1. Department of Biochemistry, North-West University, Mmabatho 2735, South Africa
2. Department of Biochemistry and Microbiology, University of Venda, Thohoyandou 0950, South Africa
3. Department of Chemical and Physical Sciences, Faculty of Natural Sciences, Walter Sisulu University (WSU), Private Bag X01, Umthatha, Eastern Cape 4099, South Africa