Anti-inflammatory effect of gallic acid on HaCaT keratinocytes through the inhibition of MAPK-, NF-kB-, and Akt-dependent signaling pathways

The objectives of the present study were to evaluate the antioxidant and anti-inflammatory effects of gallic acid, a naturally occurring triphenolic compound, on HaCaT keratinocytes and study its mechanisms of action. The results showed that gallic acid at concentrations lower than 30 µM was non-toxic to HaCaT cells, reduced the intracellular level of reactive oxygen species, and suppressed the release of chemokines interleukin-8 and monocyte chemoattractant protein-1 in tumor necrosis factor-α- and interferon-γ-stimulated HaCaT keratinocytes. In addition, gallic acid reduced the total protein expression of NF-κB and inhibited the phosphorylation of ERK1/2, p38 MAPK, and Akt in stimulated HaCaT keratinocytes. In conclusion, our study revealed that gallic acid exhibited antioxidant and anti-inflammatory effects on keratinocytes, probably through the inhibition of MAPK-, NF-κB-, and Akt-dependent signaling pathways

Contribution of ENT4 to adenosine uptake in AC16 human cardiomyocytes under simulated ischemic conditions and its potential role in cardioprotection

Background: Nucleoside transporters are crucial in regulating the functions of adenosine. This study investigated the contribution of equilibrative nucleoside transporter (ENT) type 4 to adenosine transport in cardiomyocytes under simulated ischemic conditions and whether the inhibition of ENT4 could protect cardiomyocytes against ischemia-reperfusion injury. Methods: AC16 human cardiomyocytes were used to create a model to simulate ischemia/reperfusion injury. ENT4 activity was inhibited by decynium-22 or specific siRNA against ENT4. The protein expressions of nucleoside transporters were measured by western blot analysis. The transport activity was studied by [3?H]adenosine uptake. The cell injury was studied by biochemical assays. Results: The [3?H]adenosine uptake in AC16 cells was predominantly mediated by ENTs. ENT1 to ENT4 were present in AC16 cells and their protein expression levels were comparable in normal and ischemic conditions. Decynium-22 or siRNA against ENT4 did not affect the adenosine uptake in AC16 cells under normal conditions but could inhibit the adenosine uptake in AC16 cells by 28% under ischemic conditions. In addition, the cell viability and lactate dehydrogenase release of AC16 cells under ischemia conditions could be reduced by decynium-22 or siRNA against ENT4. Conclusion: The cell culture model has suggested that ENT4 may play a role in adenosine transport in cardiomyocytes under ischemic conditions. Inhibition or downregulation of ENT4 may be a potential approach for cardioprotection but this notion should be further validated using animal model

Neuroprotective Effects of Polysaccharides and Gallic Acid from <i>Amauroderma rugosum</i> against 6-OHDA-Induced Toxicity in SH-SY5Y Cells

The pharmacological activity and medicinal significance of Amauroderma rugosum (AR) have rarely been documented. We examined the antioxidant and neuroprotective effects of AR on 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in an SH-SY5Y human neuroblastoma cell model of Parkinson’s disease (PD) and explored the active ingredients responsible for these effects. The results showed that the AR aqueous extract could scavenge reactive oxygen species and reduce SH-SY5Y cell death induced by 6-OHDA. In addition, the AR aqueous extract increased the survival of Caenorhabditis elegans upon juglone-induced toxicity. Among the constituents of AR, only polysaccharides and gallic acid exhibited antioxidant and neuroprotective effects. The AR aqueous extract reduced apoptosis and increased the expression of phospho-Akt, phospho-mTOR, phospho-MEK, phospho-ERK, and superoxide dismutase-1 in 6-OHDA-treated SH-SY5Y cells. The polysaccharide-rich AR extract was slightly more potent than the aqueous AR extract; however, it did not affect the expression of phospho-Akt or phospho-mTOR. In conclusion, the AR aqueous extract possessed antioxidant and neuroprotective properties against 6-OHDA-induced toxicity in SH-SY5Y cells. The mechanism of action involves the upregulation of the Akt/mTOR and MEK/ERK-dependent pathways. These findings indicate the potential utility of AR and its active ingredients in preventing or treating neurodegenerative disorders associated with oxidative stress such as PD

Protective effects of Amauroderma rugosum on dextran sulfate sodium-induced ulcerative colitis through the regulation of macrophage polarization and suppression of oxidative stress

Background: Amauroderma rugosum (AR) is a medicinal mushroom commonly used to treat inflammation, gastric disorders, epilepsy, and cancers due to its remarkable anti-inflammatory and anti-oxidative properties. This study was designed to evaluate the pharmacological effects of AR and its underlying mechanism of action against ulcerative colitis (UC) in vitro and in vivo. Methods: A UC mouse model was established by administration of dextran sulfate sodium (DSS). AR extract was administered intragastrically to mice for 7 days. At the end of the experiment, histopathology, macrophage phenotype, oxidative stress, and inflammatory status were examined in vivo. Furthermore, RAW 264.7, THP-1, and Caco-2 cells were used to elucidate the mechanism of action of AR in vitro. Results: AR extract (0.5–2 mg/mL) significantly suppressed lipopolysaccharide (LPS) and interferon-gamma (IFN-γ)-induced M1 macrophage (pro-inflammatory) polarization in both RAW 264.7 and THP-1 cells. LPS-induced pro-inflammatory mediators (nitric oxide, TNF-α, IL-1β, MCP-1, and IL-6) were reduced by AR extract in a concentration-dependent manner. Similarly, AR extract downregulated MAPK signaling activity in LPS-stimulated RAW 264.7 cells. AR extract elicited a concentration-dependent increase in the mRNA expression of M2 (anti-inflammatory) phenotype markers (CD206, Arg-1, Fizz-1, and Ym-1) in RAW 264.7 cells. Moreover, AR extract suppressed DSS-induced ROS generation and mitochondrial dysfunction in Caco-2 cells. The in vivo experiment revealed that AR extract (200 mg/kg) increased colon length compared to the DSS-treated group. In addition, disease activity index, spleen ratio, body weight, oxidative stress, and colonic inflammation were markedly improved by AR treatment in DSS-induced UC mice. Finally, AR suppressed M1 and promoted M2 macrophage polarization in UC mice. Conclusion: The AR extract protected against DSS-induced UC by regulating macrophage polarization and suppressing oxidative stress. These valuable findings suggest that adequate intake of AR can prevent and/or treat UC