Physiologically based pharmacokinetic modeling for confirming the role of CYP3A1/2 and P-glycoprotein in detoxification mechanism between glycyrrhizic acid and aconitine in rats.

Fuzi, an effective common herb, is often combined with Gancao to treat disease in clinical practice with enhancing its efficacy and alleviating its toxicity. The major toxic and bioactive compounds in Fuzi and Gancao are aconitine (AC) and glycyrrhizic acid (GL), respectively. This study aims to elucidate detoxification mechanism between AC and GL from pharmacokinetic perspective using physiologically based pharmacokinetic (PBPK) model. In vitro experiments exhibited that AC was mainly metabolized by CYP3A1/2 in rat liver microsomes and transported by P-glycoprotein (P-gp) in Caco-2 cells. Kinetics assays showed that the Km and Vmax of AC towards CYP3A1/2 were 2.38 µM and 57.3 pmol/min/mg, respectively, whereas that of AC towards P-gp was 11.26 µM and 147.1 pmol/min/mg, respectively. GL markedly induced the mRNA expressions of CYP3A1/2 and MDR1a/b in rat primary hepatocytes. In vivo studies suggested that the intragastric and intravenous administration of GL significantly reduced systemic exposure of AC by 27% and 33%, respectively. Drug-drug interaction (DDI) model of PBPK predicted that co-administration of GL would decrease the exposure of AC by 39% and 45% in intragastric and intravenous dosing group, respectively. The consistency between predicted data and observed data confirmed that the upregulation of CYP3A1/2 and P-gp was the crucial detoxification mechanism between AC and GL. Thus, this study provides a demonstration for elucidating the compatibility mechanisms of herbal formula using PBPK modeling and gives support for the clinical co-medication of Fuzi and Gancao.

Pharmacokinetics-based comprehensive strategy to identify multiple effective components in Huangqi decoction against liver fibrosis.

BACKGROUND: Huangqi decoction (HQD) has been used to treat chronic liver diseases since the 11th century, but the effective components in HQD against liver fibrosis have not been definitively clarified. PURPOSE: To investigate and identify multiple effective components in HQD against liver fibrosis using a pharmacokinetics-based comprehensive strategy. METHODS: The absorbed representative components in HQD and their metabolites were detected in human plasma and urine using high-resolution mass spectrometry combined with a database-directed method, and then pharmacokinetics in multiple HQD components in human plasma was analyzed by ultra-performance liquid chromatography coupled with triple-quadruple mass spectrometry. Furthermore, the anti-fibrotic effect of potential effective HQD components was studied in LX-2 cells and that of a multi-component combination of HQD (MCHD) was verified in a mouse CCl4-induced hepatic fibrosis model. RESULTS: Twenty-four prototype components in HQD and 17 metabolites were identified in humans, and the pharmacokinetic characteristics of 14 components were elucidated. Among these components, astragaloside IV, cycloastragenol, glycyrrhizic acid, glycyrrhetinic acid, liquiritigenin, and isoliquiritigenin downregulated the mRNA expression of α-SMA; cycloastragenol, calycosin-7-O-ß-D-glucoside, formononetin, glycyrrhetinic acid, liquiritin, and isoliquiritin downregulated the mRNA expression of Col I; and calycosin, liquiritigenin, isoliquiritigenin, cycloastragenol, and glycyrrhetinic accelerated the apoptosis of LX-2 cells. MCHD reduced serum aminotransferase activity and hepatic collagen fibril deposition in mice with CCl4-induced hepatic fibrosis. CONCLUSION: Using the pharmacokinetics-based comprehensive strategy, we revealed that multiple effective HQD components act together against liver fibrosis.

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.

Glycyrrhizin: An old weapon against a novel coronavirus.

