1. Department of Pharmacognosy, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
2. Department of Pharmaceutical Chemistry, Al-Neelain University, Khartoum 11114, Sudan
3. Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8576, Japan
4. Department of Pharmacognosy, Faculty of Pharmacy, University of Khartoum, Khartoum 11111, Sudan