Gephyromycin, the first bridged angucyclinone, from Streptomyces griseus strain NTK 14.

The new, highly oxygenated angucyclinone gephyromycin was isolated from an extract of a Streptomyces griseus strain. Its unprecedented ether-bridged structure was elucidated by NMR methods and substantiated by single crystal X-ray analysis. The absolute configuration was evidenced by quantum chemical CD calculations.