Eugenol to treat Candida species infection

Eugenol, the chief phenolic component of Clove and Cinnamomum essential oil, is a novel therapeutic agent for the inhibition of Candida species infection, according to a review published in Frontiers in Pharmacology.¹

Eugenol could assist in the clinical management of candidiasis, especially localized forms like vulvovaginal and oral candidiasis, due to its fungicidal activity and inhibitory effect on germ tube formation.

The compound may also provide a synergistic effect in combination with fluconazole.

The review is 1 of 3 articles in the publication on the research topic discovering novel microbe-modulating agents from natural resources.

The authors cited high occurrence and mortality rates stemming from candidiasis, along with costly medical care, as reasons for new treatments.

Eugenol has been used to inhibit growth and different virulence factors of Candida, including strains with decreased susceptibility to antifungals; foremost, fluconazole.

“The results showed that this compound could bind to Candida membrane and decrease ergosterol biosynthesis, consequently leading to cell wall and membrane damage,” wrote the authors.

Eugenol not only reduced germ tube formation, thus decreasing nutrient absorption from host tissues, but increased the levels of lipid peroxidation and reactive oxygen species; hence, inducing oxidative stress and causing high permeability in the fungal cell membrane.

Eugenol inhibited Candida cells’ adhesion capacity. The compound also inhibited the formation of biofilms and eliminated Candida biofilms on a variety of surfaces.

The authors noted that by disrupting fungal cell integrity, eugenol might boost the entry of the antifungal drugs into the Candida cell and enhance treatment efficacy.

Overall, eugenol could be used in the clinical management of various presentations of candidiasis, particularly mucocutaneous presentations like oral and vulvovaginal infections.

Because of the potent anti-biofilm capacity of eugenol against Candida, coating medical implant devices with this compound may be practical in preventing implant-associated Candida infections.

The combined use of eugenol with various antifungals, especially fluconazole, might also be helpful in treating infections caused by drug-resistant Candida.

A recently published study in the journal Molecules found that eugenol could increase the efficacy of fluconazole against clinical Candida strains.2 For the study, the essential oil and methanolic and ethanolic extracts obtained from the aerial parts of Ocimum campechianum Mill. (Ecuador) were chemically characterized via gas-chromatography coupled to mass spectrometry detector (GC-MS) andhigh-performance liquid chromatography coupled to diode array-mass spectrometry detectors (HPLC-DAD-MS), then studied for their in vitro biological activity.

Essential oil and eugenol demonstrated notable activity against Pseudomonas syringae pv. syringae and a moderate effect against clinical Candida strains, along with potential synergism with fluconazole.

Studies on the genotoxicity and cytotoxicity of eugenol arecontroversial and limited. A dose of 2.5 mg/kg body weight of eugenol is considered safe by the Food and Agriculture Organization of the United Nations, but high concentrations of the compound could be harmful and pro-oxidative.

The review advocates in vivo and animal studies, toxicology studies, clinical trials and molecular analysis to improve formulations and develop novel antifungal agents based on eugenol.

References

1. Didehdar M, Chegini Z, Shariati A. Eugenol: a novel therapeutic agent for the inhibition of Candida species infection. Front Pharmacol. Published online August 9, 2022. doi:org/10.3389/fphar.2022.872127

2. Tacchini M, Echeverria Guevara MP, Grandini A, et al. Ocimum campechianum mill. from Amazonian Ecuador: chemical composition and biological activities of extracts and their main constituents (eugenol and rosmarinic acid). Molecules 26 (1), 84. doi:10.3390/molecules26010084