Malfilanol C, a new sesquiterpenoid isolated from the deep-sea-derived Aspergillus puniceus A2 fungus

The chemical examination of the rice solid fermentation products of the deep-sea-derived fungus Aspergillus puniceus A2 resulted in the isolation of one new sesquiterpenoid malfilanol C (1), together with a rare analogue malfilanol B (2). The planar structure of 1 was resolved on the basis of the extensive analyses of the spectroscopic data (HRESIMS and NMR spectra), and its absolute configuration was assigned by quantum chemical calculation of the ECD data. Compound 1, featuring a bicyclo[5.4.0]-undecane nucleus skeleton, was the third example of this subclass sesquiterpenoids found from nature. Additionally, the subclass sesquiterpenoids 1 and 2 were discovered from marine-derived-fungi for the first time. All the isolated metabolites were evaluated the antibacterial activities against Staphylococcus aureus ATCC 29213 and Escherichia coli ATCC 25922. Compound 1 exhibited weak antibacterial activity against S. aureus ATCC 29213.