1. Graduate Institute of Pharmaceutical Sciences, College of Pharmacy, Kaohsiung Medical University, Kaohsiung 807, Taiwan, Republic of China, Graduate Institute of Natural Products, Chang Gung University, Taoyuan 333, Taiwan, Republic of China, School of Pharmacy, College of Pharmacy, Taipei Medical University, Taipei 110, Taiwan, Republic of China, and Department of Pharmacy, Tajen University, Pingtung 907, Taiwan, Republic of China