Regioselective Synthesis ofPyrano[3,2-f]quinolin-2(7H)-onesand Furo[3,2-f]quinolin-2-ones

Summary.  A simple and efficient synthesis of the hitherto unreported ring systems pyrano[3,2-f]quinolin-2(7H)-one and furo[3,2-f]quinolin-2-one was accomplished via a thermal [3,3]-sigmatropic rearrangement. Received March 7, 2000. Accepted May 4, 2000     

Palladium-Catalyzed [3+2] and [2+2+2] Annulations of 4-Iodo-2-quinolones with Activated Alkynes through Selective C−H Activation

The palladium-catalyzed reaction of 4-iodo-2-quinolones with activated alkynes was investigated. Cyclopenta[de]quinoline-2(1 H)-ones and/or phenanthridine-6(5 H)-ones were obtained through [3+2] annulation involving aromatic C−H activation or [2+2+2] annulation involving vinylic C−H activation, respectively. Reasonable mechanisms for the formation of these annulation products have been proposed based on density functional theory calculations.     

7种喹诺酮类药物固体表面室温磷光或延迟荧光分析法研究

建立了滤纸为基质的7种喹诺酮类药物的固体表面室温磷光(SS-RTP)或延迟荧光(SS-DF)分析测定的新方法．对影响喹诺酮类药物发光强度的各种因素,包括介质pH条件、重原子种类、浓度等进行了详细的研究．实验表明,除氧氟沙星在pH=6．5条件下有较强室温磷光发射外,其余6种药物均在酸性条件下有较强RTP或DF发射,其适宜pH为1．6或1．8．方法的稳定性好,线性范围宽,检出限低．7种喹诺酮类药物在尿样中的回收率最大为104．3％,最小为97．7％,能够满足痕量分析的要求．     

Selective sample preparation for the analysis of (fluoro)quinolones in baby food: molecularly imprinted polymers versus anion-exchange resins

In this work, an analytical method for simultaneous analysis of several quinolones (cinoxacin, oxolinic acid, nalidixic acid, and flumequine) and fluoroquinolones (norfloxacin, enrofloxacin, enoxacin, ciprofloxacin, and danofloxacin) in baby-food samples is described for the first time. The method is based on isolation of these analytes by ultrasound-assisted extraction procedure followed by a solid-phase extraction sample clean-up step and final determination of the analytes by HPLC using UV detection. For the extraction step, 2 g baby food was mixed with methanol in a centrifuge tube and one single extraction cycle of 15 min at room temperature was carried out. After centrifugation, supernatant was collected and two different solid-phase extraction procedures were developed and evaluated for sample clean-up. The first was based on use of strong anion-exchange cartridges whereas the second was based on use of a ciprofloxacin-imprinted polymer. Both sample clean-up procedures had their own advantages and drawbacks, and the analytical performance and applicability of each procedure was established and properly discussed. The anion-exchange resin-based method enabled simultaneous determination of quinolones and fluoroquinolones, reaching limits of detection ranging from 0.03 to 0.11 μg g⁻¹. In contrast, the use of a ciprofloxacin-imprinted polymer did provide selectivity towards fluoroquinolones, leading to chromatograms free from co-extractives reaching limits of detection one order of magnitude lower than those obtained by the first approach.     

固相萃取-高效液相色谱-荧光检测土壤中喹诺酮类抗生素

建立了固相萃取-高效液相色谱-荧光(HPLC-FLD)检测土壤中4种喹诺酮类抗生素的分析方法.样品采用50% Mg(NO_3)_2-10% NH_3 · H_2O(96∶ 4,V/V)超声提取,过HLB柱富集净化,再用乙腈-0.067 mol/L H_3PO_4溶液洗脱.采用高效液相色谱-荧光检测器,以乙腈-0.067 mol/L H_3PO_4(用三乙胺调节至pH 2.5)为流动相,于激发波长280 nm、发射波长450 nm处进行检测.土壤样品中4种喹诺酮类抗生素的加标回收率在60.4%～99.3%之间,检出限为0.58～1.0 μg/kg.对蔬菜基地土壤样品分析结果表明,本方法能够满足实际样品的分析要求,4种喹诺酮类抗生素均被检出,土壤中抗生素污染问题值得关注.     

