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A sensitive and specific liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS) method for the simultaneous determination of spironolactone and its active metabolite canrenone in human plasma has been developed and validated. After the addition of estazolam as the internal standard (IS), plasma samples were extracted with methylene chloride : ethyl acetate mixture (20 : 80, v/v) and separated by high-performance liquid chromatography (HPLC) on a reversed-phase C18 column with a mobile phase of methanol-water (57 : 43, v/v). Analytes were determined in a single quadrupole mass spectrometer using an atmospheric pressure chemical ionization (APCI) source. LC-APCI-MS was performed in the selected-ion monitoring (SIM) mode using target ions at m/z 341.25 for spironolactone and canrenone, m/z 295.05 for estazolam. The method was proved to be sensitive and specific by testing six different plasma batches. Calibration curves of spironolactone and canrenone were linear over the range 2-300 ng/ml. The within- and between-batch precisions (relative standard deviation (RSD)%) were lower than 10% and the accuracy ranged from 85 to 115%. The lower limit of quantification (LLOQ) was identifiable and reproducible at 2 ng/ml. The proposed method was successfully applied to study the pharmacokinetics of spironolactone and its major metabolite in healthy male Chinese volunteers.

This work concentrates on the in vitro metabolism of anthraquinone derivatives from rhubarb. Different metabolic reactions for anthraquinone derivatives were dependent on the substituent group in the skeleton. Monohydroxylation in the exocyclic methyl group was the major metabolic modification for emodin. Aloe-emodin containing a hydroxymethyl group was mainly metabolized through a methylation reaction. For rhein, both hydrogenation and methyl substitution on the benzene ring were the major metabolic reactions. Hydroxyl substitution on the benzene ring was the predominant metabolic reaction for chrysophanol. For physcion, demethylation of the exocyclic methoxy group was the most important metabolic reaction.

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The aim is to develop a simple and specific method for the extraction and chemical fingerprinting of Andrographis paniculata (Burm. f.) Nees and to apply the method to this drug from different regions. High-performance liquid chromatographic (HPLC) with gradient elution is used for developing the fingerprints, and liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) technique is employed to identify the component of the fingerprints. Nine peaks are selected as common peaks, and six compounds are elucidated by MS data. Twenty-three samples of A. paniculata from different regions of China are collected and detected by HPLC fingerprinting. Comparisons of the chromatograms show that there are obvious differences in the content of each component contained between the habitat samples in China. The results of hierarchical cluster analysis show that these samples can be clustered reasonably into three groups, and the growth of A. paniculata and their internal quality are related to their habitat. The HPLC fingerprint developed allows simple identification of A. paniculata from many natural drugs.