1. Program for Collaborative Research in the Pharmaceutical Sciences, and the Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612, Botany Division, National Museum, Manila, Republic of the Philippines, College of Pharmacy, University of the Philippines, Manila, Republic of the Philippines, and Pharmaceutical Research Institute, Bristol-Myers Squibb, Wallingford, Connecticut 06492