Currently, over 100 countries are fighting against a common enemy, the severe acute respiratory syndrome coronavirus (SARS-CoV)-2, which causes COVID-19. This has created a demand for a substance whose effectiveness has already been demonstrated in a similar scenario. Glycyrrhizin (GZ) is a promising agent against SARS-CoV-2 as its antiviral activity against SARS-CoV has already been confirmed. It is worthwhile to extrapolate from its proven therapeutic effects as there is a high similarity in the structure and genome of SARS-CoV and SARS-CoV-2. There are many possible mechanisms through which GZ acts against viruses: increasing nitrous oxide production in macrophages, affecting transcription factors and cellular signalling pathways, directly altering the viral lipid-bilayer membrane, and binding to the ACE2 receptor. In this review, we discuss the possible use of GZ in the COVID-19 setting, where topical administration appears to be promising, with the nasal and oral cavity notably being the potent location in terms of viral load. The most recently published papers on the distribution of ACE2 in the human body and documented binding of GZ to this receptor, as well as its antiviral activity, suggest that GZ can be used as a therapeutic for COVID-19 and as a preventive agent against SARS-CoV-2.

Co-delivery of glycyrrhizin and doxorubicin by alginate nanogel particles attenuates the activation of macrophage and enhances the therapeutic efficacy for hepatocellular carcinoma.

Nanocarrier drug delivery systems (NDDS) have been paid more attention over conventional drug delivery system for cancer therapy. However, the efficacy is hampered by the fast clearance of activated macrophage from the blood circulation system. In this study, glycyrrhizin (GL) was introduced into alginate (ALG) nanogel particles (NGPs) to construct multifunctional delivery vehicle to decrease the fast clearance of activated macrophage and enhance the anticancer efficacy with the combination therapy of GL and doxorubicin (DOX). Methods: We firstly synthesized the GL-ALG NGPs with intermolecular hydrogen bond and ionic bond as the multifunctional delivery vehicle. The immune response and phagocytosis of macrophage on GL-ALG NGPs were investigated on RAW 264.7 macrophages. The pharmacokinetic study of DOX loaded in GL-ALG NGPs was performed in rats. The active targeting effects of GL-ALG NGPs were further studied on hepatocellular carcinoma cell (HepG2) and H22 tumor-bearing mice. Moreover, the anticancer molecular mechanism of DOX/GL-ALG NGPs was investigated on HepG2 cells in vitro and tumor-bearing mice in vivo. Results: GL-ALG NGPs could not only avoid triggering the immuno-inflammatory responses of macrophages but also decreasing the phagocytosis of macrophage. The bioavailability of DOX was increased about 13.2 times by DOX/GL-ALG NGPs than free DOX in blood. The mice with normal immune functions used in constructing the tumor-bearing mice instead of the nude mouse also indicated the good biocompatibility of NGPs. GL-mediated ALG NGPs exhibited excellent hepatocellular carcinoma targeting effect in vitro and in vivo. The results suggested that the anticancer molecular mechanism of the combination therapy of glycyrrhizin and doxorubicin in ALG NGPs was performed via regulating apoptosis pathway of Bax/Bcl-2 ratio and caspase-3 activity, which was also verified in H22 tumor-bearing mice. Conclusion: DOX/GL-ALG NGPs could attenuate the activation of macrophage and enhance the therapeutic efficacy for hepatocellular carcinoma. Our results suggest that the combination therapy would provide a new strategy for liver cancer treatment.

Glycyrrhizic acid-loaded pH-sensitive poly-(lactic-co-glycolic acid) nanoparticles for the amelioration of inflammatory bowel disease.

Aim: To fabricate and evaluate the therapeutic efficacy of glycyrrhizic acid (GA)-loaded pH-sensitive nanoformulations that specifically target and combat mucosal inflammation of the colon. Methods: GA-loaded Eudragit® S100/poly-(lactic-co-glycolic acid) nanoparticles were developed through modified double-emulsion evaporation coupled with solvent evaporation coating techniques and analyzed for physicochemical characteristics, surface chemistry, release kinetics, site-retention and therapeutic effectiveness. Results: Nanoparticles have a particle size of approximately 200 nm, high encapsulation efficiency, desired surface chemistry with pH-dependent and sustained drug release behavior following the Gompertz kinetic model. In vivo retention and therapeutic effectiveness in the inflamed colon tissues were confirmed by macroscopic and microscopic indices, cytokine analysis and antioxidant assays. Conclusion: GA-loaded Eudragit S100/poly-(lactic-co-glycolic acid) nanoparticles could efficiently deliver GA to the colon and ameliorate the mucosal inflammation for a prolonged duration.

