Impact of dosing strategies on plasma concentrations of tenofovir: Implications in HIV pre-exposure prophylaxis in China.

BACKGROUND: Tenofovir disoproxil fumarate has been recommended for pre-exposure prophylaxis (PrEP) to prevent HIV infection. Several studies have shown short but potent intermittent PrEP could provide comparable protection to daily PrEP in men, suggesting such dosing strategy might be useful in Chinese as well. The objective of this study was to evaluate the impact of different dosing strategies on plasma concentrations of tenofovir. METHODS: An open label study in 40 Chinese healthy volunteers, randomized to receive the WHO-recommended dose of tenofovir (300mg) at four different dosing intervals: twice weekly for 4 weeks; once daily for 4 weeks with one missing dose in weeks 2-4; once daily for 4 weeks with two missing doses in weeks 2-4; and once every other day for 12 days. Plasma samples were collected at pre-dose, weekly trough and 24h post last dose and assayed using HPLC-UV. RESULTS: The tenofovir trough concentrations were below the lower limit of quantification with the twice weekly regimen. The trough concentrations (24h dosing interval) at the steady state were 51.7±12.1ng/ml and 53.5±13.8ng/ml (mean±SD) in the once daily groups. Missing doses, once or twice weekly, had no significant impact on trough concentrations. Prolongation of dosing interval to 48h resulted with concentrations at 24h and 48h (trough) of ∼40 and 20ng/ml, respectively. CONCLUSIONS: Intermittent tenofovir regimens resulted with remarkably low plasma concentrations in Chinese participants. Missing doses did not affect trough concentrations significantly.

A simple signal-on strategy for fluorescent detection of tuberculostatic drug isoniazid based on Ag clusters-MnO2 sheets nanoplatform.

As a first-line tuberculostatic drug, isoniazid (INH) plays effective and irreplaceable role in prevention and treatment of tuberculosis. In this work, a rapid and simple signal-on fluorescence approach is established for INH assay by employing a platform composed of silver nanoclusters (AgNCs) and MnO2 nanosheets. In the proposed sensing system, strong red fluorescence of poly (methacrylic acid)-stabilized AgNCs can be greatly quenched after they attach to the surfaces of MnO2 nanosheets. With the addition of INH, MnO2 nanosheets are reduced to Mn2+ and subsequently release the AgNCs, which leads to obvious fluorescence recovery again. Based on this mechanism, highly sensitive detection of INH in the range of 0.8-200 µM is realized (detection limit: 476 nM). The present strategy shows remarkable advantages including simplicity, rapidness, high sensitivity and wide detectable range. This method is also practical and comparable to high-performance liquid chromatography, which can be applied to detect INH in human urine and serum samples as well as pharmaceutical products.

Detection of B-type natriuretic peptide by establishing a low-cost and replicable fluorescence resonance energy transfer platform.

Aiming at the establishment of a sensitive and specific diagnostic method for early heart failure (HF), we developed a cost-effective fluorescence resonance energy transfer (FRET) platform for the detection of B-type natriuretic peptide (BNP), a characteristic biomarker of HF. Graphene oxide (GO) was selected as the FRET receptor in view of its advantages including commercial availability, low-cost and chemical stability, and dye-modified aptamer was used as the energy donor of FRET as well as in charge of the specific recognition of BNP. Based on the ON (strong emission) and OFF (quenching) states of FRET in the presence and absence of BNP, respectively, specific detection of BNP was achieved in the range 0.074-0.56 pg/mL with a limit of detection as low as 45 fg/mL (3σ). This FRET platform was applied to detect BNP in 45 blood samples to demonstrate its practicability in clinical diagnosis. Compared to the commonly used Siemens method (chemiluminescence immunoassay, CLIA) in hospital, our approach is more accurate and specific for HF diagnosis with areas under the receiver operating characteristic curves of 0.869 (95% CI 0.733-1.00, P < 0.05) vs 0.850 (95% CI 0.703-0.997, P < 0.05) and specificity of 68.8% vs 65.6%. This platform is promising in early diagnosis of HF through ultrasensitive and specific detection of BNP. Graphical abstract To solve the clinical diagnostic problem for early heart failure (HF) which lacks sensitivity and specificity, we established a cost-effective and rapid fluorescence analysis method based on fluorescence resonance energy transfer (FRET) platform for the detection of B-type natriuretic peptide (BNP), a characteristic biomarker of HF.

Comparative Pharmacokinetic Study of Mangiferin in Normal and Alloxan-Induced Diabetic Rats after Oral and Intravenous Administration by UPLC-MS/MS.

