Pharmacokinetic study of multicomponent in Hong-Hua-Xiao-Yao tablet.

Hong-Hua-Xiao-Yao tablet (HHXYT) is attracting attention increasingly because of its use in treatment of mammary gland hyperplasia (MGH) and menopausal syndrome. However, its pharmacokinetics remains unclear. This study developed a sensitive and rapid method for simultaneous determination of 10 compounds of HHXYT in rat plasma by liquid chromatography-tandem mass spectrometry and to compare the pharmacokinetics of these compounds in MGH rats and sham operated rats. The linearity, accuracy, precision, stability and matrix effect were within acceptable ranges. This established method was successfully applied to a pharmacokinetics study of 10 compounds in sham operated and MGH rats. According to the results, the bioavailability of glycyrrhetinic acid was highest in MGH rats and sham operated rats. The mean residence times of glycyrrhetinic acid and glycyrrhetinic acid 3-O-glucuronide were higher than those of the other compounds while the mean residence time and half-life of liquiritin, isoliquiritin and paeoniflorin were lower. Some pharmacokinetic parameters of ormononetin, liquiritigenin, isoliquiritigenin, liquiritin, isoliquiritin, paeoniflorin, protocatechuic acid and senkyunolide I were significantly different between MGH rats and sham operated rats. This study elucidated the dynamic changes of multiple components in rats after oral administration of HHXYT systematically and comprehensively, which provided guidance for clinical application.

Exploring the Pivotal Immunomodulatory and Anti-Inflammatory Potentials of Glycyrrhizic and Glycyrrhetinic Acids.

Licorice extract is a Chinese herbal medication most often used as a demulcent or elixir. The extract usually consists of many components but the key ingredients are glycyrrhizic (GL) and glycyrrhetinic acid (GA). GL and GA function as potent antioxidants, anti-inflammatory, antiviral, antitumor agents, and immuneregulators. GL and GA have potent activities against hepatitis A, B, and C viruses, human immunodeficiency virus type 1, vesicular stomatitis virus, herpes simplex virus, influenza A, severe acute respiratory syndrome-related coronavirus, respiratory syncytial virus, vaccinia virus, and arboviruses. Also, GA was observed to be of therapeutic valve in human enterovirus 71, which was recognized as the utmost regular virus responsible for hand, foot, and mouth disease. The anti-inflammatory mechanism of GL and GA is realized via cytokines like interferon-γ, tumor necrotizing factor-α, interleukin- (IL-) 1ß, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, and IL-17. They also modulate anti-inflammatory mechanisms like intercellular cell adhesion molecule 1 and P-selectin, enzymes like inducible nitric oxide synthase (iNOS), and transcription factors such as nuclear factor-kappa B, signal transducer and activator of transcription- (STAT-) 3, and STAT-6. Furthermore, DCs treated with GL were capable of influencing T-cell differentiation toward Th1 subset. Moreover, GA is capable of blocking prostaglandin-E2 synthesis via blockade of cyclooxygenase- (COX-) 2 resulting in concurrent augmentation nitric oxide production through the enhancement of iNOS2 mRNA secretion in Leishmania-infected macrophages. GA is capable of inhibiting toll-like receptors as well as high-mobility group box 1.

Evaluation of the Percutaneous Absorption of Drug Molecules in Zebrafish.

In recent decades, zebrafish (Danio rerio) has become a widely used vertebrate animal model for studying development and human diseases. However, studies on skin medication using zebrafish are rare. Here, we developed a novel protocol for percutaneous absorption of molecules via the zebrafish tail skin, by applying a liquid solution directly, or using a filter paper imbibed with a chemical solution (coating). Human skin is capable of absorbing felbinac and loxoprofen sodium hydrate (LSH), but not glycyrrhetinic acid (GA) and terbinafine hydrochloride (TH). To evaluate the possibility and the quality of transdermal absorption in zebrafish, we transdermally administered these four drugs to zebrafish. Pharmacokinetics showed that felbinac was present in the blood of zebrafish subjected to all administration methods. Felbinac blood concentrations peaked at 2 h and disappeared 7 h after administration. GA was not detected following transdermal administrations, but was following exposure. LSH was not found in the circulatory system after transdermal administration, but TH was. A dose-response correlation was observed for felbinac blood concentration. These findings suggest that zebrafish are capable of absorbing drug molecules through their skin. However, the present data cannot demonstrate that zebrafish is a practical model to predict human skin absorption. Further systemic studies are needed to observe the correlations in percutaneous absorption between humans and zebrafish.

