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An aminobenzo(b)fluorene called stealthin C was synthesized, isolated from a Streptomyces murayamaensis culture and incorporated into kinamycin D. It was found to be a new intermediate in the biosynthesis of the benzo(b)fluorene antibiotic after analysis of a deuterated sample showed it to be specifically incorporated into kinamycin D. It is also postulated to be the hydroxylation substrate for the biosynthesis of stealthin A by S. viridochromogenes.

A mutant strain MC1 of Streptomyces murayamaensis, blocked in the mutagenic biosynthesis of kinamycins, yields kinafluorenone by acetylation in pyridine. Spectroscopic analysis shows that the colored metabolite has a molecular formula C25H20O8 and a benzo(b)fluorenone structure, the first such compound isolated from a natural source. It is formed at the nitrogen insertion step of the biosynthetic pathway. Bioassays of its triacetate show no detectable antibiotic activity.

Prekinamycin (Cpd A) belongs to the family of kinamycin antibiotics that lacks the oxidative capability in one ring. Syntheses of previously reported kinamycins showed that their structures are similar to that of 5-diazobenzo[b]fluorenes. A comparison of the structure of Cpd A isolated from Streptomyces murayamaensis and the structure of synthetic Cpd A, however, that the two have completely different structures, and therefore are different from each other. The structure of Cpd A was shown to match that of another prekinamycin, Cpd B.