Natural bioactive compounds-The promising candidates for the treatment of intestinal failure-associated liver disease

Parenteral nutrition (PN) is a life-saving procedure conducted to maintain a proper nutritional state in patients with severe intestinal failure who cannot be fed orally. A serious complication of PN therapy is liver failure, known as intestinal failure-associated liver disease (IFALD). The pathogenesis of IFALD is multifactorial and includes inhibition of the farnesoid X receptor (FXR) by PN components, bacteria translocation from impaired intestines, and intravenous line-associated bloodstream infection. Currently, the most frequently researched therapeutic option for IFALD is using lipid emulsions based on soy or fish oil and, therefore, free from phytosterols known as FXR antagonists. Nevertheless, the potential side effects of the lack of soybean oil delivery seem to outweigh the benefits, especially in the pediatric population. PN admixture provides all the necessary nutrients; however, it is deprived of exogenous natural bioactive compounds (NBCs) of plant origin, such as polyphenols, characterized by health-promoting properties. Among them, many substances have already been known to demonstrate the hepatoprotective effect in various liver diseases. Therefore, searching for new therapeutic options for IFALD among NBCs seems reasonable and potentially successful. This review summarizes the recent research on polyphenols and their use in treating various liver diseases, especially metabolic dysfunction-associated steatotic liver diseases (MASLD). Furthermore, based on scientific reports, we have described the molecular mechanism of action of selected NBCs that exert hepatoprotective properties. We also summarized the current knowledge on IFALD pathogenesis, described therapeutic options undergoing clinical trials, and presented the future perspective of the potential use of NBCs in PN therapy.

The cellular and molecular targets of natural products against metabolic disorders: a translational approach to reach the bedside

Metabolic disorders, including obesity, dyslipidemia, diabetes, nonalcoholic fatty liver disease, and metabolic syndrome, are characterized by insulin resistance, abnormalities in circulating cholesterol and lipid profiles, and hypertension. The most common pathophysiologies of metabolic disorders are glucose/lipid metabolism dysregulation, insulin resistance, inflammatory response, and oxidative stress. Although several agents have been approved for the treatment of metabolic disorders, there is still a strong demand for more efficacious drugs with less side effects. Natural products have been critical sources of drug research and discovery for decades. However, the usefulness of bioactive natural products is often limited by incomplete understanding of their direct cellular targets. In this review, we highlight the current understanding of the established and emerging molecular mechanisms of metabolic disorders. We further summarize the therapeutic effects and underlying mechanisms of natural products on metabolic disorders, with highlights on their direct cellular targets, which are mainly implicated in the regulation of glucose/lipid metabolism, insulin resistance, metabolic inflammation, and oxidative stress. Finally, this review also covers the clinical studies of natural products in metabolic disorders. These progresses are expected to facilitate the application of these natural products and their derivatives in the development of novel drugs against metabolic disorders.

Acetylated pelargonidin-3-O-glucoside alleviates hepatocyte lipid deposition through activating the AMPK-mediated lysosome-autophagy pathway and redox state

Nonalcoholic fatty liver disease (NAFLD) is a worldwide public health issue, but a widely accepted therapy is still lacking until now. Anthocyanins are natural flavonoid compounds that possess various bioactivities, but their applications are limited due to their low bioavailability and stability. Acylated anthocyanins are reported to show higher stability, whereas their effects on NAFLD are still unclear. Herein, pelargonidin-3-O-(6''-acetyl)-glucoside (Ace Pg3G) was found to dose-dependently reduce intracellular lipid droplets and triglycerides, and improve cellular oxidative stress that accompanied lipid deposition. Besides, Ace Pg3G was proved to activate AMPK phosphorylation, thus stimulating AMPK-mediated lysosome-autophagy pathway to eliminate overloaded lipid. Further study unveiled that Ace Pg3G regulated genes related to lipid metabolism downstream of AMPK to inhibit lipid synthesis and accelerate lipid oxidation. Overall, this study provided the first evidence, to our best knowledge, that Ace Pg3G ameliorated free fatty acid-induced lipid deposition in hepatocytes through regulating AMPK-mediated autophagy pathways and redox state.

