Sarubicinols A-C, Cytotoxic Benzoxazoles from a .

A chemical investigation of sp. Hu186 afforded two known quinone antibiotics, sarubicin A () and sarubicin B (), together with three unusual variants, sarubicinols A-C (-), and two new 1,4-naphthoquinone metabolites, sarubicin B () and sarubicin B (). Compounds - possess a rare 2-oxabicyclo [2.2.2] substructure and a benzoxazole ring system. Their structures were elucidated using 1D and 2D nuclear magnetic resonance and high-resolution electrospray ionization mass spectrometry data. The absolute configurations of the side-chain moieties in and were solved by electronic circular dichroism calculations. Compounds - showed moderate cytotoxic activity against four tumor cell lines.