1. Department of Organic Chemistry, Faculty of Science, University of Yaoundé I, Yaoundé, Cameroon
2. Department of Chemistry, Higher Teacher Training College, University of Yaoundé I, Yaoundé, Cameroon
3. H.E.J. Research Institute of Chemistry, International Centre for Chemical and Biological Sciences (ICCBS), University of Karachi, Karachi, Pakistan
4. Multidisciplinary Research Lab (MDRL), Bahria University Medical and Dental College, Karachi, Pakistan
5. Department of Chemistry and Polymer Science, University of Stellenbosch, Matieland, Stellenbosch, South Africa