Reinvestigation of the endophytic fungus Paraphaeosphaeria sp. FT462 from the Hawaiian plant Lycopodiella cernua (L.) Pic. Serm led to the isolation and identification of a unique -lactamisochromanone (1). The structure of 1 was determined by NMR, MS spectroscopic analysis, and quantum chemical calculations of NMR. The compound was tested inactive against A2780 and A2780cisR.