Objective:To identify the metabolites of isorhamnetin-3-O-β-D-rutinoside bio-transformed by rat intestinal flora in vitro. Method: Isorhamnetin-3-O-β-D-rutinoside was incubated with rat anaerobic intestinal flora in vitro with HPLC monitoring the biotransformation course

and a LC-MS method based on the combined use of ultra-performance liquid chromatography

electro-spray ionization

collision-induced dissociation and tandem mass spectrometry has been applied to an investigation of the structural characterization of biotransformation products. The metabolites were identified by accurate molecular weight

CID-MS-MS fragmentation information

combined with reference substance and literature data review. Result: Five metabolites-quercetin

isorhamnetin

kaempferol

quercetin-3-O-glucoside and isorhamnetin-3-O-glucoside were identified though the above method

and another compound

maybe

5

7

3'

4'-tetramethoxy flavonoid-3-O-glucoside

need more information to identify. Conclusion: During the biotransformation by rat intestinal flora in vitro

isorhamnetin-3-O-β-D-rutinoside usually lose its glycosyl ligands

-OH or be adding-CH3

and which lead to their lipophilicity and chemical diversity increasing.