BACKGROUNDS: Diabetes mellitus (DM)-induced morphological and/or functional complications may alter the pharmacokinetic profiles of mangiferin. This study aims to compare pharmacokinetic profiles of mangiferin in normal and alloxan-induced diabetic rats after oral and intravenous administration. METHODS: Mangiferin was administered orally (10 mg/kg) and intravenously (2 mg/kg) to normal and alloxan-induced diabetic Sprague-Dawley (SD) rats (n = 8). Blood samples were collected at different time points post-dose. Mangiferin and esculentoside (internal standard)  were analyzed by Waters Acquity ultra-performance liquid chromatography system and TSQ Quantum Ultra triple quadrupole mass spectrometer (UPLC-MS/MS). RESULTS: Mangiferin in normal and alloxan-induced diabetic rats experienced serious first-pass effect, which resulted in 1.71 and 0.80% of oral bioavailability respectively. Meanwhile, mangiferin was predominantly restricted to blood but not extensively distributed to organ tissues after intravenous administration. Compared with normal rats, the diabetic condition induced 53.26 and 50.90% decreases in Cmax and AUC0-t, respectively, for mangiferin after oral administration, and 63.08% decreases in Cmax after intravenous administration. CONCLUSIONS: Compared to normal rats, pharmacokinetic parameters of mangiferin were altered in diabetic condition induced by alloxan. The findings might help to provide useful evidence for modeling of diabetic rats and the clinical applications of mangiferin.

Polygonatum sibiricum polysaccharides play anti-cancer effect through TLR4-MAPK/NF-κB signaling pathways.

OBJECTIVE: To investigate the anti-cancer effect of Polygonatum sibiricum polysaccharides (PSP) and the underlying mechanism. METHODS: Tumor-bearing mice were randomly divided into normal saline (NS) group, adriamycin (ADM) group, PSP group and lipopolysaccharide (LPS) group. RAW264.7 cells were pre-treated with or without TLR4 inhibitor or MyD88 inhibitor. Quantitative RT-PCR and Western blot were performed to detect the mRNA and protein expressions, respectively. ELISA and Griess reaction was used to measure cytokines and NO levels. Flow cytometry was employed to examine T-lymphocyte subset and CCK-8 assay was used for cell viability. RESULTS: The in vivo experiment found that PSP inhibited tumor growth and improved the spleen index, thymus index, the cytokines secretion and CD4+/CD8+ lymphocytes ratio. Compared with the NS group, the mRNA and protein expressions of the critical nodes inTLR4-MAPK/NF-κB signaling pathways (except TRAM) significantly increased in PSP group, as well as the NO and cytokines levels. Nevertheless, PSP had no obvious effects on TRAM. Further analysis showed that PSP effects on the critical nodes in TLR4-MAPK/NF-κB signaling pathways were suppressed by inhibitor in vitro. CONCLUSION: The immunoenhancement effect of PSP against lung cancer is mediated by TLR4-MAPK/NF-κB signaling pathways.

Facile fabrication of 3D porous hybrid sphere by co-immobilization of multi-enzyme directly from cell lysates as an efficient and recyclable biocatalyst for asymmetric reduction with coenzyme regeneration in situ.

Ni2+-agarose bead-wrapped multi-enzyme/inorganic hybrid sphere composed of the immobilized enzymes as organic component and NaH2PO4 and NaCl as inorganic component was developed by co-immobilizing extracellular His-tagged 3-quinuclidinone reductases and glucose dehydrogenase without pre-purification. The resulting biocatalysts has 3D porous architectures as confirmed by SEM and FESEM, and it enabled the continuous biotransformation of 3-quinuclidone to (R)-3-quinuclidinol with cofactor regeneration in situ. The 3D porous biocatalysts were formed via three steps: First, immobilization of the His-tagged enzymes directly from the cell lysates supernatant. Next, formation of enzyme aggregates, ribbons and gels. Finally, the enzymes, the formed aggregates/ribbons/gels and salt were incorporated to the foam and then covered the Ni2+-agarose bead. The technique made the immobilization of these enzymes effective such that specific enzyme loading of 60.8mg/g support and enzyme loading efficiency of 92.3% were achieved. As a direct consequence, the biocatalyst catalyzed the conversion of 3-quinuclidinone (204g/L) to (R)-3-quinuclidinol in 100% yield and 100% ee at 4.5h, and the recyclability of the biocatalyst was excellent, retaining>95% conversion yield and 100% ee even after the fifteenth runs. Overall, our strategy is demonstrated to be a promising method for developing efficient and robust biocatalyst for asymmetric synthesis.

