NMR spectrum of lindgomycin from a Marine Fungus of the Lindgomycetaceae

An unusual polyketide with a new carbon skeleton, lindgomycin (1), and the recently described ascosetin (2) were extracted from mycelia and culture broth of different Lindgomycetaceae strains, which were isolated from a sponge of the Kiel Fjord in the Baltic Sea (Germany) and from the Antarctic. Their structures were established by spectroscopic means. In the new polyketide, two distinct domains, a bicyclic hydrocarbon and a tetramic acid, are connected by a bridging carbonyl. The tetramic acid substructure of compound 1 was proved to possess a unique 5-benzylpyrrolidine-2,4-dione unit. The combination of 5-benzylpyrrolidine-2,4-dione of compound 1 in its tetramic acid half and 3-methylbut-3-enoic acid pendant in its decalin half allow the assignment of a new carbon skeleton. The new compound 1 and ascosetin showed antibiotic activities with IC50 value of 5.1 (±0.2) µM and 3.2 (±0.4) µM, respectively, against methicillin-resistant Staphylococcus aureus.从分离自德国波罗的海基尔峡湾海绵以及南极海域的不同Lindgomycetaceae科菌株的菌丝体与培养液中，提取得到一种具有全新碳骨架的罕见聚酮类化合物（polyketide）林多霉素（lindgomycin，1），以及近期被报道的子囊菌素（ascosetin，2）。其结构通过波谱学手段得以解析确定。在该新型聚酮类化合物中，两个不同的结构域——双环烃类（bicyclic hydrocarbon）与吡咯烷-2,4-二酮（tetramic acid）——通过桥连羰基（bridging carbonyl）相互连接。化合物1的吡咯烷-2,4-二酮亚结构被证实含有独特的5-苄基吡咯烷-2,4-二酮（5-benzylpyrrolidine-2,4-dione）单元。化合物1的吡咯烷-2,4-二酮片段所含的5-苄基吡咯烷-2,4-二酮结构，与其十氢萘（decalin）片段上的3-甲基-3-丁烯酸侧链相结合，共同确立了其全新的碳骨架。该新型化合物1与子囊菌素均表现出抗耐甲氧西林金黄色葡萄球菌（methicillin-resistant Staphylococcus aureus）的抗菌活性，其半最大抑制浓度（IC50）分别为5.1（±0.2）μM与3.2（±0.4）μM。