Damxungmacin A and B, Two New Amicoumacins with Rare Heterocyclic Cores Isolated from Bacillus subtilis XZ-7.

Two new amicoumacins, named Damxungmacin A () and B (), were isolated from the culture broth of a soil-derived bacterium XZ-7. Their chemical structures were elucidated by spectroscopic studies (UV, IR, NMR and HR-ESI-MS). Compound possessed a 1,4-diazabicyclo[2.2.1]heptane-2-one ring system in its structure, which was reported for the first time, while had a 1-acetylmorpholine-3-one moiety, which was naturally rare. Compound exhibited moderate to weak cytotoxic activities against three human tumor cell lines (A549, HCT116 and HepG2) with IC values of 13.33, 14.34 and 13.64 μM, respectively. Meanwhile, compound showed weak antibacterial activities against some strains of , while compound at 16 μg/mL did not show antibacterial activity.