Quinolones, detection

Kovalska VB, Volkova KD, Manaev AV et al (2010) 2-Quinolone and coumarin poly-methines for the detection of proteins using fluorescence. Dyes Pigm 84 159-164... 

Snitkoff et al. [75] reported the development of an EIA for the detection of ciprofloxacin in serum, which was sensitive at picogram per milliliter levels of the antibiotic and no cross-reaction with its metabolites was observed. Gobbo et al. [118] recently described the production of PAb for ciprofloxacin with the aim of detecting fluoroquinolones in Brazilian livestock. On the other hand, Bucknall et al. [77] produced antibodies for quinolones and fluoroquinolones with the aim of developing both generic and specific immunoassays. ELISAs for ciprofloxacin, enrofloxacin, flumequine, and nalidixic acid were developed with sensitivity values around 4 pg kg 1 (on both the generic and specific assays) in bovine milk and ovine kidney. 

The aposematic beetle, Metriorrhynchus rhipidius, contains three pyrazines as warning odor components and two amides as bitter principles (Tables III, V, and VIII) (97). Of the three components with the beetlelike odor, the most characteristic is 2-methoxy-3-isopropylpyrazine (24b). The other two components are 2-methoxy-3-methylpyrazine (24a) and 2-methoxy-3-sec-butylpyrazine (24d). It would seem likely that these compounds will occur in the defensive systems of the aposematic beetles. The two amide components, detectable in the hemo-lymph exuded by adult beetles, are 3-phenylpropanamide (130) and l-methyl-2-quinolone (57), the latter being the major component. It seems likely that these bitter principles contribute to distastefulness to potential predators. 

The quinolones are rapidly and almost completely absorbed after oral administration and are widely distributed in body tissues. Levels in extravascular spaces can often exceed serum levels. Levels lower than those found in serum occur in CSF, bone, and prostatic fluids. Ciprofloxacin and ofloxacin have been detected in breast milk and ofloxacin levels in ascites fluid are close to serum levels. Food ingestion does not affect bioavailability, which ranges from 50 to 95%. The half-life for most quinolones is 3 to 4 hours. 

Another pertinent study (170) also showed that residues of quinolones could be present in certain tissues for a prolonged period after the end of medication. In this study, oxolinic acid and flumequine were especially entrapped in bone, enrofloxacin in skin, and sarafloxacin in both skin and bone. When salmon was treated with flumequine and oxolinic acid, highest residue levels of flumequine found in the backbone averaged 465 ppb and were detectable for 70 days posttreatment (171). Residues were also present in skin, back fat, and liver for 70 days posttreatment, but no residues could be found in muscle from fish sampled 48 days after treatment. 

Further investigation showed that some amounts of both the quinolones investigated could also leak out into the boiling water or the juice exuded from the baked fish. Therefore, cooking may reveal residues of quinolones that could not be detected in the raw fish muscle before preparation. It is of value to note that none of the quinolones used in this study showed any degradation at the temperatures reached when the fish were cooked. 

Following their extraction and cleanup, residues of quinolone antibiotics in sample extracts can be determined by either direct nonchromatographic methods, or gas or liquid chromatographic methods. Spectrophotometric, fluorometric, or mass spectrometric detection systems have all been successfully used in quinolone analysis (Table 29.6). 

A direct spectrometric method for screening nalidixic acid in chicken tissues (189, 190) has been reported. This method was based on fluorometric detection after derivatization of the analyte with sulfuric acid. The major drawback of this method is tliat it cannot differentiate among the various quinolones, it is less sensitive than the screening tests usually employed for regulatory purposes, and it is complicated by the necessity for derivatization. 

In liquid chromatographic analysis of quinolone antibacterials, most popular is the fluorometric detector due to the inherent fluorescence of these drugs and the advantages in terms of selectivity and sensitivity that this detector offers (Table 29.6). Fluorometric detection after postcolumn derivatization with sulfuric acid has also been reported (203). However, quinolones exhibit also remarkable ultraviolet absorption and are therefore ideal for direct determination without derivatization. Detection can be performed in the wavelength range of 254-295 nm. 

Fig. 29.6.1 Chromatograms obtained with UV and fluorescence detection from analysis of catfish tissue containing incurred quinolones. (Reprinted from Ref. 196. Copyright, (1995), by AOAC INTERNATIONAL.)...

H bonding. In a later study, Petersen et al. (1971) identified associated complexes of 2-quinolones with carboxylic acids. The 2-quinolones had been previously detected in petroleum heavy oils (Copelin, 1964 Snyder et al., 1968). Model compound studies (Petersen et al., 1971) of dimer and mixed dimer formation with 2-quinolone and carboxylic acids suggest strong association with enthalpies in the 8- to 10-kcal/mole range. 

