Objective: To establish a method for structural identification of the metabolites of dendrobine in the human liver microsome incubation system for the first time by UPLC/LTQ-Orbitrap-MS. Method: UPLC/LTQ-Orbitrap-MS was applied to systemically analyze the dendrobine metabolism in the liver microsomes of human.Chromatography separation was performed on a Thermo Hypersil Gold C18 column (2.1 mm×150 mm

1.9 μm) with acetonitrile-0.1% formic acid aqueous solution as mobile phase in gradient elution.Electrospray ionization (ESI) was applied and operated in positive ion mode. Result: Four major metabolites in phase Ⅰ metabolism and one major metabolites in phase Ⅱ metabolism of dendrobine marked as M-250([M+H]+ m/z 250.180 1)

M-262([M+H]+ m/z 262.180 0)

M-280([M+H]+ m/z 280.190 6)

M-296([M+H]+ m/z 296.185 6) and M-440([M]+ m/z 440.227 8) were observed in the human liver microsome incubation system. Conclusion: This study introduces a sensitive and efficient analysis method for detecting dendrobine and its metabolites in human liver mirosomes

and it lays a foundation for the further analysis on the pharmacokinetic research of dendrobine.