Funding for this research was provided by:
National Research Foundation (105993)
The World Academy of Science (99808)
Received: 20 August 2019
Accepted: 27 August 2020
First Online: 4 September 2020
Ethics approval and consent to participate
: Not applicable because experiments did not involve animals or humans.Sampling of plant material was from our own University Botanical Garden and from the Lowveld National Botanical Garden in accordance with an agreement between the Phytomedicine Programme and the National Biodiversity Institute.
: Not applicable.
: The authors declare that they have no competing interests.