Asperolides A–C, Tetranorlabdane Diterpenoids from the Marine Alga-Derived Endophytic Fungus <i>Aspergillus wentii</i> EN-48

Bioassay-guided fractionation of the culture extract of <i>Aspergillus wentii</i> EN-48, an endophytic fungus isolated from an unidentified marine brown algal species of the genus <i>Sargassum</i>, led to the isolation of three new tetranorlabdane diterpenoids, asperolides A–C (<b>1</b>–<b>3</b>), and five related derivatives (<b>4</b>–<b>8</b>). The structures of these compounds were established on the basis of spectroscopic interpretation, and compound <b>1</b> was confirmed by X-ray crystallographic analysis. The absolute configuration of <b>1</b> was determined by application of the modified Mosher’s method. An X-ray structure for wentilactone B (<b>6</b>) is also reported. Compounds <b>1</b>–<b>8</b> were evaluated for cytotoxic and antibacterial activities