A broad systemic review of 166 studies on medicinal and aromatic plants (MAPs) was conducted. The review was entitled, “Antimicrobial Properties of Plant Essential Oils against Human Pathogens and Their Mode of Action.”

The review assessed the results of the studies of, “Essential oils, extracted from various MAPs, [for their] strong antimicrobial activity against various bacterial, fungal, and viral pathogens.”

The review concluded that the primary mechanism of action of, “Essential oils against pathogens may be in [their] ability to disrupt the cell membrane of the targeted pathogens by increasing membrane permeability, inducing leakage of vital intracellular constituents, and interrupting the cellular metabolism and enzyme kinetics of the targeted pathogens.”

This ‘disruptive’ activity by essential oils upon pathogens results in their inability to proliferate and leads to their subsequent death.

The review noted that the presence of different kinds of chemical components such as aldehydes, phenols and terpenes makes essential oils effective agents against a variety of pathogens. 

Why All the Essential Oil Research?

More recently, the prevalence of multi resistant strains of bacteria and other microbes to drug resistance has prompted researchers to discover novel “new” antimicrobial molecules to treat human pathogens.

Scientific studies have shown in repeated case studies that essential oils have the ability to derail the growth of a wide variety of pathogens.

Studies have revealed that it is “the presence of natural bioactive chemical components of an oil [produced by the cells and organs of its mother plant] that effectively inhibit pathogenic growth.”

Importantly, it must be noted, that the characteristic aroma of an essential oil depends upon its chemical properties. In other words, the chemistry of an essential oil gives rise to its scent.

Nature's Complexity Science Can't Replicate

Science has attributed the very complex nature of essential oils to be what makes them so effective for treating cell pathogens. In other words, it is essential oils natural complexity that prevents pathogenic cells from mutating and eventuates in their death.

In contrast, when bugs are exposed to pharmaceutically derived agents [manufactured in a laboratory] which are simple in structure, the pathogens are able, over time, to mutate into new variants. This gives rise to new, more resistant strains of bugs and the subsequent release of new pharmaceuticals every years to combat them.

This vicious cycle repeats itself. Every year stronger and stronger ‘big’ gun antimicrobials are released by pharmaceutical companies to keep up with treating new variants of mutating bugs. This war on microbes by laboratory produced pharmaceutical agents results in more multi-resistant strains of microbes. This is especially the case with antibiotics as we’re seeing with the spread and high incidence of MRSA infections.

Healthcare Acquired Infections (HAI) in hospitals has become a growing cause for concern.

“In American hospitals alone, the Centers for Disease Control (CDC) estimates that HAIs account for an estimated 1.7 million infections and 99,000 associated deaths each year.” 

Future Natural Traditional Medicine

Its estimated that 80% of our world’s population is reliant upon naturally derived traditional plant-based medicines. According to the International Journal of Ayurvedic Medicine the natural medicinals market is projected to ‘grow up to 5 trillion USD by the year 2050.’

5 Most Effective Oils Against Pathogens

In this broad systemic review of 166 studies conducted on essential oils there were five EOs that stood out as THE most effective against a wide range of pathogens.

• Cinnamon (Cinnamomum zeylanicum)
• Cove (Eugenia caryophyllata)
• Thyme (Thymus vulgaris)
• Oregano (Origanum majorana)
• Rosemary (Rosmarinus officinalis)

# 1 Antimicrobial Essential Oil - Clove Bud

Of these five essential oils, the one oil that stood out above all of the rest tested was clove bud oil. Clove bud oil was hands down found to be THE most effective for treating a broad range of pathogens among all the EOS reviewed in this study. 

Why are these 5 Oils so Effective against Bugs?

The effectiveness of these EOs for antimicrobial action is connected to their major chemical components, among them carvacrol, thymol, cinnamic aldehyde, eugenol, and p-cymene (a monoterpene commonly found in thyme). 

Mechanisms of EO's antibacterial activity found included:

Bacteria

EO’s ability to destabilize a pathogen’s cellular structure, “Leading to the breakdown of membrane integrity and increased permeability, which disrupts many cellular activities, including energy production (membrane-coupled), membrane transport, and other metabolic regulatory functions.”  

Fungi

Oregano and thyme were shown to be the best inhibitors of fungal pathogens, because of their phenolic components, i.e. carvacrol and thymol, which were shown to disrupt fungal cell membranes.

Eugenol (an EO component of clove) was shown to cause ‘permanent damage’ to the common fungal infection, Candida albicans and was considered to be an “efficient antifungal agent.”

The antifungal actions of EOs were shown to be similar to the way bacteria were destroyed. Generally, fungal infections exposed to EPs  leads to the “coagulation of the cellular components because of irreversible cell membrane damage.”

Virus

EOs of oregano and clove also showed strong antiviral activity. 

Additionally, oils containing sesquiterpene chemical components showed antiviral activity, including different strains of the herpes viruses.

Patchouli (Pogostemon cablin), a sesquiterpene, when specifically targeted at the anti-influenza type A (H2N2) virus exhibited strong inhibition for the virus.

In the case of viruses the mechanisms of action are not as clearly discernible as with bacteria and fungi, but studies show the possible means of action to include inhibition for a virus’s ability to replicate by disrupting the cell’s DNA structure.