Abstract

Two new spirotetronate natural products, lobophorin L (1) and lobophorin M (2), together with three known lobophorin-like spirotetronate antibiotics (3–5) and two known ansamycins (6–7), were isolated from the marine-derived Streptomyces sp. 4506. The structures of 1 and 2 were established on the basis of HRESIMS as well as 1D and 2D NMR datasets. Antibacterial assay showed that, compounds 1 and 3–5 exhibited strong to moderate antibacterial activities against Micrococcus luteus and Bacillus thuringiensis with MIC values ranging from 0.0625 to 8 μg/mL, while compounds 3 and 6 showed weak antibacterial activities against Staphylococcus aureus and MRSA. The antibacterial activities of the lobophorins in this study indicated that the more substitution number of the sugar moieties at C-9 of the lobophorin, the stronger antimicrobial properties it may deserve, and the higher the oxidation degree of substituent group at C-3_D, the better antibacterial activities of its corresponding compound could be.

摘要

从海洋来源的链霉菌中分离出两种新的螺旋藻素天然产物 lobophorin L ( 1 ) 和 lobophorin M ( 2 )，以及三种已知的类螺旋藻素抗生素 ( 3 – 5 ) 和两种已知的安沙霉素 ( 6 – 7 ) sp. 4506. 1和2的结构是在HRESIMS以及一维和二维核磁共振数据集的基础上建立的。抗菌试验表明，化合物1和3 - 5表现出强到中度对抗菌活性藤黄微球菌和苏云金芽孢杆菌的 MIC 值为 0.0625 至 8 μg/mL，而化合物3和6对金黄色葡萄球菌和 MRSA 的抗菌活性较弱。本研究中lobophorins的抗菌活性表明lobophorin的C-9糖部分取代数越多，其抗菌性能越强，C- _3D取代基团的氧化程度越高，其相应的化合物可能具有更好的抗菌活性。