Meijuan Xu

Oral bioavailability and gender-related pharmacokinetics of celastrol following administration of pure celastrol and its related tablets in rats

ETHNOPHARMACOLOGICAL RELEVANCE Celastrol is a natural compound extracted from the traditional Chinese medicinal herb, Thunder God Vine (TGV). Owing to its potential anti-inflammatory and antitumor effects, celastrol has been considered as a promising candidate for drug development. AIM OF THE STUDY To establish a sensitive LC-MS/MS method to investigate the pharmacokinetic properties of celastrol in rats. Key pharmacokinetic issues of celastrol including oral bioavailability, comparative pharmacokinetics between pure compound and tablet preparation, as well as gender-related pharmacokinetic difference are to be addressed for the first time. MATERIALS AND METHODS Sprague-Dawley rats were administrated an intravenous dose (100 μg kg(-1)) of pure celastrol and an oral dose (1000 μg kg(-1)) of pure celastrol and TGV tablets (corresponding to 534 μg kg(-1) of celastrol), respectively. At different time points, the concentration of celastrol in rat plasma was determined by a sensitive and well-validated LC-MS/MS method. Main pharmacokinetic parameters including area under the plasma concentration-time curve (AUC), maximal plasma concentration (Cmax), the time for maximal concentration (Tmax) and mean residence time (MRT) were estimated by Drug and Statistic1.0 pharmacokinetic software (Chinese Pharmacological Association, Anhui, PR China). Statistical analysis was performed using two one-side t test with p-values less than 0.05 as the level of significance. RESULTS The standard curve of celastrol showed good linearity in the concentration range of 0.11~54.3 ng mL(-1) in our current method, with acceptable selectivity, precision, recovery, and stability. The oral absolute bioavailability of celastrol significantly increased from 17.06% for pure celastrol to 94.19% for TGV tablets containing equivalent celastrol. After oral administration of TGV tablets, the Cmax and AUC values of celastrol in female rats were (32.03±8.41) μg L(-1) and (379.49±118.19) μg h L(-1), which were significantly higher (p<0.01) than that in males with the values of (14.31±7.33) μg L(-1) and (188.17±92.33) μg h L(-1). CONCLUSION Celastrol administered orally in the rat was poorly absorbed into the systemic circulation. However, the poor absorption of celastrol could be greatly improved when celastrol-containing TGV tablets orally administered, and thereby the oral bioavailability of celastrol was significantly increased. As for gender difference, female rats showed significantly better absorption of celastrol than males.

Simultaneous characterization of prenylated flavonoids and isoflavonoids in Psoralea corylifolia L. by liquid chromatography with diode-array detection and quadrupole time-of-flight mass spectrometry

RATIONALE Prenylated flavonoids and isoflavonoids are widely distributed throughout the plant kingdom, with many biological effects. Psoralea corylifolia, which contains many kinds of prenylated components, has been widely used as a medicinal plant in Asia and India for thousands of years. The goal of this study was to characterize the components in P. corylifolia using a liquid chromatography with diode-array detection and quadrupole time-of-flight mass spectrometry (LC-DAD/Q-TOF-MS) method, and to elucidate the fragmentation behavior of the different prenyl substituent groups and their appropriate characteristic pathways in positive ion mode. METHODS The calculated accurate masses of the protonated molecules, the fragment ions, the retention behavior, and the data from UV spectra were used for identification of the components in P. corylifolia. RESULTS A total of 45 compounds, including 43 prenylated components, were identified or tentatively identified in P. corylifolia. Different diagnostic fragment ions and neutral losses were observed in different prenyl substructures: neutral loss of 56 Da (C(4)H(8)) and a fragment ion at m/z 69 (C(5)H(9)(+)) were generated by a prenyl chain; neutral losses of 42 Da (C(3)H(6)), 54 Da (C(4)H(6)), 15 Da (CH(3•)) and 16 Da (CH(4)) were observed in a ring-closed prenyl group; neutral losses of 72 Da (C(4)H(8)O), 60 Da (C(2)H(4)O(2)), 58 Da (C(3)H(6)O) and 18 Da (H(2)O) were detected in a 2,2-dimethyl-3,4-dihydroxydihydropyran ring; neutral losses of 72 Da (C(4)H(8)O), 60 Da (C(3)H(8)O) and 18 Da (H(2)O) were yielded from a 2,2-dimethyl-3-hydroxydihydropyran ring, a 2-(1-hydroxy-1-methylethyl)dihydrofuran ring or a 1-hydroxy-3-methylbut-3-enyl chain. CONCLUSIONS This method can be applied for analysis of prenylated components in P. corylifolia and other herbal medicines.

