Acremochlorin S and other prenylated chlorophenol antimicrobial metabolites from the fungus Acremonium sp. Strain MNA-F-1

Abstract

Chemical prospection for the mycelial extract of the fungus Acremonium sp. Strain MNA-F-1, derived from the inner tissue of anise roots (Pimpnella anisum L., family Apiaceae), led to the isolation and characterization of one previously undescribed natural product, acremochlorin S (1), together with five related derivatives (2–6) and an alkaloidal metabolite, ilicicolin H (7). Structure elucidation of the isolated compounds was determined through comprehensive 1D/2D NMR spectroscopic analyses and HR-ESI-MS measurements. The absolute configuration of acremochlorin S (1) was concluded based on the comparison of its experimental and calculated electronic circular dichroism (ECD) spectra implementing Time-dependent density functional theory (TDDFT). All isolated compounds were assessed for their antibacterial activity against Staphylococcus aureus, Escherichia coli and Mycobacterium tuberculosis, where several compounds revealed potent activities against tested Gram-positive strains.