Synthesis and antitumor effects of novel 18ß-glycyrrhetinic acid derivatives featuring an exocyclic α,ß-unsaturated carbonyl moiety in ring A.

A series of novel 18ß-glycyrrhetinic acid (GA) derivatives featuring an exocyclic α,ß-unsaturated carbonyl moiety in ring A were synthesized and evaluated for their antitumor activities. Compounds 5c and 5l showed stronger cytotoxicity than other compounds and reported GA analogue CDODA-Me (methyl 2-cyano-3,11-dioxo-18ß-olean-1,12-dien-30-oate). 5c and 5l induced apoptosis in cancer cells accompanying with c-Flip reduction and Noxa induction, associated with decreased HDAC3 expression and increased acetylation of H3. 5l displayed better stability properties than 5c and CDODA-Me in microsomes and plasma, 5l also showed favorable pharmacokinetic profiles and inhibited tumor growth in mice. Compound 5l represents a new type of GA derivatives with improved antitumor activity.

Simultaneous quantitation of glycyrrhetic acid and puerarin in plasma using ultra flow liquid chromatography tandem mass spectrometry and application in a pharmacokinetics study in healthy and alcoholic liver injury rats.

A rapid, sensitive, and accurate ultra flow liquid chromatography tandem mass spectrometry (UFLC-MS/MS ) method was developed and validated for simultaneous quantitation of glycyrrhetic acid and puerarin in plasma derived from healthy and alcoholic liver injury rats. Plasma samples from healthy and model rats were deproteinated with methanol using liquiritin as an internal standard. Chromatography separation was performed by a Waters BEH (ethylene-bridged hybrid) C18 column (2.1 × 50 mm; 1.7 µm) using a gradient elution from acetonitrile and water (containing 0.1% formic acid) and at a flow rate of 0.4 mL/min. Quantitation was performed on a Triple Quad 4500 tandem mass spectrometer coupled with an electrospray ionization source in negative multiple reaction monitoring mode. Specificity, carryover, dilution integrity, recovery, linearity, precision and accuracy, matrix effect, and stability were within acceptable limits. The newly established method was successfully applied to a pharmacokinetics study to investigate glycyrrhetic acid and puerarin in healthy and alcoholic liver injury rats.

A 18ß-glycyrrhetinic acid conjugate with Vorinostat degrades HDAC3 and HDAC6 with improved antitumor effects.

Semisynthetic 18ß-glycyrrhetinic acid (GA) analogues bearing 1-en-2-cyano-3-oxo substitution on ring A have enhanced antitumor effects with reduced levels of HDAC3 and HDAC6 proteins. Aiming to inhibit both HDAC protein and activity, we developed a hybrid molecule by tethering active GA analogue methyl 2-cyano-3,11-dioxo-18ß-olean-1,12-dien-30-oate (CDODA-Me) and Vorinostat (SAHA). We tested the proper hybrid approaches of GA with hydroxamic acid and turned out that GA conjugated with SAHA by a piperazine linker was the best. The conjugate (15) of CDODA-Me and SAHA linked through a piperazine group was a potent cytotoxic agent against cancer cells with apoptosis induction. Compound 15 was more effective than the simple combination of CDODA-Me and SAHA to induce apoptosis. Mechanistic studies revealed that 15 was less effective than SAHA to inhibit HDAC activity, but was more effective than CDODA-Me to decrease the levels of HDAC3 and HDAC6 proteins with upregulated levels of acetylated H3 and acetylated α-tubulin. Compound 15 represents a new HDAC3 and HDAC6 inhibitor by reducing protein levels.

LC-MS/MS analysis of puerarin and 18ß-glycyrrhetinic acid in human plasma after oral administration of Samso-eum and its application to pharmacokinetic study.

The aim of this study was to confirm pharmacokinetic screening of multiple components in healthy Korean subjects after oral administration of Samso-eum and perform quantitation of active components in the human plasma. Thirteen potential bioactive components [puerarin (PRR), daidzin, nodakenin, ginsenoside Rb1, 18ß-glycyrrhetinic acid (18ß-GTA), 6-shogaol, naringin, glycyrrhizin, hesperidin, platycodin D, naringenin, hesperetin, and 6-gingerol] were screened based on literature. The results showed that three analytes (daidzin, naringenin, and hesperetin) were detected in trace amounts. In addition, PRR and 18ß-GTA were detected in human plasma after the oral administration of Samso-eum. In this study, a liquid chromatography-electrospray ionization-tandem mass spectrometry method was validated for the simultaneous determination of PRR and 18ß-GTA in human plasma. This was the first study to evaluate pharmacokinetics of PRR and 18ß-GTA after the usual oral dose of Samso-eum (30 g containing 102.48 mg PRR, 48.18 mg glycyrrhizin) in human subjects.

