1. Department of Pharmaceutical Sciences, School of Pharmacy, Sefako Makgatho Health Sciences University, P.O. Box 218, Pretoria 0208, South Africa
2. Department of Chemistry, Faculty of Science, University of Dschang, Dschang P.O. Box 67, Cameroon
3. Department of Chemistry, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa
4. School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, LA 71209, USA
5. Department of Biochemistry and Microbiology, Rhodes University, Makhanda 6140, South Africa
6. Department of Pharmaceutical Sciences, Faculty of Science, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa
7. Department of Chemistry, Federal University of Santa Catarina, Florianópolis 88040-900, Brazil