Antiosteoporotic Tetrahydroxanthone Dimers from Aspergillus brunneoviolaceus FB‐2 Residing in Human Gut

Main observation and conclusion A complex community of human‐associated microorganisms plays diversely important roles in maintaining health, and the metabolites help to define whether a particular human‐associated microbe is a friend or a foe. This work shows that Aspergillus brunneoviolaceus FB‐2, derived from the stool of a healthy individual, produces a family of antiosteoporotic xanthone dimers including penibishexahydroxanthone A (1) and brunneoxanthones A—E (2—6, undescribed previously). The structures of 1—6 were elucidated by MS and NMR spectroscopic analysis, and the absolute configuration of 2 was established by X‐ray crystallography. Compounds 4—6 are relatively rare examples of highly oxidized heterodimeric xanthones with an 8‐ketone functionality. Finally, the prednisolone‐induced osteoporotic zebrafish enabled our demonstration that the antiosteoporotic effects of 1—6 are dose‐dependent.