Keywords: Lavandula stoechas , Ultrasound assisted extraction, Phenolic fractions, Antimicrobial activity, Hospital environment
The objective of this study was to determine the chemical families and the total phenolic content in a hydro-ethanolic extract of Lavandula stoechas, as well as to evaluate the antibacterial effect of the different phenolic fractions of this plant against pathogenic bacterial strains isolated from a hospital in the city of Fez, Morocco. The hydro-ethanolic extract was obtained and phytochemical screening of the different chemical families of the plant was conducted using colorimetric methods. The quantification of the total concentration of polyphenols in the L. stoechas extract was conducted according to the Folin–Ciocalteu method. The antimicrobial effects of the hydro-ethanolic, flavonoid and tannin extracts against Gram-positive and Gram-negative pathogenic bacteria isolated from a hospital in Fez were determined using the disc diffusion method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for all pathogenic and reference strains. The total phenolic content of L. stoechas was 130.15 ± 3.72 mg gallic acid equivalent/g plant extract. The total phenolic content of L. stoechas was 130.15 ± 3.72 mg gallic acid equivalent/g plant extract. The flavonoid extract had the highest effect against bacteria, with MIC and MBC values varying from 10 to 40 mg/ml and 20–80 mg/ml, respectively. The results also revealed that the hydro-ethanolic extract showed a MIC value of 80 mg/ml against all bacteria except Acinetobacter baumanii and Pseudomonas aeruginosa (ATCC27853). The results obtained in our study showed an important antibacterial effect of flavonoid extracts from L. stoechas compared to other extracts. These results can aid in the discovery of new antimicrobial molecules of natural origin. Further research on phenolic compounds in L. stoechas is required.