Chemical investigation of a marine-derived Streptomyces sp. KCB-132, cultivated in liquid ISP2 medium, had led to the discovery of three C-ring cleavage angucyclinone N-heterocycles, pratensilins A–C, with a novel spiro indolinone-naphthofuran skeleton. Addition of 50 μM LaCl₃ to the same medium and subsequent chemical analysis of this strain returned a new member of this rare class, pratensilin D (1), along with two new angucyclinone derivatives, featuring ether-bridged (2) and A-ring cleavage (3) structural properties. Their structures and absolute configurations were assigned by spectroscopic analysis, single-crystal X-ray diffractions, and equivalent circulating density (ECD) calculations. (+)- and (–)-1, a pair of enantiomeric nitrogen-containing angucyclinones, exhibited different strengths of antibacterial and cytotoxic activities.

海洋来源的化学研究 链霉菌sp。在液体ISP2培养基中培养的KCB-132导致发现了三个C环裂解的gu环素ñ-杂环，普拉滕西林A–C，具有新型螺吲哚酮-萘呋喃骨架。在相同的培养基中添加50μMLaCl ₃并随后对该菌株进行化学分析，返回了该稀有类别的新成员pratensilin D（1个），以及两种新的蒽环酮衍生物，其特征在于醚桥（2）和A环断裂（3）结构特性。通过光谱分析，单晶X射线衍射和等效循环密度（ECD）计算确定了它们的结构和绝对构型。（+）-和（–）-1个一对对映异构的含氮古环素，表现出不同的抗菌和细胞毒性活性。