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Scutellarein Reduces Inflammatory Responses by Inhibiting Src Kinase Activity.

Sung NY, Kim MY, Cho JY - Korean J. Physiol. Pharmacol. (2015)

Bottom Line: Flavonoids are plant pigments that have been demonstrated to exert various pharmacological effects including anti-cancer, anti-diabetic, anti-atherosclerotic, anti-bacterial, and anti-inflammatory activities.Scutellarein significantly inhibited NO production in a dose-dependent manner and reduced the mRNA expression levels of inducible NO synthase (iNOS) and tumor necrosis factor (TNF)-α in lipopolysaccharide (LPS)-activated RAW264.7 cells.Moreover, the phosphorylation levels of various upstream signaling enzymes involved in NF-κB activation were decreased by SCT treatment in LPS-treated RAW264.7 cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetic Engineering, Sungkyunkwan University, Suwon 440-746, Korea.

ABSTRACT
Flavonoids are plant pigments that have been demonstrated to exert various pharmacological effects including anti-cancer, anti-diabetic, anti-atherosclerotic, anti-bacterial, and anti-inflammatory activities. However, the molecular mechanisms in terms of exact target proteins of flavonoids are not fully elucidated yet. In this study, we aimed to evaluate the anti-inflammatory mechanism of scutellarein (SCT), a flavonoid isolated from Erigeron breviscapus, Clerodendrum phlomidis and Oroxylum indicum Vent that have been traditionally used to treat various inflammatory diseases in China and Brazil. For this purpose, a nitric oxide (NO) assay, polymerase chain reaction (PCR), nuclear fractionation, immunoblot analysis, a kinase assay, and an overexpression strategy were employed. Scutellarein significantly inhibited NO production in a dose-dependent manner and reduced the mRNA expression levels of inducible NO synthase (iNOS) and tumor necrosis factor (TNF)-α in lipopolysaccharide (LPS)-activated RAW264.7 cells. In addition, SCT also dampened nuclear factor (NF)-κB-driven expression of a luciferase reporter gene upon transfection of a TIR-domain-containing adapter-inducing interferon-β (TRIF) construct into Human embryonic kidney 293 (HEK 293) cells; similarly, NF-κ B nuclear translocation was inhibited by SCT. Moreover, the phosphorylation levels of various upstream signaling enzymes involved in NF-κB activation were decreased by SCT treatment in LPS-treated RAW264.7 cells. Finally, SCT strongly inhibited Src kinase activity and also inhibited the autophosphorylation of overexpressed Src. Therefore, our data suggest that SCT can block the inflammatory response by directly inhibiting Src kinase activity linked to NF-κB activation.

No MeSH data available.


Related in: MedlinePlus

Effect of SCT on inflammatory gene expression in LPS-treated RAW264.7 cells. (A) RAW264.7 cells (1×106 cells/ml) were incubated with LPS (1 µg/ml) for 6 h after treatment with SCT. The mRNA expression levels of iNOS and TNF-α were determined by RT-PCR. (B and C) iNOS and TNF-α mRNA expression levels were measured by real-time PCR. **p<0.01 compared with the control group.
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Figure 2: Effect of SCT on inflammatory gene expression in LPS-treated RAW264.7 cells. (A) RAW264.7 cells (1×106 cells/ml) were incubated with LPS (1 µg/ml) for 6 h after treatment with SCT. The mRNA expression levels of iNOS and TNF-α were determined by RT-PCR. (B and C) iNOS and TNF-α mRNA expression levels were measured by real-time PCR. **p<0.01 compared with the control group.

Mentions: All data (Figs. 1B, 1C, 2B, 2C, 3A right panel, 3B right panel, 4A right panel, 4B right panel, 5A, 5B lower panel, and 5C lower panel) are expressed as means±SDs. For statistical comparisons, results were analyzed using ANOVA/Scheffe's post-hoc test and the Kruskal-Wallis/Mann-Whitney test. A p-value<0.05 was considered to indicate a statistically significant difference. All statistical tests were carried out using SPSS software (SPSS Inc., Chicago, IL, USA, v.20). All results are representative of at least two biological replicates conducted using the same numbers of samples or mice.


