Volatile organic compounds and their capacity for controlling fungal infection in humans

Abstract

It is estimated that over 30% of the worlds' population has ever had a fungal infection. The most common fungal diseases are nail and skin infections, which are mainly caused by fungi of the genus Trichophyton spp., Epidermophyton spp., or Microsporum spp. Onychomycosis is a fungal infection that affects mainly nails, but can also cause foot and leg ulcerations, leading to extreme situations, such as limb amputation. Among dermatophytes, T. rubrum is mainly responsible for skin infections. Antifungal compounds, such as azoles, allylamines, and amorolfine (administered orally or topically), are usually used in the treatment of this disease. The oral mucosa and the genital tract are other targets of attack by fungal pathogens. In these cases, yeasts of the genus Candida spp. play a crucial role. It is estimated that about 75% of women have suffered Candida spp. vulvovaginitis at least once in their lives. Other opportunistic pathogenic fungi that frequently affect human health are some species belonging to the genus Cryptococcus spp. (cutaneous mycoses and opportunistic mycoses) and Aspergillus spp. (allergic reactions, keratitis and opportunistic onychomycosis). The usual problem for the treatment of these infections is the fungal resistance to azoles, polyenes, echinocandins, among other existing drugs. In this context, there is an urgent need to find out new alternatives for the treatment of fungal infections. Natural products, such as volatile organic compounds, essential oils, or their components, have shown promising antifungal activities. In this chapter, we will discuss the latest findings about the antifungal activity of volatile organic compounds, essential oils, and their individual components against fungi of clinical importance. Moreover, the structure related to the antifungal activity of these natural compounds, their mechanisms of action, and their synergistic properties will also be explored.