Simple and Rapid Method for Wogonin Preparation and Its Biotransformation

Wogonin is one of the most active flavonoids from Scutellaria baicalensis Georgi (baikal skullcap), widely used in traditional Chinese medicine. It exhibits a broad spectrum of health-promoting and therapeutic activities. Together with baicalein, it is considered to be the one of main active ingredients of Chinese medicines for the management of COVID-19. However, therapeutic use of wogonin may be limited due to low market availability connected with its low content in baikal skullcap and lack of efficient preparative methods for obtaining this compound. Although the amount of wogonin in skullcap root often does not exceed 0.5%, this material is rich in wogonin glucuronide, which may be used as a substrate for wogonin production. In the present study, a rapid, simple, cheap and effective method of wogonin and baicalein preparation, which provides gram quantities of both flavonoids, is proposed. The obtained wogonin was used as a substrate for biotransformation. Thirty-six microorganisms were tested in screening studies. The most efficient were used in enlarged scale transformations to determine metabolism of this xenobiotic. The major phase I metabolism product was 4′-hydroxywogonin—a rare flavonoid which exhibits anticancer activity—whereas phase II metabolism products were glucosides of wogonin. The present studies complement and extend the knowledge on the effect of substitution of A- and B-ring on the regioselective glycosylation of flavonoids catalyzed by microorganisms.

Safety, tolerability, pharmacokinetics, and food effect of baicalein tablets in healthy Chinese subjects: A single-center, randomized, double-blind, placebo-controlled, single-dose phase I study

ETHNOPHARMACOLOGICAL RELEVANCE

Scutellaria baicalensis (Huang-Qin in Chinese) is a dry root of the perennial herb Scutellaria baicalensis Georgi, which has been used extensively in current prescriptions. Scutellaria baicalensis is an herb high in flavonoids, and baicalein is the one flavonoid found in the highest amount in Scutellaria baicalensis.

AIM OF THE STUDY

Influenza virus could cause mild respiratory tract illness to severe pneumonia and even death. Baicalein has been proved to be one of the effective components against the influenza virus. However, there have been few reports on human trials of baicalein. The purpose of this study was to evaluate the safety of baicalein in vivo and analyze its pharmacokinetic characteristics.

MATERIALS AND METHODS

Three randomized studies were conducted to evaluate the pharmacokinetics (PK), safety, tolerability, and food effects of baicalein tablets. In the 7-month single-dose safety study, 60 subjects were enrolled and randomized to receive 100-800 mg baicalein tablets or placebo. In the single-dose PK study, 40 subjects were enrolled and randomized to receive 200 mg, 400 mg, 600 mg, 800 mg baicalein tablets. In the study of food effect on PK of baicalein, an additional 10 subjects were enrolled in the 400 mg group, this part of the trial lasted for 7 months. Blood and urine samples for PK analysis were collected at a pre-specified time. PK properties in both fasted and fed states were evaluated, as well as safety and tolerability.

RESULTS

Among the 80 subjects who were evaluable for the single-dose safety and tolerability, 56 adverse events (AEs) were observed in 32/80 subjects, of which 49 events were from 28/68 subjects in baicalein group and 7 events were from 4/12 subjects in placebo group. All AEs were mild and resolved without any medical intervention. The most common AEs were elevated high-sensitivity C-reactive protein (hs-CRP) level and high triglycerides. After a single administration of baicalein tablets (200 mg, 400 mg, 600 mg, or 800 mg), C_max were 280.44, 628.80, 845.20, 489.55 ng/mL; AUC_0-∞ were 2035.57, 2939.31, 4494.88, and 3754.43 h*ng/mL, respectively. And t_1/2z ranged from 7.80 to 14.91 h. The exposure of baicalein and its metabolites increased in a less than dose-proportional manner.

CONCLUSION

Baicalein tablets within the studied dose range were safe and well-tolerated in healthy Chinese subjects with no serious or severe adverse effects. Further investigation will be needed to assess the safety and efficacy in the target patients.

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-β-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.

Formulation and intestinal absorption of naringenin loaded nanostructured lipid carrier and its inhibitory effects on nonalcoholic fatty liver disease

In this study, we prepared naringenin (NGN) loaded nanostructured lipid carrier (NGN-NLC) and investigated its characterizations, transepithelial transport, intestinal absorption and inhibitory effects on nonalcoholic fatty liver disease (NAFLD) induced by a methionine choline deficient (MCD) diet in mice. The NGN-NLC, prepared by a method of emulsion-evaporation plus low temperature-solidification, displayed high drug loading capacity of 22.5 ± 1.7%. Compared to the NGN crude drug, the NGN-NLC, at an equal NGN dose, improved NGN release rate by 3.5-fold and elevated NGN transepithelial transport and intestinal absorption through enhancing intracellular transport of clathrin pathway and escaping p-gp efflux; at an 8-fold lower NGN dose, showed comparable pharmacokinetic parameters, but elevated liver NGN distribution by 1.5-fold, reduced MCD diet-induced hepatic lipid deposition by 3-fold. These results suggest that the NLC formulation significantly increased the inhibitory effects of NGN on NAFLD because of the improved drug release rate, transepithelial transport and intestinal absorption, and the elevated oral bioavailability and liver NGN distribution.

The comprehensive study on the therapeutic effects of baicalein for the treatment of COVID-19 in vivo and in vitro

Baicalein is the main active compound of Scutellaria baicalensis Georgi, a medicinal herb with multiple pharmacological activities, including the broad anti-virus effects. In this paper, the preclinical study of baicalein on the treatment of COVID-19 was performed. Results showed that baicalein inhibited cell damage induced by SARS-CoV-2 and improved the morphology of Vero E6 cells at a concentration of 0.1 μM and above. The effective concentration could be reached after oral administration of 200 mg/kg crystal form β of baicalein in rats. Furthermore, baicalein significantly inhibited the body weight loss, the replication of the virus, and relieved the lesions of lung tissue in hACE2 transgenic mice infected with SARS-CoV-2. In LPS-induced acute lung injury of mice, baicalein improved the respiratory function, inhibited inflammatory cell infiltration in the lung, and decreased the levels of IL-1β and TNF-α in serum. In conclusion, oral administration of crystal form β of baicalein could reach its effective concentration against SARS-CoV-2. Baicalein could inhibit SARS-CoV-2-induced injury both in vitro and in vivo. Therefore, baicalein might be a promising therapeutic drug for the treatment of COVID-19.

Self-Assembled Lecithin/Chitosan Nanoparticles Based on Phospholipid Complex: A Feasible Strategy to Improve Entrapment Efficiency and Transdermal Delivery of Poorly Lipophilic Drug

PURPOSE

Lecithin/chitosan nanoparticles have shown great promise in the transdermal delivery of therapeutic agents. Baicalein, a natural bioactive flavonoid, possesses multiple biological activities against dermatosis. However, its topical application is limited due to its inherently poor hydrophilicity and lipophilicity. In this study, the baicalein-phospholipid complex was prepared to enhance the lipophilicity of baicalein and then lecithin/chitosan nanoparticles loaded with the baicalein-phospholipid complex were developed to improve the transdermal retention and permeability of baicalein.

METHODS

Lecithin/chitosan nanoparticles were prepared by the solvent-injection method and characterized in terms of particle size distribution, zeta potential, and morphology. The in vitro release, the ex vivo and in vivo permeation studies, and safety evaluation of lecithin/chitosan nanoparticles were performed to evaluate the effectiveness in enhancing transdermal retention and permeability of baicalein.

RESULTS

The lecithin/chitosan nanoparticles obtained by the self-assembled interaction of chitosan and lecithin not only efficiently encapsulated the drug with high entrapment efficiency (84.5%) but also provided sustained release of baicalein without initial burst release. Importantly, analysis of the permeation profile ex vivo and in vivo demonstrated that lecithin/chitosan nanoparticles prolonged the retention of baicalein in the skin and efficiently penetrated the barrier of stratum corneum without displaying skin irritation.

CONCLUSION

These results indicate the potential of drug-phospholipid complexes in enhancing the entrapment efficiency and self-assembled lecithin/chitosan nanoparticles based on phospholipid complexes in the design of a rational transdermal delivery platform to improve the efficiency of transdermal therapy by enhancing its percutaneous retention and penetration in the skin.

Network Pharmacology and Bioactive Equivalence Assessment Integrated Strategy Driven Q-markers Discovery for Da-Cheng-Qi Decoction to Attenuate Intestinal Obstruction

BACKGROUND

Intestinal obstruction (IO) is a kind of acute abdomen with high morbidity and mortality. Patients suffer from poor quality of life and tremendous financial pressure. Da-Cheng-Qi decoction (DCQD), a classical purgation prescription, has clinically been proven to be an effective treatment for IO.

PURPOSE

Network pharmacology integrated with bioactive equivalence assessment was used to discover the quality marker (Q-marker) of DCQD against IO.

METHODS

As there is hardly any targets recorded in database, thus the collection of IO targets was conducted by searching those of alternative diseases which have similar pathological symptoms with IO. In order to improve the reliability of the obtained targets, IO metabolomics data was introduced. Active compounds combination (ACC) was focused as potential Q-markers via component-target network analysis and function query from the identified components corresponding to the common targets. Bioequivalence between ACC and DCQD was assessed from the aspects of intestine motility (somatostatin secretion), inflammation (IL-6 secretion) and injury (wound healing assay) in vitro and was further validated in ileus rat model. PPI network analysis of core targets followed by gene pedigree classification and experimental validation confirmed the potential intervention pathway.

