Elevated free fatty acid (FFA) is a key risk factor for insulin resistance (IR). Our previous studies found that mangiferin could decrease serum FFA levels in obese rats induced by a high-fat diet. Our research was to determine the effects and mechanism of mangiferin on improving IR by regulating FFA metabolism in HepG2 and C2C12 cells. The model was used to quantify PA-induced lipid accumulation in the two cell lines treated with various concentrations of mangiferin simultaneously for 24 h. We found that mangiferin significantly increased insulin-stimulated glucose uptake, via phosphorylation of protein kinase B (P-AKT), glucose transporter 2 (GLUT2), and glucose transporter 4 (GLUT4) protein expressions, and markedly decreased glucose content, respectively, in HepG2 and C2C12 cells induced by PA. Mangiferin significantly increased FFA uptake and decreased intracellular FFA and triglyceride (TG) accumulations. The activity of the peroxisome proliferator-activated receptor α (PPARα) protein and its downstream proteins involved in fatty acid translocase (CD36) and carnitine palmitoyltransferase 1 (CPT1) and the fatty acid β-oxidation rate corresponding to FFA metabolism were also markedly increased by mangiferin in HepG2 and C2C12 cells. Furthermore, the effects were reversed by siRNA-mediated knockdown of PPARα. Mangiferin ameliorated IR by increasing the consumption of glucose and promoting the FFA oxidation via the PPARα pathway in HepG2 and C2C12 cells.

Increased levels of oxidative stress and inflammation are the underlying mechanisms behind the aging process and age-related diseases. The purpose of our research is to explore whether epigallocatechin gallate (EGCG) can extend replicative life span by preventing the oxidative stress and inflammatory effects of WI-38 fibroblasts and the involved mechanisms in vitro. WI-38 cells were treated with different concentrations of EGCG (0, 25, 50 and 100 μM) at population doubling (PD) 25. At late-stage cells, we determined the age-associated genes with signaling through transcriptome sequencing. The expression profile of the targets in WI-38 fibroblasts was confirmed by bioinformatics analysis, qPCR and western blot. We found that EGCG markedly decreased reactive oxygen species (ROS), and inflammation factors, tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and significantly increased cell proliferation at PD 35 and 45. EGCG treatments significantly decreased p53 and retinoblastoma (Rb) expressions, markedly increased p-Rb and E2F2 expressions as well as antioxidant enzymes and superoxide dismutase (SOD) 1 and SOD2 content, and obviously decreased the expressions of inflammation factors IL-32, TNF-α expressions at PD 45 WI-38 cells. Moreover, the effects were changed by EGCG treatment by p53 siRNA or overexpression. These findings in our studies reveal that EGCG treatments improved senescence and enhanced the replicative life span through alleviating oxidative stress and inflammation in WI-38 fibroblasts.

Metabolic dysfunction-associated steatotic liver disease (MASLD) has become the most common chronic liver disease, with other fat-liver diseases potentially progressing to cirrhosis and hepatocellular carcinoma. Our study aimed to alleviate MASLD by EGCG inhibiting oxidative stress-mediated pyroptosis in zebrafish. The one month old wild-type zebrafh larval (50 per group) and three months old adult male zebrafish (15 per group) were treated with high-fat diet (HFD) feeding (powdered egg yolk) following by treatment with 25 μM EGCG for 15 days. Indicators related to liver damage, oxidative stress, inflammation, pyroptosis and aging were assessed using Oil Red O staining, H&E staining, commercial assay kits, enzyme-linked immunosorbent assay (ELISA) kits, and Western blot analysis. The results suggest that EGCG significantly reduced fatness, severe lipid deposition, triglyceride (TG), total cholesterol (TC) and free fatty acid (FFA) levels (p < 0.05). EGCG markedly reduced serum ALT, AST and ameliorated liver injury in zebrafish (p < 0.05). EGCG also showed an antioxidant effect by reducing reactive oxygen species (ROS) production malondialdehyde (MDA) and increasing superoxide dismutase (SOD) levels (p < 0.05). Moreover, EGCG obviously down-regulated the pro-inflammatory factors like tumor necrosis factor-a (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and interleukin-18 (IL-18) levels (p < 0.05). EGCG indicated a significant upregulation involved in pyroptosis pathway, such as nuclear factor erythroid 2-related factor 2 (NRF2) and downregulated the expressions of nuclear factor-κB (NF-κB), NOD-like receptor thermal protein domain associated protein 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC), cysteinyl aspartate specific proteinase-1 (caspase-1), as well as gasdermin D (GSDMD) (p < 0.01). Moreover, EGCG significantly improved aging-related markers induced by a HFD, including the level of senescence-associated β-Galactosidase (SA β-Gal) and expression of p53, p16, and p21 (p < 0.05), while ameliorating liver function in zebrafish. These results suggest that EGCG may attenuate MASLD in larval and adult zebrafish induced by 15 consecutive days HFD, which is potentially mediated by modulating the Nrf2/NF-κB/NLRP3 signaling pathway which relieve pyroptosis.

