Simultaneous determination of paeonilactone A and paeonilactone B in rat plasma after oral administration of albiflorin by UPLC/TOF/MS following picolinoyl derivatization

A new highly sensitive analytical method was developed to investigate the in vivo metabolism of albiflorin, one of the most principal components in traditional Chinese medicine. After hydrolyzation with sulfatase, the main metabolites paeonilactone A and paeonilactone B of paeoniflorin in rat plasma were successfully detected for the first time by liquid chromatography mass spectrometry following picolinoyl derivatization. Borneol was used as the internal standard compound to quantify paeonilactone A and paeonilactone B in rat plasma. Paeonilactone A and paeonilactone B show different pharmacokinetic behaviors. The maximum plasma concentration of paeonilactone A reached 36.4 ± 5.6 ng/mL at about 8 h after oral administration of albiflorin at a dose of 5 mg/kg, while the maximum plasma concentration of paeonilactone B reached 12.4 ± 3.4 ng/mL at about 2 h. The total metabolic pathway of albiflorin in rats was proposed. Albiflorin was found to be metabolized to the sulfate of paeonilactone A and paeonilactone B which may be responsible for the biological effect of albiflorin. The new analytical method may help to elucidate the clinical efficacy of traditional Chinese formula containing albiflorin.