quinocetone and olaquindox

The aim of this article is to get an overview of the metabolism of quinoxaline 1,4-di-N-oxides (QdNOs) used in food animals. The derivatives of QdNOs (carbadox, olaquindox, mequindox, quinocetone, and cyadox) are the potent synthetic antimicrobial agents that are used for improving the feed efficiency and controlling dysentery in food-producing animals. Studies have demonstrated that the toxicity of QdNOs is closely associated with the production of their metabolism, especially with the production of their reduced metabolites. To the best of our knowledge, no one has systematically compiled the metabolism data of QdNOs. Therefore, the metabolism of QdNOs in animals has been discussed in the review for the first time. These drugs undergo extensive metabolism prior to excretion. N-oxide group reduction is the major metabolic pathway of QdNOs. Moreover, the N1- and N4-oxide reductions of QdNOs by different reducing mechanisms are also described. Obvious differences in metabolic pathways for QdNOs were observed owing to the differences on the side chain of these drugs. Therefore, understanding the metabolic pathways of QdNOs in animals will provide the guides for further studies of metabolism and toxicology of these drugs, and will also provide abundant information for the food safety assessment.

Topics: Animals; Carbadox; Humans; Quinoxalines

Quinocetone (QCT) and Cyadox (CYA) are important derivative of heterocyclic N-oxide quinoxaline (QdNO), used actively as antimicrobial feed additives in China. Here, we tested and compared the genotoxic potential of QCT and CYA with olaquindox (OLA) in Ames test, HGPRT gene mutation (HGM) test in V79 cells, unscheduled DNA synthesis (UDS) assay in human peripheral lymphocytes, chromosome aberration (CA) test, and micronucleus (MN) test in mice bone marrow. OLA was found genotoxic in all 5 assays. In Ames test, QCT produced His(+) mutants at 6.9 μg/plate in Salmonella typhimurium TA 97, at 18.2 μg/plate in TA 100, TA 1535, TA 1537, and at 50 μg/plate in TA 98. CYA produced His(+) mutants at 18.2 μg/plate in TA 97, TA 1535, and at 50 μg/plate in TA 98, TA 100 and TA 1537. QCT was found positive in HGM and UDS assay at concentrations ≥10 μg/ml while negative results were reported in CA test and MN test. Collectively, we found that OLA was more genotoxic than QCT and CYA. Genotoxicity of QCT was found at higher concentration levels in Ames test, HGM and UDS assays while CYA showed weak mutagenic potential to bacterial cells in Ames test.

Topics: Animals; Anti-Infective Agents; Bone Marrow Cells; Cell Line; Cells, Cultured; Cricetinae; Cricetulus; DNA Replication; Dose-Response Relationship, Drug; Humans; Lymphocytes; Male; Mice; Mice, Inbred Strains; Micronuclei, Chromosome-Defective; Mutagens; Mutation; Quinoxalines; Random Allocation; Salmonella typhimurium

Olaquindox, one of the antimicrobial growth accelerants, is usually used as a feed additive in livestock production to improve feed efficiency. Due to health concerns over possible carcinogenic, mutagenic and photoallergenic effects of olaquindox on animals, the development of a simple, rapid and sensitive analytical method for determination of olaquindox is crucial and necessary.. In this paper, a novel and hydrophilic functionalised material of olaquindox-imprinted polymer was synthesised in aqueous solution by a surface molecular imprinting in combination with a sol-gel process. This imprinted material was characterised by Fourier transform infrared, scanning electron microscopy, and static and kinetic adsorption experiments, and results showed that it had good recognition and selective ability, and fast adsorption-desorption dynamics for olaquindox. Applying the prepared material as sorbent, a method of molecularly imprinted solid-phase extraction (MISPE) for separation and analysis of olaquindox residues in feeds coupled with HPLC was presented. Under the selected MISPE condition, the detection limit (S/N = 3) for olaquindox was 68.0 ng L(-1), the RSD for five replicate extractions of 50 µg L(-1) olaquindox was 9.8%. The blank chick feed samples spiked with olaquindox at 0.0025 and 0.010 mg g(-1) levels were extracted and determined by the developed method, with recoveries ranging from 90% to 96%.. This method was applied for enrichment and analysis of olaquindox in animal feed samples with good accuracy and repeatability. This study will provide a sensitive and fast method for the monitoring of olaquindox residues in foods.

