Screening Anti–Rheumatoid Arthritis Synovitis Effective Ingredients of Total Flavonoid From Artemisia argyi Folium Based on Spectrum–Effect Relationship

ABSTRACT Introduction Flavonoids are the main nonvolatile component responsible for the anti–rheumatoid arthritis (RA) synovitis activities of Artemisia argyi Folium. However, the effective ingredient remains unidentified. Spectrum–effect relationships analysis was a reliable and efficient strategy for herbal effective ingredient discovery. Objectives This study aimed to screen the effective ingredients within the total flavonoid from Artemisia argyi Folium (TFAA) that exhibit anti‐RA synovitis activities based on spectrum–effect relationship. Methods TFAA was obtained through ethanol extraction and subsequent purification with D101 resin from 15 distinct batches of Artemisia argyi Folium. The fingerprint of TFAA was established using HPLC, and its efficacy against RA synovitis was evaluated by determining the inhibition rate of nitric oxide (NO) on MH7A synovioblast induced by TNF‐α. Common peaks were identified using HPLC‐MS/MS and authentic standards. The spectrum–effect relationships between the fingerprints and efficacy were analyzed by gray relational analysis (GRA), canonical correlation analysis (CCA), and partial least squares regression analysis (PLSR) to pinpoint the peaks responsible for the anti‐RA synovitis activity, and the results were further verified by in vitro anti‐RA synovitis experiments and molecular docking studies. Results The fingerprint revealed 14 common peaks, and 12 compounds were identified, including four caffeoylquinic acids and eight flavonoids. Among them, five flavonoids—X10 (hispidulin), X11 (jaceosidin), X12 (centaureidin), X13 (eupatilin), and X14 (casticin)—were highly relevant to anti‐RA synovitis activity. Verification experiments confirmed their inhibitory effect on NO production and cytokine secretion in MH7A cells, showing anti‐RA synovitis potential, which was consistent with the established spectrum effect relationship. The underlying mechanism might be related to the inhibition of iNOS. Conclusion Hispidulin, jaceosidin, centaureidin, eupatilin, and casticin were the key effective ingredient of TFAA responsible for its anti‐RA synovitis effects. These compounds can serve as quality control markers for Artemisia argyi Folium and as lead compounds for anti‐RA synovitis treatment.