Imane Brahimi

This study aimed to evaluate the physicochemical characterization and antibacterial activity of the essential oil (EO) extracted from the leaves of Mentha rotundifolia (L.) Huds. Molecular interactions between bioactive ligand compounds, target bacterial proteins and DNA gyrase subunit B (GyrB), as well as an in silico ADMET prediction study, were also conducted. The EO was obtained by hydrodistillation of the plant leaves. The Gas Chromatography–Tandem Mass Spectrometry (GC-MS/MS) analysis revealed Rotundifolone (27.95%) and carvacrol (19.48%) as the major constituents. Other components identified included Piperitenone (6.09%), Cinerolon (4.73%), and Pulegone (4.47%). Antibacterial activity was assessed against six bacterial strains: Enterococcus faecalis CIP 103214, Salmonella Typhi CIP 5535, Staphylococcus aureus ATCC 9144, Bacillus cereus ATCC 33019, Streptococcus agalactiae IPM 24842, and Providencia alcalifaciens CIP 82.90T. The disk diffusion assay showed a strong inhibitory effect against E. faecalis (inhibition zone: 19.66 ± 0.3 mm), while the lowest minimum inhibitory concentration (MIC) was observed for B. cereus (0.58 ± 0.01 µL/mL). The time-kill kinetics assay showed a progressive inactivation of all tested bacterial strains after their exposure to EO for 8 h at MICs. Furthermore, Molecular docking showed remarkable affinities between EO components, target proteins and DNA gyrase subunit B (GyrB). Moreover, the in silico ADMET predictions provided preliminary insights into the safety-related properties of the major EO components. In addition, EO compounds have the potential to interact with bacterial structures. These findings highlight the in vitro antibacterial potential of the M. rotundifolia EO and suggest its promise as a natural source of bioactive compounds.

This study aimed at producing a sourdough bread supplemented with two marine algae powders of Ulva lactuca and Gelidium corneum at 2.5, 5, 7.5, and 10% (w/w, g/100 g DW) at the laboratory scale using mixed starters prepared with three lactic acid bacteria (LAB) combinations (LCS1, LCS2, and LCS3). The phytochemical composition, nutritional value, organoleptic properties, and acceptability of algae bread by consumers were then assessed. Good results were obtained for enriched bread with Gelidium at 2.5% (GB1) with a reducing sugar of 0.77 ± 0.1%, total sugar of 36.90 ± 3.15, and protein content of 8.3 ± 0.2%. While total phenolic content was 8.32 ± 1.20 mg GAE/g DW, total flavonoids was 225.00 ± 11.31 mgQE/g DW, and the antioxidant activity ranged from 71.05 ± 3.71 to 82.93 ± 3.61%. Regarding enriched bread with Ulva at 10% (UB12), reducing sugar was 0.48 ± 0.03%, total sugar was 45.45 ± 5.75%, and protein content was 3.7 ± 0.07%. The total phenolic content value was 6.45 ± 1.19 mg GAE/g DW, total flavonoids was 191.20 ± 12.52 mgQE/g DW, while the antioxidant activity values ranged from 52.06 ± 6.21 to 80.51 ± 1.72%. Microbiological analysis showed that all pathogenic bacteria were not detected in algae bread. The consumer acceptability test revealed that bread enriched at the level of 10% of algae powder was significant for the five selected criteria (general appearance, crumb color, odor, taste, and texture). Traditional bread supplemented with Gelidium powder at 2.5% and Ulva powder at 10%, prepared with combined sourdough (LCS1), showed good antioxidant and nutritional properties and consumer acceptance.