1. Department of Chemical Sciences, University of Johannesburg, Doornfontein, P.O.
Box 17011, Johannesburg 2028, South Africa
2. Department of Chemical Sciences, Olabisi Onabanjo University, P. M. B., 2002 Ago-Iwoye, Nigeria
3. School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa
4. Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Sciences, University of KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa
5. Chemistry Department, Faculty of Applied and Computer Science, Vaal University of Technology, Vanderbijlpark Campus, Boulevard, 1900 Vanderbijlpark, South Africa