Topics: Adsorption; Animal Feed; Animals; Anti-Infective Agents; Chickens; Chromatography, High Pressure Liquid; Food Additives; Gels; Kinetics; Limit of Detection; Microscopy, Electron, Scanning; Molecular Imprinting; Phase Transition; Polymers; Quinoxalines; Reproducibility of Results; Solid Phase Microextraction; Spectroscopy, Fourier Transform Infrared

To provide a detailed toxicity with wide spectrum of doses for quinocetone, a new antimicrobial growth promoting agent, acute and sub-chronic toxicological studies were conducted. For acute study, quinocetone was administered singly by oral gavage to Wistar rats and Kunming mice. Calculated LD50 was 8687.31 mg/kg b.w./day in rats and 15848.93 mg/kg b.w./day in mice. In sub-chronic study, quinocetone was fed to Wistar rats at dietary levels of 0, 50, 300 and 1800 mg/kg or olaquindox (300 mg/kg), approximately equivalent to quinocetone 5, 30, 180 or olaquindox 30 mg/kg b.w./day. There was significant decrease in body weight in both genders, total protein and creatinine in females and alkaline phosphatase in males fed with 1800 mg/kg diet, while alkaline aminotransferase values decreased in all treated groups. Significant increase in relative weights of liver and kidneys in both genders and testis in male rats were noted at 1800 mg/kg diet. Histopathological observations revealed that 1800 mg/kg quinocetone diet and 300 mg/kg olaquindox diet could induce proliferation of bile canaliculi in the portal area. In conclusion, quinocetone can induce hepatic histological changes as well as leaking of different serum enzymes. The no-observed-adverse-effect level of quinocetone was considered to be 300 mg/kg diet.

Topics: Animals; Blood Chemical Analysis; Body Weight; Diet; Dose-Response Relationship, Drug; Female; Kidney; Lethal Dose 50; Liver; Male; Mice; No-Observed-Adverse-Effect Level; Quinoxalines; Rats; Rats, Wistar; Time Factors; Toxicity Tests; Toxicity Tests, Acute

Quinoxaline-1,4-dioxides derivatives have been widely used as animal growth promoter. This study was conducted to investigate the cytotoxicity and genotoxicity of quinoxaline-1,4-dioxides derivatives, namely carbadox, olaquindox and quinocetone, in Vero cells. The cell viability results from MTT assay demonstrated the severe inhibitory effects by these chemicals in both dose and time dependent manner. Among these chemicals quinocetone exhibited the highest cytotoxicity followed by olaquindox and carbadox. DNA damage analyses using alkalic comet assay revealed pronounced increase of DNA fragmentation in all three compound treated cells. In contrast, DNA damage was significantly decreased after incubation with S9 mix. These findings suggest that the intermediate metabolites of these compounds exerted lower genotoxicity than their parent drugs. We further described chromosomal damage induced by these drugs employing cytokinesis-block micronucleus assay (MN assays). The micronucleus frequency was significantly higher in these drugs treated cells than that of controls and the nuclear division index was also markedly reduced with increasing drug concentration applied. Similar to the observation in comet assay, incorporation of S9 mix in the MN assays was able to markedly alleviate the chromosome damage. In conclusion, our results strengthened previous reports on the cytotoxicity and genotoxicity of carbadox, olaquindox and quinocetone.

Topics: Animals; Carbadox; Cell Survival; Chlorocebus aethiops; Comet Assay; DNA; DNA Damage; Dose-Response Relationship, Drug; Formazans; Micronuclei, Chromosome-Defective; Micronucleus Tests; Microsomes, Liver; Mitosis; Mutagens; Quinoxalines; Tetrazolium Salts; Vero Cells