1. Department of Chemistry, College of Natural and Applied Sciences, Makerere University, Kampala, Uganda
2. Department of Chemistry, School of Physical Sciences, University of Nairobi, Nairobi, Kenya
3. Department of Chemistry, College of Natural and Applied Sciences, University of Dar es Salaam, Dar es Salaam, Tanzania
4. National Centre for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, Mississippi, USA
5. Institut für Chemie, Universität Potsdam, Potsdam, Germany