期刊：
International Journal of Mass Spectrometry,2012年309:133-140 ISSN：1387-3806
通讯作者：
Sun, Zhi-Liang
作者机构：
[Sun, Zhi-Liang; Yu, Chun-Hong; Liu, Zhao-Ying] Hunan Agr Univ, Coll Vet Med, Natl Res Ctr Engn & Technol Utilizat Bot Funct In, Biol Vet Drugs Branch, Changsha 410128, Hunan, Peoples R China.;[Wan, Leren] Shimadzu Int Trading Shanghai Co Ltd, Shanghai 200052, Peoples R China.
通讯机构：
[Sun, Zhi-Liang] H;Hunan Agr Univ, Coll Vet Med, Natl Res Ctr Engn & Technol Utilizat Bot Funct In, Biol Vet Drugs Branch, Changsha 410128, Hunan, Peoples R China.
关键词：
Trichothecenes;Ion trap/time-of-flight mass spectrometry;Accurate mass;Fragmentation
摘要：
Five trichothecenes, T-2 toxin, HT-2 toxin, deoxynivalenol (DON), 3-acetyl-DON (3-AcDON) and nivalenol (NIV), major class of mycotoxins produced by Fusarium, were investigated by electrospray hybrid ion trap/time-of-flight mass spectrometry (IT–TOF-MS). Fragmentation mechanisms are proposed based on the MS2 and MS3 experiments and accurate mass measurements. The sodium adduct ions [M+Na]+ of type-A trichothecenes, such as T-2 toxin and HT-2 toxin, were observed in the MS spectra. However, the [M−H]− ions of type-B trichothecenes, such as NIV, and 3-AcDON, were observed in the MS spectra. Eliminations of isovaleryloxy group and acetic acid were the common fragmentation pathways of T-2 toxin and HT-2 toxin. However, the cleavage of epoxy was the common fragmentation pathways of DON, 3-AcDON and NIV. The other fragmentation pathways were found to be dependent on the substitutent group. The data reported here may help to identify analogues of the trichothecenes that are commonly co-produced by Fusarium in cultures or naturally contaminated samples.
摘要：
In this study, the stress degradation of olaquindox under conditions of hydrolysis (neutral, acidic and basic), oxidation and photolytic stress was investigated. In order to characterize each degradation product, we developed a rapid, sensitive and reliable high-performance liquid chromatography combined with hybrid ion trap/time-of-flight mass spectrometry (LC/MS-IT-TOF) method. The degradation products formed under different forced conditions were separated using an ODS-C18 column with gradient elution. Multiple scans of degradation products in MS and MS/MS modes and accurate mass measurements were performed through data-dependent acquisition. The structural elucidations of degradation products were performed by comparing the changes in the accurate molecular masses and fragment ions generated from precursor ions with those of parent drug. The present results showed that maximum degradation was observed in hydrolysis, especially in the acidic condition. The drug was also degraded significantly under photolytic conditions. A total of 12 degradation products of olaquindox were detected and characterized using the developed method. The main degradation product was formed by the complete cleavage of side chain to form 3-methyl-2-hydroxylquinoxaline-4-oxide. A degradation pathway of olaquindox was also tentatively proposed for the first time based on these characterized structures. (C) 2011 Elsevier B.V. All rights reserved.
作者：
Liu, Z. -Y.;Dai, M. -H.;Tao, Y. -F.;Chen, D. -M.;Yuan, Z. -H.*
期刊：
Journal of Veterinary Pharmacology and Therapeutics,2011年34(5):424-429 ISSN：0140-7783
通讯作者：
Yuan, Z. -H.
作者机构：
[Liu, Z. -Y.] Huazhong Agr Univ, Coll Vet Med, MAO Key Lab Food Safety Evaluat, Natl Reference Lab Vet Drug Residues HZAU, Wuhan 430070, Hubei, Peoples R China.;[Liu, Z. -Y.] Hunan Agr Univ, Fac Vet, Changsha, Hunan, Peoples R China.;[Yuan, Z. -H.] Huazhong Agr Univ, Coll Vet Med, MAO Key Lab Food Safety Evaluat, Natl Reference Lab Vet Drug Residues HZAU, Shizishan St, Wuhan 430070, Hubei, Peoples R China.