RESULTS

A combination of 11 ingredients, including emodin, physcion, aloe-emodin, rhein, chrysophanol, gallic acid, magnolol, honokiol, naringenin, tangeretin, and nobiletin was finally confirmed bioequivalence with DQCD to some extent and could serve as Q-markers for DCQD to attenuate IO. PI3K/AKT was verified as a possible affected pathway that DCQD exerted the effectiveness against IO.

CONCLUSION

For the disease with few recorded targets, searching those of alternative diseases which have similar pathological symptoms could be a feasible and effective approach. The proposed network pharmacology integrated bioactive equivalence evaluation paradigm is efficient to discover Q-marker of herbal formulae.

Characterization, in Vitro and in Vivo Evaluation of Naringenin-Hydroxypropyl-ß-Cyclodextrin Inclusion for Pulmonary Delivery

Naringenin, a flavonoid compound which exists abundantly in Citrus fruits, is proven to possess excellent antitussive and expectorant effects. However, the clinical applications of naringenin are restricted by its poor solubility and low local concentration by oral administration. The aim of the present study is to prepare a naringenin-hydroxypropyl-β-cyclodextrin (naringenin-HPβCD) inclusion as an inhalation solution for pulmonary delivery. The naringenin-HPβCD inclusion was characterized by phase solubility study, XRD, differential scanning calorimetry (DSC), proton nuclear magnetic resonance (¹HNMR), and two-dimensional rotating frame Overhauser effect spectroscopy (2D ROESY). The in vitro permeability of the inclusion was evaluated on Calu-3 cells and the pharmacokinetic profile of pulmonary delivery was investigated in Sprague-Dawley (SD) rats. Based on the linear model of phase solubility study, the relationship between naringenin and HPβCD was identified as A^L type with a 1:1 stoichiometry. XRD, DSC, and NMR studies indicated that the entire naringenin molecule is encapsulated into the cavity of HPβCD. HPβCD could increase the concentration of naringenin in the epithelium-lining fluid (ELF) of Calu-3 cells and act as a sustained release system for naringenin. The pharmacokinetic profile of naringenin-HPβCD inclusion showed rapid response and higher local concentration by pulmonary delivery. In conclusion, pulmonary delivery of naringenin-HPβCD inclusion is a promising formulation strategy, which could provide a new possibility for the clinical application of naringenin.

Safety and pharmacokinetics of naringenin: A randomized, controlled, single-ascending-dose clinical trial

AIMS

To evaluate the safety and pharmacokinetics of naringenin in healthy adults consuming whole-orange (Citrus sinensis) extract.

METHODS AND METHODS

In a single-ascending-dose randomized crossover trial, 18 adults ingested doses of 150 mg (NAR150), 300 mg (NAR300), 600 mg (NAR600) and 900 mg (NAR900) naringenin or placebo. Each dose or placebo was followed by a wash-out period of at least 1 week. Blood safety markers were evaluated pre-dose and 24 hours post-dose. Adverse events (AEs) were recorded. Serum naringenin concentrations were measured before and over 24 hours following ingestion of placebo, NAR150 and NAR600. Four- and 24-hour serum measurements were obtained after placebo, NAR300 and NAR900 ingestion. Data were analysed using a mixed-effects linear model.

RESULTS

There were no relevant AEs or changes in blood safety markers following ingestion of any of the naringenin doses. The pharmacokinetic variables were: maximal concentration: 15.76 ± 7.88 μM (NAR150) and 48.45 ± 7.88 μM (NAR600); time to peak: 3.17 ± 0.74 hours (NAR150) and 2.41 ± 0.74 hours (NAR600); area under the 24-hour concentration-time curve: 67.61 ± 24.36 μM × h (NAR150) and 199.05 ± 24.36 μM × h (NAR600); and apparent oral clearance: 10.21 ± 2.34 L/h (NAR150) and 13.70 ± 2.34 L/h (NAR600). Naringenin half-life was 3.0 hours (NAR150) and 2.65 hours (NAR600). After NAR300 ingestion, serum concentrations were 10.67 ± 5.74 μM (4 hours) and 0.35 ± 0.30 μM (24 hours). After NAR900 ingestion, serum concentrations were 43.11 ± 5.26 μM (4 hours) and 0.24 ± 0.30 μM (24 hours).

CONCLUSIONS

Ingestion of 150 to 900 mg doses of naringenin is safe in healthy adults, and serum concentrations are proportional to the dose administered. Since naringenin (8 μM) is effective in primary human adipocytes, ingestion of 300 mg naringenin twice/d will likely elicit a physiological effect.

ADMET properties of novel 5-O-benzoylpinostrobin derivatives

Background Prediction of the properties of absorption, distribution, metabolism, excretion, and toxicity (ADMET) from a compound is essential, especially for modified novel compounds. Previous research has successfully designed several modified compounds of 5-O-benzoyl derivatives from pinostrobin, a flavanone that has cytotoxic activity. This study aims to describe the properties of ADMET from the 5-O-benzoylpinostrobin derivative. Methods Prediction of the properties of ADMET was carried out using three web servers consisting of SwissADME, pkCSM, and ProTox-II. The observed parameters are divided into ADMET parameters. Results In general, absorption parameters indicate that the 5-O-benzoylpinostrobin derivative has lower water solubility than the parent pinostrobin. Distribution parameters show mixed results for distribution through the blood-brain barrier. Metabolism parameters showed different results with generally inhibitory activity shown in CYP2C19, CYP2C9, and CYP3A4. The excretion parameters showed a higher total clearance than pinostrobin except in the trifluoromethyl derivative. The toxicity parameters showed both pinostrobin and the 5-O-benzoylpinostrobin derivatives, including the class IV toxicity category with the lowest LD50 value indicated by the nitro derivative of 1500, with the possible target of the androgen receptor and prostaglandin G/H synthase 1. Conclusions Overall, the 5-O-benzoylpinostrobin derivative has the predicted ADMET profile that is relatively similar to pinostrobin, with the most noticeable difference being shown in the absorption parameters where all 5-O-benzoylpinostrobin derivatives have lower water solubility than pinostrobin.

An Investigation on Glucuronidation Metabolite Identification, Isozyme Contribution, and Species Differences of GL-V9 In Vitro and In Vivo

GL-V9 is a prominent derivative of wogonin with a wide therapeutic spectrum and potent anti-tumor activity. The metabolism characteristics of GL-V9 remain unclear. This study aimed to clarify the metabolic pathway of GL-V9 and investigate the generation of its glucuronidation metabolites in vitro and in vivo. HPLC-UV-TripleTOF was used to identify metabolites. The main metabolite that we found was chemically synthesized and the synthetic metabolite was utilized as standard substance for the subsequent metabolism studies of GL-V9, including enzyme kinetics in liver microsomes of five different species and reaction phenotyping metabolism using 12 recombinant human UDP-glucuronosyltransferase (UGT) isoforms. Results indicated that the glucuronidation reaction occurred at C5-OH group, and 5-O-glucuronide GL-V9 is the only glucuronide metabolite and major phase II metabolite of GL-V9. Among 12 recombinant human UGTs, rUGT1A9 showed the strongest catalytic capacity for the glucuronidation reaction of GL-V9. rUGT1A7 and rUGT1A8 were also involved in the glucuronidation metabolism. Km of rUGT1A7-1A9 was 3.25 ± 0.29, 13.92 ± 1.05, and 4.72 ± 0.28 μM, respectively. In conclusion, 5-O-glucuronide GL-V9 is the dominant phase II metabolite of GL-V9 in vivo and in vitro, whose formation rate and efficiency are closely related to isoform-specific metabolism profiles and the distribution of UGTs in different tissues of different species.

Simultaneous determinations of four major bioactive components in Acacia catechu (L.f.) Willd and Scutellaria baicalensis Georgi extracts by LC-MS/MS: Application to its herb-herb interactions based on pharmacokinetic, tissue distribution and excretion studies in rats

BACKGROUND

Acacia catechu (L.f.) Willd (ACW) and Scutellaria baicalensis Georgi (SBG) are two famous herbs and often used in many traditional Chinese compound prescriptions. In clinical practice, ACW-SBG couple as a famous traditional herb couple, was widely used for treating infantile cough, phlegm and fever which caused by pulmonary infection. Meanwhile, a standardized bioflavonoid composition-UP446 with ACW extract and SBG extract has been used in both special nutritional products and joint care dietary supplements. However, its herb-herb interactions based on absorption, distribution, metabolism and excretion (ADME) study had not been investigated.

PURPOSE

The aim of this study was to evaluate potential pharmacokinetic, tissue distribution and excretion interactions between ACW and SBG, and to provide useful information for the development of suitable dosage forms and clinical applications.

STUDY DESIGN AND METHODS

A sensitive and reliable LC-MS/MS method was established to the quantification of four major bioactive components in rat biological samples. The method was validated for accuracy, precision, linearity, range, selectivity, lower limit of quantification (LLOQ), recovery, and matrix effect. All validation parameters met the acceptance criteria according to regulatory guidelines. Based on this, we obtained and compared the parameters about pharmacokinetics, tissue distribution and excretion of four major bioactive components in this study.

