Screening bioactive compounds from Qianghuo (Notopterygium incisum) volatile oil via COX-2 magnetic ligand fishing

Qianghuo (the rhizomes and radixes of Notopterygium incisum Ting ex H.T. chang) is a traditional Chinese medicine, and widely used as an anti-inflammatory, anodyne, antifebrile agent. Qianghuo volatile oil also exhibits the same properties, and the effects are probably related to the inhibition of cyclooxygenase (COX), but its bioactive components are not clear yet. To figure out the bioactive components of Qianghuo volatile oil target to cyclooxygenase-2 (COX-2), a ligand fishing method using immobilized COX-2 magnetic beads (COX-2-MB S ) and gas chromatography–mass spectrometry (GC–MS) were developed to identify the compounds that act on COX-2. Nine ligands, including 3-carene, β-caryophyllene, eucalyptol, α-terpinene, Limonene, δ-terpinene, α-pinene, β-pinene and γ-terpinene, were specifically captured by COX-2-MB S . Among them, 3-carene, β-caryophyllene, and eucalyptol in Qianghuo volatile oil were isolated and confirmed by in vitro inhibition and in vivo anti-inflammatory activity assays as selective inhibitor against COX-2. The IC 50 values were 13.5, 10.1, and 7.6 μM, respectively. Compared with the model, 3-carene, β-caryophyllene, and eucalyptol considerably reduced ear swelling and paw edema. Moreover, 3-carene and eucalyptol significantly decreased the changes of COX-2 expression in RAW264.7 cells activated by LPS. Our study validated that the developed ligand-fishing method using COX-2-MBs coupled with GC–MS can be applied to recognize COX-2 inhibitors in Qianghuo volatile oil. In vitro/vivo assay showed 3-carene and eucalyptol in Qianghuo volatile oil had strong inhibition against COX-2. This study may provide novel methods for discovering active components for volatile oil–based drug development or aromatherapy.