[Streptonigron--a minor component of bruneomycin complex]

A mutant strain of the bruneomycin-producing culture which produced up to 10% of the minor component was selected. The component was identified as streptonigrone. It was isolated and its physicochemical properties and antibacterial activity were investigated. Trimethylsilyl derivatives of streptonigrone and bruneomycin were prepared. Their PMR spectra and electron impulse mass spectra were studied. Streptonigrone was shown to have antibacterial and cytotoxic activities which was 1 to 2 orders of magnitude lower than that of bruneomycin.