Ranjala Ratnayake, Ernest Lacey Dr., Shaun Tennant Dr., Jennifer H. Gill Dr., Robert J. Capon Prof.
Chemistry. (Weinheim an der Bergstrasse, Germany), 2006, 13, 1610-1619.
Publication Date: January 18, 2007
https://doi.org/10.1002/chem.200601236
Abstract:
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.
