1. Korea Research Institute of Bioscience and Biotechnology (KRIBB), 52 Eoun-dong, Yuseong-gu, Daejeon 305-806, Korea, Faculty of Science, University of Yaounde I, P.O. Box 812 Yaounde, Cameroon, Makerere University, P.O. Box 7062 Kampala, Uganda, and College of Pharmacy, Chosun University, 375 Seosuk-dong, Dong-gu, Gwangju 501-759, Korea