1. Department of Chemistry, Faculty of Natural and Agricultural Sciences, University of Pretoria, Lynnwood Road, Pretoria 0028, South Africa
2. Pharmaceutical Technologies, CSIR Future Production: Chemicals, Meiring Naudé Road, Pretoria 0184, South Africa
3. Department of Physiology, Faculty of Health Science, University of Pretoria, Lynnwood Road, Pretoria 0031, South Africa