Evaluation of microbial testing methods for the mutagenicity of quinoline and its derivatives

Scientific opinion on flavouring group evaluation 77, revision 3 (FGE.77Rev3): consideration of pyridine, pyrrole and quinoline derivatives evaluated by JECFA (63rd meeting) structurally related to pyridine, pyrrole, indole and quinoline derivatives evaluated by EFSA in FGE.24Rev2

The Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids of the EFSA was requested to consider evaluations of flavouring substances assessed since 2000 by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and to decide whether further evaluation is necessary, as laid down in Commission Regulation (EC) No 1565/2000. The present consideration concerns a group of 22 pyridine, pyrrole and quinoline derivatives evaluated by JECFA (63rd meeting). The revision of this consideration is made since additional genotoxicity data have become available for 6-methylquinoline [FL-no: 14.042]. The genotoxicity data available rule out the concern with respect to genotoxicity and accordingly the substance is evaluated through the Procedure. For all 22 substances [FL-no: 13.134, 14.001, 14.004, 14.007, 14.030, 14.038, 14.039, 14.041, 14.042, 14.045, 14.046, 14.047, 14.058, 14.059, 14.060, 14.061, 14.065, 14.066, 14.068, 14.071, 14.072 and 14.164] considered in this Flavouring Group Evaluation (FGE), the Panel agrees with the JECFA conclusion, 'No safety concern at estimated levels of intake as flavouring substances' based on the Maximised Survey-derived Daily Intake (MSDI) approach. Besides the safety assessment of these flavouring substances, the specifications for the materials of commerce have also been evaluated, and the information is considered adequate for all the substances. For the following substances [FL-no: 13.134, 14.001, 14.030, 14.041, 14.042, 14.058, 14.072], the Industry has submitted use levels for normal and maximum use. For the remaining 15 substances, use levels are needed to calculate the modified Theoretical Added Maximum Daily Intakes (mTAMDIs) in order to identify those flavouring substances that need more refined exposure assessment and to finalise the evaluation.

A Novel Strategy to Predict Carcinogenicity of Antiparasitics Based on a Combination of DNA Lesions and Bacterial Mutagenicity Tests

Genotoxicity and carcinogenicity testing of pharmaceuticals prior to commercialization is requested by regulatory agencies. The bacterial mutagenicity test was considered having the highest accuracy of carcinogenic prediction. However, some evidences suggest that it always results in false-positive responses when the bacterial mutagenicity test is used to predict carcinogenicity. Along with major changes made to the International Committee on Harmonization guidance on genotoxicity testing [S2 (R1)], the old data (especially the cytotgenetic data) may not meet current guidelines. This review provides a compendium of retrievable results of genotoxicity and animal carcinogenicity of 136 antiparasitics. Neither genotoxicity nor carcinogenicity data is available for 84 (61.8%), while 52 (38.2%) have been evaluated in at least one genotoxicity or carcinogenicity study, and only 20 (14.7%) in both genotoxicity and carcinogenicity studies. Among 33 antiparasitics with at least one old result in in vitro genotoxicity, 15 (45.5%) are in agreement with the current ICH S2 (R1) guidance for data acceptance. Compared with other genotoxicity assays, the DNA lesions can significantly increase the accuracy of prediction of carcinogenicity. Together, a combination of DNA lesion and bacterial tests is a more accurate way to predict carcinogenicity.

Final Report on the Safety Assessment of Oxyquinoline and Oxyquinoline Sulfate

Oxyquinoline is a heterocyclic phenol which is used as a fungicide and bactericide in cosmetic formulations at concentrations at, or less than 1.0%. Oxyquinoline is metabolized and excreted in the urine as glucuronides. The acute oral LD50 toxicity in rats was 1.2 g/kg. In subchronic studies, no deaths occurred in male and female rats at 5 doses up to 12,000 ppm or in male and female mice up to doses of 6000 ppm. Solid 100% Oxyquinoline was mildly irritating to rabbit skin and a 100 mg dose of Oxyquinoline was only slightly irritating to the eye. No sensitization test data were available for either of these cosmetic ingredients. Oxyquinoline and Oxyquinoline Sulfate were mutagenic when assayed using the Ames procedure with metabolic activation. Mutagenic activity was also demonstrated in the mouse lymphoma assay. Oxyquinoline was noncarcinogenic in several oral rodent feeding studies. The data from this negative oral carcinogenic assay were judged to be insufficient to evaluate the safety of use of Oxyquinoline and Oxyquinoline Sulfate when cosmetic products containing these ingredients are applied to the skin.

It is concluded that the available carcinogenicity and sensitization test data are insufficient to support a conclusion on the safety of Oxyquinoline and Oxyquinoline Sulfate as used in cosmetic products.