RESULTS

This work revealed that the parameters including plasma pharmacokinetics, tissue distribution and excretion of (+)-catechin (C), (-)-epicatechin (EC), baicalin (BL) and baicalein (BLE) in single administration had significant differences compared co-administration. The results illustrated that interactions between two herbs are related to the effect of competitive gastrointestinal absorption inhibition and drug metabolism by liver metabolic enzymes. Moreover, the alteration of C and EC in the tissue of lung maybe could enhance the pharmacological activity for treating pulmonary infection.

CONCLUSION

This is the first report to evaluate the pharmacokinetics, tissue distribution and excretion of co-administration of ACW or SBG to rats and compared its properties of four major bioactive components. The results demonstrate that herb -herb interactions occurred in this herb couple.

Enhanced Solubility and Permeability of Salicis cortex Extract by Formulating as a Microemulsion

A microemulsion system was developed and investigated as a novel oral formulation to increase the solubility and absorption of Salicis cortex extract. This extract possesses many pharmacological activities, in particular, it is beneficial for back pain and osteoarthritic and rheumatic complaints. In this work, after qualitative and quantitative characterization of the extract and the validation of an HPLC/diode array detector analytical method, solubility studies were performed to choose the best components for microemulsion formulation. The optimized microemulsion consisted of 2.5 g of triacetin, as the oil phase, 2.5 g of Tween 20 as the surfactant, 2.5 g of labrasol as the cosurfactant, and 5 g of water. The microemulsion was visually checked, characterized by light scattering techniques and morphological observations. The developed formulation appeared transparent, the droplet size was around 40 nm, and the ζ-potential result was negative. The maximum loading content of Salicis cortex extract resulted in 40 mg/mL. Furthermore, storage stability studies and an in vitro digestion assay were performed. The advantages offered by microemulsion were evaluated in vitro using artificial membranes and cells, i.e., parallel artificial membrane permeability assay and a Caco-2 model. Both studies proved that the microemulsion was successful in enhancing the permeation of extract compounds, so it could be useful to ameliorate the bioefficacy of Salicis cortex.

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.

Beneficial effects of naringenin in liver diseases: Molecular mechanisms

Liver diseases are caused by different etiological agents, mainly alcohol consumption, viruses, drug intoxication or malnutrition. Frequently, liver diseases are initiated by oxidative stress and inflammation that lead to the excessive production of extracellular matrix (ECM), followed by a progression to fibrosis, cirrhosis and hepatocellular carcinoma (HCC). It has been reported that some natural products display hepatoprotective properties. Naringenin is a flavonoid with antioxidant, antifibrogenic, anti-inflammatory and anticancer properties that is capable of preventing liver damage caused by different agents. The main protective effects of naringenin in liver diseases are the inhibition of oxidative stress, transforming growth factor (TGF-β) pathway and the prevention of the transdifferentiation of hepatic stellate cells (HSC), leading to decreased collagen synthesis. Other effects include the inhibition of the mitogen activated protein kinase (MAPK), toll-like receptor (TLR) and TGF-β non-canonical pathways, the inhibition of which further results in a strong reduction in ECM synthesis and deposition. In addition, naringenin has shown beneficial effects on nonalcoholic fatty liver disease (NAFLD) through the regulation of lipid metabolism, modulating the synthesis and oxidation of lipids and cholesterol. Moreover, naringenin protects from HCC, since it inhibits growth factors such as TGF-β and vascular endothelial growth factor (VEGF), inducing apoptosis and regulating MAPK pathways. Naringenin is safe and acts by targeting multiple proteins. However, it possesses low bioavailability and high intestinal metabolism. In this regard, formulations, such as nanoparticles or liposomes, have been developed to improve naringenin bioavailability. We conclude that naringenin should be considered in the future as an important candidate in the treatment of different liver diseases.

Pharmacokinetic Assessments of Liquiritin, Protocatechuic Aldehyde and Rosmarinic Acid in Rat Plasma by UPLC-MS-MS After Administration of ZibuPiyin Recipe

The three analytes of the Traditional Chinese Medicine ZibuPiyin Recipe (ZBPYR), namely, liquiritin, protocatechuic aldehyde and rosmarinic acid, may synergistically play an important role in regulating memory and learning. However, the pharmacokinetic behaviors of these compounds after their co-administration remain unclear. To this end, a selective and sensitive ultra-performance liquid chromatography-tandem mass spectrometry method was developed and validated in rat plasma for the study of these three major bioactive ingredients in ZBPYR. The analytes in the plasma samples were separated on a Shiseido Capcell core C18 column using bendrofluazide as an internal standard, with a gradient mobile phase system of acetonitrile-water containing 0.1% formic acid. Electrospray ionization in the negative-ion mode and multiple reaction monitoring were used to identify and quantify the three analytes. All of the calibration curves showed good linearity (r > 0.992) over the concentration range, with a lower limit of quantification of 5 ng/mL. The precision of the analytical method was evaluated by intra- and inter-day assays, and the percentage of relative standard deviation (SD) was within 15%. Satisfactory extraction efficiency (between 83.4 and 99.4%) and matrix effects (76.4-107.4) were obtained by liquid-liquid extraction. The pharmacokinetic results showed that the three bioactive ingredients were rapidly absorbed and had a short terminal half-life in rats after oral administration of ZibuPiyin recipe. This UPLC-MS-MS study method used in this study may be useful for assessing the pharmacokinetic characteristics of various compounds, which would be helpful in determining their clinical potential.

Fabrication of surfactant-stabilized nanosuspension of naringenin to surpass its poor physiochemical properties and low oral bioavailability

BACKGROUND

Nanosuspension is a biphasic system consisting of native drug particles dispersed in an aqueous surfactant or polymeric solution with a particle size between 10 to 1000 nm. In contrast to other drug delivery systems, nanosuspension offer the unique advantage of increasing solubility of the native drug resulting into faster drug absorption and hence achieving faster maximum plasma concentration.

HYPOTHESIS/PURPOSE

The present study aims to evaluate surfactants/polymer stabilized nanosuspensions of naringenin (NN), a phytomedicine, to surpass its poor physiochemical properties and low oral bioavailability.

STUDY DESIGN

Optimization and characterization (DLS, SEM, PXRD and DSC) of nanosuspensions followed by in-vitro drug dissolution studies and pharmacokinetic study in male Sprague-Dawley rats were performed.

METHODS

Nanosuspensions were prepared by precipitation-ultrasonication method with varying concentrations of different surfactants and polymer such as sodium cholate (SC), sodium lauryl sulphate (SLS), poly ethylene glycol 4000 (PEG), polysorbate 80 (Tween^® 80), poloxomer-188 and D-α-Tocopherol polyethylene glycol 1000 succinate (TPGS or Vitamin E-TPGS).

RESULTS

Nanosuspension prepared with 0.5% w/v d-α-Tocopherol polyethylene glycol 1000 succinate (TPNS) and 7.5 mg NN, showed the smallest size of 118.1 ± 2.7 nm. TPNS showed increase in drug dissolution in simulated gastric fluid pH 1.2 (SGF) and phosphate buffer pH 6.8 (PB). TPNS demonstrated an improved pharmacokinetic profile compared to pure NN resulting 2.14 and 3.76 folds increase in C_max and AUC, respectively. In addition, TPNS were stable over a period of six months.

CONCLUSION

The developed formulation strategy of nanosuspension could be exploited to improve the solubility and bio-availability of poorly soluble NN and other phytomedicines.

Bioavailability of Bergamot (Citrus bergamia) Flavanones and Biological Activity of Their Circulating Metabolites in Human Pro-Angiogenic Cells

Myeloid angiogenic cells (MACs) play a key role in endothelial repairing processes and functionality but their activity may be impaired by the lipotoxic effects of some molecules like stearic acid (SA). Among the dietary components potentially able to modulate endothelial function in vivo, (poly)phenolic compounds represent serious candidates. Here, we apply a comprehensive multidisciplinary approach to shed light on the prospects of Bergamot (Citrus bergamia), a citrus fruit rich in flavanones and other phenolic compounds, in the framework of lipotoxicity-induced MACs impairment. The flavanone profile of bergamot juice was characterized and 16 compounds were identified, with a new 3-hydroxy-3-methylglutaryl (HMG) flavanone, isosakuranetin-7-O-neohesperidoside-6″-O-HMG, described for the first time. Then, a pilot bioavailability study was conducted in healthy volunteers to assess the circulating flavanone metabolites in plasma and urine after consumption of bergamot juice. Up to 12 flavanone phase II conjugates (sulfates and glucuronides of hesperetin, naringenin and eriodyctiol) were detected and quantified. Finally, the effect of some of the metabolites identified in vivo, namely hesperetin-7-O-glucuronide, hesperetin-3′-O-glucuronide, naringenin-7-O-glucuronide and naringenin-4′-O-glucuronide, was tested, at physiological concentrations, on gene expression of inflammatory markers and apoptosis in MACs exposed to SA. Under these conditions, naringenin-4′-O-glucuronide and hesperetin-7-O-glucuronide were able to modulate inflammation, while no flavanone glucuronide was effective in curbing stearate-induced lipoapoptosis. These results demonstrate that some flavanone metabolites, derived from the in vivo transformation of bergamot juice phenolics in humans, may mitigate stearate-induced inflammation in MACs.

