A new laboratory study has found clove oil and its active component to be effective antifungal agents against Candida and other fungal pathogens.
Researchers at the University of Porto, Portugal, studied the composition and antifungal activity of clove essential oil which is extracted from the Syzygium aromaticum plant.
Commercially available clove oil was analyzed by the scientists and found to have a high concentration of eugenol (85.3%), the active antifungal ingredient. To find out exactly how strong the antifungal effects of clove oil and eugenol are against a range of fungal organisms including strains of Candida, Aspergillus, and dermatophytes, the minimal inhibitory concentration (MIC), and minimal fungicidal concentration (MFC) were determined.
In microbiology the MIC represents the minimum amount of an antimicrobial substance needed to inhibit the growth of a microorganism after it is incubated overnight. So in the context of this study it is the lowest dose of clove oil or eugenol needed to prevent the growth of the strains of Candida, Aspergillus, and dermatophytes tested. The MFC in contrast is the minimum amount of an antifungal required to actually kill a given fungal organism. The MIC is considered a more accurate measure as recognised standards for measuring the MIC are established whereas they are not for MFC.
The researchers found that both whole clove oil and eugenol showed inhibitory activity against all the fungal strains tested.
To find out exactly how clove oil and eugenol exert their antifungal activity against yeast and fungal organisms the researchers used a variety of techniques. They report that when concentrations just over the MICs for each species were used the cells of the organisms were ruptured and cell death occurred due to extensive lesions of the cell membranes.
Clove oil and eugenol also caused a significant reduction in the quantity of ergosterol produced by Candida species and other test organisms. Ergosterol is an important component of yeast/fungal cell membranes.
Finally, the researchers found that concentrations below the MIC values for both whole clove oil and eugenol almost entirely prevented the production of hyphae by Candida albicans. Hyphae are branching filaments that extend out from the cells of Candida albicans and other fungi and can penetrate tissues in the body. Hyphae penetrating the walls of the intestines are thought by some to contribute to increased intestinal permeability, or leaky gut syndrome.
The Portuguese researchers conclude that "...clove oil and eugenol have a considerable antifungal activity against clinically relevant fungi, including fluconazole resistant strains, deserving further investigation for its clinical applications on the treatment of fungal infections".
Fluconazole (Diflucan) is one of the most common systemic antifungal drugs in use today so the fact that clove oil is effective against strains of fungi resistant to it is significant.
Clove oil has the benefits of being cheap and and potentially having fewer side-effects than azole drugs such as Diflucan which can be toxic to the liver.
Clove oil may therefore be useful in many situations involving fungal infections, e.g. in those with compromised immune systems such as AIDS patients and cancer patients undergoing chemotherapy, or even those with chronic fatigue syndrome (ME/CFS), fibromyalgia, Gulf War syndrome, and related conditions, who often have recurrent Candida/fungal infections.
It has also been suggested that Candida overgrowth in the GI tract may be responsible for a host of symptoms in people with chronic unexplained illness, since Candida produces a variety of toxins including ethanol and acetaldehyde. Doctors working at Biolab (UK) have published a number of studies suggestive of this, for example.
Source: Pinto E Vale-Silva L Cavaleiro C Salgueiro L (2009) Antifungal activity of the clove essential oil from Syzygium aromaticum (Eugenia caryophyllus) on Candida, Aspergillus and dermatophyte species Journal of Medical Microbiology [Epub ahead of print]