Identification of flavonoid metabolites after oral administration to rats of a Ginkgo biloba extract.
An extract of Ginkgo biloba leaves (EGb) was administered by gastric probe to Wistar female rats, and urine and faeces samples were collected for 5 days and whole blood samples were withdrawn every 30 min for 6 h. After purification with SPE C18 cartridges, the samples were analysed by reversed-phase LC-diode array detection (LC-DAD) for residual flavonoid glycosides, aglycones and metabolites. No glycosides or aglycones were detected in urine, faeces or blood and extensive degradation of EGb flavonoids within 24 h was detected. Among the seven different phenylalkyl acids detected by LC-DAD, 3,4-dihydroxyphenylacetic acid (I), hippuric acid (II), 3-hydroxyphenylacetic acid (III), homovanillic acid (IV) and benzoic acid (VII) were directly confirmed by on-line mass spectrometry using an electrospray interface (ES-MS). Peaks V and VI needed to be collected and separately examined and they were found to be 3-(4-hydrophenyl)propionic acid and 3-(3-hydrophenyl)propionic acid, respectively. As further evidence, the identity of metabolites I, II, III, IV, V and VII was confirmed by co-chromatography with authentic standards.
Pietta
P G
PG
CNR-ITBA, Milan, Italy.
Gardana
C
C
Mauri
P L
PL
Maffei-Facino
R
R
Carini
M
M
D015102:3,4-Dihydroxyphenylacetic Acid / Q000032:analysis; D000284:Administration, Oral; D000818:Animals; D001565:Benzoates / Q000032:analysis; D019817:Benzoic Acid; D002851:Chromatography, High Pressure Liquid; D005243:Feces / Q000737:chemistry; D005260:Female; D005419:Flavonoids / Q000378:metabolism*; D044948:Flavonols; D016166:Free Radical Scavengers / Q000378:metabolism*; D006626:Hippurates / Q000032:analysis; D006719:Homovanillic Acid / Q000032:analysis; D013058:Mass Spectrometry; D010648:Phenylacetates / Q000032:analysis; D010936:Plant Extracts / Q000008:administration & dosage / Q000378:metabolism*; D011422:Propionates / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D013053:Spectrophotometry
D001565:Benzoates; D005419:Flavonoids; D044948:Flavonols; D016166:Free Radical Scavengers; D006626:Hippurates; D010648:Phenylacetates; D010936:Plant Extracts; D011422:Propionates; D015102:3,4-Dihydroxyphenylacetic Acid; D019817:Benzoic Acid; C008069:3-hydroxybenzeneacetic acid; C030514:hippuric acid; D006719:Homovanillic Acid