Simultaneous Determination and Pharmacokinetic Characterization of Glycyrrhizin, Isoliquiritigenin, Liquiritigenin, and Liquiritin in Rat Plasma Following Oral Administration of Glycyrrhizae Radix Extract.

Glycyrrhizae Radix is widely used as herbal medicine and is effective against inflammation, various cancers, and digestive disorders. We aimed to develop a sensitive and simultaneous analytical method for detecting glycyrrhizin, isoliquiritigenin, liquiritigenin, and liquiritin, the four marker components of Glycyrrhizae Radix extract (GRE), in rat plasma using liquid chromatography-tandem mass spectrometry and to apply this analytical method to pharmacokinetic studies. Retention times for glycyrrhizin, isoliquiritigenin, liquiritigenin, and liquiritin were 7.8 min, 4.1 min, 3.1 min, and 2.0 min, respectively, suggesting that the four analytes were well separated without any interfering peaks around the peak elution time. The lower limit of quantitation was 2 ng/mL for glycyrrhizin and 0.2 ng/mL for isoliquiritigenin, liquiritigenin, and liquiritin; the inter- and intra-day accuracy, precision, and stability were less than 15%. Plasma concentrations of glycyrrhizin, isoliquiritigenin, liquiritigenin, and liquiritin were quantified for 24 h after a single oral administration of 1 g/kg GRE to four rats. Among the four components, plasma concentration of glycyrrhizin was the highest and exhibited a long half-life (23.1 ± 15.5 h). Interestingly, plasma concentrations of isoliquiritigenin and liquiritigenin were restored to the initial concentration at 4-10 h after the GRE administration, as evidenced by liquiritin biotransformation into isoliquiritigenin and liquiritigenin, catalyzed by fecal lysate and gut wall enzymes. In conclusion, our analytical method developed for detecting glycyrrhizin, isoliquiritigenin, liquiritigenin, and liquiritin could be successfully applied to investigate their pharmacokinetic properties in rats and would be useful for conducting further studies on the efficacy, toxicity, and biopharmaceutics of GREs and their marker components.

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.

Comparative pharmacokinetics of nine major bioactive components in normal and ulcerative colitis rats after oral administration of Lizhong decoction extracts by UPLC-TQ-MS/MS.

Lizhong decoction (LZD), a classic formula, has been used to treat ulcerative colitis (UC) for thousands of years in clinical practice. However, the pharmacokinetic characteristics of its major bioactive components in rats under different physiological and pathological states are not clear. Thus, in this study, a rapid and sensitive analytical method, ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS/MS) method, was developed and applied to simultaneously determine glycyrrhizic acid, liquiritin, isoliquiritin, glycyrrhizin, isoliquiritigenin, 6-gingerol, ginsenoside Rg1, ginsenoside Rb1 and ginsenoside Re in normal and UC rats after oral administration of LZD extract. A Waters BEH C18 UPLC column was used for chromatographic separation, while acetonitrile and 0.1% formic acid were selected as mobile phase. The linearity of nine analytes was >0.9920. Inter- and intra-day accuracy was ≤ 11.4% and precision was from 1.1 to 12.7%. Additionally, stable and suitable extraction recoveries were also obtained. The established method was validated and found to be specific, accurate and precise for nine analytes. Furthermore, it was successfully applied to the pharmacokinetic investigation of nine major components after oral administration of LZD extracts to normal and model rats, respectively. The results showed that the pharmacokinetic parameters (Cmax , Tmax , AUC0-t , AUC0-∞ ) in the plasma of UC rats were significantly different from those of normal rats, which could provide a reference for the clinical application of LZD.

Brain-targeted glycyrrhizic-acid-loaded surface decorated nanoparticles for treatment of cerebral ischaemia and its toxicity assessment.

