ABSTRACTA new azaphilone derivative, named fusarone (1), has been isolated from the ethyl acetate soluble extract of the fermentation broth of an endophytic fungus, Fusarium sp. LN‐12, isolated from the leaves of Melia azedarach Linn. The structure of the new compound was established on the basis of extensive spectroscopic analysis, including 1D‐NMR and 2D‐NMR (1H‐1H COSY, TOCSY, HSQC, HMBC, and NOESY) experiments. The absolute configurations of fusarone (1) and of a second related azaphilone were determined by means of electronic circular dichroism spectroscopy and optical rotation calculations. Chirality 24:621–627, 2012. © 2012 Wiley Periodicals, Inc.