Molds are widespread microbes which could be found in indoor and outdoor environment. They have been recognized as possible causative agents of the indirect (noninfectious) pathologic changes in humans. Possible mechanisms of these pathologic events include immune (IgE)-mediated (hypersensitivity pneumonitis, allergic rhinitis and asthma), toxic (mucosal irritation) and carcinogenic (mycotoxins) mechanisms [1]. Prevention of those toxic effects includes decrease and elimination of molds conidia (in air) and mycelium (in walls) in indoor environment using fungicides, and mechanical methods, as well as heating/moisture control. Since some chemical fungicides exert adverse effects, the aim of presented study was to evaluate antifungal activity of low-molecular-weight natural metabolites from the class of alcohols: 2-phenyl-ethanol (2-PE) and levomenthol (LM) using serial broth twofold dilution assay [2] and vaporous microathmospheric contact assay [3] against twenty-two allergenic and/or toxigenic strains of ten mold species (Aspergillus, Penicillium, Absidia, Chaetomium, and Trichoderma) isolated from indoor air and from damp dwellings. 2-PE inhibited growth of molds with MIC values between 0.65 and 7.67mg/mL, and LM between 0.78 and 13.21mg/mL. Also, 2-PE exhibited stronger antifungal activity against Aspergillus spp. and Penicillium spp. (MICmean 7.67±4.04mg/mL; 5.78±4.41mg/mL, respectively) than LM (MICmean 13.21±10.06mg/mL; 13.20±10.17mg/mL, respectively). The most sensitive were Chaetomium globosum and Absidia spp. for which MICs of 2-PE were below 2.6mg/mL. In addition, 2-PE exhibited stronger activity with significantly lower MIC values against all tested molds, comparing to LM (MICmean 2-PE 5.59±4.32mg/mL; MICmean LM 10.15±9.98mg/mL, p<0.05). Contrary to the results of the dilution assay, a vaporous microathmospheric contact assay showed that 2-PE was less effective (inhibition of mycelium development in 5mg/100cm3) than LM (inhibition of mycelium development in 0.1mg/100cm3). These results indicate that fungicidal activity depends on nature of contact of 2-PE/LM with mycelium and/or conidia of molds, as well as volatility of tested substances.
References: [1] Chapman, M. D. (2006) Med Mycol 44:S29-S32. [2] Šegvić Klarić, M. et al. (2006) Lett Appl Microbiol 44: 36–42. [3] Inouye, S. et al. (1998) Mycoses 41: 403–410.
