1. Department of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa, South Africa
2. Natural Products Research Unit, Department of Chemistry, Lagos State University, Ojo, Lagos, Nigeria
3. Department of Chemistry, University of Zululand, KwaDlangezwa, South Africa
4. Department of Chemistry and Chemical Technology, Walter Sisulu University, Mthatha, South Africa