Phenol group of terpenoids is crucial for antibacterial activity upon ion leakage

Abstract

Plant tissues are natural sources of bioactive molecules to control pathogens that cause infections in plants and humans, as they contain secondary metabolites with antibacterial activities. Especially, terpenoids are responsible for the protection of various plants against herbivores and pathogens. In this study, we studied the antibacterial activity of 12 different terpenoid or related structures in a comparative way and revealed that the phenolic terpenoids are superior to other substituted derivatives against both Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus bacteria. We also aimed to analyse effect of these compounds on the bacteria cell wall structure and maintenance of homeostasis. We observed an immediate loss of cell membrane integrity and ion leakage upon treatment of both Gram‐negative and Gram‐positive cells with phenolic terpenoids carvacrol and thymol. After prolonged treatment, leakage of genetic material and increase of membrane permeability for molecules were also observed. Hydroxyl group of the phenol moiety was essential for this effect, since neither the O‐methyl derivatives nor the benzylic partners were as effective. We thus propose that perturbation of ion homeostasis upon increase in cell wall permeability is key for the action of terpenoids against bacteria cells.

Potential Application of Luteolin as an Active Antibacterial Composition in the Development of Hand Sanitizer Products

“…Many secondary metabolites produced by normal metabolic pathways in plants have potential antimicrobial activities. Compounds, including polyphenols, flavonoids, quinones, and terpenoids, can target bacteria by changing membrane permeability, inhibiting the synthesis of enzymes, or blocking biochemical reactions [ 2 , 3 , 4 ]. Among these compounds, it has been described that flavonoids can exert their antibacterial effects, namely by direct killing of bacteria, synergistic activation of antibiotics, and reducing bacterial pathogenicity [ 5 ].…”

Tagetes lucida Cav. essential oil and the mixture of its main compounds are antibacterial and modulate antibiotic resistance in multi-resistant pathogenic bacteria

“…The antibacterial capacity is related to the structure of the molecules; for example, the compounds with oxygen or hydroxyl groups in their structure are more likely to have antiseptic and antimicrobial activity (Ergüden 2021). Specifically, geraniol, linalool and estragole possess that property; hence their antibacterial activity is due to the presence of those functional groups (Domingo and López‐Brea 2003; Rojas et al .…”

Comparative Physicochemical and Biochemical Characterization of Small-Molecule Glucosides

“…Monoterpenols and phenols as well as alkyl glycosides show a broad-spectrum antimicrobial activity. ,, Therefore, the minimal inhibitory concentrations (MIC) of SMGs against E. coli BL21 were determined and plotted against their log P values (Figure ).…”