Aryl benzofuran derivatives from the stem bark of Calpocalyx dinklagei attenuate inflammation

Calpocalyx dinklagei Harms (Fabaceae) is a tropical medicinal tree, which is indigenous to Western Africa. A phytochemical study of this local plant species from its stem bark has led to the isolation of two previously undescribed aryl benzofuran derivatives, named dinklagein A and B, together with eight known compounds. Their chemical structures were elucidated by use of extensive spectroscopic methods (IR, HREI-MS and 1D and 2D NMR). Among all isolates, dinklagein A displayed remarkably potent inhibitory activity against the production of nitric oxide (NO) in the lipopolysaccharide (LPS) induced RAW264.7 macrophages. SAR and molecular docking investigations on iNOS and previously undescribed compounds (dinklagein A and B) supported experimental data. Furthermore, dinklagein A dose dependently suppressed the LPS-stimulated iNOS expression at both mRNA and protein level. It also attenuated IL-1β release, mRNA expressions of IL-1β and COX-2 at low doses. These results suggest that dinklagein A can be developed as natural, multi-target agent against several inflammatory diseases.

Naringenin ameliorates pathological changes in liver and kidney of diabetic mice: a preliminary study

The effect of naringenin, a flavonoid found in grapefruit, orange, and tomato, on lipid peroxidation and histopathological changes in the liver and kidneys of alloxan-induced diabetic mice were investigated. Two days after alloxan injection (75 mg kg-1, i.v.), naringenin ethanolic solution (0.5 % v/v) was given to mice intraperitoneally (50 mg kg-1 per day) for seven days. Naringenin's impact on lipid peroxidation was measured by the 2-thiobarbituric acid test and histopathological changes were examined under a light microscope. Naringenin administration resulted in a significant decrease of lipid peroxidation level in liver and kidney tissue, as well as in a decreased number of vacuolated liver cells and degree of vacuolisation. Indications of tissue repair in kidney suggested that amelioration of diabetes-induced renal damage could be achieved over a longer period of time. Findings suggest that naringenin could be considered a dietary supplement in the prevention or treatment of diabetic complications and other diseases connected with oxidative stress, and gives a hope that it could show similar effects in the treatment of diabetes in humans.

Effects of Intestinal Microecology on Metabolism and Pharmacokinetics of Oral Wogonoside and Baicalin

Baicalin and wogonoside are two of the most abundant flavonoid glycosides in the root of Scutellaria baicalensis Georgi, which is a widely used peroral herbal medicine with anticancer, antiviral, antibacterial and anti-inflammatory properties. In the present study, the effects of intestinal microecology on the metabolism and pharmacokinetics of orally administered baicalin and wogonoside were investigated by UPLC-QTOF/MS measurement of the difference in metabolites between normal and antibiotic-pretreated rats. In the antibiotic-pretreated rats, the plasma concentration-time profile and pharmacokinetic parameters of the two flavonoid glycosides and their relevant aglycone forms were significantly changed compared with those in normal rats. Further, hydrolysis and glucuronidated metabolites were not detected in the cecum contents and urine samples from antibiotic-pretreated rats. These results suggested that intestinal microbiota may play a key role in the pharmacokinetics and metabolism of peroral baicalin and wogonoside. According to our findings, it is recommended that the root of S. baicalensis should not be co-administered with antibiotics in clinical use.

Pharmacokinetics and pharmacodynamics of Da-Cheng-Qi decoction in the liver of rats with severe acute pancreatitis

AIM

To explore the pharmacokinetics and pharmacodynamics of Da-Cheng-Qi decoction (DCQD) in the liver of rats with severe acute pancreatitis (SAP) based on an herbal recipe tissue pharmacology hypothesis.

METHODS

Healthy male Sprague-Dawley rats were randomly divided into a sham operation group (SOG); a model group (MG); and low-, median- and high-dose treatment groups (LDG, MDG, and HDG, respectively). Different dosages (6, 12 and 24 g/kg for the LDG, MDG, and HDG, respectively) of DCQD were administered to the rats with SAP. The tissue concentrations of aloe-emodin, rhein, emodin, chrysophanol, honokiol, rheo chrysophanol, magnolol, hesperidin, naringenin and naringin in the liver of the treated rats were detected by high-performance liquid chromatography tandem mass spectrometry. Alanine transaminase (ALT) and aspartate transaminase (AST) in serum, inflammatory mediators in the liver and pathological scores were evaluated.

RESULTS

The major components of DCQD were detected in the liver, and their concentrations increased dose-dependently. The high dose of DCQD showed a maximal effect in ameliorating the pathological damages, decreasing the pro-inflammatory mediators tumor necrosis factor-α and interleukin (IL)-6 and increasing anti-inflammatory mediators IL-4 and IL-10 in the liver. The pathological scores in the pancreas for the MG were significantly higher than those for the SOG (P < 0.05). DCQD could reduce the pathological scores in the pancreas and liver of the rats with SAP, especially in the HDG. Compared to the SOG, the ALT and AST levels in serum were higher in the MG (P < 0.05), while there was no statistical difference in the MG and HDG.

CONCLUSION

DCQD could alleviate liver damage by altering the inflammatory response in rats with SAP based on the liver distribution of its components.

Development of a UPLC-TQ/MS Approach for the Determination of Eleven Bioactive Components in Haizao Yuhu Decoction Plus-Minus Haizao and Gancao Drug Combination after Oral Administration in a Rat Model of Hypothyroidism

Haizao Yuhu Decoction (HYD) has been used for approximately 500 years and is well-known in Traditional Chinese Medicine for its efficacy in the treatment of thyroid-related diseases. In this study, a rapid liquid chromatography-tandem mass spectrometry method was developed for the determination of liquiritin, naringin, hesperidin, peimine, liquiritigenin, glycyrrhizic acid, bergapten, nobiletin, osthole, and glycyrrhetinic acid in rat plasma to investigate the pharmacokinetic profile of different HYD prescriptions in a rat model of hypothyroidism. The differences in pharmacokinetic parameters among the groups were compared by Student's t-test. The pharmacokinetic profile of liquiritin, naringin, hesperidin, peimine, liquiritigenin, glycyrrhizic acid, bergapten, nobiletin, osthole, and glycyrrhetinic acid showed significant differences between Haizao and Gancao anti-drug combination and other herbs in HYD. These results may contribute to the rational clinical use of HYD and reveal the compatibility profile of the Haizao and Gancao anti-drug combination.

[Preparation of Baicalein Liposome-Lyophilized Powder and Its Pharmacokinetics Study]

OBJECTIVE

To prepare baicalein liposome-lyophilized powder, and to investigate the particle size distribution, encapsulation efficiency, stability, in vitro release and in vivo pharmacokirietics in rats. METHODs: Baicalein liposome was prepared by the ethanol injection, the encapsulation efficiency was measured by column chromatography, glucose, lactose and mannitol were selected as lyoprotectants. Pharmacokinetics study in rats was carried out by oral administration and analysis of rats pharmacokinetic parameters.

RESULTS

The baicalein liposomes were spherical, the mean diameter was (93.1 ± 11.2) nm, PDI was 0.258, the encapsulation efficiency was (83.9 ± 0.4)%. In vitro release test results showed that it had a significant slow-release effect, freeze-dried mannitol for the best protective agent. The pharmacokinetic parameters of baicalein liposomes and solution were as follows: AUC(0 --> 24 (129.04 ± 12.73) μg/mL x h and (73.31 ± 9.34) μg/mL x h; C(max) (15.07 ± 3.13) μg/mL and (9.38 ± 2.42) μg/mL; T(max) 1 and 1.5 h.

CONCLUSION

Baicalein liposome has the higher entrapment efficiency and the smaller particle size. In vitro studies show that baicalein liposome has a slow-release effect and can significantly improve the bioavailability in rats.

Plasma Pharmacokinetics of Polyphenols in a Traditional Japanese Medicine, Jumihaidokuto, Which Suppresses Propionibacterium acnes-Induced Dermatitis in Rats

Most orally administered polyphenols are metabolized, with very little absorbed as aglycones and/or unchanged forms. Metabolic and pharmacokinetic studies are therefore necessary to understand the pharmacological mechanisms of polyphenols. Jumihaidokuto (JHT), a traditional Japanese medicine, has been used for treatment of skin diseases including inflammatory acne. Because JHT contains various types of bioactive polyphenols, our aim was to clarify the metabolism and pharmacokinetics of the polyphenols in JHT and identify active metabolites contributing to its antidermatitis effects. Orally administered JHT inhibited the increase in ear thickness in rats induced by intradermal injection of Propionibacterium acnes. Quantification by LC-MS/MS indicated that JHT contains various types of flavonoids and is also rich in hydrolysable tannins, such as 1,2,3,4,6-penta-O-galloyl glucose. Pharmacokinetic and antioxidant analyses showed that some flavonoid conjugates, such as genistein 7-O-glucuronide and liquiritigenin 7-O-glucuronide, appeared in rat plasma and had an activity to inhibit hydrogen peroxide-dependent oxidation. Furthermore, 4-O-methylgallic acid, a metabolite of Gallic acid, appeared in rat plasma and inhibited the nitric oxide reaction. JHT has numerous polyphenols; it inhibited dermatitis probably via the antioxidant effect of its metabolites. Our study is beneficial for understanding in vivo actions of orally administered polyphenol drugs.

