高效液相色谱-串联质谱分析微量格尔德霉素类似物

Analysis of geldanamycin analogues in trace amounts by LC-MS/MS

摘要:

安莎类抗生素例如利福霉素和安丝菌素, 通常由一组化学结构相似的组分组成。格尔德霉素为苯安莎类抗生素,已经发现4个组分。本研究采用高效液相色谱-串联质谱方法对格尔德霉素(GDM)制品中的微量组分进行了分析, 发现5个新的和1个已知的GDM类似物。依据质谱数据、结合GDM生物合成机制, 对6个GDM类似物的化学结构进行了推测: 分子式为C29H42N2O10的新化合物3个, 分别为GDM安莎链上C2-C3、C4-C5和C8-C9之间的C-C双键变为单键并同时单羟基化的GDM衍生物; 分子式为C28H38N2O8的新化合物2个, 其中1个为17(或12, 或4)-去甲氧基格尔德霉素, 另1个为4, 5-双氢-10, 11-脱水-17-去甲基-17-羟基格尔德霉素; 分子式为C29H42N2O9的已知化合物1个, 为4,5-双氢格尔德霉素。这些GDM类似物的发现有助于加深对GDM生物合成的认识, 并对通过基因阻断、组合生物合成技术获得GDM衍生物的研究有启示作用。

Abstract:

Ansamycins, such as rifamycin and ansamitocin, usually consist of a group of structural similar components. Geldanamycin, a benzenic ansamycin, has been found to consist of four structural similar components. We analyzed the geldanamycin (GDM) preparation from Streptomyces hygroscopicus 17997 by LC-ESI(+)-MS/MS, and discovered five novel and one known GDM analogues in trace amounts. Based on the ESI(+)-MS/MS spectra of these GDM analogues, and the present understanding of GDM biosynthesis, we proposed the possible chemical structures of these GDM analogues. Three novel GDM analogues, all having the same molecular formula of C29H42N2O10, were GDM biosynthetic derivatives with one of the three C-C double bonds between C2-C3, C4-C5 and C8-C9 in GDM changed to mono-hydroxylated C-C single bond. The other two novel GDM analogues, having the same molecular formula of C28H38N2O8, were 17(or 12, or 4)-desmethoxylgeldanamycin and 4,5-dihydro-10,11-dehydrate-17-desmethyl-17-hydroxylgeldanamycin, respectively. The known GDM analogue, having the molecular formula of C29H42N2O9, was 4, 5-dihydrogeldanamycin, an intermediate in GDM biosynthesis. The discovery of novel GDM analogues provided us new insights in understanding the biosynthetic details of GDM, and clues of obtaining GDM derivatives by gene-disruption and combinatorial biosynthesis.