Metabolism studies of casticin in rats using HPLC-ESI-MS(n).

Casticin (3',5-dihydroxy-3, 4',6,7-tetramethoxyflavone) has been revealed to possess various kinds of pharmacological activities, including immunomodulatory, anti-hyperprolactinemia, anti-tumor and neuroprotetective activities. In order to gain an understanding of the biotransformation of casticin in vivo, a systematic method based on liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS(n) ) was developed to identify the metabolites of casticin in rats after oral administration of single dose of casticin at 200 mg/kg. By comparing their changes in molecular masses (ΔM), retention times and spectral patterns with those of the parent drug, the parent compound and 25 metabolites were identified in rat plasma, urine and six selected tissues. This is the first systematic metabolism study of casticin in vivo. The results indicated that methylation, demethylation, glucuronidation and sulfation were the main biotransformation pathways of casticin in vivo.