Dipterocarpus tuberculatus Roxb. Ethanol Extract Has Anti-Inflammatory and Hepatoprotective Effects In Vitro and In Vivo by Targeting the IRAK1/AP-1 Pathway.

Dipterocarpus tuberculatus Roxb. has been used traditionally as a remedy for many diseases, especially inflammation. Therefore, we analyzed and explored the mechanism of the anti-inflammatory effect of a Dipterocarpus tuberculatus Roxb. ethanol extract (Dt-EE). Dt-EE clearly and dose-dependently inhibited the expression of pro-inflammatory cytokines such as IL-6, TNF-α, and IL-1ß in lipopolysaccharide (LPS)-treated RAW264.7 cells. Also, Dt-EE suppressed the activation of the MyD88/TRIF-mediated AP-1 pathway and the AP-1 pathway related proteins JNK2, MKK4/7, and TAK1, which occurred as a result of inhibiting the kinase activity of IRAK1 and IRAK4, the most upstream factors of the AP-1 pathway. Finally, Dt-EE displayed hepatoprotective activity in a mouse model of hepatitis induced with LPS/D-galactosamine (D-GalN) through decreasing the serum levels of alanine aminotransferase and suppressing the activation of JNK and IRAK1. Therefore, our results strongly suggest that Dt-EE could be a candidate anti-inflammatory herbal medicine with IRAK1/AP-1 inhibitory and hepatoprotective properties.

Sauropus brevipes ethanol extract negatively regulates inflammatory responses in vivo and in vitro by targeting Src, Syk and IRAK1.

CONTEXT: Sauropus brevipes Müll. Arg. (Phyllanthaceae) has been used as an effective ingredient in a decoction for the treatment of diarrhoea. However, there was no report on its modulatory role in inflammation. OBJECTIVE: This study investigates anti-inflammatory effect of S. brevipes in various inflammation models. MATERIALS AND METHODS: The aerial part of S. brevipes was extracted with 95% ethanol to produce Sb-EE. RAW264.7 cells pre-treated with Sb-EE were stimulated by lipopolysaccharide (LPS), and Griess assay and PCR were performed. High-performance liquid chromatography (HPLC) analysis, luciferase assay, Western blotting and kinase assay were employed. C57BL/6 mice (10 mice/group) were orally administered with Sb-EE (200 mg/kg) once a day for five days, and peritonitis was induced by an intraperitoneal injection of LPS (10 mg/kg). ICR mice (four mice/group) were orally administered with Sb-EE (20 or 200 mg/kg) or ranitidine (positive control) twice a day for two days, and EtOH/HCl was orally injected to induce gastritis. RESULTS: Sb-EE suppressed nitric oxide (NO) release (IC50=34 µg/mL) without cytotoxicity and contained flavonoids (quercetin, luteolin and kaempferol). Sb-EE (200 µg/mL) reduced the mRNA expression of inducible NO synthase (iNOS). Sb-EE blocked the activities of Syk and Src, while inhibiting interleukin-1 receptor associated kinases (IRAK1) by 68%. Similarly, orally administered Sb-EE (200 mg/kg) suppressed NO production by 78% and phosphorylation of Src and Syk in peritonitis mice. Sb-EE also decreased inflammatory lesions in gastritis mice. DISCUSSION AND CONCLUSIONS: This study demonstrates the inhibitory effect of Sb-EE on the inflammatory response, suggesting that Sb-EE can be developed as a potential anti-inflammatory agent.

Dipterocarpus tuberculatus ethanol extract strongly suppresses in vitro macrophage-mediated inflammatory responses and in vivo acute gastritis.

ETHNOPHARMACOLOGICAL RELEVANCE: Dipterocarpus tuberculatus Roxb. (Dipterocarpaceae) has been traditionally used to treat various inflammatory symptoms. However, no mechanistic studies on the anti-inflammatory actions of D. tuberculatus have been reported. This study is therefore aimed at exploring the anti-inflammatory effects of 95% ethanol extracts (Dt-EE) of this plant. MATERIALS AND METHODS: The regulatory activity of Dt-EE and its molecular mechanism on the release of nitric oxide (NO) and prostaglandin (PG)E2 in lipopolysaccharide (LPS)-treated macrophage-like RAW264.7 cells were elucidated by evaluating the activation of transcription factors and their upstream signals and by analyzing the kinase activities of target enzymes. Furthermore, to confirm its availability for oral use, an EtOH/HCl-induced acute gastritis model was tested with this extract. RESULTS: Dt-EE effectively suppressed LPS-mediated inflammatory responses such as the production of NO and PGE2 from macrophages in a dose-dependent manner. In particular, Dt-EE clearly blocked the activation of NF-κB by blocking the phosphorylation of its upstream enzymes IKK and Akt. Using a direct enzyme assay, Dt-EE was shown to block the enzyme activity of PDK1. Finally, this extract also remarkably ameliorated inflammatory lesions in the stomach induced by EtOH/HCl. CONCLUSION: Our data strongly suggest that Dt-EE can be considered as a novel anti-inflammatory remedy with PDK1/NF-κB inhibitory properties and can also be used to treat gastritis symptoms. In addition, our findings can serve as a basis for further phytochemical and pharmacological studies in the future.