Liquid chromatograph/tandem mass spectrometry assay for the simultaneous determination of chlorogenic acid and cinnamic acid in plasma and its application to a pharmacokinetic study

A rapid and high sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for simultaneous determination of chlorogenic acid and cinnamic acid in human plasma was developed. The analytes and internal standard (IS), tinidazole, were extracted from human plasma via liquid/liquid extraction with ether-ethyl acetate (1:1, v/v) and separated on an Agilent Zorbax SB C18 column within 5min. Quantitation was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique, operating in multiple reaction monitoring (MRM) and negative ion mode. The precursor to product ion transitions monitored for chlorogenic acid, cinnamic acid and IS were m/z 352.9-->191.1, 146.8-->103.1, 245.6-->126.0, respectively. The assay was validated with linear range of 1.00-800.00ng/mL for chlorogenic acid and 0.50-400.00ng/mL for cinnamic acid. The intra- and inter-day precisions (RSD%) were within 9.05% for each analyte. The absolution recoveries were greater than 74.62% for chlorogenic acid and 76.21% for cinnamic acid. Each analyte was proved to be stable during all sample storage, preparation and analytic procedures. The method was successfully applied to a pharmacokinetic study of Mailuoning injection in 10 healthy volunteers.

Determination of rimantadine in rat plasma by liquid chromatography/electrospray mass spectrometry and its application in a pharmacokinetic study.

A rapid and sensitive liquid chromatography/mass spectrometry (LC/MS) method was developed and validated for the determination of rimantadine in rat plasma. Rimantadine was extracted by protein precipitation with methanol, and the chromatographic separation was performed on a C(18) column. The total analytical run time was relatively short (4.6 min), and the limit of assay quantification (LLOQ) was 2 ng/mL using 50 microL of rat plasma. Rimantadine and the internal standard (amantadine) were monitored in selected ion monitoring (SIM) mode at m/z 180.2 and 152.1, respectively. The standard curve was linear over a concentration range from 2 to 750 ng/mL, and the correlation coefficients were greater than 0.999. The mean intra- and inter-day assay accuracy ranged from 100.1-105.0% to 100.3-104.0%, respectively, and the mean intra- and inter-day precision was between 1.3-2.3% and 1.8-3.0%, respectively. The developed assay method was successfully applied to a pharmacokinetic study in rats after oral administration of rimantadine hydrochloride at the dose of 20 mg/kg.

Pharmacokinetics and tolerance of toal astragalosides after intravenous infusion of astragalosides injection in healthy Chinese volunteers.

Total astragalosides (TA) are the principal active constituents isolated from Radix Astragali, which has been extensively used in the traditional Chinese medicine for hundreds of years. However, few detailed pharmacokinetic studies about TA or its main component in human have been done to date. The aim of this study was to investigate the pharmacokinetic (PK) characteristics of astragaloside IV (AGS-IV), the primary ingredient of TA, and tolerance of TA after single- and multi-intravenous infusion of astragalosides injection (AI) in healthy Chinese volunteers. A LC-MS/MS assay was developed for AGS-IV determination in human plasma and urine, and the PK parameters were estimated using non-compartmental methods. The mean maximum plasma concentration (Cmax) values of AGS-IV were 2.12, 3.59, 3.71 and 5.17 μg ml(-1) after single doses of 200, 300, 400 and 500 ml of AI, respectively. The corresponding mean values of area under the plasma concentration (AUC(0-∞)) were 4.38, 9.75, 13.59 and 18.22 μg h ml(-1), respectively, and the mean values of elimination half-life (t1/2) were 2.14, 2.59, 2.62 and 2.69 h, respectively. In the repeated dose study, no significant difference was observed between the PK parameters, peak time (Tmax), t1/2 and AUC, of day 1 and day 7. Cumulative urinary excretion of AGS-IV was 3.91% within 24 h after administration of 500 ml AI. AI was safe and well tolerated, and the adverse events, such as raised total bilirubin and rash, were mild and resolved spontaneously. In summary, the pharmacokinetic properties of AGS-IV are based on linear pharmacokinetics over the doses ranging from 200 to 500 ml of AI. No accumulation of AGS-IV was observed after repeated administration of AI once daily. AI was safe and well tolerated in this study, although cases of transient adverse events were observed.

