1. Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0204, Departments of Chemistry and Biochemistry, the Skaggs School of Pharmacy and Pharmaceutical Science, University of California, San Diego, La Jolla, California 92093-0204, and Xenobe Research Institute, 3371 Adams Avenue, San Diego, California 92164-4073