The in vivo and in vitro metabolism of jatrorrhizine has been investigated using a specific and sensitive LC/MS/MS method. In vivo samples including rat feces, urine and plasma collected separately after dosing healthy rats with jatrorrhizine (34 mg/kg) orally, along with in vitro samples prepared by incubating jatrorrhizine with rat intestinal flora and liver microsome, respectively, were purified using a C(18) solid-phase extraction cartridge. The purified samples were then separated with a reversed-phase C(18) column with methanol-formic acid aqueous solution (70:30, v/v, pH3.5) as mobile phase and detected by on-line MS/MS. The structural elucidation of the metabolites was performed by comparing their molecular weights and product ions with those of the parent drug. As a result, seven new metabolites were found in rat urine, 13 metabolites were detected in rat feces, 11 metabolites were detected in rat plasma, 17 metabolites were identified in intestinal flora incubation solution and nine metabolites were detected in liver microsome incubation solution. The main biotransformation reactions of jatrorrhizine were the hydroxylation reaction, the methylation reaction, the demethylation reaction and the dehydrogenation reaction of parent drug and its relative metabolites. All the results were reported for the first time, except for some of the metabolites in rat urine.
1. In vitro metabolism of the antiprogestin drug mifepristone (RU-486) was studied after incubation with rat, monkey and human hepatic S9 fractions in the presence of an NADPH-generating system. 2. Unchanged mifepristone (approximately 45% of the sample(s) in rat; approximately 70% in monkey; approximately 65% in human) plus six metabolites, three known and three new, were profiled, quantified and tentatively identified on the basis of MS and MS/MS data. 3. The proposed metabolic pathways for mifepristone are proposed, and the two metabolic steps are (A) N-demethylation and (B) methyl oxidation. 4. Step A formed N-desmethyl mifepristone (M1) in major amounts (approximately 35% s in rat, 16% in monkey and human) and N,N-didesmethyl mifepristone (M2) in minor amounts (< 5% s in all species). Step B, or in conjunction with step A, produced four minor/trace metabolites, namely hydroxymethyl mifepristone (M3), hydroxymethyl M1 (M4), hydroxymethyl M2 (M5) and formyl mifepristone (M6).
Two impurities in the natural vitamin E extracted from oil deodorizer distillate were separated and characterized by high-performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS) and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). The impurities were purified and collected by normal-phase HPLC. The accurate masses were determined using FTICR-MS and fragmentation behavior was studied by GC-MS. The results showed that the impurities had identical MS spectra and similar electron impact (EI) fragmentation patterns. Based on the spectra, the structures of the two impurities were proposed as the enantiomers of sesamin. The presented method is rapid and effective, and can be applied for the food safety to the vitamin E manufacturing industry.
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