Molecular Mechanisms of Fucoxanthin in Alleviating Lipid Deposition in Metabolic Associated Fatty Liver Disease

Metabolic-associated fatty liver disease (MAFLD) is witnessing a global surge; however, it still lacks effective pharmacological interventions. Fucoxanthin, a natural bioactive metabolite derived from marine brown algae, exhibits promising pharmacological functions, particularly in ameliorating metabolic disorders. However, the mechanisms underlying its therapeutic efficacy in addressing MAFLD remain elusive. Our present findings indicated that fucoxanthin significantly alleviated palmitic acid (PA)-induced hepatic lipid deposition in vitro and obesity-induced hepatic steatosis in ob/ob mice. Moreover, at both the protein and transcriptional levels, fucoxanthin effectively increased the expression of PPARα and CPT1 (involved in fatty acid oxidation) and suppressed FASN and SREBP1c (associated with lipogenesis) in both PA-induced HepG2 cells and hepatic tissues in ob/ob mice. This modulation was accompanied by the activation of AMPK. The capacity of fucoxanthin to improve hepatic lipid deposition was significantly attenuated when utilizing the AMPK inhibitor or siRNA-mediated AMPK silencing. Mechanistically, fucoxanthin activates AMPK, subsequently regulating the KEAP1/Nrf2/ARE signaling pathway to exert antioxidative effects and stimulating the PGC1α/NRF1 axis to enhance mitochondrial biogenesis. These collective actions contribute to fucoxanthin's amelioration of hepatic steatosis induced by metabolic perturbations. These findings offer valuable insights into the prospective utilization of fucoxanthin as a therapeutic strategy for managing MAFLD.

The Reduced Gut Lachnospira Species Is Linked to Liver Enzyme Elevation and Insulin Resistance in Pediatric Fatty Liver Disease

The objective of this study was to investigate gut dysbiosis and its metabolic and inflammatory implications in pediatric metabolic dysfunction-associated fatty liver disease (MAFLD). This study included 105 children and utilized anthropometric measurements, blood tests, the Ultrasound Fatty Liver Index, and fecal DNA sequencing to assess the relationship between gut microbiota and pediatric MAFLD. Notable decreases in Lachnospira spp., Faecalibacterium spp., Oscillospira spp., and Akkermansia spp. were found in the MAFLD group. Lachnospira spp. was particularly reduced in children with MAFLD and hepatitis compared to controls. Both MAFLD groups showed a reduction in flavone and flavonol biosynthesis sequences. Lachnospira spp. correlated positively with flavone and flavonol biosynthesis and negatively with insulin levels and insulin resistance. Body weight, body mass index (BMI), and total cholesterol levels were inversely correlated with flavone and flavonol biosynthesis. Reduced Lachnospira spp. in children with MAFLD may exacerbate insulin resistance and inflammation through reduced flavone and flavonol biosynthesis, offering potential therapeutic targets.

Tangeretin attenuates acute lung injury in septic mice by inhibiting ROS-mediated NLRP3 inflammasome activation via regulating PLK1/AMPK/DRP1 signaling axis

OBJECTIVE

NLRP3 inflammasome-mediated pyroptosis of macrophage acts essential roles in the progression of sepsis-induced acute lung injury (ALI). Tangeretin (TAN), enriched in citrus fruit peel, presents anti-oxidative and anti-inflammatory effects. Here, we aimed to explore the potentially protective effect of TAN on sepsis-induced ALI, and the underlying mechanism of TAN in regulating NLRP3 inflammasome.

MATERIAL AND METHODS

The effect of TAN on sepsis-induced ALI and NLRP3 inflammasome-mediated pyroptosis of macrophage were examined in vivo and in vitro using a LPS-treated mice model and LPS-induced murine macrophages, respectively. The mechanism of TAN regulating the activation of NLRP3 inflammasome in sepsis-induced ALI was investigated with HE staining, Masson staining, immunofluorescent staining, ELISA, molecular docking, transmission electron microscope detection, qRT-PCR, and western blot.

RESULTS

TAN could evidently attenuate sepsis-induced ALI in mice, evidenced by reducing pulmonary edema, pulmonary congestion and lung interstitial fibrosis, and inhibiting macrophage infiltration in the lung tissue. Besides, TAN significantly suppressed inflammatory cytokine IL-1β and IL-18 expression in the serum or bronchoalveolar lavage fluid (BALF) samples of mice with LPS-induced ALI, and inhibited NLRP3 inflammasome-mediated pyroptosis of macrophages. Furthermore, we found TAN inhibited ROS production, preserved mitochondrial morphology, and alleviated excessive mitochondrial fission in LPS-induced ALI in mice. Through bioinformatic analysis and molecular docking, Polo-like kinase 1 (PLK1) was identified as a potential target of TAN for treating sepsis-induced ALI. Moreover, TAN significantly inhibited the reduction of PLK1 expression, AMP-activated protein kinase (AMPK) phosphorylation, and Dynamin related protein 1 (Drp1) phosphorylation (S637) in LPS-induced ALI in mice. In addition, Volasertib, a specific inhibitor of PLK1, abolished the protective effects of TAN against NLRP3 inflammasome-mediated pyroptosis of macrophage and lung injury in the cell and mice septic models.

