The kibdelones are a novel family of bioactive heterocyclic polyketides produced by a rare soil actinomycete, Kibdelosporangium sp. (MST-108465). Complete relative stereostructures were assigned to kibdelones A-C (1-3), kibdelone B rhamnoside (5), 13-oxokibdelone A (7), and 25-methoxy-24-oxokibdelone C (8) on the basis of detailed spectroscopic analysis and chemical interconversion, as well as mechanistic and biosynthetic considerations. Under mild conditions, kibdelones B (2) and C (3) undergo a facile equilibration to kibdelones A-C (1-3), while kibdelone B rhamnoside (5) equilibrates to a mixture of kibdelone A-C rhamnosides (4-6). A plausible mechanism for this equilibration is proposed and involves air oxidation, quinone/hydroquinone redox transformations, and a choreographed sequence of keto/enol tautomerizations that aromatize ring C via a quinone methide intermediate. Kibdelones exhibit potent and selective cytotoxicity against a panel of human tumor cell lines and display significant antibacterial and nematocidal activity.

中文翻译：

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Kibdelones：一种来自澳大利亚罕见的放线菌的新型抗癌聚酮化合物。

Kibdelones是由稀有的土壤放线菌Kibdelosporangium sp生产的一种新型生物活性杂环聚酮化合物。（MST-108465）。在详细的光谱分析和化学分析的基础上，将完整的相对立体结构分配给基伯得隆AC（1-3），基伯得隆B鼠李糖苷（5），13-氧代异黄酮A（7）和25-甲氧基-24-氧代异丁酮C（8）。相互转化，以及机理和生物合成方面的考虑。在温和的条件下，基卜达隆B（2）和C（3）易于与基卜达隆AC（1-3）平衡，而Kibdelone B鼠李糖甙（5）则平衡为Kibdelone AC鼠李糖苷（4-6）的混合物。提出了一种可能的平衡机理，涉及空气氧化，醌/对苯二酚氧化还原转化，以及精心设计的酮/烯醇互变异构序列，可通过醌甲基化物中间体芳香化环C。Kibdelones对一组人类肿瘤细胞系表现出强力和选择性的细胞毒性，并显示出显着的抗菌和杀线虫活性。