Evaluation of 8-Hydroxyquinoline Derivatives as Hits for Antifungal Drug Design.

Clioquinol is an 8-hydroxyquinoline derivative that was widely used from the 1950s to 1970s as an oral antiparasitic agent. In 1970, the oral forms were withdrawn from the market due to reports of toxicity, but topical formulations for antifungal treatment remained available. Thus, the purpose of this study was to evaluate the toxicity, anti-Candida and antidermatophyte activity and to determine pharmacodynamic characteristics of clioquinol and other 8-hydroxyquinoline derivatives (8-hydroxy-5-quinolinesulfonic acid and 8-hydroxy-7-iodo-5-quinolinesulfonic acid). Antifungal activity was tested by broth microdilution and the fungicidal or fungistatic effect was checked by a time-kill assay. Permeation and histopathological evaluation were performed in Franz diffusion cells with ear skin of pigs and examined under light microscopy. An HET-CAM test was used to determine the potential irritancy. The three compounds were active against all isolates showing anti-Candida and antidermatophyte activity, with MIC ranges of 0.031-2 µg/ml, 1-512 µg/ml, and 2-1024 µg/ml for clioquinol, 8-hydroxy-5-quinolinesulfonic acid, and 8-hydroxy-7-iodo-5-quinolinesulfonic acid, respectively. All compounds showed fungistatic effect for Candida, 8-hydroxy-5-quinolinesulfonic acid, and 8-hydroxy-7-iodo-5-quinolinesulfonic acid showed a fungicidal effect for M. canis and T. mentagrophytes, and clioquinol showed a fungicidal effect only for T. mentagrophytes. Furthermore, they presented a fungicidal effect depending on the time and concentration. The absence of lesions was observed in histopathological evaluation and no compound was irritating. Moreover, clioquinol and 8-hydroxy-5-quinolinesulfonic acid accumulated in the epithelial tissue, and 8-hydroxy-7-iodo-5-quinolinesulfonic acid had a high degree of permeation. In conclusion, 8-hydroxyquinoline derivatives showed antifungal activity and 8-hydroxy-5-quinolinesulfonic acid demonstrated the potential for antifungal drug design.

[(89)Zr]oxinate4 for long-term in vivo cell tracking by positron emission tomography.

PURPOSE: (111)In (typically as [(111)In]oxinate3) is a gold standard radiolabel for cell tracking in humans by scintigraphy. A long half-life positron-emitting radiolabel to serve the same purpose using positron emission tomography (PET) has long been sought. We aimed to develop an (89)Zr PET tracer for cell labelling and compare it with [(111)In]oxinate3 single photon emission computed tomography (SPECT). METHODS: [(89)Zr]Oxinate4 was synthesised and its uptake and efflux were measured in vitro in three cell lines and in human leukocytes. The in vivo biodistribution of eGFP-5T33 murine myeloma cells labelled using [(89)Zr]oxinate4 or [(111)In]oxinate3 was monitored for up to 14 days. (89)Zr retention by living radiolabelled eGFP-positive cells in vivo was monitored by FACS sorting of liver, spleen and bone marrow cells followed by gamma counting. RESULTS: Zr labelling was effective in all cell types with yields comparable with (111)In labelling. Retention of (89)Zr in cells in vitro after 24 h was significantly better (range 71 to >90%) than (111)In (43-52%). eGFP-5T33 cells in vivo showed the same early biodistribution whether labelled with (111)In or (89)Zr (initial pulmonary accumulation followed by migration to liver, spleen and bone marrow), but later translocation of radioactivity to kidneys was much greater for (111)In. In liver, spleen and bone marrow at least 92% of (89)Zr remained associated with eGFP-positive cells after 7 days in vivo. CONCLUSION: [(89)Zr]Oxinate4 offers a potential solution to the emerging need for a long half-life PET tracer for cell tracking in vivo and deserves further evaluation of its effects on survival and behaviour of different cell types.

Cytotoxicity of 111In-oxine on mesenchymal stem cells: a time-dependent adverse effect.

BACKGROUND: Radioactive labeling with indium (In) tracers has been among the most widely used methods for tracking stem cells. As the first experiment on human stem cells, we designed a study to continuously follow the influence of In labeling on stem cell viability during the 2-week period of postlabeling. METHODS: After culturing mesenchymal stem cells (MSCs), we divided the cells into six samples, each of which contained 1x10 MSCs. The first sample was considered as the control. The remaining five samples (samples 2-6) were labeled with the following doses of In-oxine, respectively: 0.76, 1.64, 3.48, 5.33, and 7.16 MBq/10 MSCs. To evaluate the effects of In-oxine labeling on cellular viability and count, all samples were examined immediately after labeling (2 h) as well as 24, 48 h, and 5, 7, and 14 days postlabeling. RESULTS: No statistically significant relationship was found between labeling efficiency and administered dose. Associations between the specific activity and radiotracer dosage was significant (P=0.001, r=0.9). In addition, a negative correlation was noted between radiotracer dosage and viability during the 2-week period of follow-up. CONCLUSION: Cytotoxic effects of In on human stem cells is a time-dependent phenomenon and hence, assessment of the stem cell viability immediately after labeling (which is frequently made in clinical trials) is unable to detect adverse effects of this radiopharmaceutical on the integrity of stem cells. Even low doses of In-oxine are accompanied by significant cell loss in a 2-week period. Although it has been confirmed that nuclear medicine techniques are the most sensitive methods for stem cell tracking, we recommend that the application of this tracking technique should be treated with great reserve, and if necessary, as little of In-oxine as possible should be added to the cells (or only a limited portion of the cells should be labeled) to minimize cell death.

