Evaluation de l’activité antioxydante et antimicrobienne de l’extrait hydroéthanolique de laurier noble (Laurus nobilis L.) sur la souche pathogène de Staphylococcus aureus (ATCC 33862)

Abstract

Algeria is full of aromatic plants of biological interest that it would be interesting to develop in the agri-food sector. In this work, we studied the hydroethanolic extract of the leaves of Laurus nobilis L. harvested in the region of "Tizi Ghénif", located in the South-East of the wilaya of Tizi-Ouzou. First, our objective focused on the quantification of total polyphenols and flavonoids, as well as the evaluation of the antioxidant activity of the extract of this plant. Then, the antibacterial activity was evaluated on the Staphylococcus aureus strain ATCC 33862, one of the germs responsible for food poisoning. The physicochemical results obtained revealed a polyphenol content of 25.33 ± 0.4mg EAG/ml of extract. Similarly, the content of flavonoids is about 13.01± 0.2 mg EQ/ml of extract. Regarding the evaluation of the antioxidant power by the DPPH* method, it revealed that the extract can act as a good free radical scavenger, with an IC50 of 23.00 ± 1.7 μg E Vit C / ml of extract. The latter is better than that of ascorbic acid used as a control, which has a value of 77.36 ± 0.3 μg E vit C/ml. The effect is highly significant (p˂0.01), with a high Scravenger power, around 49.79 ± 00.10μg E Vit C/ml of extract and high inhibition rate of 85.78 ± 0.2%. On the microbiological level, the extract has good antibacterial activity, with an inhibition diameter ranging from 10.67 to 18.67 mm at different concentrations from 20 to 100 mg/ml. The CMB/CMI ratio is less than 0.4 which means that the extract has a bactericidal power on the strain of Staphylococcus aureus studied. From the results obtained, we conclu that the hydroethanolic extract of bay leaves with sauce could be used as a food additive to replace the chemical additives currently used to extend the life of foods, other more indepth tests to explore this track are needed to complete this study.