1. Department of Chemistry, Faculty of Science and Agriculture, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa
2. School of Further and Continuing Education, Faculty of Science and Agriculture, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa
3. Centre of Phytomedicine, Department of Botany, Faculty of Science and Agriculture, University of Fort Hare, Alice 5700, Private Bag X1314, South Africa
4. School of Chemistry and Physics, University of KwaZulu-Natal, Pietermaritzburg Campus, Scottsville 3209, South Africa