Using a series of bioassay-guided steps involving preparative
and semipreparative normal phase (NP) and reversed phase (RP) high-performance liquid chromatography (HPLC), the
organic layer from the liquid−liquid partition was fractionated
and purified to afford diazaquinomycin H (1, 0.3 mg, 0.00026%
yield) and diazaquinomycin J (2, 0.3 mg, 0.00026% yield). See
the Supporting Information for more detailed descriptions of
fermentation and extraction methods for B026 and subsequent
isolation and purification methods for 1 and 2.