Determination of diosbulbin B in rat plasma and urine by LC–MS/MS and its application in pharmacokinetic and urinary excretion studies

Development and application of a rapid and sensitive LC-MS/MS method for simultaneous quantification of six diterpene lactones in rats after oral administration of Rhizoma Dioscoreae Bulbiferae extract

Diterpene lactones have been considered as the main therapeutic and hepatotoxic constituents of Rhizoma Dioscoreae Bulbiferae in recent years. In this work, a simple, rapid and accurate LC-MS/MS method was established and validated to determine six diterpene lactones in rat plasma simultaneously, including Diosbulbin B (DIOB), Diosbulbin C (DIOC), Diosbulbin D (DIOD), Diosbulbin G (DIOG), Diosbulbin J (DIOJ) and Diosbulbin L (DIOL), after oral administration of Rhizoma Dioscoreae Bulbiferae extract. The six diterpene lactones, with the inclusion of two pairs of isomer (DIOB & D, DIOC & L), and Buspirone (internal standard, IS) were successfully separated using an XDB-C₁₈ column with the gradient elution, consisting of water with 0.1% (v/v) FA and methanol with 0.1% (v/v) FA, under a flow rate of 0.50 mL/min in 5.8 min. Precursor-product ion transitions were optimized to be m/z 362.1 → 317.1, 363.1 → 207.1, 345.0 → 299.2, 364.3 → 347.0, 396.3 → 379.3, 363.2 → 345.1 and 386.3 → 122.2 for DIOB, DIOC, DIOD, DIOG, DIOJ, DIOL and buspirone at positive ion mode with an electrospray ionization source (ESI), respectively. The linearity ranges of this present method were 0.50 to 500 μg/L for DIOB, 20.0 to 20,000 μg/L for DIOC and 2.00 to 2000 μg/L for DIOD, DIOG, DIOJ and DIOL, respectively. And the LLOQs were as low as 0.20 μg/L for DIOB, 20.0 μg/L for DIOC and 2.00 μg/L for DIOB, D, G, J and L. The accuracy of each analyte was within the range of 95.8% to 101.0% and the precision was <11.3%. No matrix effect and carry over was observed, and the recovery of the six analytes ranged from 87.3% to 109% with the RSD <11.4% within the concentrations range. The validated method was further applied to the pharmacokinetics investigation of DIOB, DIOC, DIOD, DIOG, DIOJ and DIOL successfully after oral administration of Rhizoma Dioscoreae Bulbiferae extract at 1.53 g/kg in rats.

A C8-Modified Graphene@mSiO2 Composites Based Method for Quantification of Gallic Acid in Rat Plasma after Oral Administration of Changtai Granule and Its Application to Pharmacokinetics

A rapid, effective extraction technique has been established for measuring the gallic acid in rat plasma by using sandwich-structured graphene/mesoporous silica composites with C₈-modified interior pore-walls as adsorbent. The unique characteristics of the graphene-silica composites excluded large molecules, like proteins, from the mesopore channels as a result of size exclusion effect, leading to a direct extraction of drug molecules from protein-rich biological samples such as plasma without any other pretreatment procedure. Followed by elution and centrifugation, the gallic acid-absorbed composites were rapidly isolated before LC-MS/MS. Serving as a reliable tool for analysis of Traditional Chinese Medicine: Changtai Granule, the newly developed method was fully validated and successfully applied in the pharmacokinetic study of gallic acid in rat plasma. Extraction recovery, matrix effect and stability were satisfactory in rat plasma. According to the results of pharmacokinetic studies, Changtai Granule exhibited greater adsorption, distribution and clearance properties of gallic acid in the treatment of ulcerative colitis. Hence, this study may offer a valuable alternative to simplify and speed up sample preparation, and be useful for clinical studies of related preparations.

Describing the holistic toxicokinetics of hepatotoxic Chinese herbal medicines by a novel integrated strategy: Dioscorea bulbifera rhizome as a case study

It is vital to monitor the holistic toxicokinetics of toxic Chinese herbal medicines (CHMs) for safety. Although an integrated strategy based on the area under the curve (AUC) has been proposed to characterize the pharmacokinetic/toxicokinetic properties of CHMs, improvement is still needed. This study attempted to use 50% inhibitory concentration (IC₅₀) as weighting coefficient to investigate holistic toxicokinetics of the major diosbulbins i.e. diosbulbin A (DA), diosbulbin B (DB), and diosbulbin C (DC) after oral administration of Dioscorea bulbifera rhizome (DBR) extract. Firstly, the cytotoxicities of the three diosbulbins on human hepatic L02 cells were evaluated and the IC₅₀ values were calculated. Then, integrated toxicokinetics of multiple diosbulbins based on AUC and IC₅₀ were determined. Finally, correlations between integrated plasma concentrations and hepatic injury biomarkers including alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and total bile acid (TBA) were analyzed. As a result, integrated plasma concentrations were correlated well with TBA and the correlation between TBA and IC₅₀-weighting integrated plasma concentrations was better than that of AUC-weighting integrated plasma concentrations. In conclusion, the newly developed IC₅₀-weighting method is expected to generate more reasonable integrated toxicokinetic parameters, which will help to guide the safe usage of DBR in clinical settings.