Transformation of Contaminant Candidate List (CCL3) compounds during ozonation and advanced oxidation processes in drinking water: Assessment of biological effects

The removal of emerging contaminants during water treatment is a current issue and various technologies are being explored. These include UV- and ozone-based advanced oxidation processes (AOPs). In this study, AOPs were explored for their degradation capabilities of 25 chemical contaminants on the US Environmental Protection Agency's Contaminant Candidate List 3 (CCL3) in drinking water. Twenty-three of these were found to be amenable to hydroxyl radical-based treatment, with second-order rate constants for their reactions with hydroxyl radicals (OH) in the range of 3-8 × 10(9) M(-1) s(-1). The development of biological activity of the contaminants, focusing on mutagenicity and estrogenicity, was followed in parallel with their degradation using the Ames and YES bioassays to detect potential changes in biological effects during oxidative treatment. The majority of treatment cases resulted in a loss of biological activity upon oxidation of the parent compounds without generation of any form of estrogenicity or mutagenicity. However, an increase in mutagenic activity was detected by oxidative transformation of the following CCL3 parent compounds: nitrobenzene (OH, UV photolysis), quinoline (OH, ozone), methamidophos (OH), N-nitrosopyrolidine (OH), N-nitrosodi-n-propylamine (OH), aniline (UV photolysis), and N-nitrosodiphenylamine (UV photolysis). Only one case of formation of estrogenic activity was observed, namely, for the oxidation of quinoline by OH. Overall, this study provides fundamental and practical information on AOP-based treatment of specific compounds of concern and represents a framework for evaluating the performance of transformation-based treatment processes.

Accelerated degradation of exogenous indole by Burkholderia unamae strain CK43B exposed to pyrogallol-type polyphenols

In modified Winogradsky's (MW) medium supplemented with excessive indole (1), Burkholderia unamae strain CK43B isolated from polyphenol-rich Shorea rhizosphere showed almost no cell growth, but it showed drastic cell growth given further supplementation of gallic acid, a simple plant polyphenol. This active cell growth of B. unamae CK43B was due to the stimulating effect of gallic acid on 1-degradation of bacterial cells, which acquired a nitrogen source in 1. Under aerobic culture conditions with appropriate concentrations (0.5-2.0 mM) of gallic acid, B. unamae CK43B started to decompose exogenous 1 in a dose-dependent manner, and finally accumulated catechol (5) via anthranilic acid (4). Pyrogallol also showed a cometabolic effect on decarboxylation-coupled oxidative deamination of B. unamae CK43B, producing 5 from 4, as gallic acid did. These results suggest that pyrogallol-type plant polyphenols act as stimulators on B. unamae CK43B, causing it to degrade an N-heterocyclic aromatic compound (NHAC) including nitrogen-containing humic substances.

Studies on genotoxicity and carcinogenicity of antibacterial, antiviral, antimalarial and antifungal drugs

This review provides a compendium of retrievable results of genotoxicity and animal carcinogenicity studies performed of antibacterial, antiviral, antimalarial and antifungal drugs of long-term or intermittent frequent use. Of the 48 drugs considered, 9 (18.75%) do not have retrievable data, whereas the other 39 (81.25%) have at least one genotoxicity or carcinogenicity tests result. Of these 39 drugs, 24 tested positive in at least one genotoxicity assay and 19 in at least one carcinogenicity assay; 14 of them gave a positive response in both at least one genotoxicity assay and at least one carcinogenicity assay. Concerning the predictivity of genetic toxicology findings for the results of long-term carcinogenesis assays, of 23 drugs with both genotoxicity and carcinogenicity data: 2 (8.7%) were neither genotoxic nor carcinogenic, 2 (8.7%) tested positive in at least one genotoxicity assay but were non-carcinogenic, 4 (17.4%) tested negative in genotoxicity assays but were carcinogenic, and 15 (65.2%) gave a positive response in at least one genotoxicity assay and in at least one carcinogenicity assay. Only 18 (37.5%) of the 48 drugs examined had all data required by present guidelines for testing of pharmaceuticals, but a fraction of them (49%) were developed and marketed prior to the present regulatory climate. In the absence of compelling indications, the prescription of the 19 drugs that are animal carcinogens should be avoided.

Detection of methylquinoline transformation products in microcosm experiments and in tar oil contaminated groundwater using LC-NMR

N-heterocyclic compounds are known pollutants at tar oil contaminated sites. Here we report the degradation of methyl-, and hydroxy-methyl-substituted quinolines under nitrate-, sulfate- and iron-reducing conditions in microcosms with aquifer material of a former coke manufacturing site. Comparison of degradation potential and rate under different redox conditions revealed highest degradation activities under sulfate-reducing conditions, the prevailing conditions in the field. Metabolites of methylquinolines, with the exception of 2-methylquinolines, were formed in high amounts in the microcosms and could be identified by (1)H NMR spectroscopy as 2(1H)-quinolinone analogues. 4-Methyl-, 6-methyl-, and 7-methyl-3,4-dihydro-2(1H)-quinolinone, the hydrogenated metabolites in the degradation of quinoline compounds, were identified by high resolution LC-MS. Metabolites of methylquinolines showed persistence, although for the first time a transformation of 4-methylquinoline and its metabolite 4-methyl-2(1H)-quinolinone is described. The relevance of the identified metabolites is supported by the detection of a broad spectrum of them in groundwater of the field site using LC-NMR technique. LC-NMR allowed the differentiation of isomers and identification without reference compounds. A variety of methylated 2(1H)-quinolinones, as well as methyl-3,4-dihydro-2(1H)-quinolinone isomers were not identified before in groundwater.

