1. Division of Nutritional Biochemistry, Institute of Microbiology and Biochemistry, National Taiwan University, 1, Sec. 4, Roosevelt Rd., Taipei, 106, Taiwan, Department of Chemistry, National Taiwan University, Taipei, Taiwan, Department of Biochemical Science and Technology, National Taiwan University, Taipei, Taiwan, College of Pharmacy, China Medical University, Taichung, 404, Taiwan, and Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 115, Taiwan