Background. The long-term exposure to ultraviolet radiation (UVR) raises oxidative stress and chronic inflammation levels, which in turn has a series of deleterious effects on skin health, such as sunburn, photoaging, and skin cancer. Hence, our study was determined to investigate the effects and mechanisms of epigallocatechin gallate (EGCG) in zebrafish and human skin fibroblasts (HSF) cells to alleviate ultraviolet-induced photoaging. Methods. The 4 days postfertilization (dpf) zebrafish larvae and HSF cells were treated with 10J/cm² UVA30mJ/cm² UVB, or 25, or 50μM EGCG for 72hr. The indicators involving in oxidative stress, inflammatory, and photoaging were measured by the kits, ELISA Kits and western blot methods. Results. EGCGs protect against UVR-induced skin damage in zebrafish and HSF cells. EGCG markedly decreased the reactive oxygen species (ROS), malondialdehyde, 8-OHdG levels, increased superoxide dismutase (SOD) activity, and significantly inhibited inflammatory factors levels including tumor necrosis factor-α (TNF-α), interleukin-1α (IL-1α), interleukin-6 (IL-6) in zebrafish, and HSF cells irradiated with UVR. We found that EGCG could reduce UVR-induced p38 mitogen-activated protein kinase (p38 MAPK) phosphorylation and effectively inhibited the activity of the transcriptional factor nuclear factor-κB (NF-κB), thereby reducing the protein-1 (AP-1), TNF-α, IL-1α, IL-6, and matrix metalloproteinase-1 (MMP-1) expressions, which are critical mediators of skin aging cascade causing the photoaging. Conclusion. These results validate that EGCG for protection of photoaging in zebrafish and HSF cells induced by UVR, which is closely related to the regulation of p38 MAPK/NF-κB, AP-1 signaling pathway which relieve oxidative stress, inflammation, and collagen degradation.

Background: Hyperlipidemia is a critical risk factor for obesity, diabetes, cardiovascular diseases, and other chronic diseases. Our study was to determine the effects and mechanism of mangiferin (MF) and epigallocatechin gallate (EGCG) compounds on improving hyperlipidemia in HepG2 cells.Methods: HepG2 cells were treated with 0.25 mM palmitic acid (PA) and then incubated with MF (12.5, 25, and 50 μM) or EGCG (25, 50, and 100 μM) or MF:EGCG (0:0, 6.25:12.5, 25:50, and 50:100 μM:μM) for 24 h. The improvement of hyperlipidemia was verified by Oil Red O staining, changes in triglyceride (TG) and free fatty acid (FFA) levels, and the expression of lipid metabolizing proteins in western blotting.Results: MF (12.5, 25, and 50 μM) or EGCG (25, 50, and 100 μM) markedly lowered lipid accumulations by lipid index levels. Furthermore, we found that the optimum concentration of MF and EGCG compounds was 25:50 (μM:μM), which significantly reduced the FFA level, TG, and total cholesterol (TC) accumulations and increased FFA uptake in HepG2 cells, and the effect was better than that of single phytochemicals. The adenosine 5 ^′‐monophosphate (AMP)‐activated protein kinase (AMPK) protein and its downstream proteins sirtuin 1 (SIRT1), peroxisome proliferator‐activated receptor α (PPARα), and those involved in fatty acid translocase (CD36) and carnitine palmitoyltransferase 1 (CPT1) were also markedly increased in HepG2 cells. The upregulation of protein expression was reversed when AMPK‐specific inhibitor Compound C was added.Conclusions: MF and EGCG (25:50 μM) compounds protect against hyperlipidemia by promoting the FFA oxidation, alleviating TG and TC accumulations via the AMPK/PPARα pathway in PA‐treated HepG2 cells.

Non-alcoholic fatty liver disease (NAFLD) is a common chronic liver disease. Disturbed phagocytic regulation may affect lipid clearance, inflammatory balan