6,9-Dihydroxytetrangulol, a novel angucyclinone antibiotic accumulated in kiqO gene disruptant in the biosynthesis of kinanthraquinone.

A novel angucyclinone, 6,9-dihydroxytetrangulol, was isolated from Streptomyces lividans TK23 transformed with a kinanthraquinone biosynthetic gene cluster in which the kiqO gene was disrupted. The chemical structure was elucidated by spectroscopic analyses. It showed significant antibacterial activities with an IC50 value of 1.9 μM against Staphylococcus aureus and moderate anticancer activities against HL-60 cells.