Synthesis and fluorescence properties of six fluorescein-nitroxide radical hybrid-compounds.

Six fluorescein-nitroxide radical hybrid-compounds (2ab, 3ab, 4, and 5) were synthesized by the condensation of 5- or 6-carboxy-fluorescein and 4-amino-TEMPO (2ab), 5- or 6-aminofluorescein and 4-carboxy-TEMPO (3ab), and fluorescein and 4-carboxy-TEMPO (4), or by reaction of the 3-hydroxyl group of fluorescein with DPROXYL-3-ylmethyl methanesulfonate (5). Fluorescence intensities (around 520nm) after reduction of the radical increased to 1.43-, 1.38-, and 1.61-folds for 2a, 2b and 3b respectively; 3a alone exhibited a decrease in intensity on reduction. Since 4 was readily solvolyzed in PBS or even methanol to afford fluorescein and 4-carboxy-TEMPO, its fluorescence change could not be measured. Hybrid compound 5 containing an ether-linkage between the fluorescein phenol and 3-hydroxymethyl-DPROXYL hydroxyl centers, was stable and on reduction, showed a maximum increase (3.21-fold) in relative fluorescence intensity in PBS (pH5.0), despite its remarkably low absolute fluorescence intensity.

Evaluation of glucose-linked nitroxide radicals for use as an in vivo spin-label probe.

In vivo incorporation and reduction abilities of 4-carboxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-carboxy-TEMPO) (1), 3-carboxy-2,2,5,5-tetramethylpyrroline-1-oxyl (3-carboxy-dehydro-PROXYL, 3-carboxy-DPRO) (2), 4-hydroxy-TEMPO and 3-hydroxymethyl-DPRO O-ß-D-glucosides (3 and 5), and newly designed forms of 6-O-(TEMPO-4-carbonyl and DPRO-3-carbonyl)-D-glucose (4 and 6) were evaluated using white radish sprouts. For each of these compounds, electron spin resonance (ESR) spectrometry was used to measure two effects: the rate of in vitro reduction via the addition of ascorbic acid; and, the rate of successful incorporation into radish sprouts for a reduction to the corresponding hydroxyl amine. DPRO-radicals 2, 5, and 6 were detected significantly more than TEMPO-radicals 1, 3, and 4 in vitro and in vivo for both experiments. Four glucose-linked nitroxide radicals were reduced faster than the glucose-non-linked ones in the in vitro experiment, but were nonetheless detected more each time in radish sprouts due to the absorbability. Glucose ester-linked radicals 4 and 6 were detected more than glycosides 3 and 5, which suggests that glucose ester-linked DPRO-radical 6 is the best for use as a spin-label probe that a plant will incorporate.

[Attenuation of arbekacin-induced nephrotoxicity in rats by pazufloxacin mesilate].

The protective effect of pazufloxacin (PZFX) mesilate, a parenteral quinolone antimicrobial agent, on arbekacin (ABK)-induced nephrotoxicity was evaluated with 8-week-old male Sprague-Dawley rats. Animals were injected with ABK at a dose of 32 mg/kg intramuscularly, or a combination of ABK in the same manner with PZFX mesilate at a dose of 208 mg/kg (160 mg/kg convert to PZFX, active principle of PZFX mesilate) intravenously once a day for 4 days. In consequent, ABK induced increases in protein, beta 2-microglobulin and N-acetyl-beta-(D)-glucosaminidase in urine, and histopathological phospholipidosis in kidneys. The extent of these changes was reduced when ABK was given in a combination with PZFX mesilate. Renal cortex level of ABK increased after an administration of ABK 1 hour to 4 hours; however, the increase was suppressed by coadministration of PZFX mesilate. Taken together, these results suggest that PZFX mesilate has the protective effect on ABK-induced nephrotoxicity, and that this was attributable to a suppression of uptake of ABK in cortical renal tubules.

Comparative articular toxicity of garenoxacin, a novel quinolone antimicrobial agent, in juvenile beagle dogs.

The articular toxicity of garenoxacin (formerly T-3811 or BMS-284756) was experimentally examined utilizing juvenile beagle dogs. Garenoxacin and two other reference quinolones were administered at intravenous dosages of 30 and 60 mg/kg. Each group consisted of 3 male dogs (Experiment I). Oral dosages of 50 mg/kg of 3 compounds were also given daily to male only and female only groups (Experiment II) over a period of 7 days. We evaluated the articular toxicity of garenoxacin compared to ciprofloxacin and norfloxacin. In Experiment I, no articular toxicity was detected in the 30 mg/kg garenoxacin group. One animal from the 60 mg/kg garenoxacin group developed detectable histopathological lesions in the articular cartilages of the shoulder, elbow and knee joints. In the 30 mg/kg ciprofloxacin group and the 30 and 60 mg/kg norfloxacin groups, histopathological articular cartilage lesions of the shoulder, elbow, carpus, hip, knee and tarsus joints were observed in all of the dogs. The area under the plasma concentration-time curve (AUC0-->infinity) values, after the first dose was administered, for the 30 mg/kg groups given garenoxacin, ciprofloxacin and norfloxacin were 164, 68.1 and 65.7 micrograms.hr/mL, respectively. In Experiment II, the degree of histopathological change was most significant in the ciprofloxacin group, followed by the norfloxacin group, and with comparatively the least changes in the garenoxacin group. The AUC0-->infinity values, obtained after the 6th day of antimicrobial administration, were 202 and 173 micrograms.hr/mL for male and female dogs, respectively, from the 50 mg/kg garenoxacin group. The AUC0-->infinity values for the garenoxacin group after the 6th daily administration were 7.8 to 17.0 times greater for male dogs and 3.8 to 13.2 times greater for female dogs than those obtained from the ciprofloxacin and norfloxacin groups. The concentrations of garenoxacin in the synovia, articular cartilage and the synovialis 4 hr following the last garenoxacin administration were 2.0 to 6.5 times higher for male dogs and 1.5 to 3.3 times higher for female dogs than the antimicrobial levels measured in the ciprofloxacin and norfloxacin groups. As discussed above, although the garenoxacin concentrations in plasma and joint tissue were higher than those for ciprofloxacin and norfloxacin, however, the articular toxicity of garenoxacin was much less than that of the other two antimicrobials.