通讯机构：
[Yuan, Z. -H.] H;Huazhong Agr Univ, Coll Vet Med, MAO Key Lab Food Safety Evaluat, Natl Reference Lab Vet Drug Residues HZAU, Shizishan St, Wuhan 430070, Hubei, Peoples R China.
摘要：
Liu, Z.‐Y., Dai, M.‐H., Tao, Y.‐F., Chen, D.‐M., Yuan, Z.‐H. Inhibition of cytochrome P450 2A participating in coumarin 7‐hydroxylation in pig liver microsomes. J. vet. Pharmacol. Therap. 34, 424–429. Five commonly used human cytochrome P450 (CYP) inhibitors were examined for their effects on coumarin 7‐hydroxylase (CYP2A) activity in pig liver microsomes. The K m and V max values for coumarin 7‐hydroxylation in pig liver microsomes were estimated to be 1 μm and 0.26 nmol·mg/min, respectively. The following human CYP inhibitors caused little or no inhibition of CYP2A as defined by a K i > 200 μm: quinidine (CYP2D6), troleandomycin (CYP3A4), and sulfaphenazole (CYP2C9). The other two human CYP inhibitors were classified as strong inhibitors of CYP2A: 8‐methoxypsoralen (CYP2A6) and α‐naphthoflavone (CYP1A1/2). In the absence of a preincubation period, 8‐MOP inhibited the 7‐hydroxylation of coumarin with a K i value of 1.1 μm, which decreased to 0.1 μm when 8‐MOP was preincubated with pig liver microsomes for 3 min. α‐Naphthoflavone inhibited the 7‐hydroxylation of coumarin with a K i value of 32 μm, which did not increase ability to inhibitor CYP2A when α‐naphthoflavone was preincubated with pig liver microsomes for 3 min. These results of this study suggest that 8‐MOP is a potent, mechanism‐based inhibitor of pig CYP2A activity in pig liver microsomes.
摘要：
Olaquindox is a growth-promoting feed additive for food-producing animals. Its toxicities were reported to be closely related to the metabolism. To provide the interpretation of toxicities in animals, this study explored the metabolism of olaquindox in rats, chickens and pigs of different genders by qualitative metabolite profiling. Animals were fed olaquindox in an oral dose, and then their urine, plasma, feces, liver, kidney and muscle were collected. Liquid chromatography combined with hybrid ion trap/time-of-flight mass spectrometry was used for structural investigation and identification of metabolites. The structures of metabolites were elucidated based on the accurate MS2 spectra and comparison of their changes in accurate molecular masses and fragment ions with those of parent drug or metabolite. A total of 18, 18 and 16 metabolites of rats, chickens and pigs were identified, respectively. Among the identified metabolites, 8 known metabolites were confirmed as an early study had stated, and 15 metabolites were found for the first time in vivo. The major metabolic pathways of olaquindox were proposed to be N-O reduction and oxidation of hydroxyl to carboxylic acid followed by N-O reduction. The qualitative species difference on the metabolite profiles of olaquindox among the three species was observed. However, metabolite profiles of olaquindox appeared to be qualitatively similar between female and male for the same species. The proposed metabolic pathways of olaquindox in animals will provide comprehensive data to clarify the metabolism of olaquindox among different species, and will give scientific explanation for toxicities and residues of olaquindox. (C) 2010 Elsevier Ireland Ltd. All rights reserved.
