lipid Accumulation of 3T3-L1 Preadipocytes by Regulating the Expression of Lipogenic Genes and Adipokines

Purposes: Nuciferine, a main aporphine alkaloid component found in lotus leaf (Nelumbo nucifera), has been demonstrated to possess the property of reducing fat mass and alleviating dyslipidemia in vivo. The purpose of this study is to explore the effects of nuciferine on the proliferation and differentiation of 3T3-L1 cells and further investigate the possible underlying molecular mechanisms.

Methods: 3T3-L1 preadipocytes were treated with 0∼20 μM nuciferine for 24∼120 h, the cell viability was assessed using CCK8. 3T3-L1 preadipocytes and human primary preadipocytes were then induced differentiation and the effects of nuciferine on the lipid metabolism in differentiating and fully differentiated adipocytes were observed by the methods of intracellular triglyceride (TG) assay, Oil Red O staining, RT-qPCR and western blot. Transient transfection and dual luciferase reporter gene methods were used to assess the effects of nuciferine on FAS promoter activities.

Results: Nuciferine inhibited the proliferation of 3T3-L1 preadipocytes in a dose- and time-dependent manner. 20 μM nuciferine significantly attenuated lipid accumulation and reduced intracellular TG contents by 47.2, 59.9 and 55.4% on the third, sixth and ninth day of preadipocytes differentiation, respectively (all p < 0.05). Moreover, the mRNA levels of PPARγ, C/EBPα, C/EBPβ, FAS, ACC, HSL and ATGL were notably decreased by 39.2∼92.5% in differentiating preadipocytes when treated with 5∼20 μM nuciferine (all p < 0.05). In fully differentiated adipocytes treated with 20 μM nuciferine for 48 h, the mRNA levels of FAS, ACC and SREBP1 were remarkably downregulated by 22.6∼45.2% compared with the controls (0 μM) (all p < 0.05), whereas the expression of adipokines FGF21 and ZAG were notably promoted by nuciferine. Similarly, in fully differentiated human primary adipocytes, the mRNA levels of FAS, ACC, SREBP1 were decreased and the expression of FGF21 and ZAG were elevated after treated with nuciferine (all p < 0.05). Further mechanism studies showed that 2.5∼20 μM nuciferine significantly decreased FAS promoter activities in 3T3-L1 preadipocytes.

Conclusion: Nuciferine inhibited the proliferation and differentiation of 3T3-L1 preadipocytes. The inhibitory effects of nuciferine on adipogenesis might be due to the downregulation of PPARγ, C/EBPα and C/EBPβ, which led to the reduction of intracellular lipid accumulation in 3T3-L1 cells and by downregulating the expression of critical lipogenic enzymes, especially of FAS, which was achieved by inhibiting the FAS promoter activities. Besides, nuciferine promoted the expression of adipokines in fully differentiated adipocytes.

Preparative separation of structural isomeric pentacyclic triterpenes from Eriobotrya japonica (Thunb.) leaves by high speed countercurrent chromatography with hydroxypropyl-β-cyclodextrin as additive

Maslinic acid and corosolic acid with high purity were successfully separated from Eriobotrya japonica (Thunb.) leaves by two-step countercurrent chromatographic separation. Two biphasic solvent systems composed of petroleum ether-ethyl acetate-ethanol-water (6:4:5:5, v/v) and petroleum ether-ethyl acetate-ethanol-0.10 mol/L of hydroxypropyl-β-cyclodextrin with pH 7.0 (8:2:3.5:6.5, v/v) were selected according to the partition performance of the main structural isomeric pentacyclic triterpenes. The influences of pH value and concentration of hydroxypropyl-β-cyclodextrin in separation of two isomers were investigated. In first step countercurrent chromatographic separation, a mixture of two target structural isomers (14.12 mg of sample I) was separated from 40.00 mg of a partially purified sample. In second step countercurrent chromatographic separation, maslinic acid and corosolic acid were completely isolated from 12.00 mg of sample I with hydroxypropyl-β-cyclodextrin as aqueous phase additive. The recoveries of the two isomers were over 90%, yielding 5.18 mg of maslinic acid and 5.47 mg of corosolic acid, respectively.