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A new austin-type meroterpene, namely, ustusaustin A (1), together with seven related known analogues (2–8), were isolated and identified from the culture extract of Aspergillus ustus TK-5, an endophytic fungus obtained from the marine ascidian Pyura momus. The structures of these compounds were established on the basis of detailed interpretation of their NMR and MS data, and the relative and absolute configurations of 1 was confirmed by X-ray crystallographic analysis. Among them, ustusaustin A (1) represents the first example of 1'-nor-austin analogues with an unique 7-benzoylation. Compounds 1–4, 6, and 7 exhibited potent neuraminidase inhibitory activity and this is the first report of neuraminidase inhibitory activity for austin-type meroterpenes. [ABSTRACT FROM AUTHOR]

One new dihydrobenzofuran derivative (1), known depsipeptide emericellamide A (2), three known drimanes (3–5) and two artifact drimane derivatives (6, 7) were isolated from the marine-derived fungus Aspergillus ustus KMM 4664. Their structures were determined by detailed analysis of spectroscopic data and by comparison with related known compounds. The absolute configuration of 1 was determined by time-dependent density functional theory (TD-DFT) calculations of ECD spectra. Compound 7 showed significant ability of the inhibition of spermatozoa to fertilize egg-cells of the sea urchin Strongylocentrotus intermedius with IC50 value 21 µM. [ABSTRACT FROM AUTHOR]