1. Institute of Pharmaceutical Biology and Biotechnology, Faculty of Mathematics and Natural Sciences; Heinrich-Heine University; Düsseldorf 40204 Düsseldorf Germany
2. Pharmaceutical and Medicinal Chemistry Department, Faculty of Pharmaceutical Sciences; University of Port Harcourt; 500004 Port Harcourt Nigeria
3. Pharmaceutical and Medicinal Chemistry Department, Faculty of Pharmaceutical Sciences; University of Nigeria, Nsukka; Enugu State Nigeria