* Corresponding authors

^a The Salk Institute for Biological Sciences, 10010 North Torrey Pines Rd, La Jolla, CA 92037, USA
E-mail: hucang@salk.edu

^b Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA, USA

^c Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX 78666, USA

^d Dipartimento di Scienze Chimiche, Universita’ di Napoli Federico II, Complesso Universitario Monte Sant'Angelo, Via Cintia 4, 80126 Napoli, Italy

^e Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, CA 92093, USA

^f Xenobe Research Institute, P. O. Box 3052, San Diego, CA 92163, USA
E-mail: i@xenobe.org