The formation of a host-guest inclusion complex system between ß-cyclodextrin and baicalin and its dissolution characteristics.

OBJECTIVES: Baicalin (BCL) has potential therapeutic benefits, but its clinical outcomes are restricted mainly because of low water solubility. This study sought to improve the water solubility of BCL by the formation of inclusion complex with ß-cyclodextrin (ß-CD). METHODS: The inclusion complex was studied by solubility test, differential scanning calorimeter (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), 1 H Nuclear magnetic resonance (1 HNMR) and scanning electron microscopy (SEM). Molecular docking was conducted to verify the experimental findings. The dissolution rate was determined by dialysis membrane method. In vivo absorption studies in rats were conducted and high-performance liquid chromatography (HPLC) was used to analyse the plasma level of BCL after oral administration. KEY FINDINGS: The DSC, FTIR, XRD, 1 HNMR and SEM findings suggested the formation of inclusion complex between BCL and ß-CD in 1 : 1 stoichiometry. Molecular docking demonstrated the insertion of benzene ring of BCL into ß-CD cavity by hydrophobic interactions and possible H-bond formation. Moreover, ß-CD markedly improved the solubility of BCL and displayed AL -type phase diagrams. The improvement in dissolution rate of the inclusion complex was reflected in the earlier Tmax , higher Cmax and larger AUC0-t than that of BCL after oral administration. CONCLUSIONS: ß-cyclodextrin complex can be used as an effective formulation strategy for development of BCL-loaded delivery system with better therapeutic outcomes.

Simultaneous determination of eleven compounds related to metabolism of bioamines in rat cortex and hippocampus by HPLC-ECD with boron-doped diamond working electrode.

A simple and rapid high-performance liquid chromatography method with electrochemical detection employing boron-doped diamond electrode (BDD) was established for simultaneous determination of eleven bioamines with their precursor amino acids and metabolites, including two precursors (tyrosine and tryptophan), three catecholamines (dopamine, norepinephrine and epinephrine) and their four metabolites (3,4-dihydroxyphenylacetic acid, 3-methoxytyramine, homovanillic acid, and 3-methoxy-4-hydroxyphenylglycol), as well as serotonin and its metabolite (5-hydroxyindoleacetic acid), in a single run of 20 min using vanillic acid as internal standard. The separation was performed on an ODS2 column (250 mm × 4.6 mm, 5.0 µm) with column oven temperature of 30 °C. Quantification was accomplished at an oxidation potential of 700 mV vs Ag/AgCl reference electrode after a range of applied voltages were tested. Several parameters of this new chromatographic method were validated after optimizaton of the analytical conditions. The new method was successfully applied to test cortex and hippocampus samples from Sprague-Dawley rats with good separation. These eleven compounds in cortices and hippocampi were compared, which was used for monitoring their variations in neuroscience research.

Determination of the potential illegal addition of ß-blockers to function foods by QuEChERS sample preparation and UPLC-MS/MS analysis.

A novel method was established for the determination of 11 ß-blockers in sedative functional foods using QuEchERS sample preparation coupled with UPLC-MS/MS. The analytes were extracted twice with acetic acid-acetonitrile-methanol (0.1:3:7, v/v/v), and the extracts were purified with mixed QuEchERS adsorbents. Separation was performed on a C18 column, and detection using electrospray ionisation in positive-ion mode. The linear range for the 11 analytes was from 1 to 500 µg l(-1), and the correlation coefficients were above 0.9990. The limits of detection and quantification were 0.02-0.16 and 0.07-0.54 µg kg(-1), respectively. The average recovery for 11 analytes at the three spiking levels varied from 71.8% to 121.9%, and the relative standard deviation was 2.4-12.6%. The method was applied to the analysis of ß-blockers in 22 real samples, but none of the analytes was detected. The proposed method is sensitive, efficient, reliable and applicable to real samples.

Supramolecular assemblies constructed from ß-cyclodextrin-modified montmorillonite nanosheets as carriers for 5-fluorouracil.