Pharmacokinetic study of eight bioactive components following oral administration of Zhiqiao Gancao decoction and observation of its clinical efficacy.

Zhiqiao Gancao (ZQGC) decoction is widely used in China due to its therapeutic effect on lumbar disc herniation (LDH). In this study, we compared the clinical therapeutic effects among oral ZQGC decoction treatment, bed rest, and oral anti-inflammatory drug celecoxib treatment using visual analog scale, Oswestry Disability Index, and MacNab scores. The results showed that ZQGC decoction can significantly improve the symptoms of patients with LDH. A selective, sensitive, and rapid ultra-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the determination of eight bioactive components in rat plasma. The plasma samples were extracted by simple protein precipitation with methanol. The protonated analytes were quantitated simultaneously in positive and negative ion modes by multiple reaction monitoring with a mass spectrometer. The calibration curve of eight components in plasma showed good linearity (r > .996) and the extraction recovery was 81.19% ± 2.15% - 100.39 ± 3.36 (relative standard deviation: 1.21%-10.70%). The accuracy of all the lower limit of quantitation values was quantified within 80%-120%, and the precision was less than 15%. This validated method was successfully applied to the pharmacokinetics study in rat plasma after ZQGC decoction oral treatment. Our research can provide experimental basis for the rational clinical application of ZQGC decoction in the treatment of LDH.

Tumor-Associated Fibroblast-Targeted Regulation and Deep Tumor Delivery of Chemotherapeutic Drugs with a Multifunctional Size-Switchable Nanoparticle.

Tumor-associated fibroblasts (TAFs), which form a predominant stromal cellular component of the tumor microenvironment, hinder the delivery of nanomedicine to deep tumor cells and lead to poor prognosis of tumors. However, depletion of TAFs by therapeutic agents results in the secretion of damage response program (DRP) molecules to weaken the efficacy of tumor treatment. This paper reports a multifunctional size-switchable nanoparticle (denoted DGL (dendrigraft poly-l-lysine) (DGL)/GEM@PP/GA) for TAF-targeted regulation and deep tumor penetration. After accumulation at the tumor site, in response to overexpressed matrix metalloproteinase-2 (MMP-2) in the tumor microenvironment, gemcitabine (GEM)-conjugated small nanoparticles (DGL/GEM) are released from DGL/GEM@PP/GA, leaving 18ß-glycyrrhetinic acid (GA)-loaded large nanoparticles (PP/GA). The released DGL/GEM can penetrate to the deep region of the tumor as well as intracellularly release GEM to kill tumor cells. However, residual GA-loaded nanoparticles with lower tumor penetration ability could accumulate around tumor vessels and be preferentially absorbed by TAFs to regulate the secretion of Wnt 16, which is an important DRP molecule. By taking actions on both tumor cells and TAFs, DGL/GEM@PP/GA displayed significant and long-term antitumor effect in stroma-rich pancreatic cancer and breast cancer models.

A simple method for evaluation pharmacokinetics of glycyrrhetinic acid and potential drug-drug interaction between herbal ingredients.

A simple validated high performance liquid chromatography method was developed for the evaluation of the effect of three kinds of active ingredients in traditional Chinese medicine (TCM) on the pharmacokinetics of glycyrrhetinic acid (GA),a kind of active component from the most commonly used TCM licorice. Our results revealed that all of the calibration curves displayed good linearity. Intra- and inter-day precision for GA ranged from 2.54 to 3.98% and from 4.95 to 7.08%, respectively. The recovery rates for GA were determined to be 96.3-106.4%. All the samples showed satisfactory precision and accuracy in various stability tests. Plasma pharmacokinetic parameters including area under the concentration-time curve (AUC), elimination half-life (t1/2), time to peak concentration(Tmax) and peak concentration Cmax were calculated. No significant difference was found as compared the groups administrating GA with and without other ingredients from TCM.

Comparative pharmacokinetics and metabolites study of seven major bioactive components of Shaoyao-Gancao decoction in normal and polycystic ovary syndrome rats by ultra high pressure liquid chromatography with tandem mass spectrometry.

