Spirobisnaphthalene analogues from the endophytic fungus Preussia sp.

A study on the chemical constituents of the endophytic fungus Preussia sp. led to the isolation of three new spirobisnaphthalene analogues, spiropreussione A (1), spiropreussione B (2), and spiropreussomerin A (3). Compound 2 is a spirobisnaphthalene analogue with a cyclopenteno-naphthoindene fragment bridged to a 1,8-dioxygenated naphthalene fragment, and compound 1 is the second compound in this series with a spiro-nonadiene skeleton. The structures of 1-3 were elucidated using spectroscopic data interpretation. Compound 1 showed cytotoxicity toward A2780 and BEL-7404 cells with IC(50) values of 2.4 and 3.0 microM, respectively, and weak activity against Staphylococcus aureus (CMCC B26003) with a MIC value of 25 microM.