This study aimed to elucidate the ameliorative effect and mechanism of quercetagetin, quercetin and lutein, alone and in combination, on acute lung injury. An lipopolysaccharide-induced inflammation model was established based on RAW264.7 cells. The optimal mixture ratios between quercetagetin or quercetin and lutein were determined based on the content of nitric oxide (NO) in RAW264.7 cells using combination index (CI) analysis. The individual and combined effects of quercetagetin, quercetin and lutein on the contents of malondialdehyde (MDA), inflammatory cytokines (including tumor necrosis factor α (TNF-α), interleukin (IL)-1β and IL-6) and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) in LPS-stimulated RAW264.7 cells were investigated. In addition, the relative expression levels of p65, p50, silent information regulator 1 (SIRT1), nuclear factor-erythroid 2 related factor 2 (Nrf2), and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) were evaluated by Western blot. The results showed that the lowest NO level in RAW264.7 cells was observed by treatment with a mixture of high-dose quercetagetin and lutein of 3:1 (30 μg/mL + 10 μg/mL). Quercetagetin, lutein and their combination all decreased the contents of MDA and inflammatory cytokines, increased the activities of SOD and GSH-PX, down-regulated the expression of nuclear factor kappa-B (NF-κB) p65, p50 and NLRP3, and up-regulated the expression of SIRT1 and Nrf2, the combination being more effective than either treatment alone.

Objective: To study the effect and mechanism of luteoloside on the differentiation and lipid metabolism of 3T3-L1 preadipocytes. Methods: The cytotoxicity of different concentrations of luteoloside on 3T3-L1 preadipocyte was detected using methyl thiazolyl tetrazolium (MTT) assay. Cell differentiation was induced by the cocktail method, and lipid droplets were observed by oil red O staining. The contents of triglyceride and total cholesterol in differentiated cells, as well as the secretion of related inflammatory factors such as tumor necrosis factor-α (TNF-α), interleukin (IL)-6, IL-10, leptin (LEP) and Adiponectin (ADPN) were measured. The relative expression levels of peroxisome proliferators activated receptor (PPAR) γ, CCAAT-enhancer-binding proteins (C/EBP)-α, sterol regulatory element-binding protein 1 (SREBP1), PPARα, uncoupling protein 1 (UCP-1), and carnitine palmitoyltransferase 1 (CPT-1) were analyzed by Western blotting. Results: The survival rate of 3T3-L1 preadipocytes decreased with the increase in luteoloside concentration, being above 80% at luteoloside concentrations of 5–60 μg/mL. Treatment with luteoloside significantly inhibited the differentiation of 3T3-L1 preadipocytes and reduced lipid accumulation. Luteoloside down-regulated the contents of TC and TG, the secretion of TNF-α, IL-6 and LEP, but up-regulated the secretion of IL-10 and ADPN. Luteoloside down-regulated the protein expression levels of PPARγ, C/EBP-α and SREBP1, but up-regulated those of PPARα, UCP-1 and CPT-1. Conclusion: Luteoloside can suppression the differentiation and lipid metabolism of 3T3-L1 preadipocytes. The mechanism may be that luteoloside down-regulates the protein expression of PPARγ, C/EBP-α, and SREBP1 to inhibit fat synthesis. Furthermore, it activates PPARα to upregulate downstream proteins and promote fat consumption. Luteoloside may also regulate the secretion of cytokines and promote cellular lipolysis, thus improving lipid metabolism imbalance.