Eugenol Induces Phenotypic Alterations and Increases the Oxidative Burst in Cryptococcus.

Júnia C O Alves,Gabriella F Ferreira,Julliana R Santos,Andrea S Monteiro,Luciana S Guzzo,Vera L Dos Santos,Áquila R C Santos,Lourimar V N F Sousa,João F S Rodrigues,Thiago R L Romero,Ângelo M L Denadai,Brenda S Mendes,Wallace R N Neto,Emmanueli I Farah,Luís C N Silva,Daniel A Santos,Andrea C Perez

doi:10.3389/fmicb.2017.02419

Abstract

Eugenol is a phenolic compound and the main constituent of the essential oil of clove India. Although there are reports of some pharmacological effects of eugenol, this study is the first that proposes to evaluate the antifungal effects of this phenol against both Cryptococcus gattii and C. neoformans cells. The effect of eugenol against yeast cells was analyzed for drug susceptibility, alterations in cell diameter, capsule properties, amounts of ergosterol, oxidative burst, and thermodynamics data. Data demonstrated that there is no interaction between eugenol and fluconazole and amphotericin B. Eugenol reduced the cell diameter and the capsule size, increased cell surface/volume, changed positively the cell surface charge of cryptococcal cells. We also verified increased levels of reactive oxygen species without activation of antioxidant enzymes, leading to increased lipid peroxidation, mitochondrial membrane depolarization and reduction of lysosomal integrity in cryptococcal cells. Additionally, the results showed that there is no significant molecular interaction between eugenol and C. neoformans. Morphological alterations, changes of cellular superficial charges and oxidative stress play an important role in antifungal activity of eugenol against C. gattii and C. neoformans that could be used as an auxiliary treatment to cutaneous cryptococcosis.

Highlights

Cryptococcosis is a systemic mycosis caused mainly by Cryptococcus neoformans and C. gattii species (Hagen et al, 2015)
With complete reduction of growth after 36 h against C. gattii and 72 h against C. neoformans, both in minimum inhibitory concentration (MIC) concentration (Figure 1B), and 2× MIC
It was observed that there was no interaction between eugenol and the antifungal drugs fluconazole and amphotericin B against two C. gattii strains and two C. neoformans strains (Figure 1C)

Summary

Introduction

Cryptococcosis is a systemic mycosis caused mainly by Cryptococcus neoformans and C. gattii species (Hagen et al, 2015). Disseminated cryptococcosis is the worst prognostic of the disease, and can affect several organs beyond lungs, such as the central nervous system and skin (Chayakulkeeree and Perfect, 2006). Pathological manifestations in the skin, that occurs in 10– 20% of patients, are characterized by different clinical features including ulcers, subcutaneous nodules, and cellulitis (Chayakulkeeree and Perfect, 2006; Capoor et al, 2008; Ikeda et al, 2014). An alternative strategy for the treatment of cutaneous and subcutaneous cryptococcosis would be the application of formulations based on natural products derived from plants such as essential oils (Lemos et al, 2005; Baptista et al, 2015). Essential oils are complex mixtures of organic compounds, like diterpenes, monoterpenes, sesquiterpenes, and phenylpropanoids (Tadic, 2012; Gazim et al, 2014)

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