Anti-inflammatory activities of Gouania leptostachya methanol extract and its constituent resveratrol.

Gouania leptostachya DC. var. tonkinensis Pitard. Rhamnaceae is a traditional medicinal plant used in Thailand for treating various inflammatory symptoms. However, no systematic studies have been performed concerning the anti-inflammatory effects or molecular mechanisms of this plant. The immunopharmacological activities of a methanol extract from the leaves and twigs of G. leptostachya (Gl-ME) were elucidated based on the gastritis symptoms of mice treated with HCl/EtOH and the inflammatory responses, such as nitric oxide (NO) release and prostaglandin E2 (PGE2) production, from RAW264.7 cells and peritoneal macrophages. Moreover, inhibitory target molecules were also assessed. Gl-ME dose-dependently diminished the secretion of NO and PGE2 from LPS-stimulated RAW264.7 cells and peritoneal macrophages. The gastritis lesions of HCl/EtOH-treated mice were also attenuated after Gl-ME treatment. The extract (50 and 300 µg/mL) clearly reduced mRNA expression of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2, nuclear translocation of p65/nuclear factor (NF)-κB, phosphorylation of p65-activating upstream enzymes, such as protein kinase B (AKT), inhibitor of κBα kinase (IKK), and inhibitor of κB (IκBα), and the enzymatic activity of Src. By HPLC analysis, one of the major components in the extract was revealed as resveratrol with NO and Src inhibitory activities. Moreover, this compound suppressed NO production and HCl/EtOH-induced gastric symptoms. Therefore, these results suggest that Gl-ME might be useful as an herbal anti-inflammatory medicine through the inhibition of Src and NF-κB activation pathways. The efficacy data of G. leptostachya also implies that this plant could be further tested to see whether it can be developed as potential anti-inflammatory preparation.