Isolation and identification of ten metabolites of breviscapine in rat urine.

Breviscapine, is the total flavonoid components (the content of scutellarin > or =85%) extracted from the dried whole plant of Erigeron breviscapus (VANT.) HAND.-MAZZ, and its preparations are generally used in the clinic for the treatment of cerebral and cardio-vascular diseases in China. In this paper, the metabolites of breviscapine in the urine of rats after oral administration were investigated. The ten metabolites were isolated by open-column chromatography and preparative high-performance liquid chromatography, and their structures were elucidated by MS, NMR spectroscopy including (1)H-NMR, (13)C-NMR, and NOESY (nuclear Overhauser enhancement spectroscopy), enzymatic hydrolysis and chemical evidence. The ten metabolites were identified as scutellarein-6,7-di-O-beta-D-glucuronide (M-1), scutellarein (M-2), 6-O-methyl-scutellarin (M-3), 6-O-methyl-scutellarein (M-4), scutellarein-6-O-beta-D-glucuronide (M-5), scutellarein-5-O-beta-D-glucuronide (M-6), scutellarin (M-7), scutellarein-7-O-sulfate (M-8), apigenin-5-O-beta-D-glucuronide (M-9), and apigenin-4'-O-beta-D-glucuronide (M-10) respectively. The results of this study indicated that the metabolites of brevisvapine were excreted in rats urine as glucuronidated, sulfated or methylated forms, as well as the aglycone of scutellarin-scutellarein after oral administration, and the metabolic pathways were also proposed.