Satureja montana L. and Origanum majorana L. Decoctions: Antimicrobial Activity, Mode of Action and Phenolic Characterization

Medicinal and aromatic plants are known to have a wide range of uses and health benefits, and should be exploited for their bioactivity. Here we evaluated the antimicrobial activity of decoctions of <i>Satureja montana</i> L. and <i>Origanum majorana</i> L. against Gram-positive and Gram-negative bacteria and <i>Candida</i> spp. as well as their mechanism of action and phenolic characterization. The <i>Satureja montana</i> and <i>Origanum majorana</i> extracts were effective against a broad set of species, including the Gram-positive <i>Staphylococcus aureus</i>, <i>Enterococcus faecalis,</i> and <i>Streptococcus dysgalactiae</i> and the Gram-negative <i>Klebsiella pneumoniae</i> and <i>Pseudomonas aeruginosa</i>. Both extracts were found to have rosmarinic acid as the main phenolic compound and to exert their antimicrobial activity at the level of the cell membrane. Membrane perturbations by the extracts impaired cell membrane integrity only a few hours after exposure. This study confirms the bioactive potential of <i>Satureja montana</i> and <i>Origanum majorana</i> decoctions, and supports the development of novel formulations with wide antimicrobial properties based on these medicinal and aromatic herbs.