Preparation and Characterization of Naringenin-Loaded Elastic Liposomes for Topical Application

Excessive production of radical oxygen species in skin is a contributor to a variety of skin pathologies. Naringenin is a potent antioxidant. The purpose of the present study was to develop elastic liposomes for naringenin topical application. Naringenin-loaded elastic liposomes containing different amounts of Tween 80 and cholesterol were prepared. The physicochemical properties including vesicle size, surface charge, encapsulation efficiency, and permeability capacity were determined to evaluate the effect of components. The stability of formulation and skin irritation caused by drug-loaded elastic liposomes were also evaluated for assessment of the clinical utility of elastic liposomes. Saturated aqueous solution of naringenin and naringenin dissolved in 10% Tween 80 solution (5 mg/mL) were used as the control group. The result showed that in using elastic liposomes as carrier, the deposition amounts in the skin of naringenin were significantly increased about 7.3~11.8-fold and 1.2~1.9-fold respectively, when compared with the saturated aqueous solution and Tween 80 solution-treated groups. The level of drug was more than 98.89±3.90% after 3 months of storage at 4℃. In a skin irritation test, the result showed experimental formulation exhibit considerably less irritating than the positive control (paraformaldehyde-treated) group, suggesting its potential therapeutic application.

The influence of compatibility of processed radix Aconiti Kusnezoffii on the pharmacokinetic of four components in Glycyrrhiza uralensis Fisch

ETHNOPHARMACOLOGICAL RELEVANCE

Glycyrrhiza uralensis Fisch. and processed radix Aconiti kusnezoffii are the main components in many Chinese traditional patent medicines with the ratio of 1:1, which are used for treatment of rheumatoid arthritis, heart failure and so on. Glycyrrhizic acid, glycyrrhetic acid, liquiritigenin and isoliquiritigenin are the essential bioactive triterpenes and flavones in the extract of G. uralensis, which were analysis by a simple but accurate method.

MATERIALS AND METHODS

In the present study, a specific HPLC method was developed and validated for simultaneous determination of pharmacokinetic parameters of glycyrrhizic acid, glycyrrhetic acid, liquiritigenin and isoliquiritigenin in G. uralensis after oral administration of single herb extract and a combination of two herbs extracts respectively.

RESULTS

The calibration curves of the four components had good linearity higher than 0.9991 in the measured range. The intra-day and inter-day precisions (RSD) at different levels were both within 9.73%, and the accuracies (RE) were in the range of -7.9-8.0%. Compared with pharmacokinetic parameters of G. uralensis administered orally, values of AUC and Cmax of liquiritigenin and isoliquiritigenin decreased significantly (p<0.05), plasma concentrations of glycyrrhizic acid rose slightly and bimodal phenomenon of concentration-time of isoliquiritigenin and glycyrrhetinic acid disappeared after combined administration.

DISCUSSION AND CONCLUSIONS

Some components in the extract of processed radix A. kusnezoffii showed different effects on the pharmacokinetics of the four ingredients in G. uralensis.

Chronic administration of a microencapsulated probiotic enhances the bioavailability of orange juice flavanones in humans

Orange juice (OJ) flavanones are bioactive polyphenols that are absorbed principally in the large intestine. Ingestion of probiotics has been associated with favorable changes in the colonic microflora. The present study examined the acute and chronic effects of orally administered Bifidobacterium longum R0175 on the colonic microflora and bioavailability of OJ flavanones in healthy volunteers. In an acute study volunteers drank OJ with and without the microencapsulated probiotic, whereas the chronic effects were examined when OJ was consumed after daily supplementation with the probiotic over 4 weeks. Bioavailability, assessed by 0-24h urinary excretion, was similar when OJ was consumed with and without acute probiotic intake. Hesperetin-O-glucuronides, naringenin-O-glucuronides, and hesperetin-3'-O-sulfate were the main urinary flavanone metabolites. The overall urinary excretion of these metabolites after OJ ingestion and acute probiotic intake corresponded to 22% of intake, whereas excretion of key colon-derived phenolic and aromatic acids was equivalent to 21% of the ingested OJ (poly)phenols. Acute OJ consumption after chronic probiotic intake over 4 weeks resulted in the excretion of 27% of flavanone intake, and excretion of selected phenolic acids also increased significantly to 43% of (poly)phenol intake, corresponding to an overall bioavailability of 70%. Neither the probiotic bacterial profiles of stools nor the stool moisture, weight, pH, or levels of short-chain fatty acids and phenols differed significantly between treatments. These findings highlight the positive effect of chronic, but not acute, intake of microencapsulated B. longum R0175 on the bioavailability of OJ flavanones.

Pharmacokinetics, safety, and tolerability of single and multiple-doses of pinocembrin injection administered intravenously in healthy subjects

ETHNOPHARMACOLOGICAL RELEVANCE

Pinocembrin is the most abundant flavonoid in propolis. Preclinical studies have suggested that pinocembrin protects rat brain against oxidation and apoptosis induced by ischemia-reperfusion both in vivo and in vitro. To investigate the safety, tolerability and pharmacokinetics of a new neuroprotective agent, pinocembrin.

MATERIALS AND METHOD

A double-blind, placebo-controlled, randomized study was carried out in 58 healthy subjects. Single ascending doses of pinocembrin (20-150 mg) were evaluated in 5 cohorts. Multi-dose was studied at pinocembrin 60 mg.

RESULTS

Pinocembrin was well tolerated. No serious adverse events occurred. No subjects were discontinued because of a treatment emergent AE. Treatment related adverse event was acute urticaria. Two subjects in 150 mg cohort developed grade II urticaria during the study. One subject discontinued after 3 days at 60 mg bid because of diarrhea. In the single-dose study, the mean peak plasma pinocembrin concentration was obtained at the end of the 30-min infusion. The Cmax ranged from 0.28 μg mL(-1) to 2.46 μg mL(-1). AUC (0,∞) ranged from 10.34 μg mL(-1) min to 89.34 μg mL(-1) min. The T1/2 was similar across 5 dose groups, ranging from 40 to 55 min. Both urinary and feces excretion levels of pinocembrin were extremely low and similar among each dose groups, with mean values ranging from 0.07% to 0.17% and 0.94% to 1.94% of the administered dose, respectively. Linear increases in Cmax and AUC(0,∞) were observed. The pharmacokinetics of pinocembrin in multiple-dose was similar to those observed in the single-dose study, with no evidence of accumulation. Both urinary and feces excretion levels of pinocembrin were extremely low.

CONCLUSIONS

Pinocembrin displayed linear plasma pharmacokinetics over the dose range, 20-150 mg and was well tolerated up to 120 mg day(-1) when administered intravenously to healthy adults. No major safety concerns were identified that would preclude further clinical development of pinocembrin injection.

Comparisons of the pharmacokinetic profile of four bioactive components after oral administration of gan-sui-ban-xia decoction plus-minus gansui and gancao drug combination in normal rats

Gan-Sui-Ban-Xia Decoction (GSBXD) was first presented by Zhang Zhongjing in the book Synopsis of Golden Chamber during the Han Dynasty period. The formula was then used for the treatment of persistent fluid retention with floating pulse in Traditional Chinese Medicine (TCM), which in modern medicine is known as malignant ascites. Here, a rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed for the determination of glycyrrhizinic acid, liquiritin, paeoniflorin, albiflorin after oral administration of GSBXD plus-minus Gansui and Gancao anti-drug combination to investigate the possible pharmacokinetic profile differences of different prescriptions with GSBXD in normal rats. The differences of pharmacokinetic parameters among groups were tested by the Student’s t-test with p < 0.05 as the level of significance. Significant differences were found between the Gansui and Gancao anti-drug combination and other herbs in GSBXD on pharmacokinetic profile of glycyrrhizinic acid, liquiritin, paeoniflorin and albiflorin. The obtained knowledge might contribute to the rationality of the clinic use of GSBXD and also reveal the compatibility conditions of the Gansui and Gancao anti-drug combination.

In vivo gastroprotective effect along with pharmacokinetics, tissue distribution and metabolism of isoliquiritigenin in mice

As numerous herbal products have been used as dietary supplements or functional foods, the demands of the pharmacokinetic and pharmacodynamic characteristics of active compounds are increasing in order to secure a consistent outcome (i.e., efficiency and safety). In this study, the pharmacokinetics including tissue distribution, metabolism, and protein binding of isoliquiritigenin, a chalcone found in Glycyrrhiza glabra, and its metabolite, liquiritigenin, at various doses in mice are reported. Also, correlations between the preferential tissue distribution and pharmacological effect of isoliquiritigenin in certain organs were investigated using the in vivo gastroprotective effect of isoliquiritigenin in mice with indomethacin-induced ulcer. The absorbed fraction of isoliquiritigenin was high, but the absolute bioavailability was low mainly due to its metabolism. In spite of the low bioavailability, the gastroprotective effect of isoliquiritigenin was attributed to its high distribution in the stomach. Isoliquiritigenin prevented the occurrence of gastric ulcers by indomethacin, which is associated with increased gastric mucous secretion because the pretreatment with isoliquiritigenin presumably counteracted the decreased cyclooxygenase 2 by indomethacin. This may suggest that the pharmacokinetic properties of isoliquiritigenin are useful to predict its efficacy as a gastroprotective agent in a target organ such as the stomach.

The Natural Flavonoid Pinocembrin: Molecular Targets and Potential Therapeutic Applications

Pinocembrin is a natural flavonoid compound extracted from honey, propolis, ginger roots, wild marjoram, and other plants. In preclinical studies, it has shown anti-inflammatory and neuroprotective effects as well as the ability to reduce reactive oxygen species, protect the blood-brain barrier, modulate mitochondrial function, and regulate apoptosis. Considering these pharmaceutical characteristics, pinocembrin has potential as a drug to treat ischemic stroke and other clinical conditions. In this review, we summarize its pharmacologic characteristics and discuss its mechanisms of action and potential therapeutic applications.

