Dihydroisatropolone C from Streptomyces and Its Implication in Tropolone-Ring Construction for Isatropolone Biosynthesis

Isatropolones/isarubrolones are actinomycete secondary metabolites featuring a tropolone-ring in their structures. From the isatropolone/isarubrolone producer Streptomyces sp. CPCC 204095, 7,12-dihydroisatropolone C (H2ITC) is discovered and identified as a mixture of two interchangeable diastereomers differing in the C-6 configuration. As a major metabolite in the mycelial growth period of Streptomyces sp. CPCC 204095, H2ITC can be oxidized spontaneously to isatropolone C (ITC), suggesting H2ITC is the physiological precursor of ITC. Characterization of H2ITC makes us propose dihydrotropolone-ring construction in the biosynthesis of isatropolones.

Automated summary

Isatropolones/isarubrolones are secondary metabolites produced by actinomycetes, characterized by the presence of a tropolone ring in their structures. A study on the producer strain Streptomyces sp. CPCC 204095 led to the discovery of 7,12-dihydroisatropolone C (H2ITC) as a major metabolite during the mycelial growth period. H2ITC can spontaneously oxidize into isatropolone C (ITC), indicating that H2ITC serves as the physiological precursor of ITC. The characterization of H2ITC suggests the involvement of dihydrotropolone-ring construction in the biosynthesis of isatropolones.