Supramolecular assemblies generated from self-assembling ß-cyclodextrin-modified montmorillonite nanosheets were evaluated as anticancer drug carriers in vitro. The results showed that the assemblies had a high loading capacity of 5-fluorouracil (5-FU) under the optimized conditions that included a temperature of 80 °C and a pH level of 11. Scanning electron microscopy (SEM) images showed no morphological changes in the assemblies even after 20 days of storage at room temperature. Moreover, SEM and atomic force microscopy (AFM) observations revealed that the incorporation of 5-FU hardly affected the morphology of the assemblies. Furthermore, the assemblies showed sustained release behavior in vitro, and SEM and AFM analyses indicated that the kinetics of 5-FU release were closely associated with morphological changes in the surface of the assemblies during drug release. Cell viability assays showed that the blank assemblies had low cytotoxicity against A549 cells, while the inhibitory effects of 5-FU-loaded assemblies against A549 cells increased significantly with an increased concentration. More importantly, fluorescence microscopy imaging and transmission electron microscopy (TEM) demonstrated that both blank assemblies and 5-FU-loaded assemblies can easily penetrate cultured human ovarian cancer SKOV3 cells. These results suggest that the supramolecular assemblies may potentially be used as building blocks for the development of new anti-cancer drug delivery systems.

Pharmacokinetics of single- and multiple-dose emtricitabine in healthy male Chinese volunteers.

Emtricitabine (FTC) is used for the treatment of HIV infection and pre-exposure chemoprophylaxis. It is often used in combination with tenofovir disoproxil fumarate (TDF). This study was designed to evaluate FTC pharmacokinetics in healthy male Chinese volunteers. Sixty subjects were recruited into this single-centre, randomised, open-label study and randomly received single (groups A, B and C) or multiple oral doses (once daily for 6 days; groups D, E and F) of 200-mg FTC capsules alone (A and D), or combined with 300-mg TDF tablets (B and E), or 200 mg of FTC plus 300 mg of TDF with a high-fat diet (C and F), respectively. FTC was well-tolerated in all groups. After a single dose, there were no differences in the mean AUC0-∞ values; however, there were significant differences in the mean Tmax values (1.05, 1.40 and 2.10 h for groups A, B and C, respectively; p < 0.05). In the multiple-dose study, our results were significantly different from published t1/2 values following single-dose FTC.

[Effects of pomegranate tannins on experimental gastric damages].

OBJECTIVE: To observe the antiulcer effects of pomegranate tannins in animal models. METHOD: Gastric ulcer models were established by pylorus ligation, intragastric absolute ethanol, and water-immersion stress, respectively. The ulcer index, the contents of nitric oxide (NO) and malondialdehyde (MDA), the activities of glutathione peroxidase (GSH-PX) and superoxide dismutase (SOD) from gastric mucosa of rats, the gastric juice volume, free acidity, total acidity,total acid output, the pepsin activity, the amount of adherent mucus and free mucus were measured, respectively. RESULT: Pomegranate tannins (500, 150, 50 mg x kg(-1)) significantly inhibited ulcerative formation induced by both water immersion stress and pylorus ligation, obviously decreased the gastric mucosa damages induced by intragastric absolute ethanol, in dose-dependent manner. Pomegranate tannins significantly inhibited absolute alcohol-induced elevation of MDA as well as decreasing of NO level, and activities of both SOD and GHS-PX from gastric mucosa. Pomegranate tannins significantly increased the secretion of adherent mucus and free mucus, but did not affect elevation of the free acidity, total acidity, and total acid output, gastric juice volume, gastric pepsin activity induced by pylorus ligation. CONCLUSION: Pomegranate tannins play a protective role against gastric ulcer. Its antiulcer effect is related to increasing secretion of adherent mucus and free mucus from the stomach wall, which may inhibit generation of oxygen-derived free radicals, and decrease the consumption of GSH-PX and SOD, and maintain content of NO at normal level.

A resonance light-scattering (RLS) serving for various quantitative events since 1995: a comment proposed towards how to apprehend well the meaning of RLS and its corresponding guiding role.

A resonance light-scattering (RLS), which was creatively suggested for the first time by Pasternack et al. in 1993 [R.F. Pasternack, C. Bustamante, P.J. Collings, A. Giannetto, E.J. Gibbs, J. Am. Chem. Soc. 115 (1993) 5393], have been enjoyably practiced by numerous investigators for various quantitative events since 1995, and hitherto many research papers and some review papers have got published on lots of international journals specialized in or related to analytical and/or bioanalytical sciences. As revealed from these published papers of interests, however, it is a pity that the meaning of RLS is often apprehended unsatisfactorily both in theory and in practice. In this comment, as a result, I would like to do my best to propose an apprehension of the meaning of RLS as full and exact as possible and simultaneously I would like to deliver the important guiding role of this proposed apprehension in the course of the applications of RLS for various quantitative purposes.

