Rapid characterization and pharmacokinetic study of aristolochic acid analogues using ion mobility mass spectrometry.

Aristolochic acid analogues (AAAs), naturally existing in herbal Aristolochia and Asarum genera, were once widely used in traditional pharmacopeias because of their anti-inflammatory properties, but lately they were identified as potential nephrotoxins and mutagens. A method for rapid characterization of AAAs in serum was developed using ion mobility spectrometry coupled with mass spectrometry (IMS-MS). Five AAAs, containing four aristolochic acids and one aristolactam, were separated and identified within milliseconds. AAAs were separated in gas phase based on the difference of their ion mobility (K0), and then identified based on their K0 values, m/z, and product ions from MS/MS. Quantitative analysis of AAAs was performed using an internal standard with a satisfactory sensitivity. Limits of detection (signal-to-noise = 3) and quantification (signal-to-noise = 10) were 1-5 ng/mL and 3-8 ng/mL, respectively. The method was validated and successfully applied to the pharmacokinetics study of AAAs in rats, offering a promising way for fast screening and evaluation of AAAs in biological samples.

Effects of rhein and Rheum palmatum L. extract on the pharmacokinetics and tissue distribution of aristolochic acid I and its demethylated metabolite in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Aristolochic acid nephropathy (AAN) is a kidney disease caused by the administration of plants containing aristolochic acids (AAs). Aristolochic acid I (AAI) is the main toxic component in AAs. Organic anion transporters (OATs) 1 and 3 mediate the renal uptake of AAI, which is related to AAN. In our previous study, we found that anthraquinones derived from the herbal medicine Rheum palmatum L. (RP) inhibited both OAT1 and OAT3, with rhein exhibiting the greatest potency among the components. AIM OF THE STUDY: This study aimed to investigate the effects of rhein and RP extract on the pharmacokinetics and tissue distribution of AAI and its demethylated metabolite (8-hydroxy-aristolochic acid I [AAIa]) in rats. MATERIALS AND METHODS: Rhein and RP extract were used as OAT inhibitors, and AAI was used as the toxic substrate. The pharmacokinetics and tissue distribution of AAI and AAIa in rats following the intravenous injection of AAI (10 mg/kg) in the presence and absence of rhein (100 mg/kg) or RP extract (5 g crude drug/kg) were investigated. RESULTS: Co-administration with rhein increased AUC0-∞ of AAI and AAIa by 39 and 44%, respectively. However, the renal level of AAI was decreased to 50, 42, and 58% of those in rats treated with AAI alone at 5, 10, and 20 min after treatment, respectively, and the renal level of AAIa was decreased to 58, 57, and 61% of the level in rats treated with AAI alone, respectively, at these time points. In the RP extract co-administration group, AAI and AAIa plasma exposure was not significantly increased, but renal accumulation of AAI was decreased to 63, 58, and 68% of that in rats treated with AAI alone at 5, 10, and 20 min after treatment, respectively. In addition, renal accumulation of AAIa was decreased to 74, 70, and 70% of that in rats treated with AAI alone at 5, 10, and 20 min after treatment, respectively. CONCLUSIONS: This study indicated that co-administration with rhein significantly increased the plasma exposure of AAI and AAIa while decreased their renal accumulation in rats. RP extract reduced the renal accumulation of AAI and AAIa, but have no significant effect on their plasma exposure levels in rats.

Comparative studies on the multi-component pharmacokinetics of Aristolochiae Fructus and honey-fried Aristolochiae Fructus extracts after oral administration in rats.

BACKGROUND: Aristolochiae Fructus (AF) and honey-fried Aristolochiae Fructus (HAF) have been used in China for a long time as anti-tussive and expectorant drugs. Few clinical cases have been reported to be associated with the toxicity of AF and HAF, although relatively high amounts of aristolochic acids (AAs) have been found in them. Our previous experiments have verified from the chemical changes and from traditional toxicology that honey-processing can significantly reduce the toxicity of AF. To further elucidate the detoxification mechanism of honey-processing, comparative pharmacokinetics of AAs in AF and HAF are performed in this study. METHODS: An HPLC-MS/MS (high-performance liquid chromatography-tandem mass spectrometry) method was developed and validated for the determination of AA I, AA II, AA C, AA D and 7-OH AA I in rat plasma. The multi-component pharmacokinetics of AAs in AF and HAF extracts were investigated after the oral administration of three doses to rats. The relative pharmacokinetic parameters were compared systematically. RESULTS: The five AAs shared a similar nonlinear PK (pharmacokinetic) process. They involve rapid absorption and elimination, and they were fit into a two-compartmental open model. Some significant pharmacokinetic differences were observed between the AF and HAF groups: the C max and AUC values of AA I and AA II in the AF groups were much higher than those of the HAF groups. CONCLUSIONS: Honey-frying technology can reduce the toxicity of AF by significantly decreasing the absorption of AA I and AA II. The PK parameters obtained in this work could provide valuable references for the toxicity research and clinical use of Aristolochiaceae herbs, including AF and HAF. Process diagram of comparative pharmacokinetics study.

Three-phase hollow fiber liquid-phase microextraction based on a magnetofluid for the analysis of aristolochic acids in plasma by high-performance liquid chromatography.

A new and fast sample preparation technique based on three-phase hollow fiber liquid-phase microextraction with a magnetofluid was developed and successfully used to quantify the aristolochic acid I (AA-I) and AA-II in plasma after oral administration of Caulis akebiae extract. Analysis was accomplished by reversed-phase high-performance liquid chromatography with fluorescence detection. Parameters that affect the hollow fiber liquid-phase microextraction processes, such as the solvent type, pH of donor and acceptor phases, content of magnetofluid, salt content, stirring speed, hollow fiber length, extraction temperature, and extraction time, were investigated and optimized. Under the optimized conditions, the preconcentration factors for AA-I and AA-II were >627. The calibration curve for two AAs was linear in the range of 0.1-10 ng/mL with the correlation coefficients >0.9997. The intraday and interday precision was <5.71% and the LODs were 11 pg/mL for AA-I and 13 pg/mL for AA-II (S/N = 3). The separation and determination of the two AAs in plasma after oral administration of C. akebiae extract were completed by the validated method.

Cloud point extraction-HPLC method for the determination and pharmacokinetic study of aristolochic acids in rat plasma after oral administration of Aristolochiae Fructus.

Based on cloud-point extraction (CPE), a high performance liquid chromatography method (HPLC) was developed and validated for the determination of aristolochic acids (AAs) in rat plasma after oral administration of Aristolochiae Fructus (AF). Non-ionic surfactant Genapol X-080, an environmentally friendly solvent, was used for the micelle-mediated extraction. Various influencing factors on CPE process were investigated and optimized. AAs were extracted from rat plasma after adding 1ml of 4.5% (v/v) surfactant in the presence of 0.2mol/l HCl and 20mg NaCl, and the incubation temperature and time were 50°C and 10min, respectively. Base-line separation was obtained for the AAs in rat plasma with the optimized chromatography conditions. The detection limits (LOD) reached downward 10ng/ml. The intra-day and inter-day precisions were less than 7.8%, the accuracies were within ±5.5%, and the average recovery factors were in the range of 94.5-105.4%. In comparison with liquid-liquid extraction, the CPE method has a considerable LOD and higher recoveries. The proposed CPE-HPLC method was specific, sensitive and reliable, and could be an effective tool for the determination of AAs in biological matrixes. With the method the pharmacokinetics of AAs were investigated successfully after oral administration of AF by rats.