1. Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
2. Center for Research and Development of Natural Products for Health, Chiang Mai University, Chiang Mai 50200, Thailand
3. Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand
4. Department of Chemistry and the Texas Center for Superconductivity, University of Houston, Houston, Texas 77204-5003, United States