In vitro inhibitory effects of ethanol extract of Danshen (Salvia miltiorrhiza) and its components on the catalytic activity of soluble epoxide hydrolase

BACKGROUND Soluble epoxide hydrolase (sEH) has been demonstrated to be a key enzyme involved in the pathologic development of several cardiovascular diseases and inflammation, and inhibition of sEH is therefore very helpful or crucial for the treatment of ischemia-reperfusion injury, cardiac hypertrophy, hypertension and inflammation. Danshen, the dried root of Salvia miltiorrhiza (Fam. Labiatae), has been used for the treatment of cardiovascular and cerebrovascular diseases in China and other countries for hundreds of years. Recent studies indicated that Danshen and its preparations also have potential for the management of inflammation. However, little information is available about the possibility of Danshen and its components on sEH inhibition. PURPOSE AND METHODS Danshen extracts and its constituents were tested for sEH inhibition using its physiological substrate, 8,9-EET, based on a LC-MS/MS assay in this study. RESULTS Among the tested 15 compounds, tanshinone IIA and cryptotanshinone were found to be the potent (Ki = 0.87 μM) and medium (Ki = 6.7 μM) mixed-type inhibitors of sEH, respectively. Salvianolic acid C (Ki = 8.6 μM) was proved to be a moderate noncompetitive sEH inhibitor. In consistent with the inhibition results of the pure compounds, the 75% ethanol extract of Danshen (EE, IC50 = 86.5 μg/ml) which contained more tanshinone IIA and cryptotanshinone exhibited more potent inhibition on sEH than the water extract (WE, IC50 > 200 μg/ml) or 1 M NaHCO3 (BE, IC50 > 200 μg/ml) extract. CONCLUSION These data indicated that using the ethanol fraction of Danshen and increasing the amounts of tanshinone IIA, cryptotanshinone and salvianolic acid C, especially the contents of tanshinone IIA in Danshen extract or preparations to enhance the inhibitory effects on sEH might be efficient ways to improve its cardiovascular protective and anti-inflammatory effects, and that herbal medicines could be an untapped reservoir for sEH-inhibition agents and developing sEH inhibitors from the cardiovascular protective and anti-inflammatory herbs is a promising approach.

A correlative study of polymorphisms of CYP2C19 and MDR1 C3435T with the pharmacokinetic profiles of lansoprazole and its main metabolites following single oral administration in healthy adult Chinese subjects

Considering that the genotypes of CYP2C19 and MDR1 C3435T are two major factors attributed to the inter-individual pharmacokinetic variability of lansoprazole (LSZ), the aim of the study was to simultaneously elucidate the effects of CYP2C19 and MDR1 C3435T polymorphisms on the pharmacokinetics difference of LSZ and its metabolites 5′-hydroxy lansoprazole (HLSZ) and lansoprazole sulphone (LSZS) following oral administration of LSZ tablets in healthy Chinese subjects. Plasma concentration of LSZ, HLSZ and LSZS were quantified by a sensitive and specific LC–MS/MS method, while the genotypes of CYP2C19 and MDR1 C3435T for each subject were identified by a direct sequencing method. Statistical analysis was performed in the pharmacokinetic parameters including Cmax, t1/2, Tmax, MRT0–τ, AUC0–2 and AUC0–τ among different genotype groups of CYP2C19 and MDR1 C3435T. Compared to the CYP2C19 EMs, the CYP2C19 PM group showed slower elimination and better oral bioavailability of LSZ, much higher plasma concentrations of LSZS and lower concentrations of HLSZ with statistically significance. Despite a tendency of more favorable absorption and rapid elimination of LSZ in wild genotype, no significant pharmacokinetics difference was observed between the wild genotype of MDR1 C3435T and its mutant types. In conclusion, the pharmacokinetics difference of LSZ in Chinese subjects depends much more on the CYP2C19 polymorphism than on the polymorphism of MDR1 C3435T.

