A comprehensive review on pharmacological, toxicity, and pharmacokinetic properties of phillygenin: Current landscape and future perspectives

Phillyrin and its metabolites exert antipyretic effects by targeting the NAD+ binding domain of GAPDH, MDH2 and IDH2

BACKGROUND

Fever is one of the main pathophysiological reactions that occurs during the acute phase of various diseases. Excessive body temperature can lead to various adverse consequences such as brain tissue damage and abnormal immune responses. Phillyrin (Phr) is the main active ingredient in Forsythia suspensa (Thunb.) Vahl (Lian Qiao) and has antipyretic effects; however, its antipyretic mechanism of action remains unclear.

PURPOSE

This study aimed to explore the antipyretic mechanisms of Phr and provide a new treatment plan for fever.

METHODS

The antipyretic effects of Phr were evaluated using a mouse model of pneumonia fever. The main metabolites of Phr involved in its antipyretic function were identified using a mitochondrial temperature-sensitive probe. Further synthesis of the main metabolite, phillygenin (Phg), an alkynylated probe, was performed, and chemical proteomics was used to capture and analyze its direct target for antipyretic effects. The mechanism of action of Phg and its antipyretic targets was explored using metabolomics and various molecular biology methods.

RESULTS

Phr showed significant antipyretic and anti-inflammatory effects in a mouse model of lipopolysaccharide-induced fever. Phg reversibly targeted the nicotinamide adenine dinucleotide (NAD+) binding domain of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), malate dehydrogenase 2 (MDH2), and isocitrate dehydrogenase 2 (IDH2) to inhibit their enzymatic activity. In-depth analysis of cellular metabolomics and mitochondrial stress testing indicated that inhibition of GAPDH, MDH2, and IDH2 enzyme activity by Phg led to a decrease in cellular energy supply and heat production regulated by glycolysis, tricarboxylic acid cycle, and oxidative phosphorylation signaling pathways. Phg specifically targeted macrophages and inhibited LPS-induced macrophage activation by downregulating GAPDH enzyme activity, thereby exerting anti-inflammatory effects. In vivo experiments also confirmed that the antipyretic effect of Phr in LPS-induced fever model mice was related to its main metabolites, Phg and Phg-sulfonate (Phg-S), which directly targeted the NAD+ binding domain of GAPDH, IDH2, and MDH2, inhibiting the activity of these enzymes, thereby reducing energy supply and regulating febrile-related inflammatory factors.

CONCLUSION

This study reported for the first time that the antipyretic effect of Phr is produced by targeting GAPDH, IDH2, and MDH2 to regulate energy supply and febrile-related inflammatory factors through its main metabolites Phg and Phg-S. This study not only provides potential drugs for fever treatment but also provides new ideas for improving clinical fever treatment plans.

Emerging role of natural lipophagy modulators in metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as non-alcoholic fatty liver disease (NAFLD), is a seriously increasing liver disorder affecting nearly 32% of adults globally. Hepatic triglycerides (TG) accumulation is the hallmark of MASLD, which results from dysregulated lipid and fatty acid uptake, increased de novo lipogenesis (DNL), and decreased lipid removal. More recently, selective autophagy of lipid droplets (LDs), termed lipophagy, has emerged to be closely associated with disrupted hepatic lipid homeostasis. Recent studies have indicated that a series of natural products have shown promise as an alternative approach in attenuating MASLD via regulating lipophagy in vivo and in vitro. Therefore, lipophagy could be a new approach for natural products to be used to improve MASLD. This article aims to provide a comprehensive overview on the interrelationship between dysregulated lipid metabolism, lipophagy, and MASLD pathogenesis. In addition, the role of some natural products as lipophagy modulators and their impact on MASLD will be discussed.

Characterisation of an edible active film prepared from bacterial nanocellulose/forsythia essential oil Pickering emulsions with funoran and its application in fresh meat

This study sought to develop an edible active film by integrating Pickering emulsions of forsythia essential oil and bacterial nanofibers at various concentrations into a film-forming matrix composed of funoran (F). The stability of the emulsions was evaluated through examination of the micro-morphology, particle size and distribution, 7-day emulsification index, and embedding rate of the Pickering emulsions. Subsequently, selected Pickering emulsions were incorporated into F to generate the edible active film. Scanning electron microscopy, Fourier-transform infrared spectroscopy, and Raman spectroscopy revealed that the Pickering emulsion was uniformly distributed throughout the F film, interconnected by hydrogen bonds. X-ray Diffraction spectra exhibited changes in peak intensity and shifts in position attributable to the edible active film. Pickering emulsion had a minimal impact on thermal stability. The film's tensile strength significantly increased, while elongation at break decreased. The heightened concentration of hydroxyl groups in the film led to increased thickness, reduced moisture content, and enhanced hygroscopicity. The edible active film exhibited superior antioxidant and antibacterial properties, thereby more efficiently shielding against oxygen and water vapour. In preservation tests involving chicken and lamb, the Pickering emulsion led to elevations in pH, total volatile basic nitrogen, and thiobarbituric acid reactive substance levels in the meat.

Phillygenin inhibits neuroinflammation and promotes functional recovery after spinal cord injury via TLR4 inhibition of the NF-κB signaling pathway

Background

Spinal cord injuries (SCIs) trigger a cascade of detrimental processes, encompassing neuroinflammation and oxidative stress (OS), ultimately leading to neuronal damage. Phillygenin (PHI), isolated from forsythia, is used in a number of biomedical applications, and is known to exhibit anti-neuroinflammation activity. In this study, we investigated the role and mechanistic ability of PHI in the activation of microglia-mediated neuroinflammation and subsequent neuronal apoptosis following SCI.

