Preparative resolution of gatifloxacin enantiomers with pre-column esterification strategy and comparing their enantioselectivity to bacteria and antibody / 生物医学与环境科学（英文）

Gatifloxacin (GFX) is a kind of chiral fluoroquinolones compound due to the methyl group at the C-3 position of the piperazine ring[1]. Although the enantiomers of GFX show similar levels of antimicrobial activity and pharmacokinetics[2], the other biological activities (i.e., toxicity or enantioselective recognition to various receptors in vivo) of GFX enantiomers have not yet been studied. With this in mind, we developed a rapid and cost-effective high performance liquid chromatographic (HPLC) separation procedure for GFX enantiomers with a pre-column esterification strategy. With significant enhancement of drug solubility and optimization for chromatographic conditions, the proposed method was scaled up to preparative HPLC to obtain optical active S-(-)- and R-(+)-GFX. The antibacterial activities of GFX enantiomers after preparative separation were further verified by measuring the Minimum Inhibitory Concentration (MIC) values against Escherichia coli ATCC 25922. In addition, the binding selectivity of GFX enantiomers to protein receptor were evaluated by antibody using enzyme-linked immunosorbent assay (ELISA) for the first time.

Effect of ketoconazole on the activity of CYP4503A4 and CYP450 1A2 of hepatic microsomes in healthy adults / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe the effect of ketoconazole on the activity of cytochrome P450 (CYP) 1A2 and 3A4 in hepatic microsomes of healthy adults.</p><p><b>METHODS</b>Human hepatic microsomes obtained from healthy adults were randomly divided into control group and ketoconazole-treatment groups at different concentrations. After 15 min of culture, the substrates (testosterone for CYP3A4 and phenacetin for CYP1A2) were added and incubated for another 20 min. The metabolites (6-testosterone and acetaminophen) were then measured with high-performance liquid chromatography (HPLC) to assess the activities of CYP3A4 and 1A2.</p><p><b>RESULTS</b>Significant difference was found between the groups in the quantity of 6-testosterone and the relative activity of CYP3A4 (P<0.05). The IC(50) of ketoconazole for CYP3A4 was 0. 16 mg/L. Both the quantity of 6-testosterone and the relative activity of CYP3A4 were reduced gradually with the increment of ketoconazole concentration. Significant differences were found between the ketoconazole groups and the control group in both the quantity of acetaminophen and the relative activity of CYP1A2 (P<0.05). Ketoconazole at low doses reduced CYP1A2 activity and but increased the activities at high doses (P<0.05).</p><p><b>CONCLUSION</b>In the range of maximum clinical blood concentration, ketoconazole can inhibit the activity of CYP3A4, but not that of CYP1A2, in the hepatic microsomes in healthy adults.</p>

RNA interference-mediated silencing of cytochrome P450 3A4 gene in CHL-3A4 cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of small hairpin interfering RNA (shRNA) in suppressing cytochrome P450 3A4 (CYP3A4) gene expression in CHL-3A4 cells.</p><p><b>METHODS</b>Three shRNA expression vectors targeting CYP3A4 gene (CYP3A4 I, C YP3A4 II, and CYP3A4 III, respectively) were designed, synthesized and transfected into CHL-3A4 cells via liposomes. The inhibitory effect of shRNA on CYP 3A4 gene expression was detected by Western blotting and RT-PCR, and the effect of shRNA transfection in suppressing cyclophosphamide-induced cytotoxicity was measured using MTT assay.</p><p><b>RESULTS</b>The vector carrying CYP3A4 III shRNA significantly reduced the expression of CYP3A4 gene at both the mRNA (75%) and protein levels (80%) in CHL3A4 cells. The cytotoxicity of cyclophosphamide was markedly inhibited by CYP3A4 III-mediated suppression of CYP3A4 gene expression by 75% in CHL-3A4 cells.</p><p><b>CONCLUSION</b>The vector-mediated RNA interference can suppress CYP3A4 gene expression in CHL-3A4 cells, and RNA interference technique provides a new means for studying cytochrome P450 gene function in mammalian cells.</p>

Pharmacokinetics of hylotelephin in Beagle dogs / 药学学报

<p><b>AIM</b>To investigate the pharmacokinetics of hylotelephin in Beagle dogs and obtain the main pharmacokinetic parameters.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>The pharmacokinetics of hylotelephin after iv administration showed a rapid distribution and elimination process in Beagle dogs and was of first order kinetics.</p>