Ocular pharmacokinetics of naringenin eye drops following topical administration to rabbits

PURPOSE

To investigate the ocular pharmacokinetics of 1% naringenin eye drops following topical administration to rabbits.

METHODS

One drop (50 μL) of 1% naringenin eye drops was instilled into both eyes of each rabbit. The animals were sacrificed at predetermined intervals after dosing, and ocular tissues and plasma were then collected. Concentrations of naringenin were analyzed using specific electrospray ionization liquid chromatography-tandem mass spectrometry method, which is proved to be sensitive, specific, precise, and suitable for determination of naringenin in ocular tissues and plasma of rabbits.

RESULTS

Ocular exposure to naringenin, based on AUC(0-t), was highest in cornea, followed by aqueous humor, retina, and vitreous body. The Cmax of naringenin in cornea, aqueous humor, vitreous body, and retina were 67945.30 ± 4109.34 ng/g, 1325.69 ± 239.34, 160.52 ± 38.78 ng/mL, and 1927.08 ± 660.77 ng/g at 0.083, 0.75, 0.083, and 0.083 h after topical administration, respectively. The half-lives for these tissues were 9.37, 0.65, 1.17, and 4.62 h, respectively. There was no significant difference between free naringenin and total naringenin in plasma based on Cmax and Tmax. Cmax of total naringenin in plasma at 0.083 h was 35.12 ± 0.54 ng/mL.

CONCLUSIONS

Measurable concentrations of naringenin were achieved in ocular tissues after topical application in rabbits. Topical instillation of naringenin may be an effective approach in the treatment of posterior section diseases.

Pharmacokinetics of flavanone glycosides after ingestion of single doses of fresh-squeezed orange juice versus commercially processed orange juice in healthy humans

Orange juice is a rich source of flavonoids considered beneficial to cardiovascular health in humans. The objective of this study was to analyze the pharmacokinetics of the main flavanone glycosides, hesperidin and narirutin, in humans after the consumption of two styles of orange juice, fresh-squeezed (FOJ) and commercially processed (POJ), differing in their amounts of soluble and insoluble forms of these compounds. Healthy human subjects consumed 11.5 mL/kg body weight of FOJ, and after an interval of 30 days, consumed the same quantity of POJ. The results showed that there were no significant differences in the Tmax of the pharmacokinetic curves for the metabolites of hesperidin and narirutin following the consumption of the two styles of juices, and corrected for differences in doses in the POJ and FOJ, there were also no significant differences in the AUC and Cmax values and percent absorption of these compounds.

Safety, tolerability, and pharmacokinetics of a single ascending dose of baicalein chewable tablets in healthy subjects

ETHNOPHARMACOLOGICAL RELEVANCE

The root of Scutellaria baicalensis Georgi has been used extensively in traditional Chinese medicine for the treatment of inflammation, fever, cough, dysentery, and hypertension. Baicalein is a flavonoid isolated from the root of Scutellaria baicalensis Georgi and is a novel neuroprotective agent under development for the treatment of Parkinson׳s disease. We aimed to investigate the pharmacokinetic (PK) properties of baicalein and its main metabolite, bacalin, after single-dose administration in healthy Chinese subjects. The safety and tolerability of baicalein were also assessed.

MATERIALS AND METHODS

This was a Phase I, randomized, double-blind, single-dose trial of baicalein (100-2800 mg) in 72 healthy adults. Samples of blood, urine and feces were collected at regular intervals up to 48 h after administration of the study drug. Baicalein and baicalin were then analyzed using liquid chromatography-tandem mass spectrometry (LC/MS/MS). The maximum concentration that the drug achieved after dosing (Cmax), time to Cmax (Tmax), terminal half-life (t₁/₂), area under the curve from time zero to time of last quantifiable concentration (AUC(0, t)), area under the curve from time zero to infinity (AUC(0, ∞)), apparent total plasma clearance (CL/F), and apparent total volume of distribution (V/F) were determined using non-compartmental models. Dose proportion was tested using a method combining the equivalence criterion and power model. Physical examinations, vital signs, ECG findings, hematology, and urinalysis were monitored before and at regular intervals after administration of the study drug.

RESULTS

The PK profile of baicelein and baicelin was characterized by a median Tmax of 0.75-3.5 h and 0.5-3 h, respectively, followed by a multiphasic profile with a t₁/₂ of 1.90-15.01 h and 4.22-10.80 h, respectively. The estimates of the proportionality coefficient (90% CI) for Cmax, AUC₀-t and AUC₀-∞ were 0.83 (0.70-0.96), 0.91 (0.81-1.00) and 0.92 (0.82-1.02), respectively. All values overlapped within the pre-specified range of (0.89-1.11), (0.93-1.07), and (0.93-1.07), respectively. Dose proportionality was inconclusive for a baicalein dose range of 100-2800 mg. The total urinary clearance of baicalein and baicalin was <1%. Approximately 27% of baicalein was eliminated as unchanged drug in feces. Baicalein was well tolerated. Eleven treatment-related adverse events were observed, and all were rated as "mild" and resolved without further treatment. No serious adverse events occurred.

CONCLUSIONS

Single oral doses of 100-2800 mg of baicalein were safe and well tolerated by healthy subjects. Clinical laboratory assessments showed no signs of toxicity in the liver or kidney. The favorable safety profile and PK properties warrant further clinical studies for baicalein.

[Pharmacokinetics and pharmacodynamics of huangqin tang in febrile rats]

The pharmacodynamic (PD) and pharmacokinetic (PK) properties of Huangqin Tang (HQT) were investigated in yeast-induced febrile rats. Blood sample and rectal temperature data of the rats were collected at different times after single oral administration of HQT at 20 g x kg(-1). The plasma concentrations of paeoniflorin, baicalin, wogonoside, baicalein, wogonin, oroxylin A, glycyrrhizic acid and glycyrrhetinic acid were quantified by a sensitive liquid chromatography-tandem mass spectrometric (LC-MS) method. The blood concentrations of PGE2, 1L-1β and TNF-α were detected by radioimmunoassay (RIA). All pharmacokinetic parameters were processed by non-compartmental analysis using WinNonlin software. The potential relationship between the mean concentration of eight constituents and the antifebrile efficacy was investigated by calculating Pearson correlation coefficients. It was found that HQT had significant antifebrile efficacy in yeast-induced febrile rats, but had no effect to normal rats. The antifebrile effect of HQT can be attributed to the inhibition of PGE2, 1L-1β and TNF-α. The constituents (baicalin, wogonoside, baicalein, wogonin, oroxylin A, glycyrrhizic acid and glycyrrhetinic acid) in febrile rats had delayed absorption and elimination, a longer residence time in the body, and higher C(max) and AUC than those in normal rats. Febrile condition could affect the pharmacokinetic behaviour of HQT in vivo; the flavonoids with the same backbone showed the similar fate in the body; baicalein and wogonin had a strong positive correlation (R > 0.66, P ≤ 0.02) with the antifebrile efficacy determined. Together, these constituents demonstrated different pharmacokinetic properties in the febrile body.

Comparative pharmacokinetic investigation on baicalin and wogonoside in type 2 diabetic and normal rats after oral administration of traditional Chinese medicine Huanglian Jiedu decoction

ETHNOPHARMACOLOGICAL RELEVANCE

Huanglian Jiedu decoction (HLJDD) is used traditionally in China for the treatment of diabetes mellitus in clinical practice, which has been proved to be effective. The purpose of this study was to investigate the pharmacokinetic characteristics (especially the area under the curve, AUC) of baicalin and wogonoside in type 2 diabetic rats after oral administration of HLJDD extract and to explore its possible mechanism.

MATERIALS AND METHODS

HLJDD extract and Radix scutellariae extract were prepared and the contents of baicalin and wogonoside contained in two extracts were assayed with high performance liquid chromatography (HPLC). Type 2 diabetic rats were induced by high fat diet and intraperitoneal injection of streptozotocin. Pharmacokinetics of baicalin and wogonoside in type 2 diabetic and normal control rats after oral administration of HLJDD extract or Radix scutellariae extract were investigated. Pharmacokinetics of baicalin in type 2 diabetic and normal rats after oral administration of pure baicalin was also investigated.

RESULTS

The pharmacokinetic parameters (especially AUCs) of baicalin and wogonoside in type 2 diabetic rats after oral administration of HLJDD extract were remarkably different from those in normal rats. And the alterations of the AUCs of baicalin and wogonoside in type 2 diabetic rats after oral administration of Radix scutellariae extract were similar to those after oral administration of HLJDD extract. Moreover, the increase of the AUC of baicalin in type 2 diabetic rats after oral administration of pure baicalin was similar to that after oral administration of HLJDD extract or Radix scutellariae extract.

CONCLUSION

The pharmacokinetic behaviors of baicalin and wogonoside (especially the systemic exposure [AUCs] of baicalin and wogonoside) were significantly altered in type 2 diabetic rats after orally administrated HLJDD extract. And the increased AUCs of baicalin and wogonoside in type 2 diabetic rats after oral administration of HLJDD extract resulted from neither the effects of other herbs contained in HLJDD nor the effects of other components contained in Radix scutellariae. It might result from the effects of the pathological status of type 2 diabetes mellitus.

