1. a Department of Pharmacognosy, Faculty of Pharmacy , King Saud University , P.O. Box 2457, Riyadh-11451, Saudi Arabia
2. b Women students-Medical studies and Sciences sections , King Saud University , P.O. Box 22452, Riyadh-11495, Saudi Arabia
3. c Department of Chemistry , Virginia Polytechnic Institute and State University , Blacksburg, Virginia 24061-0212, USA