CONCLUSION

TAN attenuates sepsis-induced ALI by inhibiting ROS-mediated NLRP3 inflammasome activation via regulating PLK1/AMPK/DRP1 signaling axis, and TAN is a potentially therapeutic candidate against ALI through inhibiting pyroptosis.

Mechanism of Action and Related Natural Regulators of Nrf2 in Nonalcoholic Fatty Liver Disease

With the acceleration of people's pace of life, non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in the world, which greatly threatens people's health and safety. Therefore, there is still an urgent need for higher-quality research and treatment in this area. Nuclear factor Red-2-related factor 2 (Nrf2), as a key transcription factor in the regulation of oxidative stress, plays an important role in inducing the body's antioxidant response. Although there are no approved drugs targeting Nrf2 to treat NAFLD so far, it is still of great significance to target Nrf2 to alleviate NAFLD. In recent years, studies have reported that many natural products treat NAFLD by acting on Nrf2 or Nrf2 pathways. This article reviews the role of Nrf2 in the pathogenesis of NAFLD and summarizes the currently reported natural products targeting Nrf2 or Nrf2 pathway for the treatment of NAFLD, which provides new ideas for the development of new NAFLD-related drugs.

Nobiletin Ameliorates Hepatic Lipid Deposition, Oxidative Stress, and Inflammation by Mechanisms That Involve the Nrf2/NF-κB Axis in Nonalcoholic Fatty Liver Disease

Nobiletin (NOB), a flavonoid with significant antioxidant potential, holds promise for treating nonalcoholic fatty liver disease (NAFLD). In this work, we aim to assess the effects and investigate the molecular mechanisms of NOB on NAFLD. After using a methionine choline-deficient diet to induce C57BL/6J mice, as well as oleic acid to induce HepG2 and L02 cells, we administered NOB as an intervention. The results indicated that the NOB significantly ameliorated lipid deposition, oxidative stress, and inflammation in NAFLD in both models. Its mechanism may involve the Nrf2, SREBP-1c, and NF-κB signaling pathways. Furthermore, Nrf2 is not only a direct target for NOB to improve oxidative damage but also indirectly involved in lipid-lowering and anti-inflammatory processes in NAFLD. By inhibiting Nrf2, we found that the regulatory role of Nrf2 in lipid metabolism is not related to SREBP-1c but is closely associated with NF-κB in terms of inflammation. Our results suggest that Nrf2 is one of the most critical targets for NOB against NAFLD in multiple aspects.

Nrf2-mediated therapeutic effects of dietary flavones in different diseases

Oxidative stress (OS) is a pathological status that occurs when the body's balance between oxidants and antioxidant defense systems is broken, which can promote the development of many diseases. Nrf2, a redox-sensitive transcription encoded by NFE2L2, is the master regulator of phase II antioxidant enzymes and cytoprotective genes. In this context, Nrf2/ARE signaling can be a compelling target against OS-induced diseases. Recently, natural Nrf2/ARE regulators like dietary flavones have shown therapeutic potential in various acute and chronic diseases such as diabetes, neurodegenerative diseases, ischemia-reperfusion injury, and cancer. In this review, we aim to summarize nrf2-mediated protective effects of flavones in different conditions. Firstly, we retrospected the mechanisms of how flavones regulate the Nrf2/ARE pathway and introduced the mediator role Nrf2 plays in inflammation and apoptosis. Then we review the evidence that flavones modulated Nrf2/ARE pathway to prevent diseases in experimental models. Based on these literature, we found that flavones could regulate Nrf2 expression by mechanisms below: 1) dissociating the binding between Nrf2 and Keap1 via PKC-mediated Nrf2 phosphorylation and P62-mediated Keap1 autophagic degradation; 2) regulating Nrf2 nuclear translocation by various kinases like AMPK, MAPKs, Fyn; 3) decreasing Nrf2 ubiquitination and degradation via activating sirt1 and PI3K/AKT-mediated GSK3 inhibition; and 4) epigenetic alternation of Nrf2 such as demethylation at the promoter region and histone acetylation. In conclusion, flavones targeting Nrf2 can be promising therapeutic agents for various OS-related disorders. However, there is a lack of investigations on human subjects, and new drug delivery systems to improve flavones' treatment efficiency still need to be developed.

