2006 Annual Report 4d.Progress report. This reports serves to document research conducted under a Specific Cooperative Agreement between ARS and the University if Illinois, Urbana, IL. Additional details of research can be found in the report for the parent project 3620-42000-033-00D, entitled, "Fungal Endophytes of Maize: Gene Products Conferring Resistance to Aflatoxin and Fumonisin." Pyrrocidine A is a newly discovered antibiotic produced by the 'protective' maize endophyte Acremonium zeae. This antibiotic exhibits potent activity against kernel rotting fungal pathogens of maize including the aflatoxin producer Aspergillus flavus, as well as pathogens of humans, including Candida albicans and species of Gram-positive bacteria. Research identified in Objective 5 of the ARS parent CRIS will investigate the epidemiology and biocontrol potential of A. zeae in maize. The Preharvest Mycotoxins Panel reviewing this ARS CRIS project posed the following question: "What safety information is available for pyrrocidines that could convince regulators that its levels could be increased in corn grain and not pose a safety risk for consumers?" An in vivo study performed by a university scientist in the Department of Pathobiology, University of Illinois, shows that pyrrocidine A and B are cytotoxic to HepG2 cells (a cell line derived from a human hepatocellular carcinoma) and PK15 cells (a cell line derived from a normal pig kidney) within 24 hours of treatment. These results warrant a study of the in vivo toxicity of pyrrocidine A in mice that will include a pilot study to determine toxic dose levels followed by a study of potential target organs and dose response for pyrrocidine A toxicity including comprehensive histopathology and clinical pathology.