# Fungal Pigments and Their Roles Associated with Human Health
## 5 Medical Relevance of Fungal Pigments
### Medical Roles of Melanins  
Recent studies with fungi capable of producing melanin (also called melanotic fungi) have revealed a wide spectrum of functions for this kind of pigment, ranging from drought and radiation resistance to increased virulence in fungal pathogens. For example, melanotic fungi are present in diverse environments including but not limited to radiation-contaminated soils (e.g., the Chernobyl nuclear power station and the surrounding soils), Antarctic deserts, ancient cave paintings, and spacecraft, etc. In fact, melanized fungi, including spores of _Aspergillus niger_, _Cidasporium herbarum_, _Ullocalium chartatum_, _Basipetospora halophile_, etc., have been reported to be able to grow on the Mir Space Station and International Space Station. Some edible mushrooms (Basidiomycetes) are rich in melanins as well. Melanins contain persistent free radical centers, as detected by electron paramagnetic resonance (EPR) spectroscopy. These free radical centers allow melanins acting as antioxidants to scavenge free radicals and to protect the fungi from oxidative stress and damage by ionizing radiation in both atmospheric and terrestrial environments [129]. In a recent study [130], [PERSON] et al. compared the effects of densely-ionizing deuterons and sparsely ionizing X-rays on two melanogaster fungal species, namely the fast-growing pathogenic basiodiomycete _Cryptococcus neoformans_ and the slow-growing Antarctic rock-inhibiting _Cryomyces antarcticus_ to their non-melanized counterparts. _C. antarcticus_ showed more resistance to deuterons than _C. neoformans_, and similar resistance to X-rays was observed for both species. Melanin offered protection against high-dose (1.5 kGy) deuterons for both _C. neoformans_ and _C. antarcticus_ (\(p<10^{-4}\)). In addition, melanin protected _C. antarcticus_ (\(p<10^{-4}\)) and probably _C. neoformans_ against X-rays (0.3 kGy). The use of both XTT (2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)25-[(phenyl-amino)carbonyl]-2H-tetrazol hydroxide) and MTT (2-(4,5-dimethyl-2-thiazol)]23,5-diphenyl-2H-tetrazololium bromide) assays in parallel helped define the location of the melanin-mediated electron transfer in the cells. Deuterons increased XTT activity in melanized strains of both species, while the activity in non-melanized cells remained unchanged or decreased. The opposite was observed with levels of ATP (the indicator of the metabolic activity of cells): upon exposure to deuterons, ATP decreased in melanized strains, but not in non-melanized ones. Larger and more distinct differences in both XTT and ATP were found in _C. neoformans_ than in _C. antarcticus_. Further research by [PERSON] et al. revealed that _C. antarcticus_ could produce both 1,8-dihydroxymorphthalene (DHN) and L-3,4- dihydroxyphenylalanine (L-DOPA) melanins, which likely contribute to its ability to thrive under diverse stress conditions [131]. Together, these results indicate for the first time that melanin could protect both fast- and slow-growing fungi from high-dose radiation (deuterons in this case) under physiological conditions [130]. Indeed, the remarkable ability of melanin to confer resistance to radiation led to further research that revealed that melanized fungi could harvest radiation energy for their growth and reproduction. Broadly speaking, such an ability has both fundamental ecological significance and practical implications. Ecologically, the ability of melanotic fungi to make use of electromagnetic radiation for their physiological processes helps us understand energy flows in the biosphere. Practically, the understanding paves the way for potentially developing melanin-based radiation resistant materials and equipment. In astrobiology and space travel, melanin represents a new type of material with which to experiment for space travel [132]. The unique stress-resistance properties of _C.