1. School
of Chemistry and Physics, University of KwaZulu-Natal, Pietermaritzburg, South Africa
2. Emory
Institute for Drug Development, Emory University, Atlanta, Georgia 30322, United States
3. Department
of Chemistry, Emory University, Atlanta, Georgia 30322, United States
4. Department
of Biochemistry, Stellenbosch University, Stellenbosch, South Africa