OBJECTIVE: Enhancement of CS-GA-PCL-NPs (Glycyrrhizic Acid-encapsulated-chitosan-coated-PCL-Nanoparticles) bioavailability in brain. METHODS: Double emulsification solvent evaporation method in order to develop CS-PCL-NPs (Chitosan-coated-PCL-Nanoparticles) followed by characterization of particle size and distribution, zeta potential, encapsulation efficiency and drug release (in vitro). To determine drug-uptake and its pharmacokinetic profile in brain as well as plasma, UHPLC (triple quadrupole Q-trap) MS/MS method was developed and optimized for CS-GA-PCL-NPs as well as to follow-up examined effective role of optimized NPs in reduction of all brain injury parameters after MCAO through the grip strength, locomotor activity, inflammatory cytokines levels, measurement of infarction volume and histopathological changes in neurons with safety/toxicity after i.n. in animals. RESULTS: The developed NPs showed an average particle size, entrapment efficiency with PDI (polydispersity index) of 201.3 ± 4.6 nm, 77.94 ± 5.01% and 0.253 ± 0.019, respectively. Higher mucoadhesive property for CS-GA-PCL-NPs as compared to conventional and homogenized nanoformulations was observed whereas an elution time of 0.37 min and m/z of 821.49/113.41 for GA along with an elution time of 1.94 min and m/z of 363.45/121.40 was observed for hydrocortisone i.e. Internal standard (IS). Similarly, %CV i.e. inter and intra assay i.e. 0.49-4.41%, linear dynamic range (10-2000 ng/mL) and % accuracy of 90.00-99.09% was also observed. AUC0-24 with augmented Cmax was noted (**p < .01), in Wistar rat brain as compared to i.v. treated group during pharmacokinetics studies. In MCA-occluded rats, enhanced neurobehavioral activity i.e. locomotor and grip strength along with a decrease in cytokines level (TNF-α and IL-1ß) was observed, following i.n. administration. CONCLUSIONS: CS-coated-GA-loaded-PCL-NPs when administered i.n. enhanced the bioavailability of the drug in rat brain as compared to i.v. administration. The observation from toxicity study concludes; the developed NPS are safe and free of any health associated risk.

Pretreatment with broad-spectrum antibiotics alters the pharmacokinetics of major constituents of Shaoyao-Gancao decoction in rats after oral administration.

The influence of broad-spectrum antibiotics on the pharmacokinetics and biotransformation of major constituents of Shaoyao-Gancao decoction (SGD) in rats was investigated. The pharmacokinetic behaviors of paeoniflorin (PF), albiflorin (AF), liquiritin (LT), isoliquiritin (ILT), liquiritin apioside (LA), isoliquiritin apioside (ILA), and glycyrrhizic acid (GL), seven major constituents of SGD, as well as glycyrrhetinic acid (GA), a major metabolite of GL, were analyzed. A 1-week pretreatment with broad-spectrum antibiotics (ampicillin, metronidazole, neomycin, 1 g L-1; and vancomycin, 0.5 g L-1) via drinking water reduced plasma exposure of the major constituents. The AUC0-24 h of PF and LT was significantly decreased by 28.7% and 33.8% (P < 0.05 and P < 0.005), respectively. Although the differences were not statistically significant, the AUC0-24 h of AF, ILT, LA, ILA, and GL was decreased by 31.4%, 50.9%, 16.9%, 44.1%, and 37.0%, respectively, compared with the control group. In addition, the plasma GA exposure in the antibiotic-pretreated group was significantly lower (P < 0.005) than the control group. The in vitro stability of the major constituents of SGD in the rat intestinal contents with or without broad-spectrum antibiotics was also investigated. The major constituents were comparatively stable in the rat duodenum contents, and the biotransformation of GL mainly occurred in the rat colon contents. In summary, broad-spectrum antibiotics suppressed the absorption of the major constituents of SGD and significantly inhibited the biotransformation of GL to GA by suppressing the colon microbiota. The results indicated a potential clinical drug-drug interaction (DDI) when SGD was administered with broad-spectrum antibiotics.

Neuroprotective effect of Trichosanthes kirilowii cassia twig on cerebral ischemia-reperfusion injury in rats.