A Comprehensive Review on Pharmacokinetic Profile of Some Traditional Chinese Medicines

Herbal medicines are the oldest and most widely used form of treatment for welfare of mankind. Herbal medicines possess strong reputation as complementary treatment across the globe due to their easy accessibility and safety. Particularly traditional Chinese medicines (TCM) are very popular due to their desirable therapeutic effects. They already have been proven for their remarkable potential in treatment of wide range of disease ailments. The major drawback in using herbal medicines is lack of standardisation aspects due to the complexity of chemical constituents. Pharmacokinetics study of such medicines helps forecast a range of events related to efficacy, safety, and toxicity profile of them. Apart from this, pharmacokinetics studies also recommended by various regulatory agencies during diverse stages of herbal drug development. Thus it is highly essential to have knowledge about the pharmacokinetic properties of any herbal drug. Thus it was thought that it will be worthwhile to compile the pharmacokinetic data of TCM which will be helpful for the researchers involved in further research on TCM. To portray entire picture about absorption, distribution, metabolism, and excretion (ADME) of some TCM, this well-designed scientific review covers the pharmacokinetic profile of 50 TCM available from 2003 and onwards.

The HepaRG cell line, a superior in vitro model to L-02, HepG2 and hiHeps cell lines for assessing drug-induced liver injury

Drug-induced liver injury (DILI) is a leading cause of discontinuation of new drug approval or withdrawal of marketed medicine based on safety due to organ vulnerability. The aim of this research is to investigate the potential abilities of four different in vitro cell models (L-02, HepG2, HepaRG, and hiHeps cell lines) in assessing marketed drugs labeled with apparently different types of liver injury. A total of 17 drugs with versatile pharmacological profiles were chosen, of which, 14 drugs are recognized as DILI agents and 3 drugs are DILI irrelevant. Preliminary cellular screening assays indicated that the HepaRG cell line had an advantage over other cell lines in predicting drugs associated with DILI in vitro as it had the highest Youden's index (71.4%). A multi-parametric screening assay showed that oxidative stress, mitochondrial damage, and disorders of neutral lipid metabolism were changed notably in the HepaRG cell line after DILI-related drugs exposure, accounting for its high sensitivity in comparison with other three cell lines. In addition, aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and malate dehydrogenase (MDH) all correlated with the cytotoxic effects of diclofenac sodium (p < 0.05), buspirone hydrochloride (p < 0.01), and danazol (p < 0.01) in the HepaRG cell line. We conclude that the HepaRG cell line is a superior in vitro cell model to other three cell lines for evaluating drugs with DILI potential.

Sample preparation for liquid chromatographic analysis of phytochemicals in biological fluids

INTRODUCTION

Natural products have been used traditionally for the treatment and prevention of diseases for thousands of years and are nowadays consumed as dietary supplements and herbal medicine. To ensure the safe and effective use of these herbal products, information about bioavailability of active compounds in plasma or target tissues should be provided via validated analytical methods combined with appropriate sampling methods.

OBJECTIVE

To provide comprehensive and abridged information about sample preparation methods for the quantification of phytochemicals in biological samples using liquid chromatography analysis.

METHODS

Sample pre-treatment procedures used in analytical methods for in vivo pharmacokinetic studies of natural compounds or herbal medicines were reviewed. These were categorised according to the biological matrices (plasma, bile, urine, faeces and tissues) and sample clean-up processes (protein precipitation, liquid-liquid extraction and solid-phase extraction).

RESULTS

Although various kinds of sample pre-treatment methods have been developed, liquid-liquid extraction is still widely used and solid-phase extraction is becoming increasingly popular because of its efficiency for extensive clean up of complex matrix samples. However, protein precipitation is still favoured due to its simplicity.

CONCLUSION

Sample treatment for phytochemical analysis in biological fluids is an indispensable and critical step to obtain high quality results. This step could dominate the overall analytical process because both the duration of the process as well as the reliability of the data depend in large part on its efficiency. Thus, special attention should be given to the choice of a proper sample treatment method that targets analytes and their biomatrix.

Gender-related pharmacokinetics and absolute bioavailability of diosbulbin B in rats determined by ultra-performance liquid chromatography-tandem mass spectrometry

ETHNOPHARMACOLOGICAL RELEVANCE

Diosbulbin B (DB) is the main constituent of furano-norditerpenes in Dioscorea bulbifera Linn., which is widely distributed in China and was usually used as a remedy for sore throat, struma and tumor. Owing to its potential antitumor activity, DB has been considered as a promising candidate for drug development.

AIM OF THE STUDY

To study the pharmacokinetic properties and excretion of DB in rats by a sensitive UPLC-MS/MS method. Absolute bioavailability and gender-related pharmacokinetic properties, as well as excretion fractions of DB in urine and feces after oral and intravenous administrations would be addressed for the first time.

MATERIALS AND METHODS

Sprague-Dawley rats were administrated orally (32mg/kg) and intravenously (0.5mg/kg) of DB, respectively. The concentrations of DB in rat plasma were determined by a sensitive and well-validated LC-MS/MS method. Main pharmacokinetic parameters including area under the plasma concentration-time curve (AUC), elimination half time (t1/2), mean residence time (MRT), apparent volume of distribution (Vd) and clearance rate (CL) were estimated using a non-compartmental pharmacokinetics data analysis software. Urine and feces of rats were collected within 48h after oral administration (32mg/kg) and detected by UPLC-MS/MS and HPLC, respectively.

RESULTS

The standard curves of DB in rat plasma and urine showed good linearity in the concentration range of 1.0-515ng/mL in the method, with acceptable selectivity, precisions, recoveries, and stability. The oral absolute bioavailability of DB in female rats was 2.0%, significantly higher than that of males (0.3%) (p<0.05). Female rats demonstrated longer t1/2 and MRT (p<0.01), bigger Vd and higher CL (p<0.05) than males after intravenous administration of DB. Bigger but no significant difference in excretion fractions of urine and feces in female rats were observed, comparing to those in males.

CONCLUSION

A simple and sensitive UPLC-MS/MS method was developed to determine the pharmacokinetic profiles of DB in rats, as well as the excretion in rat urine. Gender exerted a significant influence on the pharmacokinetics and bioavailability of DB in rats. Female rats showed significantly better absorption of DB than males after oral administration.