swertiamarin and erythrocentaurin

The metabolism of swertiamarin in vivo was studied by LC-MS following 2,4-dinitrophenylhydrazine derivatization. The ionization efficiency of the main metabolite erythrocentaurin was greatly enhanced by the new analytical method developed, and erythrocentaurin was successfully detected for the first time in rat plasma after oral administration of swertiamarin. Methyl 4-formylbenzoate was used as the internal standard to quantify erythrocentaurin in rat plasma in negative mode by UPLC-TOF-MS, and it was found that erythrocentaurin reached the maximum mean plasma concentration of 425.8 ± 127.6 ng/mL at about 2 h after oral administration of swertiamarin at a dose of 200 mg/kg. A metabolic pathway of swertiamarin to erythrocentaurin was proposed. Swertiamarin is first hydrolyzed by bacterial β-glucusidase to give the aglycone, which is readily converted to erythrocentaurin. The monoterpene compound swertiamarin was found to be metabolized to dihydroisocoumarin and alkaloid compounds in vivo, which may be responsible for the pharmacological effect of swertiamarin. The results may shed light on the clinical efficacy of swertiamarin and the new analytical method may assist in studies for the metabolism of other natural iridoids and secoiridoids in vivo.

Topics: Administration, Oral; Animals; Chromatography, High Pressure Liquid; Iridoid Glucosides; Isocoumarins; Limit of Detection; Metabolic Networks and Pathways; Phenylhydrazines; Pyrones; Rats; Rats, Wistar; Swertia; Tandem Mass Spectrometry

The metabolism of swertiamarin (STM) in vivo was studied by LC/MS following picolinoyl derivatization. Incubation of erythrocentaurin (ECR), one of the main in vitro metabolites of STM by intestinal bacteria, with liver microsome indicated that STM may be metabolized to the final metabolite 3,4-dihydro-5-(hydroxymethyl) isochroman-1-one (HMIO) in vivo. After hydrolyzation with sulfatase, HMIO was successfully detected in rat plasma after oral administration of STM by LC/MS following picolinoyl derivatization. 4-Methoxyphenyl methanol was used as the internal standard to quantify HMIO in rat plasma. The full metabolic pathway of STM in rats is proposed. STM is first hydrolyzed by bacterial β-glucusidase to give aglycone, which is readily converted to ECR and nitrogen-containing metabolite. ECR is further reduced to HMIO by both liver and intestinal bacteria and HMIO is finally converted to the new sulfate conjugate metabolite. The monoterpene compound STM was found to be metabolized to dihydroisocoumarin and alkaloid compounds in vivo, which may be responsible for the pharmacological effect of STM. The results may shed light on clinical efficacy of STM and the new analytical method developed may assist in studies of the metabolism of other natural iridoids and secoiridoids in vivo.

Topics: Administration, Oral; Animals; Chromans; Chromatography, Liquid; Drug Stability; Iridoid Glucosides; Isocoumarins; Mass Spectrometry; Microsomes, Liver; Pyrones; Rats; Rats, Wistar; Reproducibility of Results

When cultivated with Aspergillus niger, swertiamarin, an important drug, is rapidly transformed into erythrocentaurin and (5Z)-5-ethylidene-8-hydroxy-3,4,5,6,7,8-hexahydro-1H-pyrano[3,4-c]pyridin-1-one (M(1)), a new compound with high anti-inflammatory activity. A simple and rapid HPLC method for simultaneous determination of swertiamarin and its two metabolites in broth of A. niger is described. The chromatographic separation was achieved on a C(18) ODS column (250 x 4.6 mm i.d.) by gradient elution with 0.04% formic acid in water and 0.04% formic acid in acetonitrile as the gradient mixtures. The flow rate was 1 mL/min, the detection wavelength was 237 nm and the column temperature was kept at 30 degrees C. The retention times of swertiamarin, erythrocentaurin and M(1) were 14.6, 16.8 and 24.8 min, respectively. The mean absolute recoveries of three analysts were over 96%. Quantification limits were 0.02 microg/mL for swertiamarin and 0.05 microg/mL for both of the two metabolites. The method was applied for the quantification of swertiamarin and its two metabolites during the fermentation process and the evaluation of the bioavailabilities in the Caco-2 monolayer.

Topics: Aspergillus niger; Cell Line; Chromatography, High Pressure Liquid; Glucosides; Humans; Iridoid Glucosides; Iridoids; Isocoumarins; Pyrones; Reproducibility of Results