Efficacy of Various Extracting Solvents on Phytochemical Composition, Antioxidant Potential, Total Phenolic Content, and Antibacterial Properties, of Moroccan Mentha longifolia L. Leaf Extracts against Multidrug-Resistant Pathogenic Bacteria

Abstract

The current work attempts to explore the influence of three extraction solvents on phytochemical composition, content of polyphenols, antioxidant potential, and antibacterial capacity of Moroccan Mentha longifolia L. leaves hydroethanolic, acetonic, and water extracts. To achieve this goal, the chemical composition was identified using an HPLC-DAD examination. The contents of polyphenolswere assessed, while the total antioxidant capacity (TAC), the DPPH test, and the reducing power test (RP) were utilized to determine antioxidant capacity. To assess the antibacterial activity, the microdilution technique was carried out to calculate the minimum inhibitory (MIC) and minimum bactericidal concentrations (MBC) ofextracts against four nosocomial bacteria (Bacillus cereus, Pseudomonas aeruginosa, Escherichia coli, andStaphylococcus aureus).Additionally, the antibacterial and antioxidant activities of all tested extracts were examined in silico against the proteins NADPH oxidaseand Bacillus cereusphospholipase C. Study reveals M. longifolia extracts contain high phenolicand flavonoids.Additionally, the hydroethanolic extract contained the highest amounts of phenolic and flavonoid content, with values of 23.52± 0.14 mg GAE/g DW and 17.62± 0.36 mg QE/g DW, respectively comparedto the other two extracts. The same extract showed the best antioxidant capacity(IC₅₀=39 µg/mL± 0.00), and the higher RP (EC₅₀ of 0.261± 0.00 mg/mL), compared to the acetonic and water extractregarding these tests. Furthermore, the hydroethanolic and acetonic extracts expressed the highest TAC (74.40± 1.34, and 52.40± 0.20 mg EAA/g DW respectively), compared withthe water extract. Regarding antibacterial activity, the MIC value ranges between 1.17and 12.50 mg/mL. The in-silico results showed that the antibacterial activity of all extracts is principally attributed to kaempferol and ferulic acid, while antioxidant capacity is attributed to ferulic acid.