Methods

A rat model of SCI was used to investigate the impact of PHI on inflammation, axonal regeneration, neuronal apoptosis, and the restoration of motor function. In vitro, neuroinflammation models were induced by stimulating microglia with lipopolysaccharide (LPS); then, we investigated the influence of PHI on pro-inflammatory mediator release in LPS-treated microglia along with the underlying mechanisms. Finally, we established a co-culture system, featuring microglia and VSC 4.1 cells, to investigate the role of PHI in the activation of microglia-mediated neuronal apoptosis.

Results

In vivo, PHI significantly inhibited the inflammatory response and neuronal apoptosis while enhancing axonal regeneration and improving motor function recovery. In vitro, PHI inhibited the release of inflammation-related factors from polarized BV2 cells in a dose-dependent manner. The online Swiss Target Prediction database predicted that toll-like receptor 4 (TLR4) was the target protein for PHI. In addition, Molecular Operating Environment software was used to perform molecular docking for PHI with the TLR4 protein; this resulted in a binding energy interaction of -6.7 kcal/mol. PHI inhibited microglia-mediated neuroinflammation, the production of reactive oxygen species (ROS), and activity of the NF-κb signaling pathway. PHI also increased mitochondrial membrane potential (MMP) in VSC 4.1 neuronal cells. In BV2 cells, PHI attenuated the overexpression of TLR4-induced microglial polarization and significantly suppressed the release of inflammatory cytokines.

Conclusion

PHI ameliorated SCI-induced neuroinflammation by modulating the TLR4/MYD88/NF-κB signaling pathway. PHI has the potential to be administered as a treatment for SCI and represents a novel candidate drug for addressing neuroinflammation mediated by microglial cells.

The translational potential of this article

We demonstrated that PHI is a potential drug candidate for the therapeutic management of SCI with promising developmental and translational applications.

Phillygenin Inhibits TGF-β1-induced Hepatic Stellate Cell Activation and Inflammation: Regulation of the Bax/Bcl-2 and Wnt/β-catenin Pathways

Hepatic fibrosis (HF), a precursor to cirrhosis and hepatocellular carcinoma, is caused by abnormal proliferation of connective tissue and excessive accumulation of extracellular matrix in the liver. Notably, activation of hepatic stellate cells (HSCs) is a key link in the development of HF. Phillygenin (PHI, C21H24O6) is a lignan component extracted from the traditional Chinese medicine Forsythiae Fructus, which has various pharmacological activities such as anti-inflammatory, antioxidant and anti-tumour effects. However, whether PHI can directly inhibit HSC activation and ameliorate the mechanism of action of HF has not been fully elucidated. Therefore, the aim of the present study was to investigate the in vitro anti-HF effects of PHI and the underlying molecular mechanisms. Transforming growth factor-β1 (TGF-β1)-activated mouse HSCs (mHSCs) and human HSCs (LX-2 cells) were used as an in vitro model of HF and treated with different concentrations of PHI for 24 h. Subsequently, cell morphological changes were observed under the microscope, cell viability was analyzed by MTT assay, cell cycle and apoptosis were detected by flow cytometry, and the mechanism of anti-fibrotic effect of PHI was explored by immunofluorescence, ELISA, RT-qPCR and western blot. The results showed that PHI suppressed the proliferation of TGF-β1-activated mHSCs and LX-2 cells, arrested the cell cycle at the G0/G1 phase, decreased the levels of α-SMA, Collagen I, TIMP1 and MMP2 genes and proteins, and promoted apoptosis in activated mHSCs and LX-2 cells. Besides, PHI reduced the expression of inflammatory factors in activated mHSCs and LX-2 cells, suggesting a potential anti-inflammatory effect. Mechanically, PHI inhibited TGF-β1-induced HSC activation and inflammation, at least in part through modulation of the Bax/Bcl-2 and Wnt/β-catenin pathways. Overall, PHI has significant anti-HF effects and may be a promising agent for the treatment of HF.

Review of research progress on intestinal microbiota based on metabolism and inflammation for depression

Depression is a prevalent mental illness, affecting a significant portion of the global population. Recent research has highlighted the crucial role of the gut microbiota in both metabolic and central nervous health. By reviewing literature from various databases, including Pubmed, Science Direct, Web of Science, and Scopus, spanning the years 2005-2023, a comprehensive search was conducted using keywords such as "Depression" and "Gut Microbiota". The gut microbiota acts as a "second brain" in humans and can communicate bidirectionally with the brain through the Brain-gut-microbiota axis pathway. This communication involves the immune and nervous systems. However, there are challenges in detecting and treating depression effectively. To address these limitations, researchers have been exploring the relationship between gut microbiota and depression. Studies have shown that gut microbial metabolites, such as lipopolysaccharides and short-chain fatty acids, can induce pro-inflammatory cytokines that contribute to neuroinflammation and increase the risk of depression. The kynurenine pathway, triggered by gut microbial metabolites, has also been associated with neuroinflammation. Thus, investigating these microbial metabolites can provide insights into depression treatment. This review focuses on analyzing the connection between gut microbial metabolites, inflammation, and depression. It explores novel mechanisms contributing to depression, specifically focusing on the mediation of inflammation through the release of pro-inflammatory cytokines. The objective is to provide valuable insights into the mechanisms underlying depression and to propose potential treatments.