[Pharmacokinetics of hylotelephin in Beagle dogs].

AIM: To investigate the pharmacokinetics of hylotelephin in Beagle dogs and obtain the main pharmacokinetic parameters. METHODS: An HPLC method with UV detection was developed to study the pharmacokinetics of hylotelephin in dogs by joining an internal standard (anthracene). Benzoyl chloride was used to the pre-column derivatization of hylotelephin and methanol-water (64:36) was used as the mobile phase. According to the 3P97 pharmacokinetic program, the main parameters were calculated. RESULTS: The hylotelephin pharmacokinetics conforms to a two-compartment open model after a single iv dose of hylotelephin 10.6 or 21.3 mg x kg(-1) in Beagle dogs. The parameters of two groups were as follows: T(1/2) alpha were 2.3 and 2.1 min, T(1/2) beta were 1.9 and 2.0 h, K12 were 0. 12 and 0.11 min, K21 were 0.17 and 0.21 min, K10 were 0.011 and 0.0094 min, Vc were 0.54 and 0.54 L x kg(-1), AUC were 1.8 and 4.1 g x min x L(-1), CL were 0.0048 and 0.0056 L x kg(-1) x min(-1), MRT were 2.10 and 2.4 h, respectively. CONCLUSION: The pharmacokinetics of hylotelephin after iv administration showed a rapid distribution and elimination process in Beagle dogs and was of first order kinetics.

[Protective effects of total alkaloids from rhizoma Coptis chinensis on alcohol-induced gastric lesion in rats].

OBJECTIVE: To study the effects of total alkaloids(TA) from rhizoma Coptis chinensis on alcohol-induced gastric lesion in rats and the possible mechanisms. METHOD: The experimental gastric damges were established by intragastric(ig) absolute ethanol, and possible protective effects of TA given orally previously were evaluated by following parameters: gastric damage indexes, gastric juice volume, acidity, and mucus quantity. The contents of NO, MDA, *OH, and SOD activity were also measured in gastric mucosa. RESULT: TA showed significantly inhibitive effects on gastric damages induced by ig ethanol in a dose dependent manner. The effects of TA (120 mg x kg(-1)) were stronger than that of both cimitidine(70 mg x kg(-1)) and berberine(100 mg x kg(-1)), the quantity of later was equal to TA as calculated with berberine. TA significantly suppressed secretion of gastric acid caused by ethanol without clear influences on gastric juice volume and mucus secretion. TA obviously blunted ethanol-induced elevation of MDA and *OH, as well as decrease of NO level and SOD activity from gastric mucosa. CONCLUSION: It is suggested that the TA is a potent protective agent against ethanol-induced gastric damages. The mechanism of actions may be related with inhibiting the secretion of gastric acid and blunting the increase of MDA and *OH, as well as the decrease of NO level and SOD activity from gastric mucus.

[Study of total alkaloids from Rhizoma Coptis Chinensis on experimental gastric ulcers].

OBJECTIVE: To study the effects of total alkaloids (TA) extracted from Rhizoma Coptis Chinensis on experimental gastric ulcer models. METHODS: Four kinds of experimental ulcer models were established respectively by water-immersion stress, intragastric ethanol, acetic acid erosion, and pylorus ligation. The anti-ulcer effects of TA were evaluated, and compared with that of berberine (Ber) and cimetidine (Cim). RESULTS: TA showed significant inhibitory effects on ulcerative formation induced by water-immersion stress, intragastric ethanol, and pylorus ligation in dose-dependent manner, and showed therapeutic effect on acetic acid erosion-inducing ulcer, in comparison with the control group. The anti-ulcer activity of Ber was less than TA containing equal content of Ber. TA significantly reduced the free acidity, total acidity and total acid output, but didn't affect the gastric juice volume, gastric pepsin activity, adherent mucus quantity of stomach wall and free mucus dissolving in gastric juice. The suppressive activities of TA on gastric acid secretion didn't occur when it was administered into dodecadactylon at a dose of 360 mg/kg wt. Moreover, when compared with Cim, the inhibitory effect of TA on gastric acid secretion isn't proportional to the inhibitory effects on the formation of the 4 kinds of experimental ulcers. CONCLUSION: TA is a potent candidate in therapeutic drugs for treating gastric ulcer. Its anti-ulcer effective components and mechanism is not only related to Ber and inhibition of gastric acid, but also to other ingredients of TA and mechanism so far unknown.