In this study, in-depth observation and investigation of blood-brain barrier permeability and neuroprotective effect of Trichosanthes kirilowii cassia twig particles on rats with cerebral ischemia-reperfusion injury were performed. Focal cerebral ischemia-reperfusion injury model was established by middle cerebral artery occlusion method, reperfusion was implemented 2 hours after ischemia; qualitative analysis and investigation of trichosanthes kirilowii cassia twig particles in plasma, brain tissue and cerebrospinal fluid in normal and middle cerebral artery occlusion (MCAO) rats were done by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS); changes in neurological deficits, cerebral infarction stereometry, blood-brain barrier permeability and histopathological changes of MCAO model rats were observed. Qualitative analysis by HPLC-MS/MS results showed that ingredients, paeoniflorin, albiflorin, liquiritin in Trichosanthes kirilowii cassia twig particles can reach the brain through the blood-brain barrier. In the model group, glycyrrhizin and glycyrrhizic acid can be detected in brain tissue or cerebrospinal fluid. In addition, Trichosanthes kirilowii cassia twig particles can significantly lower neurological deficits of rats in middle cerebral artery occlusion model, reduce the Evans blue penetration, contract infarct size, and reduce pathological tissue injury of cerebral ischemia reperfusion. The ingredients of Trichosanthes kirilowii cassia twig particles can reach the brain tissue through the blood-brain barrier and play a role in neuroprotection of rats with cerebral ischemia-reperfusion injury, which has important research significance and brings scientific experimental, theoretical basis for clinical drug use.

Glycyrrhizin has a high likelihood to be a victim of drug-drug interactions mediated by hepatic organic anion-transporting polypeptide 1B1/1B3.

BACKGROUND AND PURPOSE: Intravenous glycyrrhizin, having anti-inflammatory and hepatoprotective properties, is incorporated into the management of liver diseases in China. This investigation was designed to elucidate the molecular mechanism underlying hepatobiliary excretion of glycyrrhizin and to investigate its potential for drug-drug interactions on organic anion-transporting polypeptide (OATP)1B. EXPERIMENTAL APPROACH: Human transporters mediating hepatobiliary excretion of glycyrrhizin were characterized at the cellular and vesicular levels and compared with rat hepatic transporters. The role of Oatp1b2 in glycyrrhizin's elimination and pharmacokinetics was evaluated in rats using the inhibitor rifampin. A physiologically based pharmacokinetic (PBPK) model for glycyrrhizin, incorporating transporter-mediated hepatobiliary excretion, was established and applied to predict potential drug-drug interactions related to glycyrrhizin in humans. KEY RESULTS: Hepatobiliary excretion of glycyrrhizin involved human OATP1B1/1B3 (Oatp1b2 in rats)-mediated hepatic uptake from blood and human multidrug resistance-associated protein (MRP)2/breast cancer resistance protein (ABCP)/bile salt export pump (BSEP)/multidrug resistance protein 1 (Mrp2/Abcp/Bsep in rats)-mediated hepatic efflux into bile. In rats, rifampin impaired hepatic uptake of glycyrrhizin significantly increasing its systemic exposure. Glomerular-filtration-based renal excretion of glycyrrhizin was slow due to extensive protein binding in plasma. Quantitative analysis using the PBPK model demonstrated that OATP1B1/1B3 have critical roles in the pharmacokinetics of glycyrrhizin, which is highly likely to be a victim of drug-drug interactions when co-administered with potent dual inhibitors of these transporters. CONCLUSIONS AND IMPLICATIONS: Transporter-mediated hepatobiliary excretion governs glycyrrhizin's elimination and pharmacokinetics. Understanding glycyrrhizin's potential drug-drug interactions on OATP1B1/1B3 should enhance the therapeutic outcome of glycyrrhizin-containing drug combinations on liver diseases.

Effects of glycyrrhizin on the pharmacokinetics of asiatic acid in rats and its potential mechanism.

