1. Department of Pharmaceutical Chemistry, Faculty of Pharmacy; Helwan University; Ain Helwan, P.O. Box 11795 Cairo Egypt
2. Department of Tanning Materials and Leather Technology; National Research Centre; P.O. Box 12622 Dokki, Cairo Egypt
3. Department of Pharmaceutical Chemistry, Faculty of Pharmacy; Cairo University; Kasr-El-Aini Street, P.O. Box 11562, Cairo Egypt