1. Department of Biology and Biochemistry, University of Houston, Houston, TX 77204-5001, USA
2. Department of Chemistry, The Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5003, USA
3. Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
4. Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan