Determination of toosendanin and trans-anethole in Fructus Meliae Toosendan and Fructus Foeniculi by HPLC-MS/MS and GC-MS/MS in rat plasma and their potential herb-herb interactions.

ETHNOPHARMACOLOGICAL RELEVANCE: The objective of traditional Chinese medicine (TCM) combination theory is to "reduce toxicity and increase efficiency", especially to solve the liver toxicity of many TCMs. Fructus Meliae Toosendan (CLZ)-Fructus Foeniculi (XHX) is a typical traditional Chinese herb pair that decreases the toxicity and increases the efficiency of the herbs. Fructus Meliae Toosendan (CLZ, cold-natured) has significant liver toxicity. However, it has been widely used in combination with Fructus Foeniculi (XHX, hot-natured) for thousands of years in TCM, in which form it shows no hepatotoxicity, indicating that the combined use of XHX and CLZ can reduce the hepatotoxicity of CLZ. Herb-herb interactions could affect herb pharmacokinetics and in vivo efficacy. The herb-herb interactions between CLZ and XHX are still unknown. MATERIALS AND METHODS: This study used liquid chromatography tandem mass spectrometry (LC-MS) and gas chromatography tandem mass spectrometry (GC-MS) to establish methods for detecting toosendanin and trans-anethole, the main active substances of CLZ and XHX, respectively. Additionally, we investigated their herb-herb interactions via pharmacokinetic and pharmacodynamic studies. RESULTS: The results indicate that the established analytical methods are suitable for detecting toosendanin and trans-anethole, and the methodology meets the requirements of biological sample testing methods. Compared with the CLZ group, the pharmacokinetic parameters Cmax , AUC(0-t) , AUC(0-∞) , MRT(0-t) and MRT(0-∞) of toosendanin in the CLZ-XHX group notably decreased and the values of Vz/F remarkably increased. Compared with the XHX group, the pharmacokinetic parameters Cmax , AUC0-t , AUC0-∞, Tmax and t1/2z of trans-anethole notably increased in the CLZ-XHX group, and the values of CLz/F and Vz/F obviously decreased. CONCLUSION: The pharmacokinetic results indicate that XHX can significantly decrease the absorption and bioavailability and accelerate the elimination process of toosendanin in CLZ. XHX could decrease the risk of in vivo accumulation of the toxic constituent of CLZ, toosendanin, thus decreasing its toxicity. It has also been shown that CLZ can significantly increase absorption and bioavailability and attenuate the elimination process of trans-anethole in XHX, thus enhancing its efficacy. Hepatotoxicity studies indicate that CLZ has significant hepatotoxicity, and its combined use with XHX can decrease its liver-damaging properties.

In-syringe reversed dispersive liquid-liquid microextraction for the evaluation of three important bioactive compounds of basil, tarragon and fennel in human plasma and urine samples.

In the present study, an efficient and environmental friendly method (called in-syringe reversed dispersive liquid-liquid microextraction (IS-R-DLLME)) was developed to extract three important components (i.e. para-anisaldehyde, trans-anethole and its isomer estragole) simultaneously in different plant extracts (basil, fennel and tarragon), human plasma and urine samples prior their determination using high-performance liquid chromatography. The importance of choosing these plant extracts as samples is emanating from the dual roles of their bioactive compounds (trans-anethole and estragole), which can alter positively or negatively different cellular processes, and necessity to a simple and efficient method for extraction and sensitive determination of these compounds in the mentioned samples. Under the optimum conditions (including extraction solvent: 120 µL of n-octanol; dispersive solvent: 600 µL of acetone; collecting solvent: 1000 µL of acetone, sample pH 3; with no salt), limits of detection (LODs), linear dynamic ranges (LDRs) and recoveries (R) were 79-81 ng mL(-1), 0.26-6.9 µg mL(-1) and 94.1-99.9%, respectively. The obtained results showed that the IS-R-DLLME was a simple, fast and sensitive method with low level consumption of extraction solvent which provides high recovery under the optimum conditions. The present method was applied to investigate the absorption amounts of the mentioned analytes through the determination of the analytes before (in the plant extracts) and after (in the human plasma and urine samples) the consumption which can determine the toxicity levels of the analytes (on the basis of their dosages) in the extracts.

[Pharmacokinetic study on dry powder inhalation administration of α-asarone in rats].

To study the pharmacokinetic characteristics and absolute bioavailability of α-asarone through dry powder inhalation in rats, and compare with that through oral administration and intravenous injection. A HPLC method was established for the determination of α-asarone in rat plasma to detect the changes in plasma concentrations of α-asarone through dry powder inhalation (20 mg · kg(-1)), oral administration (80 mg · kg(-1)) and intravenous injection (20 mg · kg(-1)) in rats. DAS 2.0 software was used to calculate the pharmacokinetic parameters. The absolute bioavailability of α-asarone was calculated according to AUC(0-t)) of administration routes and administration doses. According to the results, α-asarone showed good linear relations (r = 0. 999 4) at concentrations between 0.282-14.1 mg · L(-1), with the limit of detection (LOD) at 0.212 mg · L(-1). Through dry powder inhalation, oral administration and intravenous injection of α-asarone, the metabolic processes of α-asarone in rats conformed to one, two and three compartment models respectively, with the elimination half-life of (95.48 ± 48.28), (64.34 ± 27.59), (66.99 ± 29.76) min. According to the bioavailability formula, the absolute bioavailability of α-asarone through dry powder inhalation and oral administration were 78.32% and 33. 60%, respectively. This study showed that significant increase in elimination half-life and absolute bioavailability of α-asarone through dry powder inhalation, which lays a theoretical foundation for preparing α-asarone dry powder inhalers.

Electrophysiological and haemodynamic effects of vernakalant and flecainide in dyssynchronous canine hearts.

AIMS: About one-third of patients with mild dyssynchronous heart failure suffer from atrial fibrillation (AF). Drugs that convert AF to sinus rhythm may further slowdown ventricular conduction. We aimed to investigate the electrophysiological and haemodynamic effects of vernakalant and flecainide in a canine model of chronic left bundle branch block (LBBB). METHODS AND RESULTS: Left bundle branch block was induced in 12 canines. Four months later, vernakalant or flecainide was administered using a regime, designed to achieve clinically used plasma concentrations of the drugs, n = 6 for each drug. Epicardial electrical contact mapping showed that both drugs uniformly prolonged myocardial conduction time. Vernakalant increased QRS width significantly less than flecainide (17 ± 13 vs. 34 ± 15%, respectively). Nevertheless, both drugs equally decreased LVdP/dtmax by ∼15%, LVdP/dtmin by ∼10%, and left ventricular systolic blood pressure by ∼5% (P = n.s. between drugs). CONCLUSIONS: Vernakalant prolongs ventricular conduction less than flecainide, but both drugs had a similar, moderate negative effect on ventricular contractility and relaxation. Part of these reductions seems to be related to the increase in dyssynchrony.

A rapid HPLC-ESI-MS/MS method for determination of ß-asarone, a potential anti-epileptic agent, in plasma after oral administration of Acorus calamus extract to rats.

ß-Asarone (BAS), a phenylpropanoid from Acorus calamus Linn., has shown biological effects in the management of cognitive impairment conditions such as Alzheimer's disease. The present paper describes a selective and sensitive liquid chromatography-tandem mass spectrometric method (HPLC-MS/MS) using electrospray ionization source (ESI) for quantification of BAS in rat plasma. Briefly, the plasma samples were pre-treated using a simple solid-phase extraction method. The separation of BAS and the internal standard, caffeine, was achieved on an Agilent Zorbax XDB C(18) column (50 × 2.1 mm i.d., 5 µm) using 0.2 mL/min isocratic mobile phase flow. The detection was performed using an Applied Biosystems Hybrid Q-Trap API 2000 mass spectrometer equipped with an ESI source operated in positive mode. Also, the developed bioanalytical method was validated as per the US FDA bioanalytical guidelines over the concentration range of 9.79-4892.50 ng/mL (r(2) ≥ 0.9951) for BAS from rat plasma. The mean percentage recovery (n = 3) for the low, middle and high quality control samples was 86.92 ± 3.89, 85.30 ± 1.09 and 87.24 ± 4.03%, respectively. The applicability of the validated HPLC-MS/MS method was demonstrated by successful measurement of BAS from plasma following oral administration of Acorus calamus rhizome extracts to three female albino Wistar rats.