The effects of Glycyrrhizae uralenis and its major bioactive components on pharmacokinetics of daphnetin in Cortex daphnes in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Glycyrrhizae uralenis (GU) is often prescribed together with Cortex daphnes (CD) in traditional Chinese medicinal practice to increase the efficacy of CD on the treatment of rheumatoid arthritis (RA), but the reasons were still unknown. In order to clarify the rationality of herbaceous compatibility between CD and GU, the comparative evaluations on pharmacokinetic behaviors of daphnetin (a predominantly active ingredient in CD) after intragastric administration of CD and CD-GU (combination of CD and GU) extract were studied. In addition, the effects of glycyrrhizin and liquiritin, active ingredients of Glycyrrhiza triterpenes and Glycyrrhiza flavones respectively, on the pharmacokinetics of daphnetin were also investigated.

MATERIALS AND METHODS

Five groups of rats were orally administered with CD extract, CD-GU extract, pure daphnetin, co-administration of daphnetin and glycyrrhizin as well as co-administration of daphnetin and liquiritin at the same single dose of daphnetin (20 mg/kg). The rat plasma concentrations of daphnetin were determined by our developed UPLC-MS/MS method. The pharmacokinetics of daphnetin in above groups were investigated and compared.

RESULTS

Comparing with oral administration of CD extract, AUC and Tmax of daphnetin significantly increased after giving CD-GU (p<0.05). In addition, in comparison to daphnetin alone, co-administration of daphnetin with liquiritin significantly increased the AUC and Cmax of daphnetin for ~1.5-fold, while co-administered with glycyrrhizin showed limited impact on the pharmacokinetics of daphnetin.

CONCLUSIONS

In this study, it was found that liquiritin, one of the major components of GU, significantly enhanced the bioavailability of the main component daphnetin in CD. In addition, the bioavailability of daphnetin in the CD-GU prescription was also significantly higher than that in CD alone, which could be due to liquiritin. Such results explained the mechanism of the increased efficacy in treating RA with the combined use of CD and GU.

[Pharmacokinetic study on peoniflorin, astilbin, rosmarinic acid, isofraxidin and liquiritin in rat blood after oral administration of shaolin xiaoyin tablets]

To establish a method for the determination of astilbin, peoniflorin, rasmarinci acid, isofraxidin and liquiritin contained in Shaolin Xiaoyin tablets, in order to lay a foundation for designing late-stage dosage forms and clinical medication schemes. In this paper, efforts were made to establish a method for the determination of the blood concentration of the five components and study the in vivo pharmacokinetics in rats. The blood concentration was determined by HPLC. Phenomenex C18 column (4.6 mm x 250 mm, 5 microm) was adopted and eluted with methanol-acetonitrile-0.05% formic acid, the flow rate was 0.8 mL x min(-1), and the wavelength was 275 nm. The samples were processed by the solid phase extraction method. After oral administration of Shaoling Xiaoyin tablets, the rat bloods were collected at different time points to determine the blood concentrations. The experimental results showed that the baseline separation could be adopted for the five components, and astilbin, peoniflorin, rasmarinci acid, isofraxidin and liquiritin showed good linear relations within ranges of 2.48-248, 0.213 6-21.36, 0.531-53.1, 0.704-70.4, 0.253-25.3 mg x L(-1). All the five components could be absorbed in blood and excreted quickly. The method established in this paper is rapid and accurate, and could be used for in vivo analysis on preparations containing similar components. The main components in Shaoling Xiaoyin tablets could be absorbed and excreted quickly, and thus suitable to be made into sustained release tablets. Common preparations are required to be taken for 4-6 times a day.

[Effect of different compatibility of zhizi dahuang decoction on pharmacokinetics of naringenin and hesperetin]

An HPLC-UV method was developed for the determination of total naringenin and total hesperetin in rat plasma after oral administration of Citrus aurantium Immaturus extracts and Zhizi Dahuang decoction. Plasma samples were pretreated with liquid-liquid extraction procedure and acid hydrolysis method was used for converting conjugated naringenin and hesperetin to their respective free forms. Plasma samples were separated on a C18 column (4.6 mm x 150 mm, 5 microm), using 0.1% phosphoric acid and methanol as mobile phase at a flow rate of 1.0 mL x min(-1) with gradient elution. DAS 2.0 software was applied to calculate the pharmacokinetic parameters while the SPSS 16.0 software was used for statistical analysis. Significant differences were observed, the C(max) AUC(0-t) of total naringenin in ZS group was 73.5% and 65.9% higher than those in ZZDHD group, respectively; the C(max), AUC(0-t) of total hesperetin in ZS group was 63.5% and 119.1% higher than those in ZZDHD group, respectively. There is a obvious decrease in C(max) and AUC(0-t) of total naringenin and total hesperetin after compatibility and their pharmacokinetic characteristics changed greatly due to the combination of other herbs. The established method was rapid, sensitive, selective and accurate, and it could be applied in the determination of total naringenin and total hesperetin in rat plasma.

Influence of mefenamic acid on the intestinal absorption and metabolism of three bioactive flavones in Radix Scutellariae and potential pharmacological impact

CONTEXT

Mefenamic acid (MEF) and the dried root of Scutellaria baicalensis Georgi (Radix Scutellariae, RS) share a high possibility of combined medication to treat inflammation.

OBJECTIVE

The present study investigates the impact of MEF on absorption/disposition of three major components in RS (baicalein, B; wogonin, W; oroxylin A, OA) and further pharmacological changes.

MATERIALS AND METHODS

The apparent permeability (P(app)) and percentage of metabolism of B, W and OA at 10 μΜ were measured at the absence/presence of MEF (100 μΜ) in the Caco-2 cell monolayer model. A modified whole blood assay was employed to quantify prostaglandin E₂ (PGE₂) 4, 6 and 8 h post-oral administration with water suspension of MEF at 40 mg/kg and RS at 200 mg/kg.

RESULTS

In the presence of MEF, Papp of B, W and OA were increased from 1.69 ± 0.89 × 10⁻⁶, 1.57 ± 0.10 × 10⁻⁶ and 3.09 ± 0.70 × 10⁻⁶ cm/sec to 5.24 ± 0.27 × 10⁻⁶, 6.08 ± 0.19 × 10⁻⁶ and 4.13 ± 0.38 × 10⁻⁶, whereas their percentage of metabolism was decreased from 72.75 ± 2.44%, 73.27 ± 3.25% and 89.84 ± 2.99% to 21.11 ± 0.69%, 17.90 ± 5.55% and 45.44 ± 3.38%. PGE2 level was much lower in the co-administration group (49.04 ± 2.03 pg/ml) than in the MEF group (73.13 ± 3.03 pg/ml) or RS group (494.37 ± 11.75 pg/ml) 4 h post MEF dosing, suggesting a synergic effect.

DISCUSSION AND CONCLUSION

Co-administration of MEF and RS could induce potential alterations in their pharmacokinetic profiles and anti-inflammatory effects.

[Experimental study of pinostrobine oxime biotransformation]

We have experimentally studied pathways of elimination of an oximized derivative of phytoflavonoid pinostrobine by HPLC/mass spectrometry. Four potential metabolites of pinostrobine oxime have been found and there was an attempt to determine their molecular structures on the basis of their fragmentation under positive electrospray ionization conditions. It is established that pinostrobine oxime is removed from the organism mainly unchanged and also in the form of glucuronated derivative.

Long-circulating nanoliposomes (LCNs) sustained delivery of baicalein (BAI) with desired oral bioavailability in vivo

Long-circulating nanoliposomes (LCNs) containing Baicalein (BAI) were prepared by diethyl ether injection method in this paper. Using soybean phosphatidylcholine (SPC) and cholesterol (CHOL) as the carrier ingredients, BAI-loaded LCNs were formulated in optimized condition with encapsulation efficiency (EE) of 41.5±4.77%. The average diameter of BAI-loaded LCNs was ∼709 nm determined by dynamic light scattering (PDI 0.43). Drug storage stability study showed that BAI-loaded LCNs were highly stable in phosphate-buffered saline (PBS, pH 7.4) at 4 °C. Additionally, the pharmacokinetic behaviors of BAI-loaded LCNs were studied using Kunming mice as experimental animals. Parallelly, free BAI solution was studied as control. As expected, it is found that LCNs-encapsulated BAI yields greater BAI oral bioavailability with 4.52 times of free BAI. These results suggest the potential applications of LCNs for the delivery of BAI.

Pharmacokinetics of isoliquiritigenin and its metabolites in rats: low bioavailability is primarily due to the hepatic and intestinal metabolism

Isoliquiritigenin, a chalcone found in licorice has shown a variety of biological activities including antioxidative, anti-inflammatory, estrogenic, chemopreventive and antitumor effects. Thus, pharmacokinetics of isoliquiritigenin and its metabolites [liquiritigenin, glucuronidated isoliquiritigenin (M1), and glucuronidated liquiritigenin (M2)] after intravenous and oral administration of isoliquiritigenin was evaluated in rats. The pharmacokinetics of isoliquiritigenin, liquiritigenin, M1, and M2 showed no dose dependence after both intravenous and oral administration of isoliquiritigenin. Although approximately 92.0 % of the oral isoliquiritigenin was absorbed, the extent of the absolute bioavailability value was only 11.8 % of the oral dose. The low absolute bioavailability value of isoliquiritigenin might be due to the considerable metabolism of isoliquiritigenin in the small intestine and liver. This was supported by the facts that the ratios of AUC(M1)/AUC(isoLQ) and AUC(M2)/AUC(isoLQ) were high (over 0.25), isoliquiritigenin disappeared, and M1 and M2 were formed mainly in S9 fractions of the liver and small intestine. The affinities of liquiritigenin, isoliquiritigenin, M1, and M2 were high in the liver, small intestine, large intestine, and/or kidney.

