1. Department of Pharmacology and Toxicology, University of Western Ontario, London, Ontario, Canada, N6A 5C1, Department of Biochemistry, Wilson Rd., Michigan State University, East Lansing, Michigan, Michigan 48824-1319, Department of Chemistry, McMaster University, Hamilton, Ontario, L8N 4M1, Canada, Agriculture and Agri-Food Canada, Vineland Station, Vineland, Ontario, L0R 2E0, Canada, and CanTox, Inc., 2233 Argentia Rd. Mississauga, Ontario, l5N 2X7, Canada