摘要：
Bisdesoxyolaquindox is a reduced metabolite of olaquindox which is used as a medicinal feed additive in veterinary medicine. The relevant metabolism studies of bisdesoxyolaquindox have been carried out for the first time in rat, chicken, and pig liver subcellular fractions in order to understand the metabolic enzymes that are possibly responsible for the metabolism of olaquindox. The metabolites were characterized by high-performance liquid chromatography combined with hybrid ion trap/time-of-flight mass spectrometry. The major metabolic pathways of bisdesoxyolaquindox in the three species were the oxidation of hydroxyl to bisdesoxyolaquindox-2'-carboxyl acid (O10) and the N-dealkylation of the side chain to 3-methylquinoxaline 2-carboxamide (O12). Other metabolic pathways were also proposed which involved the direct methyl oxidation and N-oxide on the quinoxaline ring in the three species as well as N-hydroxylation only in rat. The intrinsic clearance values in the liver microsomes for O10 and O12 were ranked in the order of chicken > pig >> rat and rat > pig >> chicken, respectively. Inhibition studies indicated that 8-methoxypsoralen, 4-methylpyrazole and alpha-naphthoflavone could inhibit the formations of O10 and O12 in all species. Quinidine, troleandomycin, diethyldithiocarbamate, and disulfiram showed an interspecies difference in the inhibition of the formation of two metabolites. In rat and pig liver cytosol, 4-methylpyrazole, menadione and chlorpromazine strongly inhibited the formation of O10. Both diethyldithiocarbamate and disulfiram were found to inhibit O10 formation in rat cytosol but not in pig cytosol. These results indicated the following: In rat liver microsomes. CYP2A might be involved in the formation of O10, and CYP1A, CYP2A and CYP2E would be involved in the O12 formation. In pig liver microsomes, CYP1A and CYP2E might catalyze the formations of O10 and O12. In rat cytosol, alcohol dehydrogenase, aldehyde oxidase and aldehyde dehydrogenase should catalyze the O10 formation. In pig cytosol, alcohol dehydrogenase and aldehyde oxidase might be involved in the formation of O10. In chicken, it was found that various CYP isoenzymes were capable of catalyzing the two reactions: none of the inhibitors of cytosol enzymes inhibited O10 formation in chicken cytosol. (C) 2010 Elsevier Ireland Ltd. All rights reserved.
摘要：
Mequindox (MEQ) is a novel synthetic quinoxaline 1,4-dioxides antibacterial agent and growth promoter in animal husbandry. This study was to investigate whether reactive oxygen species (ROS), the Janus kinase-signal transducer and activator of transcription (JAK/STAT) pathway, suppressors of cytokine signaling (SOCS) and inflammatory cytokines were involved in toxicities of MEQ Our data demonstrated that high dose of MEQ (275 mg/kg) apparently led to tissue impairment combined with imbalance of redox in liver. In liver and spleen samples, hydroxylation metabolites and desoxymequindox were detected, directly confirming the potential link of N -> O group reduction metabolism with its organ toxicity. Moreover, up-regulation of JAK/STAT, SOCS family, tumor necrosis factor (TNF-alpha) and interleukin-6 (IL-6) were also observed in the high-dose group. Meanwhile, significant changes of oxidative stress indices in liver were observed in the high-dose group. As for NADPH subunit, the mRNA levels of many subunits were significantly up-regulated at low doses but down-regulated in a dose-dependent manner in liver and spleen, suggesting an involvement of NADPH in MEQ metabolism and ROS generation. In conclusion, we reported the dose-dependent long-term toxicity as well as the discussion of the potential mechanism and pathways of MEQ which raised further awareness of its toxicity following with the dose change. (C) 2010 Elsevier Ireland Ltd. All rights reserved.
期刊：
Rapid Communications in Mass Spectrometry,2011年25(2):341-348 ISSN：0951-4198
通讯作者：
Yuan, Zong-Hui
作者机构：
[Chen, Dong-Mei; Wang, Xu; Liu, Zhao-Ying; Yuan, Zong-Hui; Tao, Yan-Fei] Huazhong Agr Univ, Coll Vet Med, HZAU MAO Key Lab Food Safety Evaluat, Natl Reference Lab Vet Drug Residues, Wuhan 430070, Hubei, Peoples R China.;[Liu, Zhao-Ying] Hunan Agr Univ, Fac Vet, Changsha 410128, Hunan, Peoples R China.;[Yuan, Zong-Hui] Huazhong Agr Univ, Coll Vet Med, HZAU MAO Key Lab Food Safety Evaluat, Natl Reference Lab Vet Drug Residues, Shizishan St, Wuhan 430070, Hubei, Peoples R China.
通讯机构：
[Yuan, Zong-Hui] H;Huazhong Agr Univ, Coll Vet Med, HZAU MAO Key Lab Food Safety Evaluat, Natl Reference Lab Vet Drug Residues, Shizishan St, Wuhan 430070, Hubei, Peoples R China.
