Exploitation of the Antibacterial Activity of Micromeria graeca L. Extracts From Northern Morocco

Abstract

Micromeria graeca L. is an aromatic plant rich in bioactive molecules with potential antimicrobial properties. This study evaluated the antibacterial activity of extracts obtained using different solvents and extraction techniques. Among the tested samples, the methanolic ultrasound-assisted extract (MGME-UAE) exhibited the strongest bactericidal effect, selectively inhibiting Proteus mirabilis (inhibition zone 12.7 ± 0.6 mm; minimum inhibitory concentration [MIC] = 6.25 mg/mL). Liquid chromatography coupled with photodiode-array and electrospray ionization–mass spectrometry (LC–PDA/ESI–MS) profiling revealed sagerinic acid (30.37 ± 0.70 mg/g), 5-caffeoylquinic acid, and caffeic acid as major constituents. Mechanistic assays showed that MGME-UAE increased membrane permeability, causing significant leakage of DNA/RNA and proteins, which was further confirmed by scanning electron microscopy (SEM) visualization of cell wall disruption. These findings highlight M. graeca as a promising source of natural antibacterial agents, particularly against P. mirabilis.