Scutellarein Reduces Inflammatory Responses by Inhibiting Src Kinase Activity.

Sung NY, Kim MY, Cho JY - Korean J. Physiol. Pharmacol. (2015)

Effect of SCT on inflammatory gene expression in LPS-treated RAW264.7 cells. (A) RAW264.7 cells (1×106 cells/ml) were incubated with LPS (1 µg/ml) for 6 h after treatment with SCT. The mRNA expression levels of iNOS and TNF-α were determined by RT-PCR. (B and C) iNOS and TNF-α mRNA expression levels were measured by real-time PCR. **p<0.01 compared with the control group.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4553404&req=5

Figure 2: Effect of SCT on inflammatory gene expression in LPS-treated RAW264.7 cells. (A) RAW264.7 cells (1×106 cells/ml) were incubated with LPS (1 µg/ml) for 6 h after treatment with SCT. The mRNA expression levels of iNOS and TNF-α were determined by RT-PCR. (B and C) iNOS and TNF-α mRNA expression levels were measured by real-time PCR. **p<0.01 compared with the control group.
Mentions: All data (Figs. 1B, 1C, 2B, 2C, 3A right panel, 3B right panel, 4A right panel, 4B right panel, 5A, 5B lower panel, and 5C lower panel) are expressed as means±SDs. For statistical comparisons, results were analyzed using ANOVA/Scheffe's post-hoc test and the Kruskal-Wallis/Mann-Whitney test. A p-value<0.05 was considered to indicate a statistically significant difference. All statistical tests were carried out using SPSS software (SPSS Inc., Chicago, IL, USA, v.20). All results are representative of at least two biological replicates conducted using the same numbers of samples or mice.

Bottom Line: Flavonoids are plant pigments that have been demonstrated to exert various pharmacological effects including anti-cancer, anti-diabetic, anti-atherosclerotic, anti-bacterial, and anti-inflammatory activities.Scutellarein significantly inhibited NO production in a dose-dependent manner and reduced the mRNA expression levels of inducible NO synthase (iNOS) and tumor necrosis factor (TNF)-α in lipopolysaccharide (LPS)-activated RAW264.7 cells.Moreover, the phosphorylation levels of various upstream signaling enzymes involved in NF-κB activation were decreased by SCT treatment in LPS-treated RAW264.7 cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetic Engineering, Sungkyunkwan University, Suwon 440-746, Korea.

ABSTRACT
Flavonoids are plant pigments that have been demonstrated to exert various pharmacological effects including anti-cancer, anti-diabetic, anti-atherosclerotic, anti-bacterial, and anti-inflammatory activities. However, the molecular mechanisms in terms of exact target proteins of flavonoids are not fully elucidated yet. In this study, we aimed to evaluate the anti-inflammatory mechanism of scutellarein (SCT), a flavonoid isolated from Erigeron breviscapus, Clerodendrum phlomidis and Oroxylum indicum Vent that have been traditionally used to treat various inflammatory diseases in China and Brazil. For this purpose, a nitric oxide (NO) assay, polymerase chain reaction (PCR), nuclear fractionation, immunoblot analysis, a kinase assay, and an overexpression strategy were employed. Scutellarein significantly inhibited NO production in a dose-dependent manner and reduced the mRNA expression levels of inducible NO synthase (iNOS) and tumor necrosis factor (TNF)-α in lipopolysaccharide (LPS)-activated RAW264.7 cells. In addition, SCT also dampened nuclear factor (NF)-κB-driven expression of a luciferase reporter gene upon transfection of a TIR-domain-containing adapter-inducing interferon-β (TRIF) construct into Human embryonic kidney 293 (HEK 293) cells; similarly, NF-κ B nuclear translocation was inhibited by SCT. Moreover, the phosphorylation levels of various upstream signaling enzymes involved in NF-κB activation were decreased by SCT treatment in LPS-treated RAW264.7 cells. Finally, SCT strongly inhibited Src kinase activity and also inhibited the autophosphorylation of overexpressed Src. Therefore, our data suggest that SCT can block the inflammatory response by directly inhibiting Src kinase activity linked to NF-κB activation.

No MeSH data available.


Related in: MedlinePlus