1. Department of Pharmacy and Pharmacology; University of the Witwatersrand; 7 York Road, Parktown 2193 Johannesburg South Africa
2. Department of Pharmaceutical Sciences; Faculty of Science; 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