1. Division of Chemical Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7XH, Surrey, U.K.
2. School of Chemistry, University of KwaZulu-Natal, Durban, 4041, South Africa
3. Ethnobotany Unit, South African National Biodiversity Institute, PO Box 52099, Berea Road 4007, Durban, South Africa
4. Department of Medicine, Division of Clinical Pharmacology, University of Cape Town, K45 Old Main Building, Groote Schuur Hospital, Observatory, 7925, Cape Town, South Africa