SPERADINES B-E, FOUR NOVEL TETRACYCLIC OXINDOLE ALKALOIDS FROM THE MARINE-DERIVED FUNGUS ASPERGILLUS ORYZAE

Four novel tetracyclic oxindole alkaloids, namely, speradines B (1), C (2), D (3), and E (4) were isolated from the marine-derived fungus Aspergillus oryzae. The structures of these compounds without the absolute configurations were elucidated through 1D and 2D nuclear magnetic resonance and high-resolution mass spectrometric analyses. Among these compounds, 1 and 4 showed weak cytotoxic effects on the He La cell line.