A simple and sensitive liquid chromatography with tandem mass spectrometry method was developed for simultaneous quantification of paeoniflorin, albiflorin, oxypaeoniflorin, liquiritin, liquiritigenin, glycyrrhetinic acid, and glycyrrhizin in rat plasma after oral administration of Shaoyao-Gancao decoction, which is traditionally used in the treatment of polycystic ovary syndrome. The plasma samples were pretreated with methanol as precipitant. The method exhibited good linearity (correlation coefficient (R2 ) > 0.99) with lower quantification limits of 0.595-4.69 ng/mL for all analytes. Intra- and interbatch precision, accuracy, recovery, and stability of the method were all within accepted criteria. The results showed that the pharmacokinetic behaviors of the seven compounds were altered in the pathological status of polycystic ovary syndrome. Furthermore, a total of 36 metabolites were structurally identified based on their accurate masses and fragment ions. The major metabolic pathway involves phase I metabolic reactions (such as hydroxylation), phase II metabolic reactions (such as sulfation and glucuronidation conjugation) as well as the combined multiple-step metabolism. This study is the first report on the pharmacokinetic and metabolic information of Shaoyao-Gancao decoction in both normal and model rats, which would provide scientific evidences for the bioactive chemical basis of herbal medicines and also promote the clinical application of Shaoyao-Gancao decoction for treating polycystic ovary syndrome.

Inhibiting hepatic gluconeogenesis by chitosan lactate nanoparticles containing CRTC2 siRNA targeted by poly(ethylene glycol)-glycyrrhetinic acid.

Diabetes mellitus is a chronic metabolic disorder characterized by insulin deficiency and impaired glucose metabolism. Overexpression of cAMP response element binding protein (CREB)-regulated transcriptional coactivator 2 (CRTC2) plays an important role in high gluconeogenesis in patients with diabetes type II. Using RNA interference technology for silencing CRTC2 gene expression could be helpful in controlling the level of blood glucose and gluconeogenesis. In this study, we designed a siRNA delivery platform comprising blended chitosan lactate (CT) and polyethylene glycol (PEG) conjugated with glycyrrhetinic acid (GA) for controlling gluconeogenesis. The nanoparticles showed spherical and smooth surface with ~ 189-nm size and + 5.1 zeta potential. Targeted nanoparticles were efficiently stable in serum and different levels of heparin media over 48 h. The gene knockdown efficiency of nanoparticles was comparable to Lipofectamine®, while they had no significant in vitro and in vivo toxicity. The in vivo therapeutic efficacy of targeted nanoparticles was also confirmed by reduced amount of fasting blood sugar in diabetic rat models. Furthermore, the nanoparticles were mostly accumulated in the liver after 2 h indicating the significant targeting ability of the prepared nanoparticles. Therefore, CT/PEG-GA nanoparticles can be considered as a potential candidate for targeted delivery of siRNA into hepatocytes in order to regulate gluconeogenesis in diabetes.

Glycyrrhetinic acid-conjugated polymeric prodrug micelles co-delivered with doxorubicin as combination therapy treatment for liver cancer.

Significant synergy of doxorubicin (DOX) and glycyrrhizic acid (GA) in inhibiting the proliferation of cancer cells was demonstrated in the human hepatocellular carcinoma cell line, HepG2. A novel polymeric prodrug micellar carrier based on polyethylene glycol-derivatized GA (PEG-Fmoc-GA), was developed for co-delivery of DOX as a combined anti-cancer treatment. The PEG-Fmoc-GA polymeric prodrug micelles achieved a more effective synergistic action on cell proliferation inhibition and apoptosis induction, when co-delivered with DOX, which can be attributed to the dual effect of the cleaved GA and loaded DOX. PEG-Fmoc-GA conjugated micelles significantly facilitated the intracellular uptake of DOX by HepG2 cells, when compared to a DOX solution alone. In addition, DOX encapsulated in PEG-Fmoc-GA micelles displayed longer blood circulation time, larger drug concentration area under the curve, decreased volume distribution and clearance than DOX solution. Biodistribution studies showed that DOX/PEG-Fmoc-GA micelles were preferentially accumulated at the tumor site. Importantly, DOX/PEG-Fmoc-GA micelles demonstrated a more pronounced therapeutic efficacy in vivo compared with DOX alone with respect to both tumor growth inhibition and overall survival in a HepG2 xenograft model. Thus, PEG-Fmoc-GA polymeric prodrug micelles represent a promising dual-function co-delivery system to achieve anti-cancer synergistic activity of DOX and GA.

