Anthraquinone Derivatives and Other Aromatic Compounds from Marine Fungus Asteromyces cruciatus KMM 4696 and Their Effects against Staphylococcus aureus .

New anthraquinone derivatives acruciquinones A-C ( 1 - 3 ), together with ten known metabolites, were isolated from the obligate marine fungus Asteromyces cruciatus KMM 4696. Acruciquinone C is the first member of anthraquinone derivatives with a 6/6/5 backbone. The structures of isolated compounds were established based on NMR and MS data. The absolute stereoconfigurations of new acruciquinones A-C were determined using ECD and quantum chemical calculations (TDDFT approach). A plausible biosynthetic pathway of the novel acruciquinone C was proposed. Compounds 1 - 4 and 6 - 13 showed a significant antimicrobial effects against Staphylococcus aureus growth, and acruciquinone A ( 1 ), dendryol B ( 4 ), coniothyrinone B ( 7 ), and ω-hydroxypachybasin ( 9 ) reduced the activity of a key staphylococcal enzyme, sortase A. Moreover, the compounds, excluding 4 , inhibited urease activity. We studied the effects of anthraquinones 1 , 4 , 7 , and 9 and coniothyrinone D ( 6 ) in an in vitro model of skin infection when HaCaT keratinocytes were cocultivated with S. aureus . Anthraquinones significantly reduce the negative impact of S. aureus on the viability, migration, and proliferation of infected HaCaT keratinocytes, and acruciquinone A ( 1 ) revealed the most pronounced effect.