Potential active fractions and constituents in the flowers of Trollius chinensis Bunge responsible for treating acute pharyngitis.

Abstract

Trollius chinensis Bunge has a long history of use in China as traditional Chinese medicine and functional tea for the treatment of respiratory infections, such as pharyngitis, tonsillitis and bronchitis. Pharyngitis can impact the entire throat and adjacent lymphoid tissues, and may lead to significant systemic complications. However, the active components and mechanism of Trollius chinensis Bunge for treating acute pharyngitis remains unclear. Trollius chinensis Bunge is recognized in China both as a medicinal herb and a functional tea. Research into its properties aimed to establish its effectiveness against pharyngitis and to pinpoint the active components and mechanism. A 70% ethanol extract from the herb was prepared, which was refined using chromatography through a column containing D101 macroporous resin and varying ethanol solutions. The efficacy of the initial and refined extracts was tested using a rat model of ammonia-induced acute pharyngitis. Pathological examination, HE staining and ELISA were applied to screen activity fraction. The compounds were isolated by silica gel, sephadex LH-20 column chromatography and semi-preparative HPLC chromatography from active fraction. All of the isolated compounds were assessed for anti-inflammatory activity by acting on LPS-induced RAW 264.7 macrophage cells in vitro. Cytotoxicity of compounds was detected by CCK-8 assay. The Griess reaction was applied to evaluate the inhibitory effects of isolated compounds on NO production in RAW 264.7 cells induced by LPS. TNF-α, IL-6, IL-1β and PGE2 levels in macrophage supernatant were detected by ELISA. Molecular docking and western blot analysis were applied to study the anti-inflammatory mechanism of active compound. The fraction extracted with 30% ethanol proved particularly effective, significantly reducing pharyngitis symptoms. This was evidenced by decreased levels of cytokines (TNF-α, IL-6, IL-1β and PGE2) and visible improvements in the pharyngeal tissue histology. In pursuit of pharyngitis treatments, 23 phenolic acids and 13 flavonoids were isolated from the 30% ethanol fraction and identified using spectral analysis. Of these, three were newly discovered compounds and eight were first-time isolates from the Trollius genus. These compounds were further investigated for their ability to suppress nitric oxide production in RAW 264.7 cells triggered by lipopolysaccharide. Compounds 3, 19, and 26 exhibited strong anti-inflammatory properties. HPLC analysis of the 30% ethanol fraction revealed that orientin was the predominant component, accounting for 44.4% of this fraction. Western blot analysis demonstrated that orientin reduced the expression levels of the protein p-p65 relative to p65, p-IκBα relative to IκBα and iNOS, indicating an anti-inflammatory effect potentially through the modulation of the NF-κB signaling pathway. The finding of this study provided strong support for the use of T. chinensis as a potential functional food for treating pharyngitis.