UPLC-Q-TOF-MS and UPLC-MS/MS methods for metabolism profiles and pharmacokinetics of major compounds in Xuanmai Ganjie Granules.

Xuanmai Ganjie Granules (XMGJ), a widely used Chinese herbal formula in the clinic, is used for treatment of sore throats and coughs. Despite the chemical constituents having been clarifying by our previous studies, both of the metabolism and pharmacokinetic studies of XMGJ are unclear. This study aimed to explore the disposition process of XMGJ in vivo. A sensitive and selective ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) method was developed to analyze the absorbed components and metabolites in rat plasma and urine after oral administration of XMGJ. A total of 42 absorbed components, including 16 prototype compounds and 26 metabolites, were identified or tentatively characterized in rat plasma and urine after oral administration of XMGJ. Moreover, the pharmacokinetic studies of five compounds of XMGJ were investigated using ultra-high liquid chromatography with tandem mass spectrometry method. The results indicated that liquiritin, harpagoside, glycyrrhetic acid, liquiritigenin, formononetin and their metabolites might be the major components involved in the pharmacokinetic and metabolism process of XMGJ. This research showed a comprehensive investigation of XMGJ in vivo, which could provide a meaningful basis for further material basis and pharmacological as well as toxicological research.

Isolation of a novel glycyrrhizin metabolite as a causal candidate compound for pseudoaldosteronism.

Pseudoaldosteronism is a common adverse effect associated with traditional Japanese Kampo medicines. The pathogenesis is mainly caused by 3-monoglucuronyl glycyrrhetinic acid (3MGA), one of the metabolites of glycyrrhizin (GL) contained in licorice. We developed an anti-3MGA monoclonal antibody (MAb) and an ELISA system to easily detect 3MGA in the plasma and urine of the patients. However, we found that some metabolites of GL cross-reacted with this MAb. Mrp2-deficient Eisai Hyperbilirubinemia rats (EHBRs) were administered glycyrrhetinic acid (GA), and we isolated 22α-hydroxy-18ß-glycyrrhetyl-3-O-sulfate-30-glucuronide (1) from the pooled urine with the guidance of positive immunostaining of eastern blot as the new metabolite of GL. The IC50 of 1 for type 2 11ß-hydroxysteroid dehydrogenase (11ß-HSD2) was 2.0 µM. Similar plasma concentrations of 1 and GA were observed 12 h after oral administration of GA to EHBR. Compound 1 was eliminated via urine, whereas GA was not. In Sprague-Dawley (SD) rats orally treated with GA, compound 1 was absent from both the plasma and the urine. Compound 1 was actively transported into cells via OAT1 and OAT3, whereas GA was not. Compound 1, when produced in Mrp2-deficiency, represents a potential causative agent of pseudoaldosteronism, and might be used as a biomarker to prevent the adverse effect.

Liver-Targeted Co-delivery of Entecavir and Glycyrrhetinic Acid Based on Albumin Nanoparticle To Enhance the Accumulation of Entecavir.

Hepatitis B, one of the most common contagious viral hepatitis with high infection rate, is challenging to treat. Although the treatment for hepatitis B has been improved over the years, many therapeutic drugs still have either severe adverse effects or insufficient effectiveness via systemic administration. In this study, we confirmed that glycyrrhetinic acid can enhance the accumulation of entecavir in HepaRG cell and liver. Then we constructed a novel albumin nanoparticle co-loading entecavir and glycyrrhetinic acid (ETV-GA-AN) to improve liver accumulation of entecavir and investigated its ability to deliver both drugs to liver. In vitro cellular uptake study and in vivo tissue distribution experiment showed that these negatively charged ETV-GA-AN (112 ± 2 nm in diameter) can increase the accumulation of entecavir in hepatic HepaRG cells and improve entecavir distribution in liver. We also revealed the mechanism that glycyrrhetinic acid enhances intracellular accumulation of entecavir by inhibiting the activity of specific efflux transporters. Our delivery system is the first liver-targeted albumin nanoparticle that utilizes the site-specific co-delivery strategy to delivery entecavir and glycyrrhetinic acid. As it combines high efficiency and low toxicity, it possess great potential for treating hepatitis B.

Acid-sensitive polymeric vector targeting to hepatocarcinoma cells via glycyrrhetinic acid receptor-mediated endocytosis.

