作者:Ben Clark、Robert J. Capon、Ernest Lacey、Shaun Tennant、Jennifer H. Gill
DOI:10.1039/b600959j
日期:——
Chemical analysis of a solid phase fermentation of an Australian Penicillium citrinum strain has returned all known examples of a rare class of N-methyl quinolone lactams, quinolactacins A2 (1), B2 (2), C2 (3) and A1 (4), together with the new quinolactacins B1 (5), C1 (6), D1 (7) and D2 (8), and the novel derivatives quinolonimide (9) and quinolonic acid (10). Complete stereostructures were assigned to all these compounds by detailed spectroscopic analysis and chemical interconversion. Carefully controlled and monitored decomposition studies have confirmed that quinolactacins readily undergo C-3 epimerization and oxidation, and under appropriate conditions convert to quinolonimide and quinolonic acid. Mechanisms for key transformations are proposed. The decomposition studies suggested that only quinolactacins A2 (1) and B2 (2) are genuine natural products, with all other isolated compounds being decomposition artefacts. Quinolactacins C1 (6), C2 (3), and the racemic mixture of quinolactacins D1/D2 (8/7) all displayed notable cytotoxic activity.
通过对澳大利亚柠檬青霉菌株的固相发酵进行化学分析,发现了一类罕见的 N-甲基喹诺酮内酰胺的所有已知实例:喹内酰胺 A2 (1)、B2 (2)、C2 (3) 和 A1 (4),以及新的喹内酰胺 B1 (5)、C1 (6)、D1 (7) 和 D2 (8),以及新型衍生物喹诺酮亚胺 (9) 和喹诺酮酸 (10)。通过详细的光谱分析和化学相互转化,我们为所有这些化合物确定了完整的立体结构。经过仔细控制和监测的分解研究证实,喹内酯类化合物很容易发生 C-3 二聚化和氧化,并在适当条件下转化为喹诺酮亚胺和喹诺酮酸。提出了关键转化的机理。分解研究表明,只有喹内酯 A2 (1) 和 B2 (2) 是真正的天然产物,其他分离出来的化合物都是分解产物。喹内酯 C1 (6)、C2 (3) 和外消旋混合物喹内酯 D1/D2 (8/7) 都显示出显著的细胞毒性活性。