Ktedonoketone and 2’-oxosattabacin, benzenoid metabolites from a thermophilic bacterium Thermosporothrix hazakensis in the phylum Chloroflexi

A thermophilic bacterium Thermosporothrix hazakensis NBRC 105916 which belongs to the class Ktedonobacteria was investigated to explore its biosynthetic potential of secondary metabolites. UV-guided fractionation led to the identification of a new benzenoid metabolite designated ktedonoketone (6) and an α-diketone metabolite 2’-oxosattabacin (7) along with five known compounds. Compound 7 was previously described as a synthetic compound, but this is the first finding as a natural product. Compound 7 induced adipocyte differentiation at 10–20 μM and autophagy at 1–10 μM. Compound 6 showed weak inducing activity of adipocyte differentiation. The biosynthetic origin of hazakacin (3), an acyloin-type compound, was elucidated by ¹³C-labeled precursor-feeding experiments.