摘要：
Carbadox (methyl-3-(2-quinoxalinylmethylene)-carbazate-N-1, N-4-dioxide) is a chemotherapeutic growth promoter added to feed for starter pigs. In this work, the metabolism of carbadox in rat, pig and chicken liver microsomes has been studied firstly. The incubation mixtures were then processed and analyzed for metabolites with a sensitive and reliable method based on high-performance liquid chromatography combined with hybrid ion trap/time-of-flight mass spectrometry (LC/MS-IT-TOF). With the help of chromatographic behavior and accurate mass measurements, it is possible to rapidly and reliably characterize the metabolites of carbadox. The structural elucidations of these metabolites were performed by comparing the changes in the accurate molecular masses and fragment ions generated from precursor ions with those of parent drug. The present results showed that the metabolism of carbadox in liver microsomes had qualitative species-difference. A total of seven metabolites were identified in rat liver microsomes. Five metabolites (Cb1-Cb3, Cb5, Cb7) were observed in pig and chicken liver microsomes. In addition, metabolite Cb6 was also detected in chicken liver microsomes. The peak areas of the metabolites in the three species are different. For the formations of Cb1, Cb2, Cb5 and Cb6, the rank order was rat>chicken>pig; Cb3; pig similar to chicken>rat. Cb1, Cb2 and Cb3 have been previously reported, whereas the other four metabolites were novel. The N -> O group reduction and hydroxylation followed by N -> O group reduction were the main metabolic pathways for carbadox in the three species. Copyright (C) 2010 John Wiley & Sons, Ltd.
期刊：
Toxicology and Applied Pharmacology,2011年252(3):281-288 ISSN：0041-008X
通讯作者：
Yuan, Zonghui
作者机构：
[Wang, Yulian; Li, Tingting; Wang, Xu; Liu, Zhaoying; Liu, Yu; Ihsan, Awais; Yu, Huan; Yuan, Zonghui; Zhang, Hongfei; Yang, Chunhui; Huang, Xianju] Huazhong Agr Univ, Natl Reference Lab Vet Drug Residues, Wuhan 430070, Peoples R China.;[Yuan, Zonghui] Huazhong Agr Univ, Natl Reference Lab Vet Drug Residues HZAU, MOA Key Lab Food Safety Evaluat, Wuhan 430070, Peoples R China.;[Liu, Zhaoying] Hunan Agr Univ, Coll Vet Med, Changsha 410128, Hunan, Peoples R China.;[Huang, Xianju] S Cent Univ Nationalities, Coll Pharm, Wuhan 430074, Peoples R China.
通讯机构：
[Yuan, Zonghui] H;Huazhong Agr Univ, Natl Reference Lab Vet Drug Residues HZAU, MOA Key Lab Food Safety Evaluat, Wuhan 430070, Peoples R China.
关键词：
DNA damage;Mequindox;Oxidative stress;Quinoxaline;Rats;Testis;Testosterone;8-hydroxydeoxyguanosine (8-OHdG)
摘要：
Mequindox (MEQ) is a synthetic antimicrobial chemical of quinoxaline 1, 4-dioxide group. This study was designed to investigate the hypothesis that MEQ exerts testicular toxicity by causing oxidative stress and steroidal gene expression profiles and determine mechanism of MEQ testicular toxicity. In this study, adult male Wistar rats were fed with MEQ for 180 days at five different doses as 0, 25, 55, 110 and 275 mg/kg, respectively. In comparison to control, superoxide dismutase (SOD), reduced glutathione (GSH) and 8-hydroxydeoxyguanosine (8-OHdG) levels were elevated at 110 and 275 mg/kg MEQ whereas the malondialdehyde (MDA) level was slightly increase at only 275 mg/kg. Furthermore, in LC/MS-IT-TOF analysis, one metabolite 2-isoethanol 4-desoxymequindox (M11) was found in the testis. There was significant decrease in body weight, testicular weight and testosterone at 275 mg/kg, serum follicular stimulating hormone (FSH) at 110 and 275 mg/kg, while lutinizing hormone (LH) levels were elevated at 110 mg/kg. Moreover, histopathology of testis exhibited germ cell depletion, contraction of seminiferous tubules and disorganization of the tubular contents of testis. Compared with control, mRNA expression of StAR, P450scc and 17 beta-HSD in testis was significantly decreased after exposure of 275 mg/kg MEQ while AR and 3 beta-HSD mRNA expression were significantly elevated at the 110 mg/kg MEQ group. Taken together, our findings provide the first and direct evidence in vivo for the formation of free radicals during the MEQ metabolism through N -> O group reduction, which may have implications to understand the possible mechanism of male infertility related to quinoxaline derivatives. (C) 2011 Elsevier Inc. All rights reserved.
