Bioactive-guided isolation and identification of oligostilbenes as anti-rheumatoid arthritis constituents from the roots of Caragana stenophylla

Abstract

Ethnopharmacological relevanceThe roots of Caragana stenophylla have been used as folk medicine due to the functions of activating blood, diuresis, analgesic and tonicity, especially in treating rheumatoid arthritis and hypertension. However, the anti-rheumatoid arthritis mechanisms and bioactive ingredients have not previously been fully investigated. Aim of the studyThe aim of this study was to assess the anti-rheumatoid arthritis effects of the roots of Caragana stenophylla ethanol extract (EC), elucidate its mechanism of action and identify its active substances. Materials and methodsAnti-rheumatoid arthritis activity of EC was assessed using type II-collagen induced arthritis in rats. Arthritis severity was evaluated by foot paw volume, arthritis index, joint swelling degree and histopathology. The serum inflammatory cytokines and matrix metalloproteinases (MMPs) were also detected by immunohistochemical analysis. In addition, the protein expression of IκB, p-IκB, iNOS and COX-2 was analyzed by western blot. RAW 264.7 macrophage cells were employed to assess the anti-inflammatory effects of fractions and compounds in vitro. UPLC-Q-TOF-MS was adopted to appraise the ingredients of the active fraction of the roots of C. stenophylla. Furthermore, various chromatographic techniques and spectroscopic methods were used for isolation and structure elucidation of compounds. ResultsThe results showed that EC could reduce type II collagen-induced rheumatoid arthritis model arthritic score and histopathology markedly at dose of 240 mg/kg. Besides, EC could suppress the levels of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, IL-17, and TNF-α) and matrix metalloproteinases (MMP-3, MMP-9), and the expression levels of COX-2, p-IκB and iNOS also were declined. While, the levels of IL-10 and IκB were increased. The ethyl acetate fraction exhibited potent inhibitory effects against nitric oxide production in RAW 264.7 macrophage cells. Eleven main components including 1 flavonoid and 10 oligostilbenes from active fraction were isolated by mass directed chromatographic techniques. Their structures were determined on the basis of various spectroscopic methods and by comparison with the published NMR data. ConclusionThe roots of C. stenophylla attenuated arthritis severity, restored serum cytokine imbalances by regulating NF-κB signaling pathway in type II collagen-induced rheumatoid arthritis model. Oligostilbenes were essential ingredients in ethyl acetate extract of C. stenophylla roots. Stilbenes and flavonoids should be responsible for its anti-rheumatoid arthritis activities.