Characterization of the preferred stereochemistry for the neuropharmacologic actions of antillatoxin
Characterization of the preferred stereochemistry for the neuropharmacologic actions of antillatoxin
复制标题
DOI：
10.1021/np0303409
复制
发表时间：
2004-04-01
影响因子：
5.1
通讯作者：
Murray, TF
中科院分区：
文献类型：
--
作者：
Li, WI;Marquez, BL;Murray, TF
抗鱼毒素是一种强烈的鱼毒素和细胞毒素，以前发现的海洋蓝藻Lyngkya majuscula。随后对其作用机制的研究表明，它在药理学位点激活哺乳动物电压门控钠通道，这与先前描述的任何位点都不同。抗拉毒素的结构，最初制定的光谱信息，随后在一个立构中心（C-4）的合成四个不同的抗拉毒素立体异构体（所有可能的C-4和C-5非对映异构体）的结果进行了校正。在当前的研究中，这四种立体异构体（4 R，5 R）-、（4S，5 R）-、（4S，5S）-和（4 R，5S）-抗拉毒素在五种不同的生物测定系统中进行了表征：对金鱼的鱼毒性、使用小脑颗粒细胞（CGC）的微物理测量、CGC的乳糖脱氢酶流出、监测CGC细胞内Ca 2+浓度以及对Neuro 2a细胞的细胞毒性。在这些不同的生物措施有很大的一致性，天然antillatoxin（4 R，5 R-异构体）是大于25倍以上的效力比任何其他立体异构体。详细的NMR研究提供了一些扭转和距离的限制，建模使用MM 2 * 力场，以产生预测的解决方案的结构的四个antillatoxin立体异构体。天然（4 R，5 R）-抗拉毒素的大环和侧链呈现“L”型拓扑结构，极性取代基在大环外表面聚集，N（H）-7'与C（O）-1羰基之间存在氢键。三种非天然存在的抗拉毒素立体异构体的效力降低肯定是其整体分子拓扑结构发生显著改变的结果。
Antillatoxin is a potent ichthyotoxin and cytotoxin previously discovered from the marine cyanobacterium Lyngkya majuscula. Ensuing studies of its mechanism of action showed it to activate the mammalian voltage-gated sodium channel at a pharmacological site that is distinct from any previously described. The structure of antillatoxin, initially formulated from spectroscopic information, was subsequently corrected at one stereocenter (C-4) as a result of synthesis of four different antillatoxin stereoisomers (all possible C-4 and C-5 diastereomers). In the current study these four stereoisomers, (4R,5R)-, (4S,5R)-, (4S,5S)-, and (4R,5S)-antillatoxin, were characterized in five different biological assay systems: ichthyotoxicity to goldfish, microphysiometry using cerebellar granule cells (CGCs), lactose dehydrogenase efflux from CGCs, monitoring of intracellular Ca2+ concentrations in CGCs, and cytotoxicity to Neuro 2a cells. Across these various biological measures there was great consistency in that the natural antillatoxin (the 4R,5R-isomer) was greater than 25-fold more potent than any of the other stereoisomers. Detailed NMR studies provided a number of torsion and distance constraints that were modeled using the MM2* force field to yield predicted solution structures of the four antillatoxin stereoisomers. The macrocycle and side chain of natural (4R,5R)-antillatoxin present an overall "L-shaped" topology with an accumulation of polar substituents on the external surface of the macrocycle and a hydrogen bond between N(H)-7' and the C(O)-1 carbonyl. The decreased potency of the three non-naturally occurring antillatoxin stereoisomers is certainly a result of their dramatically altered overall molecular topologies.