Arachidonic acid metabonomics study for understanding therapeutic mechanism of Huo Luo Xiao Ling Dan on rat model of rheumatoid arthritis

Huo Luo Xiao Ling Dan (HLXLD), a traditional Chinese medicine (TCM), is commonly used for the treatment of rheumatoid arthritis (RA). To explore the potential therapeutic mechanism of HLXLD on anti-inflammatory activity. A metabolomic approach based on UFLC–MS/MS to profile arachidonic acid (AA) metabolic changes was used. The cyclooxygenase (COX) and lipoxygenase (LOX) catalyzed metabolites in plasma were quantified on 7, 14, 21, and 28 days after the rats injected with Complete Freund's adjuvant and orally administrated with HLXLD, methotrexate and dexamethasone in parallel as the positive control drugs. Nineteen metabolites involved in COX and LOX pathways in RA model group were significant increased compared with normal group (P < 0.05), including 12-hydroxyeicosatetraenoic acid (12-HETE), 15-HETE, 8-HETE, leukotriene B4(LTB4), prostaglandin E2 (PGE2), PGI2, PGD2, PGF2α, thromboxane B2 (TXB2), etc. From day 7 to day 28, the trajectory direction of HLXLD group and positive control groups gradually moved towards the initial space, and the concentrations of AA and its metabolites after HLXLD treatment were significantly reduced in dual pathways compared to control groups. HLXLD induced a substantial change in the AA metabolic profiles through refrain the expression of COX and LOX. The present investigation also highlights that distinct ingredients of this formula tend to inhibit different target to achieve a therapeutic effect.