1. Department
of Chemistry, University of the Free State, Nelson Mandela Avenue, Bloemfontein, 9301, South Africa
2. ARC Infruitec-Nietvoorbij, Private Bag X5026, Stellenbosch, 7599, South Africa
3. Department
of Pharmacognosy and Research Institute of Pharmaceutical Sciences,
School of Pharmacy, The University of Mississippi, University, Mississippi 38677, United States