A new antibacterial chromone from a marine sponge-associated fungus Aspergillus sp. LS57.

Chemical investigation for the secondary metabolite of marine-derived fungus Aspergillus sp. LS57 resulted in the isolation of one new chromone named aspergilluone A (1) containing a chromone skeleton fused with an unusual hydrogenation cyclopentanoid ring, along with three known compounds 2 – 4. The structure of 1 was elucidated by 1D and 2D nuclear magnetic resonance (NMR) spectroscopic and mass spectrometric analyses. Its absolute configuration was established by combining NMR quantum chemical calculations and comparison between the experimental and calculated circular dichroism (CD) curves. Additionally, the antibacterial assay of compound 1 was performed. As a result, compound 1 showed in vitro anti- Mycobacterium tuberculosis with MIC value of 32 μ g/mL, together with moderate antibacterial activity against Staphylococcus aureus (MIC values = 64 μ g/mL), and exhibited feeble activity against gram-positive Bacillus subtilis and gram-negative pathogen Escherichia coli (both MICs = 128 μ g/mL). [Display omitted] • One new antibacterial chromone aspergilluone A (1) containing a chromone skeleton fused with an unusual hydrogenation cyclopentanoid ring was isolated from a sponge-derived fungus Aspergillus sp. • Its absolute configuration was established by combining NMR quantum chemical calculations and comparison of the circular dichroism (CD) curves between the experimental and calculated. • Compound 1 exhibited inhibitory activities against Mycobacterium tuberculosis , Staphylococcus aureus , and Bacillus subtilis. [ABSTRACT FROM AUTHOR]