Inhibitory Effects of Danshen components on CYP2C8 and CYP2J2

The use of Chinese herbal medicines and natural products has become increasingly popular in both China and Western societies as an alternative medicine for the treatment of diseases or as a health supplement. Danshen, the dried root of Salvia miltiorrhiza (Fam.Labiatae), which is rich in phenolic acids and tanshinones, is a widely used herbal medicine for the treatment of cardio-cerebrovascular diseases. The goal of this study was to examine the inhibitory effects of fifteen components derived from Danshen on CYP2C8 and CYP2J2, which are expressed both in human liver and cardiovascular systems. Recombinant CYP2C8 and CYP2J2 were used, and the mechanism, kinetics, and type of inhibition were determined. Taxol 6-hydroxylation and astemizole O-desmethyastemizole were determined as probe activities for CYP2C8 and CYP2J2, respectively. Metabolites formations were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results demonstrated that salvianolic acid A was a competitive inhibitor of CYP2C8 (Ki = 2.5 μM) and mixed-type inhibitor of CYP2J2 (Ki = 7.44 μM). Salvianolic acid C had moderate noncompetitive and mixed-type inhibitions on CYP2C8 (Ki = 4.82 μM) and CYP2J2 (Ki = 5.75 μM), respectively. Tanshinone IIA was a moderate competitive inhibitor of CYP2C8 (Ki = 1.18 μM). Dihydrotanshinone I had moderate noncompetitive inhibition on CYP2J2 (Ki = 6.59 μM), but mechanism-based inhibition on CYP2C8 (KI = 0.43 μM, kinact = 0.097 min-1). Tanshinone I was a moderate competitive inhibitor of CYP2C8 (Ki = 4.20 μM). These findings suggested that Danshen preparations appear not likely to pose a significant risk of drug interactions mediated by CYP2C8 after oral administration; but their inhibitory effects on intestinal CYP2J2 mediated drug metabolism should not be neglected when they are given orally in combination with other drugs. Additionally, this study provided novel insights into the underling pharmacological mechanisms of Danshen components from the perspective of CYP2C8 and CYP2J2 inhibition.

SIMULTANEOUS QUANTIFICATION OF 10 BIOACTIVE CONSTITUENTS IN MAILUONING INJECTION BY UPLC-MS/MS

A rapid and comprehensive ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) method was developed for simultaneous determination of 10 major bioactive constituents in Mailuoning injection. Within 15 min, chromatographic separation was achieved on an Acquity UPLC BEH C18 column (50 mm × 2.1 mm I.D.) packed with 1.7 μm particles by a linear gradient elution. The analytes were monitored in a selected-ion reaction (SIR) mode with the electrospray ionization interface by the following ions: m/z 353.4 for isomers of chlorogenic acid, m/z 515.4 for isomers of 1,3-dicaffeoylquinic acid, m/z 179.2 for caffeic acid, m/z 192.9 for ferulic acid, m/z 503.2 for ecdysterone, and m/z 147.1 for cinnamic acid, respectively. The calibration curves of all analytes revealed good linear regression (r2 ≥ 0.9983) within test ranges. This method provided excellent sensitivity with LOQ and good precision with RSDs of intra- and interday variation less than 1.26% and 2.27%, respectively. The validated method was then applied to quantify the 10 major constituents in three batches of Mailuoning injection. The results indicated that the established method could be considered as an improved tool for quality control of Mailuoning injection.