Liver cancer is one of the top death causing cancers, traditional treatments have not settled for the requirement of patients. In this work, a smart acid-responsive micelle based on glycyrrhetinic acid modified chitosan-polyethyleneimine-4-Hydrazinobenzoic acid-doxorubicin (GA-CS-PEI-HBA-DOX) was synthesized for targeted delivery of DOX to liver cancer. A dual pH-sensitive and receptor-mediated strategy has been exploited to enhance the delivery efficiency. The micelle possesses positive charges under pH 6.8 and can be turned into negative charges above pH 7.0, which help to be accumulated in tumor tissues (pH 6.0-7.0). In the intracellular environment (pH 4.5-6.5) of tumor cells, the pH-sensitive hydrazone bonds between DOX and GA-CS-PEI-HBA would break and release as much as 90.3% of the encapsulated payloads in 48 h. In addition, GA was modified to improve the targeting abilities. The micelles exhibited high lethality to HepG2 cells while showed much lower cytotoxicity to HUVEC cells. With high drug-loading capacity and the targeted release ability, the GA-CS-PEI-HBA-DOX micelle might be employed as a promising candidate for targeted cancer treatment.

An intelligent re-shieldable targeting system for enhanced tumor accumulation.

Programmed ligand targeting strategy promotes the blood circulation stability of nanoparticles by shielding the ligand. However, the irreversible shielding causes the deshielded nanoparticles to be easily recognized and cleared by the reticuloendothelial system (RES), impeding their further retention in the tumor. Here, we for the first time prove the superiority of the intelligent re-shieldable targeting system that is based on the pH-responsive self-assembly/disassembly of gold nanoparticles. The system can enhance the stability of gold nanoparticles in the blood circulation (2.6-fold at 24h), reduce uptake by the RES (35% lower) and improve tumor accumulation (41% higher by analysis of gold content in tumor) effectively compared with the conventional irreversible system. Furthermore, preliminary study indicates that the system could be applied as computed tomography contrast agent in tumor imaging. The in vivo validity of the intelligent re-shieldable targeting system provides inspiration for the design of nanomaterials for cancer diagnosis and treatment.

Simultaneous Determination of Twenty-Five Compounds in Rat Plasma Using Ultra-High Performance Liquid Chromatography-Polarity Switching Tandem Mass Spectrometry and Its Application to a Pharmacokinetic Study.

An attempt was made to characterize the pharmacokinetic profiles of Qishen Keli (QSKL) that has been widely proved to be effective in clinical practice. A method using ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) for the simultaneous determination of 25 analytes in rat plasma was developed and validated. Satisfactory chromatographic separation was achieved on an ACQUITY UPLC HSS T3 column with gradient elution using mobile phase consisting of 0.02% aqueous formic acid (A) and acetonitrile fortified with 0.02% formic acid (B), and analyte detection was carried out using polarity-switching multiple reaction monitoring mode. Method validation assays in terms of selectivity, linearity, inter- and intra-day variations, matrix effect, and recovery demonstrated the newly developed method to be specific, sensitive, accurate, and precise. Following the oral administration of QSKL at a single dose, the qualified method was successfully applied for pharmacokinetic investigations in sham and model rats. Mild differences occurred for the pharmacokinetic patterns of most components between those two groups, whereas significant differences were observed for glycyrrhizic acid and glycyrrhetic acid. The obtained findings could provide meaningful information for the clarification of the effective material basis of QSKL.

A highly sensitive LC-MS/MS method for simultaneous determination of glycyrrhizin and its active metabolite glycyrrhetinic acid: Application to a human pharmacokinetic study after oral administration.

A highly sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method for simultaneous determination of glycyrrhizin (GL) and its active metabolite, glycyrrhetinic acid (GA), from human plasma was validated and applied to a human pharmacokinetic study. The analytes were extracted from human plasma using an Oasis MAX cartridge and chromatographic separation was performed on an Inertsil ODS-3 column. The detection was performed using an API 4000 mass spectrometer operating in the positive electrospray ionization mode. Selected ion monitoring transitions of m/z 823 → 453 for GL and m/z 471 → 149 for GA were obtained. The response was a linear function of concentration over the ranges of 0.5-200 ng/mL for GL and 2-800 ng/mL for GA (both R2 > 0.998). Using this method, the pharmacokinetics of GL after single oral administration of a clinical dose (75 mg) to six healthy male Japanese volunteers were evaluated. GL was detected in the plasma of all subjects and the average peak concentration was 24.8 ± 12.0 ng/mL. In contrast, peak concentration of GA was 200.3 ± 60.3 ng/mL, i.e. ~8-fold higher than that of GL. This is the first report clarifying pharmacokinetic profiles of GL and GA simultaneously at a therapeutic oral dose of a GL preparation.