TABLE 3.
Mode of action of select EOs/EOC against ESKAPE pathogen.
| Essential oils | Pathogen | Mode of action | References |
| Chenopodium ambrosioides/α-Terpinene | S. aureus (IS-58) | Inhibition of EPs (tetK) | Limaverde et al., 2017 |
| C. ambrosioides/α-Terpinene | S. aureus (1199B/1199) | Inhibition of EPs (norA) | Salehzadeh et al., 2018 |
| C. verum | K. pneumoniae | Induction of oxidative stress and oxidation/DBM | Yang et al., 2019 |
| C. cyminum | K. pneumoniae | Loss of plasmid integrity | Derakhshan et al., 2008 |
| Dodartia orientalis | S. aureus | DBM | Wang et al., 2017 |
| Dorema aucheri Bioss | P. aeruginosa PAO1 | QS-inhibition, reduction on virulence factors (RVF) (pyoverdine and elastase production), and the transcription of lasI | Sepahi et al., 2015 |
| Ferula asafoetida L. | P. aeruginosa PAO1 | QS-inhibition, RVF (pyocyanin, pyoverdine, elastase production), and the transcription of lasI | Sepahi et al., 2015 |
|
Melaleuca alternifolia (tea tree oil) |
P. aeruginosa NCTC 6749 | DBM and metabolic events | Cox et al., 2001 |
| Melaleuca alternifolia | Methicillin-resistant S. aureus, Carbapenem-resistant K. pneumoniae, A. baumannii, and P. aeruginosa | DBM (structural integrity and membrane permeabilization) | Oliva et al., 2018 |
| Tea tree oil | S. aureus | Cell division inhibition | Reichling et al., 2002 |
| Mentha piperita L. | S. aureus | Inhibition of α-toxin production (ITP) | Li et al., 2011 |
| Mentha piperita L. | P. aeruginosa PAO1 | QS-RVF (elastase, proteases, pyocyanin and chitinase) | Husain et al., 2015 |
| Ocimum gratissimum | P. aeruginosa and S. aureus | Change in membrane permeability (CMP) | Hyldgaard et al., 2012 |
|
Origanum vulgare (oregano oil) |
P. aeruginosa and S. aureus | Bacterial enzyme inhibition and reduce bacterial lipase and coagulase activity | Lambert et al., 2001 |
| Rosmarinus officinalis/1,8-cineol | MDR K. pneumoniae | CMP | Moreno et al., 2015 |
| Rosmarinus officinalis/Eucalyptol | MDR A. baumannii and P. aeruginosa | Inhibition of EPs | Saviuc et al., 2016 |
| Origanum vulgare L. | S. aureus | ITP | De Souza et al., 2010 |
| Perilla frutescens L. Britton | S. aureus, MRSA | ITP | Qiu et al., 2011 |
| Syzygium aromaticum/Eugenol | MRSA | Anti-QS and anti-biofilm | Al-Shabib et al., 2017 |
| Syzygium aromaticum | P. aeruginosa | QS- Inhibit swarming motility | Khan et al., 2009 |
| Thymus vulgaris/thymol | S. aureus | Inhibition of EPs (norA) | Salehzadeh et al., 2018 |
| Essential oil components | |||
| Allicin | MSSA and MRSA | ITP | Leng et al., 2011 |
| Carvacrol | S. aureus | DBM | Di Pasqua et al., 2007 |
| Carvacrol | S. aureus | Inhibit enterotoxin production completely | Souza et al., 2013 |
| Carvacrol | MRSA | Anti-QS and anti-biofilm | Sharifi et al., 2018 |
| Carvacrol | S. aureus | Changes in fatty acid composition | Noumi et al., 2018 |
| Carvacrol | P. aeruginosa | QS-Inhibition (pyocyanin production, biofilm) | Tapia-Rodriguez et al., 2017 |
| Carvone | MRSA | Disruption and separation of the cytoplasmic contents by R-cat | Oosterhaven et al., 1995 |
| Cinamoldehyde | Carbapenem resistant A. baumannii | Anti-biofilm | Mohamed et al., 2018 |
| Cinamoldehyde | P. aeruginosa PA01 | QS-Inhibition 7-fold of the lasR level, and pyocyanin production | Ahmed et al., 2019 |
| Curcumin | P. aeruginosa PA01 | QS-Inhibition 2-fold of elastase activity | Rudrappa and Bais, 2008 |
| Curcumin | P. aeruginosa PA01 | QS-Inhibition (alginate and prodigiosin production) | Packiavathy et al., 2014 |
| Eugenol | S. aureus | Inhibit enterotoxin and α-hemolysin production significantly | Qiu et al., 2010 |
| Farnesol and nerolidol | S. aureus | Cytoplasm disruption (alteration of integrity and permeability, inhibition of cell respiration, K+ leakage) | Cox et al., 2000; Inoue et al., 2004 |
| 6-Gingerol | P. aeruginosa | QS-Inhibition (biofilm formation, 53%), RVF (exoprotease, pyocyanin and rhamnolipid) | Kim et al., 2015 |
| Linalyl acetate | S. aureus | DBM and leakage of intracellular materials | Trombetta et al., 2005; Mahizan et al., 2019 |
| Linalyl anthranilate | Carbapenemase-producing K. pneumoniae | DBM and leakage of intracellular materials | Yang et al., 2021 |
| Menthol | S. aureus | DBM and leakage of intracellular materials | Trombetta et al., 2005; Mahizan et al., 2019 |
| Menthol | S. aureus, MRSA | ITP | Qiu et al., 2010 |
| Menthol | P. aeruginosa PA01 | QS-Inhibition, Anti-biofilm, RVF (protease activity, elastase activity, chitinase activity, pyocyanin production, swarming motility, EPS production) | Husain et al., 2015 |
| β-pinene | E. faecalis | Anti-biofilm | Negreiros et al., 2016 |
| Thymol | S. aureus | DBM and leakage of intracellular materials | Trombetta et al., 2005; Mahizan et al., 2019 |
| Thymol | MRSA | Anti-biofilm and anti-quorum sensing | Sharifi et al., 2018 |
| Thymol | S. aureus; MRSA | Inhibit α-hemolysin, enterotoxin production | Qiu et al., 2011 |
| α- and γ-terpinene | S. aureus | DBM | Mahizan et al., 2019 |
| Terpinene-4-ol | MRSA | Anti-QS and anti-biofilm | Perez et al., 2019 |
| Terpinene-4-ol | S. aureus | Formation of multilamellar, mesosome-like structures | Carson et al., 2002; Reichling et al., 2002 |
| Zingerone | P. aeruginosa PA01 | QS-Inhibit protease production | Kumar et al., 2015 |
CMP, change in membrane permeability; DBM, disruption of bacterial membrane; Eps, extracellular polymeric substances; ITP, inhibition of α-toxin production; QS, quorum sensing.