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.

Role of reactive oxygen species in cupric 8-quinolinoxide-induced genotoxic effect

This study demonstrates that cupric 8-quinolinoxide (CuQ) has induced genetic toxicity in bacteria and mammalian cells through a mechanism of reactive oxygen species (ROS) generation. In the Ames test with rat liver S9, CuQ dose-dependently caused a point mutation in Salmonella typhimurium TA100. The effect of CuQ on DNA damage in HL60 and V79 cells identified in the comet assay is direct and enhanced by the addition of S9. Meanwhile, the tailing length of comet DNA is related to the increasing dosage of CuQ. The genotoxic effect of CuQ on either gene mutation in bacteria or DNA damage in culture cells can be generally blocked by several antioxidants, e.g. pyrrolidinedithiocarbamate, N-acetylcysteine, Vitamins C and E. Supportive of this observation, ROS generation induced by CuQ can be demonstrated both in vitro and in vivo by using the DCFH-DA fluoroprobe. The CuQ-induced intracellular ROS level is also dramatically inhibited by the above antioxidants. Above results imply that the CuQ-induced genotoxicity could be mediated by ROS generation. The nature of ferrous-dependent and S9-enhancing in CuQ-induced ROS generation hints a Fenton-like reaction or some specific enzymes activation could be involved in this process. Furthermore, a DNA damage- and oxidative stress-dependent protein, P53, could also been induced by CuQ treatments in a time-course and dose-dependent manners. Its expression level is recoverable by antioxidants too. In conclusion, our current study strongly suggests that CuQ induces gene mutation, global DNA damage, and P53 expression through a ROS-dependent mechanism.

Mutagenic evaluation of primaquine, pentaquine and pamaquine in the Salmonella/mammalian microsome assay

The 8-aminoquinolines, primaquine, pentaquine and pamaquine, were investigated for mutagenic activity in Salmonella typhimurium strains TA100, TA98, TA97 and TA102 in the rat liver microsomal activation system. Primaquine and pentaquine induced mutations in TA97 in the presence and absence of S9 mix. Pamaquine was mutagenic to TA98 only in the absence of S9 mix.

Microbial metabolism of quinoline and related compounds. XVII. Degradation of 3-methylquinoline by Comamonas testosteroni 63

A bacterial strain which utilizes 3-methylquinoline as sole source of carbon, nitrogen and energy was isolated from activated sludge. On the basis of its morphological and physiological characteristics, this isolate was classified as Comamonas testosteroni. Four metabolites of 3-methylquinoline degradation were isolated from the culture supernatant and identified as 3-methyl-2-oxo-1,2-dihydroquinoline, 6-hydroxy-3-methyl-2-oxo-1,2-dihydroquinoline, 5,6-dihydroxy-3-methyl-2-oxo-1,2-dihydroquinoline and 2,5,6-trihydroxy-3-methylpyridine. Based on these results, a degradation pathway for 3-methylquinoline is proposed.

Mutagenicity of quinolines in Salmonella typhimurium TA100. A QSAR study based on hydrophobicity and molecular orbital determinants

The mutagenicity of 33 quinolines in the Salmonella test using TA98 and TA100 cells has been reported. Significant activity was found only with TA100 cells. Quantitative structure-activity relationships (QSAR) could be formulated using molecular orbital parameters or Hammett constants and hydrophobic parameters for those compounds with substituents in the 6, 7 and 8 positions. The QSAR points to the 2-position on the quinoline ring as being the site for activation by S9 oxidation.

Methemoglobinogenic potential of primaquine and its mutagenicity in the Ames test

Single doses of primaquine did not produce methemoglobinemia in beagle bitches. Repeated daily administration for 12 days produced a gradually rising level of methemoglobin over that time period, unaccompanied by depletion of erythrocytic reduced glutathione. Primaquine was mutagenic in the Ames test in Salmonella typhimurium strain TA 1537, with or without S9, using a liquid preincubation assay. Primaquine was non-mutagenic in this assay to strains TA 1535, TA 1538, TA 98 and TA 100, regardless of the presence or absence of S9. In the standard overpour Ames test, the drug was non-mutagenic in all 5 Salmonella strains, both with and without S9 metabolic activation.