In vivo application of a small molecular weight antifungal protein of Penicillium chrysogenum (PAF)

• PAF, the antifungal protein of Penicillium chrysogenum, was not toxic in mice.
• Its intranasal application didn't induce pathological reactions in the lung.
• PAF retained its antifungal activity in lung extracts.
• Its application on the skin did not cause inflammation.

The antifungal protein of Penicillium chrysogenum (PAF) inhibits the growth of important pathogenic filamentous fungi, including members of the Aspergillus family and some dermatophytes. Furthermore, PAF was proven to have no toxic effects on mammalian cells in vitro. To prove that PAF could be safely used in therapy, experiments were carried out to investigate its in vivo effects.Adult mice were inoculated with PAF intranasally in different concentrations, up to 2700 μg·kg− 1 daily, for 2 weeks. Even at the highest concentration – a concentration highly toxic in vitro for all affected molds – used, animals neither died due to the treatment nor were any side effects observed. Histological examinations did not find pathological reactions in the liver, in the kidney, and in the lungs. Mass spectrometry confirmed that a measurable amount of PAF was accumulated in the lungs after the treatment. Lung tissue extracts from PAF treated mice exerted significant antifungal activity. Small-animal positron emission tomography revealed that neither the application of physiological saline nor that of PAF induced any inflammation while the positive control lipopolysaccharide did. The effect of the drug on the skin was examined in an irritative dermatitis model where the change in the thickness of the ears following PAF application was found to be the same as in control and significantly less than when treated with phorbol-12-myristate-13-acetate used as positive control.Since no toxic effects of PAF were found in intranasal application, our result is the first step for introducing PAF as potential antifungal drug in therapy.