CONTEXT: Asiatic acid has been reported to possess a wide range of pharmacological activities. OBJECTIVE: This study investigates the effects of glycyrrhizin on the pharmacokinetics of asiatic acid in rats and its potential mechanism. MATERIALS AND METHODS: The pharmacokinetics of orally administered asiatic acid (20 mg/kg) with or without glycyrrhizin pretreatment (100 mg/kg/day for seven days) were investigated using a LC-MS method. Additionally, the Caco-2 cell transwell model and rat liver microsome incubation systems were used to investigate the potential mechanism of glycyrrhizin's effects on the pharmacokinetics of asiatic acid. RESULTS: The results showed that the Cmax (221.33 ± 21.06 vs. 324.67 ± 28.64 ng/mL), AUC0-inf (496.12 ± 109.31 vs. 749.15 ± 163.95 µg·h/L) and the t1/2 (1.21 ± 0.27 vs. 2.04 ± 0.32 h) of asiatic acid decreased significantly (p < 0.05) with the pretreatment of glycyrrhizin. The oral clearance of asiatic acid increased significantly from 27.59 ± 5.34 to 41.57 ± 9.19 L/h/kg (p < 0.05). The Caco-2 cell transwell experiments indicated that glycyrrhizin could increase the efflux ratio of asiatic acid from 1.63 to 2.74, and the rat liver microsome incubation experiments showed that glycyrrhizin could increase the intrinsic clearance rate of asiatic acid from 138.32 ± 11.20 to 221.76 ± 16.85 µL/min/mg protein. DISCUSSION AND CONCLUSIONS: In conclusion, these results indicated that glycyrrhizin could decrease the system exposure of asiatic acid, possibly by inducing the activity of P-gp or CYP450 enzyme.

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.

Glycyrrhetic acid, but not glycyrrhizic acid, strengthened entecavir activity by promoting its subcellular distribution in the liver via efflux inhibition.

Entecavir (ETV) is a superior nucleoside analogue used to treat hepatitis B virus (HBV) infection. Although its advantages over other agents include low viral resistance and the elicitation of a sharp decrease in HBV DNA, adverse effects such as hepatic steatosis, hepatic damage and lactic acidosis have also been reported. Glycyrrhizin has long been used as hepato-protective medicine. The clinical combination of ETV plus glycyrrhizin in China displays better therapeutic effects and lower rates of liver damage. However, there is little evidence explaining the probable synergistic mechanism that exists between these two drugs from a pharmacokinetics view. Here, alterations in the plasma pharmacokinetics, tissue distribution, subcellular distribution, and in vitro and in vivo antiviral activity of ETV after combination with glycyrrhizic acid (GL) were analysed to determine the synergistic mechanisms of these two drugs. Specific efflux transporter membrane vesicles were also used to elucidate their interactions. The primary active GL metabolite, glycyrrhetic acid (GA), did not affect the plasma pharmacokinetics of ETV but promoted its accumulation in hepatocytes, increasing its distribution in the cytoplasm and nucleus and augmenting the antiviral efficiency of ETV. These synergistic actions were primarily due to the inhibitory effect of GA on MRP4 and BCRP, which transport ETV out of hepatocytes. In conclusion, GA interacted with ETV at cellular and subcellular levels in the liver through MRP4 and BCRP inhibition, which enhanced the antiviral activity of ETV. Our results partially explain the synergistic mechanism of ETV and GL from a pharmacokinetics view, providing more data to support the use of these compounds together in clinical HBV treatment.

The Effects of Sweet Foods on the Pharmacokinetics of Glycyrrhizic Acid by icELISA.

The effect of sweet foods, such as honey, was investigated from the perspective of pharmacokinetics on the absorption of glycyrrhizic acid (GA). Due to the unique properties of indirect competitive enzyme-linked immunosorbent assay (icELISA), namely, its: specificity, sensitivity, repeatability, simple pretreatment of samples, fast and simple operation, and because it is economic and non-polluting, it has received increased attention. In this study, we used the advantages of this method to see how honey affected the pharmacokinetics of GA. The effects of honey on the pharmacokinetics of GA by ELISA were investigated for the first time. The results indicate that honey can postpone the peak concentration of GA in mouse blood, and this effect correlates well with fructose. As a representative of sweet foods, the result provides the valuable information that honey, or fructose, may act as sustained-releasing drugs in clinical scenarios; and that sweet foods may have some influences on drugs when taken together.

Investigation of the influence of glycyrrhizin on the pharmacokinetics of celastrol in rats using LC-MS and its potential mechanism.

