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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

Chemical structure and anti-inflammatory activity of SCT. (A) Molecular structure of SCT. (B) RAW-264.7 cells (1×106 cells/ml) were pretreated with SCT (left panel) or L-NAME (right panel) for 1 h and incubated with LPS (1 µg/ml) for 24 h. The nitric oxide levels were measured by the Griess assay. (C) Viability of RAW264.7 cells after treatment with SCT for 24 h. Viability was determined by a conventional MTT assay. *p<0.05 and **p<0.01 compared with the control group.
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Figure 1: Chemical structure and anti-inflammatory activity of SCT. (A) Molecular structure of SCT. (B) RAW-264.7 cells (1×106 cells/ml) were pretreated with SCT (left panel) or L-NAME (right panel) for 1 h and incubated with LPS (1 µg/ml) for 24 h. The nitric oxide levels were measured by the Griess assay. (C) Viability of RAW264.7 cells after treatment with SCT for 24 h. Viability was determined by a conventional MTT assay. *p<0.05 and **p<0.01 compared with the control group.

Mentions: Scutellarein (SCT, Fig. 1A) is the active component of Erigeron breviscapus, Clerodendrum phlomidis and Oroxylum indicum Vent and is used to treat inflammation, diabetes, nervous disorders, asthma, rheumatism, digestive disorders, and urinary disorders; it is also given as a bitter tonic [1011]. In addition, Codariocalyx motorius with structural analogue of SCT (SCT-6-O-glucuronide) was also shown to suppress LPS-induced inflammatory responses in macrophages and a HCl/EtOH-triggered gastritis symptoms [12]. From a pharmacological perspective, SCT has been reported to exert antioxidative, anti-cancer, and neuroprotective activities [1314]. Although SCT is known to have a flavonoid-derived backbone, the precise anti-inflammatory activity of SCT and its molecular mechanism of action are not yet completely understood. Therefore, in this study, we aimed to determine the immunopharmacological role of SCT and to identify the target of SCT in LPS-activated macrophages.


Scutellarein Reduces Inflammatory Responses by Inhibiting Src Kinase Activity.

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

Chemical structure and anti-inflammatory activity of SCT. (A) Molecular structure of SCT. (B) RAW-264.7 cells (1×106 cells/ml) were pretreated with SCT (left panel) or L-NAME (right panel) for 1 h and incubated with LPS (1 µg/ml) for 24 h. The nitric oxide levels were measured by the Griess assay. (C) Viability of RAW264.7 cells after treatment with SCT for 24 h. Viability was determined by a conventional MTT assay. *p<0.05 and **p<0.01 compared with the control group.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Chemical structure and anti-inflammatory activity of SCT. (A) Molecular structure of SCT. (B) RAW-264.7 cells (1×106 cells/ml) were pretreated with SCT (left panel) or L-NAME (right panel) for 1 h and incubated with LPS (1 µg/ml) for 24 h. The nitric oxide levels were measured by the Griess assay. (C) Viability of RAW264.7 cells after treatment with SCT for 24 h. Viability was determined by a conventional MTT assay. *p<0.05 and **p<0.01 compared with the control group.
Mentions: Scutellarein (SCT, Fig. 1A) is the active component of Erigeron breviscapus, Clerodendrum phlomidis and Oroxylum indicum Vent and is used to treat inflammation, diabetes, nervous disorders, asthma, rheumatism, digestive disorders, and urinary disorders; it is also given as a bitter tonic [1011]. In addition, Codariocalyx motorius with structural analogue of SCT (SCT-6-O-glucuronide) was also shown to suppress LPS-induced inflammatory responses in macrophages and a HCl/EtOH-triggered gastritis symptoms [12]. From a pharmacological perspective, SCT has been reported to exert antioxidative, anti-cancer, and neuroprotective activities [1314]. Although SCT is known to have a flavonoid-derived backbone, the precise anti-inflammatory activity of SCT and its molecular mechanism of action are not yet completely understood. Therefore, in this study, we aimed to determine the immunopharmacological role of SCT and to identify the target of SCT in LPS-activated macrophages.

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