A novel inhibitor of platelet-activating factor (PAF) acetyltransferase, an essential enzyme in the remodeling pathway of platelet-activating factor synthesis, was identified by a high throughout screen of natural product extracts of microbial origin. The compound, ZG-1494 alpha, was isolated from an ethyl acetate extract of a culture broth of Penicillium rubrum through bioassay guided fractionation. The structure of ZG-1494 alpha was determined by spectroscopic methods. A key feature of the structure, which is relatively rare among natural products, is the 5-hydroxy-3-pyrrolin-2-one moiety. A 13C-13C INADEQUATE was utilized to unambiguously determine the regiochemistry of this molecule.