Nobiletin Intake Attenuates Hepatic Lipid Profiling and Oxidative Stress in HFD-Induced Nonalcoholic-Fatty-Liver-Disease Mice

Nobiletin (NOB) is a naturally occurring compound, commonly found in citrus peel, that shows hepatoprotective and lipid-reducing effects. However, the lipid biomarkers and the potential improvement mechanisms have not been adequately explored. Therefore, we investigated the ameliorative effect and the molecular mechanism of NOB on NAFLD induced by a high-fat diet in mice. The results showed that supplementation with NOB over 12 weeks markedly improved glucose tolerance, serum lipid profiles, inflammatory factors, hepatic steatosis, and oxidative stress. These beneficial effects were mainly related to reduced levels of potential lipid biomarkers including free fatty acids, diacylglycerols, triacylglycerols, and cholesteryl esters according to hepatic lipidomic analysis. Twenty lipids, including DGs and phosphatidylcholines, were identified as potential lipid biomarkers. Furthermore, RT-qPCR and Western blot analysis indicated that NOB inhibited the expression of lipogenesis-related factors such as SREBP-1c, SCD-1, and FAS, and upregulated the expression of lipid oxidation (PPARα) and cholesterol conversion (LXRα, CYP7A1, and CYP27A1) genes as well as antioxidation-related factors (Nucl-Nrf2, NQO1, HO-1, and GCLC), indicating that NOB intake may reduce lipid biosynthesis and increase lipid consumption to improve hepatic steatosis and oxidative stress. This study is beneficial for understanding the ameliorative effects of NOB on NAFLD.

Polyphenol Profile, Antioxidant Activity, and Hypolipidemic Effect of Longan Byproducts

Longan, a popular fruit in Asia, has been used in traditional Chinese medicine to treat several diseases for centuries. Recent studies have indicated that longan byproducts are rich in polyphenols. The aim of this study was to analyze the phenolic composition of longan byproduct polyphenol extracts (LPPE), evaluate their antioxidant activity in vitro, and investigate their regulating effect on lipid metabolism in vivo. The results indicated that the antioxidant activity of LPPE was 231.350 ± 21.640, 252.380 ± 31.150, and 558.220 ± 59.810 (mg Vc/g) as determined by DPPH, ABTS, and FRAP, respectively. UPLC-QqQ-MS/MS analysis indicated that the main compounds in LPPE were gallic acid, proanthocyanidin, epicatechin, and phlorizin. LPPE supplementation prevented the body weight gain and decreased serum and liver lipids in high-fat diet-induced-obese mice. Furthermore, RT-PCR and Western blot analysis indicated that LPPE upregulated the expression of PPARα and LXRα and then regulated their target genes, including FAS, CYP7A1, and CYP27A1, which are involved in lipid homeostasis. Taken together, this study supports the concept that LPPE can be used as a dietary supplement in regulating lipid metabolism.

Paeoniflorin Protects H9c2 Cardiomyocytes against Hypoxia/Reoxygenation Induced Injury via Regulating the AMPK/Nrf2 Signaling Pathway

Myocardial ischemia/reperfusion (MIR) injury contributes to the exacerbation of heart disease by causing cardiac arrhythmias, myocardial infarction, and even sudden death. Studies have found that paeoniflorin (PF) has a protective effect on coronary artery disease (CAD). However, the mechanism of PF in MIR has not been fully investigated. The purpose of this study was to investigate the functional role of PF in H9c2 cells subjected to hypoxia/reoxygenation (H/R). Here, PF treatment enhanced cell viability in H/R-stimulated H9c2 cells. In H9c2 cells, PF treatment reduced the formation of reactive oxygen species (ROS) induced by H/R. In H/R-stimulated H9c2 cells, PF also increased the activity of antioxidant enzymes such as superoxide dismutase and glutathione peroxidase. Furthermore, PF protected H9c2 cells against H/R-induced apoptosis, as demonstrated by increased Bcl-2 expression, decreased Bax expression, and decreased caspase-3 activity. Furthermore, PF increased the levels of p-AMPK and nuclear Nrf2 expression in response to H/R stimulation. AMPK inhibition, on the other hand, abolished the PF-mediated increase in Nrf2 signaling and the cardiac-protective effect in H9c2 cells exposed to H/R. These data suggest that PF protected H9c2 cells against H/R-induced oxidative stress and apoptosis through modulating the AMPK/Nrf2 signaling pathway. Our findings support the therapeutic potential of PF in myocardial I/R damage.