A Newly Synthesized Flavone from Luteolin Escapes from COMT-Catalyzed Methylation and Inhibits Lipopolysaccharide-Induced Inflammation in RAW264.7 Macrophages via JNK, p38 and NF-κB Signaling Pathways

Heat-Killed Latilactobacillus sakei CNSC001WB and Lactobacillus pentosus WB693 Have an Anti-inflammatory Effect on LPS-Stimulated RAW 264.7 Cells

Excessive inflammatory results, such as those seen in rheumatoid arthritis and cardiovascular diseases, are known to cause various complications. Therefore, we aimed to investigate whether heat-killed Latilactobacillus sakei CNS001WB and Lactobacillus pentosus WB693 can prevent inflammatory reactions. When LPS-stimulated RAW 264.7 cells were handled with either heat-killed Lact. sakei CNSC001WB or Lact. pentosus WB693, the production of nitric oxide reduced. Furthermore, the expression of cyclooxygenase (COX)-2 and proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, and IL-6, was suppressed. The expression of prostaglandin E2 (PGE2) and leukotriene B4 (LTB4), which play important roles in inflammatory diseases, especially arthritis, was also reduced. Moreover, these strains inhibited nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) pathways, which activate various cytokines and inflammatory mediators. Additionally, heat-killed Lact. sakei CNSC001WB and Lact. pentosus WB693 inhibited the reactive oxygen species (ROS) production. Based on these results, we concluded that heat-killed Lact. sakei CNSC001WB and Lact. pentosus WB693 sufficiently inhibited the inflammatory response and may have anti-inflammatory potential.

A newly synthesized flavone avoids COMT-catalyzed methylation and mitigates myocardial ischemia/reperfusion injury in H9C2 cells via JNK and P38 pathways

Objectives

Luteolin is a flavone that provides defense against myocardial ischemia/reperfusion (I/R) injury. However, this compound is subjected to methylation mediated by catechol-O-methyltransferase (COMT), thus influencing its pharmacological effect. To synthesize a new flavone from luteolin that avoids COMT-catalyzed methylation and find out the protective mechanism of LUA in myocardial I/R injury.

Materials and Methods

Luteolin and 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) were used to synthesize the new flavone known as LUAAPH-1 (LUA). Then, the myocardial ischemia/reperfusion injury cell model was established using H9c2 cells to detect the effect in myocardial ischemia/reperfusion regulation and to identify the underlying mechanism.

Results

Pretreatment with LUA (20 μmol/l) substantially increased cell viability while reducing cell apoptosis rate and caspase-3 expression induced by I/R, and the protective effect of LUA on cell viability was stronger than diosmetin, which is the major methylated metabolite of luteolin. In addition, intracellular reactive oxygen species (ROS) production and calcium accumulation were both inhibited by LUA. Furthermore, we identified that LUA markedly relieved the promotive effects of I/R stimulation upon JNK and p38 phosphorylation.

Conclusion

LUT pretreatment conveys significant cardioprotective effects after myocardial I/R injury, and JNK and p38 MAPK signaling pathway may be involved.

Luteolin as a potential hepatoprotective drug: Molecular mechanisms and treatment strategies

Luteolin is a flavonoid widely present in various traditional Chinese medicines. In recent years, luteolin has received more attention due to its impressive liver protective effect, such as metabolic associated fatty liver disease, hepatic fibrosis and hepatoma. This article summarizes the pharmacological effects, pharmacokinetic characteristics, and toxicity of luteolin against liver diseases, and provides prospect. The results indicate that luteolin improves liver lesions through various mechanisms, including inhibiting inflammatory factors, reducing oxidative stress, regulating lipid balance, slowing down excessive aggregation of extracellular matrix, inducing apoptosis and autophagy of liver cancer cells. Pharmacokinetics research manifested that due to metabolic effects, the bioavailability of luteolin is relatively low. It is worth noting that appropriate modification, new delivery systems, and derivatives can enhance its bioavailability. Although many studies have shown that the toxicity of luteolin is minimal, strict toxicity experiments are still needed to evaluate its safety and promote its reasonable development. In addition, this study also discussed the clinical applications related to luteolin, indicating that it is a key component of commonly used liver protective drugs in clinical practice. In view of its excellent pharmacological effects, luteolin is expected to become a potential drug for the treatment of various liver diseases.

