1. Faculty of Pharmacy, Rhodes University, Grahamstown, South Africa;
2. Biomedical Biotechnology Research Unit, Rhodes University, Grahamstown, South Africa;
3. Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, South Africa;
4. School of Chemistry and Physics, Pietermaritzburg Campus, University of KwaZulu-Natal, Scottsville, South Africa