1. Department of Animal Biology and Physiology, Faculty of Sciences, University of Douala, P.O. Box 24157, Doual, Cameroon
2. Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Science, University of Douala, P.O. Box 24157, Doual, Cameroon
3. Department of Physical and Analytical Chemistry, Faculty of Experimental Sciences, University of Jaén, Campus Las Lagunillas, E-23071 Jaén, Spain