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

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.