Pharmacokinetics of beta-asarone in rabbit blood, hippocampus, cortex, brain stem, thalamus and cerebellum.

beta-Asarone has significant pharmacological effects on the central nervous system. As a potential therapeutic agent to manage brain diseases, analysis of the pharmacokinetics of beta-asarone in brain is necessary. We used cardio-perfusion method to exclude the beta-asarone in the brain blood. The brain was divided into five regions: hippocampus, cortex, brain stem, thalamus and cerebellum, and pharmacokinetic differences were investigated. We found that concentration-time profile of beta-asarone in blood, hippocampus, cortex, brain stem and cerebellum could be adequately described by a first-order equation, consistent with a linear two-compartmental model, but a first-order equation with a linear one-compartmental model in thalamus. The half lives of beta-asarone in blood, hippocampus, cortex, brain stem, thalamus and cerebellum were 1.3801, 1.300, 1.937, 7.142, 2.832 and 8.149 h, respectively. Gender differences do not significantly influence plasma pharmacokinetics of beta-asarone.

Vernakalant selectively prolongs atrial refractoriness with no effect on ventricular refractoriness or defibrillation threshold in pigs.

Vernakalant is a novel antiarrhythmic agent that has demonstrated clinical efficacy for the treatment of atrial fibrillation. Vernakalant blocks, to various degrees, cardiac sodium and potassium channels with a pattern that suggests atrial selectivity. We hypothesized, therefore, that vernakalant would affect atrial more than ventricular effective refractory period (ERP) and have little or no effect on ventricular defibrillation threshold (DFT). Atrial and ventricular ERP and ventricular DFT were determined before and after treatment with vernakalant or vehicle in 23 anesthetized male mixed-breed pigs. Vernakalant was infused at a rate designed to achieve stable plasma levels similar to those in human clinical trials. Atrial and ventricular ERP were determined by endocardial extrastimuli delivered to the right atria or right ventricle. Defibrillation was achieved using external biphasic shocks delivered through adhesive defibrillation patches placed on the thorax after 10 seconds of electrically induced ventricular fibrillation. The DFT was estimated using the Dixon "up-and-down" method. Vernakalant significantly increased atrial ERP compared with vehicle controls (34 ± 8 versus 9 ± 7 msec, respectively) without significantly affecting ventricular ERP or DFT. This is consistent with atrial selective actions and supports the conclusion that vernakalant does not alter the efficacy of electrical defibrillation.

[Comparison of kinetic behavior in both plasma and tissue after intravenous administration of alpha-asarone in lipid emulsion and aqueous solution in rats and mice].

OBJECTIVE: To compare the pharmacokinetics and tissue distribution of alpha-asarone in lipid emulsion and aqueous solution for injection and study the feasibility of lipid emulsion of alpha-asarone as the parenteral drug delivery system. METHOD: HPLC was used to determine the drug concentration in rat plasma and mice tissues after intravenous (i.v.) administration of lipid emulsion and aqueous solution of alpha-asarone at a single dose (40 mg x kg(-1)), respectively. RESULT: The plasma concentration-time profiles of lipid emulsion and aqueous solution of alpha-asarone after intravenous administration of them are similar and the drug concentration-time data were fitted to a two-compartment open model. The results of tissues distribution showed that distribution contents of alpha-asarone from lipid emulsion and aqueous solution in vivo are similar in lungs but lipid emulsion increased the uptake in livers and spleens, and decreased the uptake in hearts and kidneys for alpha-asarone. CONCLUSION: The plasma concentration-time profiles of alpha-asarone in lipid emulsion and aqueous solution are similar, but lipid emulsion significantly altered the tissue distribution of alpha-asarone, which may be beneficial to decrease its potential toxicity to heart and kidney.

Development of gas chromatography/mass spectrometry following headspace solid-phase microextraction for fast determination of asarones in plasma.

Asarones (alpha-asarone and beta-asarone) are the active components in the traditional Chinese medicine (TCM) of Acorus tatarinowii Schott, which has been used to treat epilepsy for several thousand years. To perform the pharmacokinetics (PK) study of alpha- and beta-asarone from the TCM essential oil, a simple, rapid and sensitive method was developed for the determination of asarones from the TCM in rabbit plasma, based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography/mass spectrometry (GC/MS) with electron ionization (EI). The extraction parameters of headspace volume, fiber coating, sample temperature, extraction time, stirring rate and ion strength were systemically optimized. Furthermore, the method linearity, detection limit and precision were also investigated. It was shown that the proposed method provided a good linearity (0.02-20 microg/mL, R(2) > 0.99), low detection limit (<2.0 ng/mL) and good precision (RSD < 7.0%). Finally, HS-SPME followed by GC/MS was applied to fast determination of alpha- and beta-asarone in rabbit plasma at different time points after oral adminstration of the essential oil from A. tatarinowii. The experimental results suggest that the proposed method provides an alternative approach to the PK studies of volatile compounds in TCMs.