G.E. Pellegrini, G. Carpico and E. Coni, Electrochemical sensor for the detection and presumptive identification of quinolone and tetracycline residues in milk, Anal. Chim. Acta, 520 (2004) 13-18. 

The reduction of 2, either catalytically or with zinc in acetic acid, leads to 3-amino-4-hydroxy-2-quinolone 20 [72TH000], These amino compounds are rather unstable they dimerize with loss of ammonia to "bis-amines", which in turn are readily oxidized to dyes similar to those obtained from ninhydrin and primary amines [68M1205] [68M1543], The amino derivatives 20 are therefore conveniently converted into 0,N-diacetyl derivatives, the N-acetyl derivative 21, or its dehydrated form, the oxazolo derivative 22 [95MI000], The variety of biological activity of oxazolo-quinolines of type 22 has been detected only in recent years [94JHC1647],... 

Six quinolone antibiotics (including ciprofloxacin) were separated and determined by CE on fused-silica capillaries (57 cm x 75 pm i.d. 50 cm to detector) at 25°C, with injection on the anode side, an applied voltage of 10 kV, and detection at 280 nm [56], The buffer was 100 mM HEPES/ acetonitrile (9 1). The calibration graphs were linear from 0.25 to 40 pg/mL and detection limits were approximately 0.25 ng/mL. 

Plasmid-mediated resistance has so far evidently played no role in the spread of quinolone resistance and has seldom been detected [238], although plasmid-mediated resistance of K. pneumoniae and E. coli has been reported in China and the USA [239,240]. 

A study of the pharmacokinetics of orally administered ciprofloxacin in elderly (63-76 years) and young volunteers (22-34 years) without renal impairment, revealed in the elderly group a decreased renal clearance of the quinolone with no differences detected in the terminal half-life (3.5 hours). This was accompanied, however, by a surprising increase in the absolute availability of the drug [226]. The authors cautioned about the need for a reduction of oral dosage of ciprofloxacin in the elderly population. 

L. Johnston, L. Mackay, M. Croft, Determination of (fluoro)quinolones in fish tissue and seafood by LC-ESI-MS-MS detection, J. Chromatogr. A, 982 (2002) 97. 

An analyst has a wide range of efficient extraction, cleanup, separation, and detection procedures to choose from. The choice will depend on the nature of the sample matrix (whether it is solid or liquid, or fatty or nonfatty) and the expected range and levels of quinolone residues in food. 

Ultraviolet, fluorometric, and mass spectrometric detectors have aU been successfully used for the determination of residues of quinolones in food. Quinolones exhibit remarkable ultraviolet absorption therefore, they are ideal for direct determination by ultraviolet detection anywhere in the wavelength range from 254 to 295 nm. However, the most popular is fluorometric detection, due to the... 

Pascual et al. (23) combined HPLC with fluorescence detection to measure the uptake of lomefloxacin and related quinolones by human neutrophils. A Bondapak C18 column was used with a mobile phase of 0.025 M H3PO4 adjusted to pH 3.0 with tetrabutyl-ammonium hydroxide/ acetonitrile (75 25) delivered at a flow rate of 1.5 mL/min. The excitation and emission wavelengths for the fluorescence detector were... 

ABSORPTION, FATE, AND EXCRETION The quinolones are weU absorbed after oral administration and are widely distributed. Peak serum levels of the fluoroquinolones occur within 1-3 hours of an oral dose of 400 mg. Relatively low serum levels are reached with norfloxacin and limit its usefulness to the treatment of urinary tract infections. Food does not impair oral absorption but may delay the time to peak serum concentrations. Oral doses in adults are 200-400 mg every 12 hours for ofloxacin, 400 mg every 12 hours for norfloxacin and pefloxacin, and 250-750 mg every 12 hours for ciprofloxacin. Bioavailabrlity of the fluoroquinolones exceeds 50% for all agents and 95% for several. The serum half-lives range from 3 to 5 hours for norfloxacin and ciprofloxacin to 20 hours for sparfloxacin. The volume of distribution of quinolones is high, with concentrations in urine, kidney, lung and prostate tissue, stool, bUe, and macrophages and neutrophils higher than serum levels. Quinolone concentrations in CSF, bone, and prostatic fluid are lower than in serum. Pefloxacin and ofloxacin levels in ascites fluid approach serum levels, and ciprofloxacin, ofloxacin, and pefloxacin have been detected in human breast milk. 

Edulinine from Casimiroa edulis may be formed from (+)-N-methylplatydesminium salt during isolation. (+)-Edulinine from Pelea barbigera is certainly an artifact, and was obtained only when base was employed during isolation the precursor, presumably (—)-JV-methyl-platydesminium salt, could not be detected (43). ( )-Edulinine is conveniently prepared by reaction of 4-methoxy-l-methyl-3-(3-methylbut-2-enyl)-2-quinolone with m-chloroperbenzoic acid and then with aqueous base, without isolating intermediates (2). 

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