1. The aim of this study was to investigate the effects of glycyrrhizin on the pharmacokinetics of celastrol in rats. 2. Twelve male Sprague-Dawley rats were randomly assigned to two groups: control group and test group. Test group was pretreated with glycyrrhizin at a dose of 100 mg/kg/day for 10 days, and then the two groups were orally administered with celastrol at a dose of 1 mg/kg. The concentration of celastrol was determined using a sensitive and reliable LC-MS method. 3. The results showed that glycyrrhizin could significantly decrease the plasma concentration (from 64.36 ng/mL to 38.42 ng/mL) and AUC0-t (from 705.39 to 403.43 µg·h/L) of celastrol in rats. To investigate its potential mechanism, the effects of glycyrrhizin on the transport and metabolic stability of celastrol were investigated using Caco-2 cell monolayer transwell model and rat liver microsome incubation systems. The Caco-2 cell monolayer transwell experiments indicated that glycyrrhizin could increase the efflux ratio of celastrol (4.02 versus 6.51). However, the rat liver microsome incubation experiments showed that glycyrrhizin could significantly increase the intrinsic clearance rate of celastrol from 20.3 ± 3.37 to 38.8 ± 4.18 µL/min/mg protein. 4. In conclusion, these results indicated that the herb-drug interaction between glycyrrhizin and celastrol might occur when they were coadministered.

Pharmacokinetic Effects of Cinnamic Acid, Amygdalin, Glycyrrhizic Acid and Liquiritin on Ephedra Alkaloids in Rats.

BACKGROUND AND OBJECTIVES: Ephedra alkaloids, including ephedrine (EP), pseudoephedrine (PEP) and methylephedrine (MEP), are sympathomimetic compounds with known toxicities but many Ephedra (Ephedrae herba) preparations, such as Ephedra decoction, have been clinically applied for centuries. In order to explore the possible detoxification mechanism of Ephedra alkaloids, four representative compounds in Ephedra decoction (cinnamic acid, amygdalin, glycyrrhizic acid and liquiritin) were studied for their pharmacokinetic effects on Ephedra alkaloids in Sprague-Dawley rats. METHODS: Animals were randomly divided into six groups, with six rats in each. Rats were treated orally with EP-PEP-MEP (20 mg/kg EP + 20 mg/kg PEP + 20 mg/kg MEP) and different combinations of cinnamic acid (3.03 mg/kg), amygdalin (56.97 mg/kg), glycyrrhizic acid (12.42 mg/kg), liquiritin (3.79 mg/kg) with EP-PEP-MEP, and 20 mg/kg EP + 20 mg/kg PEP + 20 mg/kg MEP + 3.03 mg/kg cinnamic acid + 56.97 mg/kg amygdalin + 12.42 mg/kg glycyrrhizic acid + 3.79 mg/kg liquiritin. Blood samples (0.5 mL) were taken from the orbital sinus venous plexus into heparinized tubes at 5, 10, 20, 30, 45, 60, 90, 120, 180, 240, 300 and 360 min (6 rats per time point in each group) following single administration. The concentrations of Ephedra alkaloids in rat plasma were determined using a validated high performance liquid chromatography method. RESULTS: Area under the concentration-time curve from 0 to 360 min (AUC0-t ) of EP, PEP and MEP were 666.99, 650.76 and 632.37 µg·min/mL, respectively. Maximum plasma concentration (C max) of EP, PEP and MEP were 4.15, 4.08 and 3.59 µg/mL, respectively. Mean residence time (MRT) of EP, PEP and MEP were 197.00, 173.97 and 183.87 min, respectively, when the rats were treated with EP-PEP-MEP. Cinnamic acid increased the AUC0-t of EP while decreased C max of EP, amygdalin and glycyrrhizic acid increased C max and AUC0-t of EP and PEP, while liquiritin decreased AUC0-t of EP and PEP. The four representative compounds reduced MRT of EP, PEP and MEP, four compounds decreased AUC0-t of MEP. The EP-PEP-MEP + cinnamic acid + amygdalin + glycyrrhizic acid + liquiritin group increased AUC0-t of EP while decreased MRT of EP, increased MRT of PEP while decreased AUC0-t of PEP. The EP-PEP-MEP + cinnamic acid + amygdalin + glycyrrhizic acid + liquiritin group decreased MRT, AUC0-t and C max of MEP. CONCLUSIONS: Significant changes in pharmacokinetic parameters of EP, PEP and MEP were observed after oral administration with different combinations. The pharmacokinetic results reported here might provide reference for clinical usage of Ephedra alkaloids.