Liu Zhaoying, Huang Lingli, Dai Menghong, Chen Dongmei, Tao Yanfei, Wang Yulian, Yuan Zonghui
National Reference Laboratory of Veterinary Drug Residues (HZAU)/MAO Key Laboratory of Food Safety Evaluation, Huazhong Agricultural University, Wuhan 430070, PR China.
Rapid Commun Mass Spectrom. 2009 Jul;23(13):2026-34. doi: 10.1002/rcm.4106.
Cyadox (CYX), (2-formylquinoxaline)-N(1),N(4)-dioxide cyanoacetylhydrazone, is a growth promoter, which is more efficient and less toxic to animals. Few studies have been performed to reveal the metabolism of CYX in animals till now. In this study, the metabolic fate of CYX in the liver microsomes of animal was investigated firstly using high-performance liquid chromatography combined with hybrid ion trap/time-of-flight mass spectrometry. CYX was incubated with rat, chicken and pig liver microsomes in the presence of a NADPH-generating system. Multiple scans of metabolites in MS and MS(2) modes and accurate mass measurements were performed simultaneously through data-dependent acquisition. Most measured mass errors were less than 10 ppm for both protonated molecules and fragment ions using external mass calibration. The structures of metabolites and their fragment ions were easily and reliably characterized based on the accurate MS(2) spectra and known structure of CYX. The relative biotransformation of CYX into characterized metabolites was estimated based on the UV absorption and the assumption that all metabolites had the same extinction coefficient as the parent compound at 305 nm. Totally, seven metabolites were identified as three reduced metabolites (cyadox 1-monoxide (Cy1), cyadox 4-monoxide (Cy2) and bisdesoxycyadox (Cy4)), three hydrolysis metabolites of the amide bond (N-decyanoacetyl cyadox (Cy5), N-decyanoacetyl cyadox 1-monoxide (Cy6) and N-decyanoacetyl bisdesoxycyadox (Cy7)) and a hydroxylation metabolite of Cy1 (Cy3). Cy1-Cy6 could be detected in rat, chicken and pig liver microsomes while metabolite Cy7 could only be observed in pig. The amounts of the metabolites in three species are different. For the formations of Cy1 and Cy3, the rank order was rat approximately chicken > pig. For Cy4 and Cy5, the order was pig > rat > chicken. Cy1 and Cy4 have been previously reported, whereas the other five metabolites were novel. The N-->O group reduction and hydroxylation were the main metabolic pathways for CYX in the three species.
喹赛多（CYX），即（2-甲酰基喹喔啉）-N(1),N(4)-二氧化物氰基乙酰腙，是一种生长促进剂，对动物更高效且毒性更低。到目前为止，很少有研究揭示CYX在动物体内的代谢情况。在本研究中，首先采用高效液相色谱结合混合离子阱/飞行时间质谱法研究了CYX在动物肝脏微粒体中的代谢命运。CYX在有NADPH生成系统存在的情况下与大鼠、鸡和猪肝微粒体一起孵育。通过数据依赖采集同时在MS和MS(2)模式下对代谢物进行多次扫描并进行精确质量测量。使用外部质量校准，对于质子化分子和碎片离子，大多数测量的质量误差小于10 ppm。基于精确的MS(2)光谱和CYX的已知结构，代谢物及其碎片离子的结构易于且可靠地表征。基于紫外吸收以及所有代谢物在305 nm处与母体化合物具有相同消光系数的假设，估计了CYX向已表征代谢物的相对生物转化。总共鉴定出七种代谢物，分别为三种还原代谢物（喹赛多1-氧化物（Cy1）、喹赛多4-氧化物（Cy2）和双去氧喹赛多（Cy4））、三种酰胺键水解代谢物（N-去氰基乙酰喹赛多（Cy5）、N-去氰基乙酰喹赛多1-氧化物（Cy6）和N-去氰基乙酰双去氧喹赛多（Cy7））以及Cy1的一种羟基化代谢物（Cy3）。Cy1 - Cy6可在大鼠、鸡和猪肝微粒体中检测到，而代谢物Cy7仅在猪中观察到。三种物种中代谢物的量不同。对于Cy1和Cy3的形成，顺序为大鼠≈鸡＞猪。对于Cy4和Cy5，顺序为猪＞大鼠＞鸡。Cy1和Cy4先前已有报道，而其他五种代谢物是新发现的。N→O基团还原和羟基化是CYX在这三种物种中的主要代谢途径。
