Foster A, Fitzsimmons B, Rokach J, Letts G
Department of Pharmacology and Medicinal Chemistry, Merck Frosst Canada Inc., Pointe Claire-Dorval, Québec.
Biochem Biophys Res Commun. 1987 Nov 13;148(3):1237-45. doi: 10.1016/s0006-291x(87)80265-6.
In a previous study in our laboratory it was observed that after [3H] LTC4 administration (luCi/kg i.v.) to the anesthetized rat, significant amounts of injected radioactivity (approximately 25%) were associated with previously unidentified biliary polar metabolite(s). In the present study we describe the isolation and characterization of the predominant polar metabolite. Rats were injected with synthetic LTC4 (20 microgram/kg i.v.) and bile collected over 30 min. After extraction and purification (2 step RP-HPLC procedure), the retention time of the metabolite was compared (plus coinjections) and found to be identical with synthetic 20-CO2H N-Ac LTE4 in two RP-HPLC systems. Also, the UV spectrum of the biologically derived metabolite was compared and found identical to the synthetic material, giving a characteristic conjugated triene absorption in the UV with a max of 281 nm and shoulders at 270 and 290 nm. Further, the trimethyl ester derivative of the metabolite showed identical chromatographic behaviors in 2 reverse and 2 normal phase HPLC systems compared with synthetic 20-CO2H N-Ac LTE4 trimethyl ester. We conclude omega-oxidation of peptide leukotrienes occurs in the rat and that 20-CO2H N-Ac LTE4 is an in vivo product of LTC4 metabolism.
在我们实验室先前的一项研究中观察到，给麻醉大鼠静脉注射[3H]LTC4（每千克体重注射1微居里）后，大量注入的放射性物质（约25%）与先前未鉴定的胆汁极性代谢物有关。在本研究中，我们描述了主要极性代谢物的分离和特性鉴定。给大鼠静脉注射合成的LTC4（每千克体重20微克），并在30分钟内收集胆汁。经过提取和纯化（两步反相高效液相色谱法）后，将代谢物的保留时间进行比较（加共注射），发现在两种反相高效液相色谱系统中与合成的20-CO2H N-Ac LTE4相同。此外，将生物来源的代谢物的紫外光谱进行比较，发现与合成材料相同，在紫外光下呈现特征性的共轭三烯吸收，最大吸收波长为281纳米，在270和290纳米处有肩峰。此外，与合成的20-CO2H N-Ac LTE4三甲酯相比，该代谢物的三甲酯衍生物在2种反相和2种正相高效液相色谱系统中表现出相同的色谱行为。我们得出结论，肽白三烯的ω-氧化在大鼠体内发生，并且20-CO2H N-Ac LTE4是LTC4代谢的体内产物。
