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

Investigating the Mechanisms of Lycii fructus in Treating Nonalcoholic Fatty Liver Disease and Diabetes Comorbidity Through Network Pharmacology and Molecular Dynamics

Non-alcoholic fatty liver disease (NAFLD) and diabetes mellitus (DM) are prevalent metabolic disorders that frequently coexist, yet their shared molecular mechanisms remain poorly understood, and current therapies often yield suboptimal outcomes. Lycium barbarum L. (Lycii fructus, LF), a traditional medicinal herb, has demonstrated clinical efficacy in treating both conditions, but its mechanism of action in comorbidity management remains unclear. Active LF compounds were identified via the TCMSP database, with potential targets predicted using Swiss Target Prediction and PharmMapper. Disease-associated proteins for NAFLD and DM were curated from OMIM, GeneCards, DisGeNET, UniProt, DrugBank, and TTD. A protein-protein interaction (PPI) network was constructed from these targets, and GO and KEGG pathway analyses were performed using the DAVID platform. Key targets were further refined through network module analysis via Metascape. Drug-likeness of bioactive compounds was assessed using SwissADME and ADMETlab 2.0. Molecular docking and dynamics simulations validated interactions between core targets and LF compounds. Mendelian randomization (MR) analysis tested causal relationships between core genes and disease phenotypes. We identified 58 shared therapeutic targets for NAFLD-DM comorbidity, including HSP90AA1, ESR1, MMP9, EGFR, AKT1, and CASP3. GO analysis implicated LF in blood pressure regulation and glucose-stimulated insulin secretion. KEGG pathways highlighted modulation of MAPK, PI3K-Akt, FoxO, and mTOR signaling. 24-methylenelanost-8-enol and cryptoxanthin monoepoxide emerged as core bioactive compounds with favorable drug-likeness. Molecular docking confirmed strong binding of 24-methylenelanost-8-enol to HSP90AA1 and cryptoxanthin monoepoxide to MMP9, further supported by dynamics simulations. MR analysis revealed a significant causal role for CASP3 in both NAFLD and DM, aligning with network pharmacology predictions. LF's therapeutic effects on NAFLD-DM comorbidity likely arise from terpenoid and cryptoxanthin mediated modulation of apoptosis and inflammation pathway. This study identifies shared molecular networks, proposes candidate mechanisms for LF's efficacy, and provides a framework for targeting multifactorial metabolic diseases.

Protective effect of curcumin against endoplasmic reticulum stress and lipid metabolism disorders in AFB1-intoxicated duck liver

Aflatoxin B1 (AFB1) is a stable and highly toxic toxin that causes multi-organ toxicity with sustained ingestion, most typically in the duck liver. Previous research has shown that AFB1 can bring about endoplasmic reticulum stress (ERS) in animals, and ERS is strongly associated with lipid metabolism. However, the relationship between AFB1-induced duck liver toxicity and ERS and lipid metabolism is currently unclear. Great attention has been paid to the prevention and treatment of AFB1 because of its great harm. Curcumin, a natural polyphenol, is notable for its powerful anti-inflammatory and antioxidant properties. Studies have shown curcumin to be protective against afb1-induced avian multi-organ toxicity. However, the effects of curcumin on the liver of ducks exposed to AFB1 are largely unknown. In the present study, we aimed to investigate whether AFB1 exposure induces ERS and lipid metabolism disorders in duck liver, while exploring the positive role of curcumin in it. One-day-old ducks (n = 80) were randomly divided in four groups: control group, AFB1 group (0.1 mg / kg.bw AFB1), Cur group (400 mg/kg curcumin), and AFB1 + Cur group (0.1 mg/kg.bw AFB1 + 400 mg/kg curcumin), and blood and liver were collected for the study after 21 days of continuous administration. Our research has found that AFB1 exposure significantly increases the levels of liver function indicators ALP, AST, and ALT in ducks' serum (P < 0.05). Duck liver undergoes fatty degeneration under the influence of AFB1. Under the effect of curcumin, AFB1-induced structural damage in duck liver was somewhat controlled. Further experimental results showed that AFB1 treatment significantly increased the expression of glucose-regulated protein 78 (P < 0.001), and activated the endoplasmic reticulum stress pathway. Meanwhile, AFB1 inhibited the LKB1-AMPK signaling pathway and disrupted lipid metabolic homeostasis. And curcumin treatment effectively reversed these changes. Overall, our results suggest that curcumin attenuates AFB1-induced hepatotoxicity in ducks by inhibiting ERS and lipid metabolism disorders.

Structure characteristics of a novel pectic polysaccharide from Fructus Corni and its protective effect on alcoholic fatty liver

Alcoholic fatty liver disease (AFLD) is characterized by the accumulation of hepatic lipid and has no effective treatment yet. Fructus Corni is a traditional Chinese medicinal herb, and its extractions have demonstrated hepatoprotective properties. We hypothesize that the polysaccharides in Fructus Corni might have therapeutic effects on AFLD. In this study, we isolated a novel homogeneous polysaccharide, APFC-2 (Mw= 63.0 kDa), from the Fructus Corni, and its structure was elucidated by monosaccharide composition, methylation analysis, partial acid hydrolysis, and NMR spectra. APFC-2 is a pectic polysaccharide characterized by a backbone of T-β-Galp-(1 → 6)-β-Galp-(1 → 3,6)-β-Galp-(1 → [4)-α-GalpA-OMe-(1 → 4)-α-GalpA-(1→]m → [2,4)-α-Rhap-(1 → 4)-α-GalpA-(1→]n, with branches comprising T-Araf-(1→, →3)-α-Araf-(1→, →3,5)-α-Araf-(1→, and →5)-α-Araf-(1→. In vivo experiments indicated that APFC-2 could significantly reduce hepatic steatosis, fasting triglyceride, and cholesterol levels in AFLD mice. Cell proliferation and Oil Red O staining results showed that APFC-2 concentration-dependently increased cell viability and significantly improved lipid metabolism in vitro. Mechanistically, APFC-2 markedly inhibited the formation of lipid both in vitro and in vivo through activating liver kinase B1 (LKB1) and then regulating adenosine 5'-monophosphate-activated protein kinase (AMPK)-SREBP-1 and AMPK-PPAR-α pathways. This research provides a theoretical basis for the potential application of Fructus Corni pectic polysaccharide as a specific activator of LKB1 for treating AFLD.