Extraction technology, components analysis and anti-inflammatory activity in vitro of total flavonoids extract from Artemisia anomala S. Moore

Artemisia anomala S. Moore exerts many pharmacological activities, including the removing of the blood stasis, relieving of the fever and analgesia, reducing the swelling and dampness. In this study, the extraction technology, chemical compositions and anti-inflammatory effect in vitro and mechanism of total flavonoids extract from Artemisia anomala S. Moore were studied. The optimal yield rate of total flavonoids extract was optimized by single factor experiments and response surface method, and the chemical constituents were analyzed by UPLC-QTOF-MS method; and the anti-inflammatory activity of the extract was evaluated with lipopolysaccharide induced RAW 264.7 cells. The highest extraction rate was 2.02% under these conditions of the concentration of ethanol 50%, the ultrasonic extraction time 30 min, and the ratio of solvent volume to material weight 20:1 (ml/g). In addition, the main components of total flavonoid extract were preliminarily identified and deduced based on mass spectrometry information and relevant literatures, and its stronger anti-inflammatory activity was demonstrated by reducing the phagocytosis, the content of nitric oxide and the level of related cytokines (tumor necrosis factor-α, interleukin-10, interleukin-6). Furthermore, it was further revealed that the anti-inflammatory effect of the extract was closely connected with the activation of TLR4-MyD88-NF-κB signalling pathway. This study indicated that the total flavonoids extract from Artemisia anomala S. Moore may be a better candidate anti-inflammatory natural medicine.

The Anti-Inflammatory Mechanism of Flaxseed Linusorbs on Lipopolysaccharide-Induced RAW 264.7 Macrophages by Modulating TLR4/NF-κB/MAPK Pathway

Flaxseed linusorbs (FLs), cyclic peptides derived from flaxseed oils, have shown multiple activities such as anticancer, antibacterial, and anti-inflammatory effects. However, the anti-inflammatory monomers of FLs and their mechanisms are still unclear. In this study, we have elucidated that FLs suppress the modulation of NF-κB/MAPK signaling pathways by targeting the inhibition of activating TLR4 in LPS-induced RAW 264.7 cells. Therefore, the transcription and expression of inflammatory cytokines (i.e., TNF-α, IL-1β, and IL-6) and inflammatory mediator proteins (i.e., iNos and Cox-2) were significantly suppressed by FLs. In addition, an in silico study discovered that eight monomers of FLs showed high-affinity bindings with TLR4. In silico data combined with HPLC results indicated that FLA and FLE, accounting for 44%, were likely the major anti-inflammatory monomers in FLs. In summary, FLA and FLE were proposed as the main anti-inflammatory active cyclopeptides via hindering TLR4/NF-κB/MAPK signaling pathways, suggesting the potential use of food-derived FLs as natural anti-inflammatory supplements in a daily diet.

Oxygen mediated oxidative couplings of flavones in alkaline water

Catalyzed oxidative C-C bond coupling reactions play an important role in the chemical synthesis of complex natural products of medicinal importance. However, the poor functional group tolerance renders them unfit for the synthesis of naturally occurring polyphenolic flavones. We find that molecular oxygen in alkaline water acts as a hydrogen atom acceptor and oxidant in catalyst-free (without added catalyst) oxidative coupling of luteolin and other flavones. By this facile method, we achieve the synthesis of a small collection of flavone dimers and trimers including naturally occurring dicranolomin, philonotisflavone, dehydrohegoflavone, distichumtriluteolin, and cyclodistichumtriluteolin. Mechanistic studies using both experimental and computational chemistry uncover the underlying reasons for optimal pH, oxygen availability, and counter-cations that define the success of the reaction. We expect our reaction opens up a green and sustainable way to synthesize flavonoid dimers and oligomers using the readily available monomeric flavonoids isolated from biomass and exploiting their use for health care products and treatment of diseases.

Downregulation of IL-8 and IL-10 by the Activation of Ca2+-Activated K+ Channel KCa3.1 in THP-1-Derived M2 Macrophages

THP-1-differentiated macrophages are useful for investigating the physiological significance of tumor-associated macrophages (TAMs). In the tumor microenvironment (TME), TAMs with the M₂-like phenotype play a critical role in promoting cancer progression and metastasis by inhibiting the immune surveillance system. We examined the involvement of Ca²⁺-activated K⁺ channel K_Ca3.1 in TAMs in expressing pro-tumorigenic cytokines and angiogenic growth factors. In THP-1-derived M₂ macrophages, the expression levels of IL-8 and IL-10 were significantly decreased by treatment with the selective K_Ca3.1 activator, SKA-121, without changes in those of VEGF and TGF-β1. Furthermore, under in vitro experimental conditions that mimic extracellular K⁺ levels in the TME, IL-8 and IL-10 levels were both significantly elevated, and these increases were reversed by combined treatment with SKA-121. Among several signaling pathways potentially involved in the transcriptional regulation of IL-8 and IL-10, respective treatments with ERK and JNK inhibitors significantly repressed their transcriptions, and treatment with SKA-121 significantly reduced the phosphorylated ERK, JNK, c-Jun, and CREB levels. These results strongly suggest that the K_Ca3.1 activator may suppress IL-10-induced tumor immune surveillance escape and IL-8-induced tumorigenicity and metastasis by inhibiting their production from TAMs through ERK-CREB and JNK-c-Jun cascades.