Wang Weiqun, Hua Yousheng, Wang Guangdi, Cole Richard B
Department of Chemistry, University of New Orleans, New Orleans, LA 70148, USA.
Anal Bioanal Chem. 2005 Sep;383(1):67-75. doi: 10.1007/s00216-005-3323-0. Epub 2005 Oct 19.
Brevetoxins are natural neurotoxins that are produced by "red tide" algae. This class of compounds can cause neurotoxic shellfish poisoning and other health problems. Brevetoxin-2 is the most abundant among the nine brevetoxins that have been characterized, whereas brevetoxin-1 is the most toxic. In this study, brevetoxin-1 and brevetoxin-2 were incubated with rat liver hepatocytes and rat liver microsomes, respectively. After clean-up steps were taken to remove the proteins, samples were analyzed by liquid chromatography (LC) coupled with electrospray mass spectrometry (LC-MS). After incubation of brevetoxin-1, two metabolites were found: brevetoxin-1-M1 (molecular weight = 900 Da), and brevetoxin-1-M2 (molecular weight = 884 Da). The increase in molecular weight combined with evidence from tandem mass spectrometry showing an increased tendency for loss of water molecules, along with considerations of established precedents for chemical transformations led to the conclusion that brevetoxin-1-M1 was formed by converting one double bond in the E or F ring of brevetoxin-1 into a diol. The second metabolite (brevetoxin-1-M2) is proposed to be a hydrolysis product of brevetoxin-1 involving opening of the lactone ring with the addition of a water molecule. The incubation study of the other starting compound, brevetoxin-2, found two metabolites in the LC-ES-MS selected ion chromatogram. Brevetoxin-2-M1 (molecular weight = 912 Da) gave a large [M-H]- peak at m/z 911, and its product ion mass spectrum allowed the deduction that this metabolite was the hydrolysis product of brevetoxin-2 involving conversion of the lactone to a carboxylic acid and an alcohol. The second metabolite (brevetoxin-2-M2, molecular weight = 896 Da) was deduced to have the same structure as that of brevetoxin-3 based on identical chromatographic retention times and similar mass spectra as those obtained for a brevetoxin-3 standard.
短裸甲藻毒素是由“赤潮”藻类产生的天然神经毒素。这类化合物可导致神经性贝类中毒及其他健康问题。在已鉴定出的九种短裸甲藻毒素中，短裸甲藻毒素 -2含量最为丰富，而短裸甲藻毒素 -1毒性最强。在本研究中，分别将短裸甲藻毒素 -1和短裸甲藻毒素 -2与大鼠肝脏肝细胞及大鼠肝脏微粒体进行孵育。在采取清理步骤去除蛋白质后，通过液相色谱（LC）与电喷雾质谱联用（LC-MS）对样品进行分析。短裸甲藻毒素 -1孵育后，发现了两种代谢产物：短裸甲藻毒素 -1-M1（分子量 = 900道尔顿）和短裸甲藻毒素 -1-M2（分子量 = 884道尔顿）。分子量的增加，结合串联质谱的证据表明水分子丢失的趋势增加，以及考虑到已有的化学转化先例，得出结论：短裸甲藻毒素 -1-M1是通过将短裸甲藻毒素 -1的E环或F环中的一个双键转化为二醇而形成的。第二种代谢产物（短裸甲藻毒素 -1-M2）被认为是短裸甲藻毒素 -1的水解产物，涉及内酯环的打开并添加了一个水分子。对另一种起始化合物短裸甲藻毒素 -2的孵育研究在LC-ES-MS选择离子色谱图中发现了两种代谢产物。短裸甲藻毒素 -2-M1（分子量 = 912道尔顿）在m/z 911处给出一个大的[M-H]-峰，其产物离子质谱图表明该代谢产物是短裸甲藻毒素 -2的水解产物，涉及内酯转化为羧酸和醇。基于与短裸甲藻毒素 -3标准品相同的色谱保留时间和相似的质谱，推断第二种代谢产物（短裸甲藻毒素 -2-M2，分子量 = 896道尔顿）与短裸甲藻毒素 -3结构相同。
