Azamerone, a Terpenoid Phthalazinone from a Marine-Derived Bacterium Related to the Genus <i>Streptomyces</i> (Actinomycetales)

A novel meroterpenoid, azamerone, was isolated from the saline culture of a new marine-derived bacterium related to the genus <i>Streptomyces</i>. Azamerone is composed of an unprecedented chloropyranophthalazinone core with a 3-chloro-6-hydroxy-2,2,6-trimethylcyclohexylmethyl side chain. The structure was rigorously determined by NMR spectroscopy and X-ray crystallography. A possible biosynthetic origin of this unusual ring system is proposed.