1. Cancer Biology Laboratory, Nobel Project, Department of Biochemistry, National Research Centre, Dokki 12622, Cairo, Egypt. Fax: +2023370931.
2. Department of Chemistry, Faculty of Science, University of Dschang, Box 67, Dschang, Cameroon
3. Department of Organic Chemistry, Faculty of Science, University of Yaoundé I, Box 812, Yaoundé, Cameroon
4. Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagmiyama-Hiroshima 739-8526, Japan