1. Pharmacognosy Department, College of Pharmacy, King Saud University, Riyadh 11451, P.O. Box 2457, Saudi Arabia, Pharmacognosy Department, College of Pharmacy, Cairo University, Cairo 11562, Egypt, and Institut de Chimie des Substances Naturelles, Centre National de la Recherche Scientifique, 91198 Gif-Sur-Yvette, France