Objective: To profile and identify metabolites of 2'-methoxykurarinone in rat plasma by UPLC-Q-Exactive Orbitrap-MS. Method: SD rats were orally administered 2'-methoxykurarinone and blood samples were collected through retro orbital sinus to obtain plasma.The extraction of analytes from rat plasma were achieved by solid-phase extraction method on a HyperSep Retain PEP column.The mobile phase consisted of acetonitrile and 0.1% formic acid in water.Separation was achieved on a Hypersil GOLD column.The data acquisition was carried out by electrospray ionization (ESI) with full scan and second stage mass scan in negative ion mode (spray voltage of 3 kV

capillary temperture at 320℃

m/z 100-1 000).Possible metabolites were detected and identified according to the information of chromatograph and mass spectrometry. Result: Seven phase Ⅰ metabolites and four phase Ⅱ metabolites of 2'-methoxykurarinone were detected in rat plasma.These metabolites were formed by a series of metabolic reactions

including dehydrogenation

hydroxylation

hydroxylation+dehydrogenation

hydration

sulfation conjugation

glucuronidation

and hydroxylation+glucuronidation. Conclusion: The method of UPLC-Q-Exactive Orbitrap-MS coupled with Xcalibur 4.0 can provide structural information of analytes

which provides a reliable method for the identification of metabolites of 2'-methoxykurarinone.The phase Ⅰ metabolic reaction of 2'-methoxykurarinone occurs mainly in the prenyl moiety.