Probing the interaction of a therapeutic flavonoid, pinostrobin with human serum albumin: multiple spectroscopic and molecular modeling investigations

Interaction of a pharmacologically important flavonoid, pinostrobin (PS) with the major transport protein of human blood circulation, human serum albumin (HSA) has been examined using a multitude of spectroscopic techniques and molecular docking studies. Analysis of the fluorescence quenching data showed a moderate binding affinity (1.03 × 10(5) M(-1) at 25°C) between PS and HSA with a 1∶1 stoichiometry. Thermodynamic analysis of the binding data (ΔS = +44.06 J mol(-1) K(-1) and ΔH = -15.48 kJ mol(-1)) and molecular simulation results suggested the involvement of hydrophobic and van der Waals forces, as well as hydrogen bonding in the complex formation. Both secondary and tertiary structural perturbations in HSA were observed upon PS binding, as revealed by intrinsic, synchronous, and three-dimensional fluorescence results. Far-UV circular dichroism data revealed increased thermal stability of the protein upon complexation with PS. Competitive drug displacement results suggested the binding site of PS on HSA as Sudlow's site I, located at subdomain IIA, and was well supported by the molecular modelling data.

[Analysis and comparison of intestinal absorption of components of Gegenqinlian decoction in different combinations based on pharmacokinetic parameters]

To analyse and compare the characteristics of the intestinal absorption of puerarin, baicalin, berberine and liquiritin in different combinations of Gegenqinlian decoction based on pharmacokinetic parameters, a sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was applied for the quantification of four components in rat's plasma. And pharmacokinetic parameters were determined from the plasma concentration-time data with the DAS software package. The influence of different combinations on pharmacokinetics of four components was studied to analyse and compare the absorption difference of four components, together with the results of the in vitro everted gut model and the rat single pass intestinal perfusion model. The results showed that compared with other combinations, the AUC values of puerarin, baicalin and berberine were increased significantly in Gegenqinlian decoction group, while the AUC value of liquiritin was reduced. Moreover, the absorption of four components was increased significantly supported by the results from the in vitro everted gut model and the rat single pass intestinal perfusion model, which indicated that the Gegenqinlian decoction may promote the absorption of four components and accelerate the metabolism of liquiritin by the cytochrome P450.

Pharmacokinetic comparisons of two different combinations of Shaoyao-Gancao Decoction in rats: competing mechanisms between paeoniflorin and glycyrrhetinic acid

ETHNOPHARMACOLOGICAL RELEVANCE

Shaoyao-Gancao Decoction (SGD), a well-known traditional Chinese medicine prescription, is a combination of Radix Paeoniae Alba (Paeonia lactiflora Pall, root) and Glycyrrhizae uralensis (Glycyrrhiza uralensis Fisch., root and rhizome, honeyed) for spasmolysis and emergency pain relief. Paeoniflorin (PF) and glycyrrhetinic acid (GA) are two typical active components of SGD for pain relief.

AIM OF THE STUDY

To study comparative pharmacokinetics of ten bioactive compounds in SGDs with two different combinations of RP and GU, and therefore to investigate the herb-herb interaction mechanisms of Shaoyao-Gancao Decoction for better spasmolysis and emergency pain relief in rats.

MATERIALS AND METHODS

Herbal IR macro-fingerprinting was implemented to provide the full chemical fingerprints of RP, GU and SGD decoctions and to investigate the variation rule of the full chemical profile of SGDs with various combinations of RP and GU. A specifically developed HPLC-MS/MS assay coupled with protein precipitation method was employed to determine the plasma concentrations of the ten analytes. Male Wistar rats were orally administered with SGD1 (RP:GU, 1:1 (w/w)) and SGD2 ((RP:GU, 4:1 (w/w)) equivalent to 9.5 g/kg body weight of GU.

RESULTS

Full chemical fingerprints of RP, GU and SGDs with various combinations of RP and GU were provided in the form of IR macro-fingerprints. Except for liquiritin, there were statistically significant differences (p<0.05 or p<0.01) of these analytes between SGD1 and SGD2 in in vivo pharmacokinetic study. Compared with the results when oral administrated with SGD1, six glycosides (PF, albiflorin, oxypaeoniflorin, isoliquiritin, ononin, and glycyrrhizin) exhibited higher systematic exposure levels (AUC0-t) and slower elimination rates (CL) whereas two glycones (GA and isoliquiritigenin) were the reverse when administrated with SGD2.

CONCLUSIONS

Increasing the amount of RP attenuated the inhibitory effect of GA via competing being consumed by intestinal bacteria (or β-glucosidase) to reduce the conversion amount of glycyrrhizin to GA and subsequently to afford significantly higher bioavailability and longer efficacy of PF, glycyrrhizin, albiflorin, oxypaeoniflorin, isoliquiritin, and ononin, leading to better spasmolysis and emergency pain relief.

Biotransformation of baicalin to baicalein significantly strengthens the inhibition potential towards UDP-glucuronosyltransferases (UGTs) isoforms

The aim of the present study was to investigate the influence of biotransformation of baicalin into baicalein towards the inhibition potential towards one of the most important drug-metabolizing enzymes (DMEs) UDP-glucuronosyltransferases (UGTs). in vitro incubation method using recombinant UGTs-catalyzed 4-methylumbelliferone (4-MU) glucuronidation was used to evaluate the inhibition towards important UGT isoforms in the liver, including UGT1A1, 1A3, 1A6, 1A9, and 2B7. At the same concentration (100 microM), baicalein showed stronger inhibition potential than baicalin towards all the tested UGT isoforms. Data fitting using Dixon plot and Lineweaver-Burk plot was carried out to determine the inhibition type, and the second plot with the slopes from Lineweaver-Burk plot towards baicalein's concentrations was used to calculate the inhibition kinetic parameters (K(i)). Competitive inhibition type was observed for UGT1A1, 1A6, 1A9 and 2B7, and noncompetitive inhibition was detected for UGT1A3. The inhibition kinetic parameters (K(i)) were calculated to be 1.2, 5.1, 15.3, 26.3, and 48.9 microM for UGT1A1, 1A3, 1A6, 1A9, and 2B7, respectively. All these information reminds us of the necessary monitoring when oral administration of baicalin or baicalin-containing herbs.

Novel pharmacokinetic studies of the Chinese formula Huang-Lian-Jie-Du-Tang in MCAO rats

Our previous studies showed that after oral administration of an Huang-Lian-Jie-Du-Tang (HLJDT) decoction, there is a higher concentration of the pure components, berberine, baicalin and gardenoside in the plasma of Middle cerebral artery occlusion (MCAO) rats than in sham-operated rats, The aim of the present study was to determine whether these components could be reliably measured in MCAO rat tissues. First, the plasma concentration-time profiles of berberine, palmatine, baicalin, baicalein and gardenoside were characterised in MCAO rats after oral administration of the aqueous extract of HLJDT. Subsequently, liver, lung and kidney tissues were obtained from sudden death MCAO rats in the absorption phase (0.25 h), the distribution phase (1.0 h) and the elimination phase (8.0 h) after administration of the HLJDT aqueous extract. An HPLC method was developed and validated for the determination of the distribution characteristics of berberine, palmatine, baicalin, baicalein and gardenoside simultaneously from the above-mentioned rat tissues. The results indicated that berberine, palmatine, baicalin and baicalein distributed rapidly and accumulated at high levels in the lung, while gardenoside distributed widely in the lung and the kidney. To the best of our knowledge, this is the first report to describe the distribution of the active ingredients derived from HLJDT in MCAO rat tissues. The tissue distribution results provide a biopharmaceutical basis for the design of the clinic application of HLJDT in cerebrovascular disease.

[LC-MS quantification and pharmacokinetics of the multi-constituents of Huangqin Tang in rat plasma after different single oral doses]

The current study aims to investigate the pharmacokinetic properties of Huangqin Tang on different oral doses. An LC-MS method for simultaneous determination of flavonoids and terpenoids in rat plasma was developed and validated. Plasma samples were treated with hydrochloric acid (containing 1% ascorbic acid), precipitated with acetonitrile, separated on a Zorbax SB-C18 column, detected by single quadruple mass spectrometry with an electrospray ionization interface, and quantified using selected ion monitoring mode. All pharmacokinetic parameters were processed by non-compartmental analysis using WinNonlin software. The results of specificity, linearity, intra-day and inter-day precisions, accuracy, and stability for LC-MS assay were suitable for the quantification of paeoniflorin, baicalin, wogonoside, baicalein, wogonin, oroxylin A, glycyrrhizic acid and glycyrrhetinic acid in rat plasma. The concentration-time profiles of baicalin, wogonoside, baicalein, wogonin, oroxylin A and glycyrrhizic acid showed double-peak phenomenon after Huangqin Tang was orally administered at 40 g x kg(-1) dose; all eight constituents in rat plasma showed good dose-exposure relationship within the dosage of 10-40 g x kg(-1); although plasma concentrations were different, the flavonoids with the same backbone showed the similar fate in the body with the corresponding dosage. In conclusion, the LC-MS assay was successfully applied for the pharmacokinetic study of multi-constituents of Huangqin Tang with different doses. Additionally, these constituents demonstrated good pharmacokinetic properties in the body.