Paeoniflorin-6′- O -benzene sulfonate (code: CP-25), is an active monomer obtained by modifying the structure of paeoniflorin (Pae). CP-25 can alleviate the course of adjuvant arthritis (AA) rats by regulating immune inflammatory response and reducing bone damage. In addition, our research has found that immune cells are important target cells for its anti-inflammatory and immunomodulatory effects. Therefore, it is of great significance to study the pharmacokinetics of CP-25 in immune cells. The aim of this study was to investigate the absorption and efflux of CP-25 in plasma and peripheral blood mononuclear cells (PBMCs) of rats. We established a sensitive ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to rapidly determine CP-25 in plasma and PBMC of rat. We found that the transport amount of CP-25 in PBMC gradually decreased with the increase of time, and reached equilibrium after 1 h. Moreover, there is a certain correlation between the concentration of CP-25 in plasma and the concentration of CP-25 in PBMC. In addition, we used several transporter inhibitors to study their effects on the efflux of CP-25 in PBMC. The efflux of CP-25 in PBMC increased with the increase of time in the first 30 min, and the efflux of CP-25 decreased gradually after 30 min. Furthermore, after multiple administration of 50 mg/kg in rats, concentration of CP-25 in PBMC is similar to the change of concentration of CP-25 in plasma. Our results suggest that CP-25 may enter PBMC by passive transport, and P-glycoprotein (P-gp), multidrug resistance-associated protein 2 (MRP2) and breast cancer resistance protein (BCRP) may be involved in the efflux of CP-25 in PBMC. This research provides a basis and guidance for further study of the clinical application of CP-25.
Hu Ruixue,Du Na,Chen Nan,Lin Li,Zhai Yanhua,Gu Zemao
The mechanisms of resistance to levofloxacin for Aeromonas hydrophila isolated from diseased fish and selected in vitro were examined in this study. Levofloxacin-resistant mutants were obtained by selection of A. hydrophila in vitro. The quinolone resistance-determining regions (QRDRs) of the gyrA and parC genes were sequenced in Lev R strains and reverse mutation strains. All Lev R strains carried a point mutation at codon 83 (Ser → Ile), and one strain (25 %) harbored a mutation at position 92 (Leu → Met) in the GyrA-QRDR. After being transferred in a levofloxacin-free medium, one strain of the mutants was successfully reversed and the reversion was related with mutations o f GyrA-QRDR at positions 81 (Gly → Asp) and 83 (Ile → Ser). No amino acid alteration was found in the ParC-QRDR. In addition, the minimum inhibitory concentration (MIC) of levofloxacin for the mutants was lower in the presence of reserpine, and all mutants were also resistant to some of the other quinolones. It was found that the mechanism of levofloxacin resistance of A. hydrophila selected in vitro was related to gyrA of type II topoisomerase, and an efflux mechanism was involved in the resistance as well.
Background Tetrandrine is a natural chemical product purified from fourstamen stephania root which recently has been shown to act similarly as synthesized drug efflux pump inhibitor verapamil. The aim of the study is to examine whether tetrandrine could potentiate anti-tubercular drugs to which Mycobacterium tuberculosis (MTB) has turned resistant via efflux mechanisms.Methods We screened 200 MTB clinical isolates using drug sensitivity test to look for those who have turned resistant to the drugs most probably due to efflux mechanisms. We found 29 isoniazid (INH) and ethambutol (EMB) - dual resistant (IEDR) strains. Then we tested if treatment with tetrandrine or verapamil could reverse drug resistance to INH and/or EMB in IEDR isolates.Results There is a parallel resistance among EMB- and INH-resistant strains in the tested clinical isolates. Among INH-resistant strains, 65% was also EMB-resistant. This suggests an involvement of efflux mechanisms which can lead to dual drug resistance in IEDR clinical isolates. Similar to a synthesized efflux pump inhibitor verapamil, tetrandrine treatment together with INH or EMB brought down the MICs from the clinical level of drug resistance to the sensitive range of both drugs. The effective rate reached 82% among IEDR clinical isolates.Conclusion sCombinational application of tetrandrine with INH or EMB increased drug efficacy. Drugs like tetrandrine may help to reduce drug dosage thus alleviate side effects.
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