This study was conducted by a coalition of European-African researchers composed of Dr Hope T. Sounouvou of the Laboratory of Pharmaceutical Technology and Biopharmacy, CIRM, University of Liege, Belgium, Dr. Habib Toukourou of the Organic Pharmaceutical Chemistry Laboratory (MOCL), School of Pharmacy, University of Abomey-Calavi, Cotonou, Benin, Prof. Fatiou Toukourou of the Laboratory of Microbiology and Food Technologies, University of Abomey-Calavi, Cotonou, Benin and Prof. Fernand Gbaguidi from the Laboratory of Organic Pharmaceutical Chemistry (MOCL) School of Pharmacy, University of Abomey-Calavi, Cotonou with colleagues from Belgium (notably from the Catholic University of Louvain).
The researchers argued that over the last decade, the advent of multi-resistant pathogens responsible for skin infections has tended to render conventional treatments obsolete; and that although many studies have reported on the antimicrobial properties of essential oils (EOs), the inconsistent use of various susceptibility testing methods has made information on the antimicrobial potential of many varieties of EOs fragmentary.
Using a single-method approach, the objective of the study was to evaluate and compare the antibacterial and antifungal properties, against skin pathogens, of EOs extracted from West African aromatic plants.
The researchers reported that twenty-three plant samples were collected in Benin and Burkina Faso and tested on 20 bacterial and fungal isolates obtained from skin lesions. Activity was assessed by determining minimum inhibitory concentrations (MICs), with readings facilitated by the use of resazurin, a blue dye metabolized to pink resorufin by living cells.
Following this screening, nine EOs were found particularly active, with MICs below 0.35% v/v. Analysis by gas chromatography coupled with mass spectrometry (GC/MS) was used to determine the phytochemical profile of these EOs: they were found exceptionally rich in oxygenated monoterpenes including aldehydes, alcohols, phenols and their derivatives.
With this study, the researchers were able to demonstrate that several West African EOs have a significant antimicrobial potential that could however be considerably impacted by climatic conditions or the place of harvest, which could induce variations in phytochemical composition. Even if their antimicrobial effects appeared to be lower than those of conventional antibiotics, these EOs constitute easily available mixtures of active compounds that could be considered, in the context of increasing multiresistance, as complementary or alternative therapies in the management of common skin infections.