Final amended report on the safety assessment of oxyquinoline and oxyquinoline sulfate as used in cosmetics.

Oxyquinoline is a heterocyclic phenol and Oxyquinoline Sulfate is its salt, both of which are described as cosmetic biocides for use in cosmetic formulations. In an earlier Cosmetic Ingredient Review (CIR) safety assessment, the available data were found insufficient to support safety. Currently, some uses are reported to the Food and Drug Administration (FDA) by industry, but industry reports to CIR indicate no use. In Europe, Oxyquinoline and Oxyquinoline Sulfate are accepted for use as stabilizers for hydrogen peroxide in rinse-off and leave-on hair care preparations, with concentration limitations. Oxyquinoline is metabolized and excreted in the urine as glucuronides. Oxyquinoline and Oxyquinoline Sulfate exhibit little acute or subchronic toxicity in animal studies. A 100-mg dose of Oxyquinoline was only slightly irritating to the eye. Oxyquinoline and Oxyquinoline Sulfate were genotoxic in certain Salmonella typhimirium strains with metabolic activation and in a mouse lymphoma assay. There was some evidence of increased chromosome aberrations in an in vitro study, and an increase in sister-chromatid exchanges (but not chromosome aberrations) in rats treated with Oxyquinoline, but no genotoxicity was found in a Drosophilia sex-linked recessive lethal test, mouse bone marrow micronucleus test, a rat bone marrow and hepatocyte micronucleus test, and unscheduled DNA synthesis in rat hepatocytes. Oxyquinoline did bind to DNA in the presence of liver enzymes. Although the International Agency for Research on Cancer concluded that the existing evidence is inadequate to determine carcinogenicity in animals, Oxyquinoline was noncarcinogenic in several rodent feeding studies, and newly available studies using genetically altered mice, in one case carrying the human c-Ha-ras gene, demonstrated that Oxyquinoline was not carcinogenic. In clinical tests, Oxyquinoline is neither an irritant nor a sensitizer when tested at 1% in petrolatum. The available data demonstrate that Oxyquinoline and Oxyquinoline Sulfate are safe as stabilizers for hydrogen peroxide in rinse-off hair care cosmetic products in the present practices of use. For leave-on cosmetic products, however, the absence of impurities and ultraviolet (UV) absorption data resulted in a finding that the available data are insufficient to support safety. The data needed in order to complete the safety assessment of Oxyquinoline and Oxyquinoline Sulfate in leave-on cosmetic products are (1) UV absorption data -- if significant absorption occurs, then photoirritation/photosensitization data will be needed; and (2) data on impurities.

Unexpected pulmonary clumping of In-111 leukocytes attributable to indium oxine reagent.

Five cases of artifactual In-111 leukocyte pulmonary activity were noted at three local hospitals in a 4-day period. Based on the differences in the preparation of the final indium leukocyte product, the problem could be attributed to the indium oxine reagent in a specific lot. This artifact of multiple small foci of marked increased activity in the lungs (clumping pattern), attributable to the In-111 oxine reagent, has not been described previously.

[Allergies to 8-hydroxyquinoline derivatives]. / Allergien gegen 8-Hydroxychinolin-Derivate.

Evaluation of our standardized test results from 1972 to 1983 indicated Vioform allergies in 1.2% of all cases and Sterosan allergies in 1.1%. Our results are within the spectrum found in the literature for Vioform between 0.3 and 5.1% and for Sterosan between 0.3 and 3.7%. In the course of those 12 years we observed a growing tendency towards Vioform and Sterosan allergies on the basis of annual percentage figures. In the last year of our observation the frequency of Vioform and Sterosan allergies amounted to 1.7% each. We conclude, therefore, that inclusion of these two substances in the standard battery is justified. According to the pertinent literature, Sterosan and Vioform allergies are, on an average, 3 to 4 times more frequent in patients suffering from leg ulcers and/or chronic venous insufficiency than amongst eczema patients.

A study on the neurotoxicity of broxyquinoline and brobenzoxaldine combination in therapeutic doses.

The neurotoxicity of a combination of broxyquinoline and brobenzoxaldine (Intestopan Forte, containing 500 mg and 100 mg of the drugs respectively per capsule) was investigated by prospective clinical and electrophysiological studies in patients and volunteer subjects given the drugs in therapeutic doses (two capsules three times a day for 5 days). Of 16 patients with intestinal amoebiasis given the drugs (study A), 13 (81.25%) were cured. Adverse effects were mild and did not affect treatment. No neurological adverse effect was reported. Neurological examinations revealed no abnormality in any patient after treatment. Seven volunteer subjects underwent medical, neurological and ophthalmological examinations, and electrophysiological studies of ulnar and peroneal nerve conduction before and after treatment with the drugs in therapeutic doses (study B). Transient paresthesias were reported by one subject on the fourth day of treatment. No medical, neurological or ophthalmological abnormality was detected in any subject after treatment. There was no significant change in motor nerve conduction velocities. There was a significant (P less than 0.001) increase in the stimulus strength for distal ulnar stimulation and a significant (P less than 0.01) decrease in stimulus duration for proximal and distal ulnar stimulation. No significant changes were seen in the peroneal nerves in these parameters. No qualitative abnormality was seen in the oscilloscopic patterns of nerve conduction after treatment. Literature on the neurotoxicity of the halogenated hydroxyquinolines is reviewed. It is concluded that broxyquinoline and brobenzoxaldine (and probably other halogenated hydroxyquinolines as well) are safe and effective in therapeutic doses; neurotoxicity is unlikely to occur when these drugs are used according to therapeutic recommendations.