Ni(II) Ternary Complex Based on Antimicrobial Drug Enoxacin: Synthesis and Biological Properties

First Ni(II) ternary complex using the quinolone antibacterial agent enoxacin (HEn) as ligand and 1,10‐phenanthroline as co‐ligand has been synthesized and characterized. It is a mononuclear structure, in which enoxacin acts as a bidentate ligand bound to the metal through the ketone oxygen and a carboxylate oxygen atom. The complex exhibited good binding propensity to human and bovine serum albumin proteins having relatively high binding constants (6.40×10⁴ and 7.12×10⁴, respectively). The investigation of the interaction of the complex with calf‐thymus (CT) DNA has been performed with UV and circular dichroism (CD) spectroscopies, indicating that they bind to CT DNA probably by the intercalative binding mode. The binding constant (K_b) of the complex with CT DNA calculated with UV is 2.03×10⁵, which is higher than that of free enoxacin drug (2.09×10⁴) and even higher than that of typical intercalation indicator (1.23×10⁵) of ethidium bromide (EB). Fluorescence competitive studies with EB have revealed that the complex exhibited the ability to displace the DNA‐bound EB using the intercalative binding site. In addition, the antimicrobial activity showed that the complex exhibited a little bit good inhibition (MIC=1.843 (g·mL^?1) against B. subtilis than free HEn.     

Thallium(III) Nitrate Mediated Ring Contraction of 2‐Aryl‐1,2,3,4‐tetrahydro‐4‐quinolones: Stereoselective Synthesis of trans Methyl 2‐Aryl‐2,3‐dihydroindol‐3‐carboxylates

The ring contraction of N‐acetyl‐2‐aryl‐1,2,3,4‐tetrahydro‐4‐quinolones 1a–d with thallium(III) nitrate in trimethyl orthoformate afforded stereoselectively trans methyl N‐acetyl‐2‐aryl‐2,3‐dihydroindol‐3‐carboxylates 5a–d by oxidative rearrangement of aryl ring A.     

超高效液相色谱-串联四极杆质谱法测定麻辣烫中喹诺酮类药物残留

建立了麻辣烫中14种喹诺酮类药物残留的超高效液相色谱-串联四极杆质谱(UPLC-MS/MS)检测方法。采用酸化乙腈提取麻辣烫中的喹诺酮类药物残留,提取溶液经盐析和C18固相萃取柱净化后,在电喷雾离子源中正离子模式下,采用多反应监测(MRM)方式进行测定,内标法定量。结果显示,14种喹诺酮类药物在7.5~100μg/L范围内线性关系良好,相关系数均大于0.990。在3个不同加标水平下的平均回收率为75.4%~110.0%,相对标准偏差(n=6)为1.3%~10.1%,14种化合物的检出限和定量下限分别为0.5,1.5μg/kg。该方法操作简单、快速,净化效果好,灵敏度高,适用于麻辣烫中多种喹诺酮类药物残留的同时定性和定量检测。     

Analysis of antibiotics from liquid sample using electrospray ionization-ion mobility spectrometry

The recent findings of antibiotic residues in aquatic environment at trace level have gained much concern for the detrimental effect on ecological and human health due to bacterial resistance. Here, the feasibility of using electrospray ionization ion mobility spectrometry (ESI-IMS) for analysis antibiotics in liquid sample is demonstrated. Reduced mobilities and collision cross sections of 18 antibiotics are experimentally measured and compared with theoretical values according to mass-mobility correlation. Gentamicin is used as an example to investigate the capability of ESI-IMS for multi-component analysis of antibiotics. Mixtures of antibiotics at different concentrations are analyzed. The estimated detection limit for amoxicillin is 0.7 mg L⁻¹ (70 pg) and the linear range of response maintains over two orders. This method will be a potential technique for the analysis of antibiotics in aquatic environment.     

Synthesis and condensation reactions of the boron difluoride complex with 3-acetyl-4-hydroxy-1-methyl-2-quinolone

A reaction of 3-acetyl-4-hydroxy-1-methyl-2-quinolone with boron trifluoride etherate gave its boron difluoride complex. Condensation of this complex with various carbonyl compounds afforded new 2-quinolone derivatives (polymethine and styryl dyes) that intensely absorb in the visible region of the spectrum and show effective fluorescence. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1701–1706, August, 2008.