Abstract

Invasive fungal infections have been gaining notoriety due to several factors, mainly their increasing incidence in immunocompromised patients. The aim of the present study was to evaluate the antifungal activity and toxicity of the 3,4,5-trihydroxybenzoic acid (3,4,5-THB) and of its derivative, the 3,4,5-tris(acetyloxy)benzoic acid (3,4,5-TAB). The 3,4,5-THB was purchased and its derivative was obtained by purifying and characterizing performed using semisynthesis reactions (esterification), recrystallization, column chromatography and infrared analytical techniques and nuclear magnetic resonance. Minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) were determined in order to evaluate the antifungal activity of the compounds against four clinical isolates and four standard strains of Candida sp. and five clinical isolates of dermatophytes, following the Clinical and Laboratory Standards Institute protocols. The toxicity of the compounds was evaluated by determining the lethal dosis (LD50) using lethality assay of Artemia salina. The most sensitive yeasts to the 3,4,5-THB were C. albicans ATCC 10231 and C. krusei ATCC 6258, both presenting a MIC of 128 μg·mL-1. For Trichophyton sp. and Epidermophyton floccosum, the MIC was 32 μg·mL-1. The 3,4,5-TAB showed a lower inhibitory activity against Candida and dermatophyte species tested. The LD50 of 3,4,5-THB was 222.60 μg·mL-1 and the 3,4,5-TAB showed 481.69 μg·mL-1 of LD50. In conclusion, the 3,4,5-trihydroxybenzoic acid showed antifungal activity against species of medical importance, mainly dermatophytosis-causing fungi, and the 3,4,5-tris(acetyloxy)benzoic acid showed no increasing antifungal activity and toxicity in relation to the original compound.

Highlights

  • There has been a significant increase in reports of serious human infections associated with fungal pathogens in recent years, especially in immunocompromised patients

  • The antifungal activity of the compounds was evaluated against eight yeasts of the species Candida albicans ATCC 10231, C. albicans M1 and C. albicans D5; C. glabrata D10R; C. parapsilosis ATCC 90018; C. krusei ATCC 6258; C. tropicalis ATCC 13803 and C. dubliniensis CD1; and five strains of dermatophytes (Trichophyton rubrum FF5, Trichophyton mentagrophytes FF7, Epidermophyton floccosum FF9, Microsporum canis FF1 and Microsporum gypseum FF3)

  • The results obtained from the antifungal susceptibility tests, Minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC), for the different compounds are shown in Table 1, the test interval was kept between 512 - 32 μg·mL−1

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Summary

Introduction

There has been a significant increase in reports of serious human infections associated with fungal pathogens in recent years, especially in immunocompromised patients. Fungal infections contribute substantially to human morbidity and mortality, the impact of these diseases in human health is not widely appreciated. Candida and Aspergillus species are the most frequent nosocomial fungal pathogens. The most common fungal diseases in humans are superficial infections of the skin, hair and nails, which affect approximately 25% of the world’s population. They are predominantly caused by dermatophytes (Microsporum, Trichophyton and Epidermophyton) and affect immunocompromised and healthy persons [1]-[5]

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