Composition and antibacterial activity of hydro-alcohol and aqueous extracts obtained from the lamiaceae family

Abstract

Context: Plant from the Lamiaceae family are considered as dietary spices and medicinal herbs traditionally used in medicine for the treatment of several pathologies. Objective: Evaluation of the in vitro antibacterial activity of ethanol and aqueous extracts of nine Moroccan plants from the Lamiaceae family against six bacterial strains regularly implicated in toxi-infection. Method: The antibacterial activities of hot (HAE), cold (CAE) aqueous extracts and ethanolic extracts (EE) were evaluated using agar-well diffusion method, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and IC50 against six food-borne bacteria (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Salmonella enterica). Total phenolic and flavonoid contents were assessed as well. Results: In the present study, the ethanol extracts were rich in polyphenols, with middling values of flavonoids, and relatively poor in condensed tannins. The presence of saponins, essential oils, irroides, alkaloids, anthocyanins, and aldehydes was recorded. The effect of the extracts was directly bactericidal for B. cereus and L. monocytogenes; for the other strains, the MBC value was twice higher than that of MIC. However, the ethanol extract (EE) of O. majorana and T. satureioides showed the highest antibacterial activity. With the principal component analysis, it was demonstrated that the nine Lamiaceae family plants possess a powerful antibacterial effect, correlated with their phenolic content. Statistical analysis: Analysis of variance was performed by uni-varied ANOVA in the software SPSS 22 Fr. Conclusion: The active compounds were thermostable and soluble in ethanol and water. The antimicrobial activities of the plants extracts investigated may contribute to understand their involvement in traditional medicine against many microbial infections.