Exploring the pharmacological mechanisms and key active ingredients of total flavonoids from Lamiophlomis rotata (Benth.) Kudo against rheumatoid arthritis based on multi-technology integrated network pharmacology

Lamiophlomis rotata (Benth.) Kudo (LR, Lamiaceae) is a traditional Tibetan medicinal material in China. Tibetan medicine classic and research report suggested that LR could be used to cure rheumatoid arthritis (RA). However, the anti-RA active ingredients and pharmacological mechanisms of LR have not been elucidated.To explore the mechanisms and key active ingredients of total flavonoids from LR (TFLR) against RA.First, the mechanisms of TFLR against RA were investigated on collagen-induced arthritis (CIA) rat model by analyzing paw appearance, paw swelling, arthritis score, spleen index, thymus index, inflammatory cytokine (TNF-α, IL-1β, IL-6 and IL-17) levels in serum, histopathology of ankle joint and synovium from knee joint (hematoxylin-eosin, safranin O-fast green and DAB-TUNEL staining), and apoptosis-related protein (PI3K, Akt1, p-Akt, Bad, p-Bad, Bcl-xL and Bcl-2) levels in the synovium of ankle joints (Western blot). Then, the crucially active ingredients of TFLR against RA were explored by network pharmacology, ingredient analysis, in vitro metabolism and TNF-α-induced human RA synovial fibroblast MH7A proliferation assays. Network pharmacology was applied to predict the key active ingredients of TFLR against RA. The ingredient analysis and in vitro metabolism of TFLR were performed on HPLC, and MH7A proliferation assay were applied to evaluate the predicted results of network pharmacology.TFLR shown excellently anti-RA effect by reducing paw swelling, arthritis score, spleen index, thymus index and inflammatory cytokine (IL-1β, IL-6 and IL-17) levels, and improving the histopathological changes of ankle joint and synovium from knee joint in CIA rats. Results of Western blot indicated that TFLR reversed the changes of PI3K, p-Akt, p-Bad, Bcl-xL and Bcl-2 levels in the ankle joint synovium of CIA rats. Results of network pharmacology exhibited that luteolin was identified as the pivotal active ingredient of TFLR against RA. The ingredient analysis of TFLR indicated that the main ingredient in TFLR was luteoloside. The in vitro metabolism study of TFLR suggested that luteoloside could be converted to luteolin in artificial gastric juice and intestinal juice. Results of MH7A proliferation assay showed that there was no significant difference between TFLR and equal luteoloside on the viability of MH7A cells, indicating that luteoloside was the key active ingredient of TFLR against RA. Additionally, the luteolin (same mol as luteoloside) showed better inhibitory effect on the viability of MH7A cells than luteoloside.TFLR showed anti-RA effect, and the mechanism was related to promoting synovial cell apoptosis mediated by PI3K/Akt/Bad pathway. Meanwhile, this work indicated that luteoloside was the key active ingredient of TFLR against RA. This work lays a foundation for providing TFLR product with clear mechanism and stable quality to treat RA.