Effective extraction of Xuetongsu and its role in preventing RA synovial hyperplasia by targeting synovial cell migration and apoptosis

Kadsura heteroclita (Roxb) Craib also named Xuetong in Tujia ethnomedicine in China, has been traditionally employed in rheumatoid arthritis (RA) treatment. Our preceding investigations have elucidated that Xuetongsu (XTS), a triterpenoid compound predominant in Xuetong, showed excellent anti-RA-fibroblast-like synoviocytes (RAFLS) proliferation effect. However, XTS belongs to the trace components of the Xuetong plant, which poses certain limitations to the research. In this study, we designed a method that enhanced the extraction yield of XTS and explored the mechanism of its inhibition of RAFLS cell proliferation and migration in the treatment of RA. The results displayed that XTS reduced RAFLS cell proliferation, with an IC₅₀ value of 4.68 ± 0.65 µM. A series of experimental techniques were utilized to show that XTS induce apoptosis in RAFLS cells at concentrations ranging from 4.5 to 18 µM, including wound healing assay, flow cytometry, and western blot analysis. Moreover, XTS at dosages of 0.42-0.84 mg/kg markedly attenuated paw swelling and synovial hyperplasia in arthritic rats, primarily through the inhibition of RAFLS migration and promotion of RAFLS apoptosis via High mobility group box 1 (HMGB-1)/Matrix metalloproteinase-9 (MMP-9)/MMP-13 signaling pathway and Bcl-2/Bax/Caspase-3 signaling pathway, respectively.