New Insights into AMPK, as a Potential Therapeutic Target in Metabolic Dysfunction-Associated Steatotic Liver Disease and Hepatic Fibrosis

AMP-activated protein kinase (AMPK) activators have garnered significant attention for their potential to prevent the progression of metabolic dysfunction-associated steatotic liver disease (MASLD) into liver fibrosis and to fundamentally improve liver function. The broad spectrum of pathways regulated by AMPK activators makes them promising alternatives to conventional liver replacement therapies and the limited pharmacological treatments currently available. In this study, we aim to illustrate the newly detailed multiple mechanisms of MASLD progression based on the multiple-hit hypothesis. This model posits that impaired lipid metabolism, combined with insulin resistance and metabolic imbalance, initiates inflammatory cascades, gut dysbiosis, and the accumulation of toxic metabolites, ultimately promoting fibrosis and accelerating MASLD progression to irreversible hepatocellular carcinoma (HCC). AMPK plays a multifaceted protective role against these pathological conditions by regulating several key downstream signaling pathways. It regulates biological effectors critical to metabolic and inflammatory responses, such as SIRT1, Nrf2, mTOR, and TGF-β, through complex and interrelated mechanisms. Due to these intricate connections, AMPK's role is pivotal in managing metabolic and inflammatory disorders. In this review, we demonstrate the specific roles of AMPK and its related pathways. Several agents directly activate AMPK by binding as agonists, while some others indirectly activate AMPK by modulating upstream molecules, including adiponectin, LKB1, and the AMP: ATP ratio. As AMPK activators can target each stage of MASLD progression, the development of AMPK activators offers immense potential to expand therapeutic strategies for liver diseases such as MASH, MASLD, and liver fibrosis.

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.

The gut-liver axis in fatty liver disease: role played by natural products

Fatty liver disease, a condition characterized by fatty degeneration of the liver, mainly classified as non-alcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD), has become a leading cause of cirrhosis, liver cancer and death. The gut-liver axis is the bidirectional relationship between the gut and its microbiota and its liver. The liver can communicate with the gut through the bile ducts, while the portal vein transports the products of the gut flora to the liver. The intestinal flora and its metabolites directly and indirectly regulate hepatic gene expression, leading to an imbalance in the gut-liver axis and thus contributing to the development of liver disease. Utilizing natural products for the prevention and treatment of various metabolic diseases is a prevalent practice, and it is anticipated to represent the forthcoming trend in the development of drugs for combating NAFLD/ALD. This paper discusses the mechanism of the enterohepatic axis in fatty liver, summarizes the important role of plant metabolites in natural products in fatty liver treatment by regulating the enterohepatic axis, and provides a theoretical basis for the subsequent development of new drugs and clinical research.

Water extract of earthworms mitigates mouse liver fibrosis by potentiating hepatic LKB1/Nrf2 axis to inhibit HSC activation and hepatocyte death

ETHNOPHARMACOLOGICAL RELEVANCE

When left untreated, liver fibrosis (LF) causes various chronic liver diseases. Earthworms (Pheretima aspergillum) are widely used in traditional medicine because of their capacity to relieve hepatic diseases.

AIM OF THE STUDY

This study aimed to explore the anti-LF effects of water extract of earthworms (WEE) and the underlying molecular mechanisms.

MATERIALS AND METHODS

A CCl4-induced mouse model of LF was used to study the impact of WEE on LF in vivo. The anti-LF activity of WEE in mice was compared with that of silybin, which can be clinically applied in LF intervention and was used as a positive control. Activation of LX-2 hepatic stellate cells (HSCs) and apoptosis and ferroptosis of AML-12 hepatocytes induced by TGFβ1 were used as in vitro models.

RESULTS

WEE drastically improved LF in mice. WEE reduced markers of activated HSCs in mice and inhibited TGFβ1-induced activation of LX-2 HSCs in vitro. Additionally, WEE suppressed CCl4-induced apoptosis and ferroptosis in mouse hepatocytes. Mechanistically, WEE induced Nrf2 to enter the nuclei of the mouse liver cells, and the hepatic levels of Nrf2-downstream antioxidative factors increased. LKB1/AMPK/GSK3β is an upstream regulatory cascade of Nrf2. In the LF mouse model, WEE increased hepatic phosphorylated LKB1, AMPK, and GSK3β levels. Similar results were obtained for the LX-2 cells. In AML-12 hepatocytes and LX-2 HSCs, WEE elevated intracellular Nrf2 levels, promoted its nuclear translocation, and inhibited TGFβ1-induced ROS accumulation. Knocking down LKB1 abolished the impact of WEE on the AMPK/GSK3β/Nrf2 cascade and eliminated its protective effects against TGFβ1.

CONCLUSIONS

Our findings reveal that WEE improves mouse LF triggered by CCl4 and supports its application as a promising hepatoprotective agent against LF. The potentiation of the hepatic antioxidative AMPK/GSK3β/Nrf2 cascade by activating LKB1 and the subsequent suppression of HSC activation and hepatocyte apoptosis and ferroptosis are implicated in WEE-mediated alleviation of LF.