1. Chemistry Department, Faculty of Science; King Saud University; Riyadh; KSA
2. Pharmacology Department, Faculty of Pharmacy; Alkharje University; Alkharje; KSA
3. Botany and Microbiology Department, Faculty of Science; King Saud University; Riyadh; KSA
4. School of Chemistry; University of Nottingham; Nottingham; NG7 2RD; UK