1. Department of Pharmacy and Pharmacology, Faculty of Health Sciences; University of the Witwatersrand; Johannesburg South Africa
2. Department of Pharmaceutical Sciences, Faculty of Sciences, Tshwane; University of Technology, Private Bag X680; Pretoria 0001 South Africa
3. Department of Pharmaceutical Sciences, SAMRC Herbal Drugs Research Unit; Tshwane University of Technology, Private Bag X680; Pretoria 0001 South Africa