Heliconols A-C:: Antimicrobial hemiketals from the freshwater aquatic fungus Helicodendron giganteum

Cultures of the freshwater aquatic fungus Helicodendron giganteum afforded three new compounds, heliconols A-C (1-3), that contain an unusual reduced furanocyclopentane unit. The structures of these metabolites were assigned by analysis of 1D and 2D NMR data. The absolute configuration of heliconol A ( 1) was assigned by single-crystal X-ray crystallographic analysis of its dibromobenzoate derivative. Heliconol A showed antifungal and antibacterial activities in disk diffusion assays.