Syk/Src/NF-κB axis is essentially targeted in anti-inflammatory and anti-gastritis effects of Bletilla striata ethanol extract

Abstract

Ethnopharmacological relevance

Traditional herbal medicine books “Shin Rhong Bon Cho Kyung” and “Hyang Yak Jip Sung Bang” mentioned that Bletilla striata (Thunb.) Rchb.f. (Orchidaceae) was often used as a medicinal plant and is used in oriental medicine to treat wounds, inflammatory symptoms, and ulcers in stomach, lung, and skin. However, systematic studies on its value as a promising anti-inflammatory remedy were not fully elucidated yet.

Aim of the study: The eventual goal of this paper was to explore anti-inflammatory and anti-gastritis effects of Bletilla striata and its inhibitory mechanism with an ethanol extract of this plant (Bs-EE).

Materials and methods

In vitro study includes nitric oxide (NO) inhibitory test by was Griess assay, cell viability check by MTT assay, mRNA level analysis of inflammatory genes by PCR and RT-PCR, and protein level analysis by Western blotting and CESTA. In vivo analysis was done with a mouse gastritis model triggered by HCl/EtOH. Phytochemical finger printing result was observed by GC/MS-MS.

Results

Our in vitro trials showed that Bs-EE dose-dependently reduced NO production in lipopolysaccharide-, Poly(I:C)-, and Pam3CSK-treated RAW264.7 cells without causing cytotoxicity, as shown by an MTT assay. The levels of inflammation-related genes (iNOS, IL-6, IL-1β) showed meaningful reductions in RT-PCR and real-time PCR. The NF-κB activity enhanced in MyD88-overexpressing HEK293T cells was strongly reduced by Bs-EE. Western blotting results indicated that the Bs-EE suppressed the phosphorylation of IκBα, IKKα/β, AKT, p65, p50, Syk, and Src, which produced anti-inflammatory effects. Both Syk and Src were found to be direct targets of Bs-EE. This extract attenuated the inflammatory effect in a murine acute gastritis model induced by HCl/EtOH.

Conclusions

These findings suggest that an ethanol extract of Bletilla striata could be developed as a promising natural anti-inflammatory drug or health functional food with NF-κB pathway inhibitory activity.