Synthesis, Characterization, and Pharmacodynamics Study of Enrofloxacin Mesylate.

INTRODUCTION: Enrofloxacin is used in the treatment of a wide variety of bacterial infections in mammals. However, its poor solubility limits the clinical use. METHODS: In order to improve the solubility of enrofloxacin, the enrofloxacin mesylate (EM) were obtained by a chemical synthesis method. The characterization of EM was carried out using ultraviolet scan (UV), synchronous thermal analysis (SDT), fourier transform infrared spectrometer (FTIR) and mass spectrometry (MS), nuclear magnetic resonance (NMR) and X-ray powder diffraction analysis (XRPD). Acute toxicity of EM in Kunming mice was studied. Besides, pharmacokinetic studies were performed in New Zealand rabbits at a single oral dose of 10 mg/kg, and the antibacterial activity of EM was also evaluated. RESULTS: EM was successfully synthesized and purified. The stoichiometric ratio of mesylate to enrofloxacin was 1:1 and the aqueous solubility of EM was 483.01±4.06 mg/mL, the solubility of EM was about 2000 times higher than enrofloxacin. The oral lethal dose (LD50) of EM was 1168.364 mg/kg, and the pharmacokinetics indicated that the oral relative bioavailability of EM was about 1.79 times and 1.48 times higher than that of enrofloxacin and enrofloxacin hydrochloride, respectively. In addition, the in vitro antibacterial activity of EM was not significantly changed compared with enrofloxacin and enrofloxacin hydrochloride. CONCLUSION: EM has higher solubility, low toxicity for oral use, and increases the oral bioavailability in rabbit. This study may be of benefit for the development of new enrofloxacin drugs.

[Stat 3 signal transduction pathway correlates with proliferation of vascular smooth muscle cells of rats].

OBJECTIVE: To investigate the role of Stat3 (one of the signal transductant and activator) signal transduction pathway in proliferation of vascular smooth muscle cells (VSMCs). METHODS: VSMC was transfected with Stat3 antisense oligonucleotide. ELISA analysis was performed on Stat3 expression in cultured rat thoracic VSMC. Cell proliferation and toxicity assay by Methyl Thiazole (MTT) was used to measure the cell proliferation. The expression of Stat3, p-Stat3, Cyclin D1 and Bcl-x(L) were measured by Western blot. RESULTS: Stat3 protein expression was positive in VSMC. Targeting of Stat3 using antisense oligonucleotide directed against the translation site, resulted in significant growth inhibition and downregulation of Stat3, p-Stat3 and Cyclin D1. CONCLUSIONS: The increase of Stat3 correlates significantly with cell proliferation of VSMC. Cyclin D1 may be the critical target gene in mediating proliferation. Blocking Stat3 signal transduction pathway may inhibit the growth of VSMCs.