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Antioxidant function of melanin in black fungi
E S Jacobson1, E Hove, H S Emery
1McGuire Veterans Affairs Medical Center, Richmond, Virginia, USA.
Abstract:
1,8-Dihydroxynaphthalene melanin in Wangiella dermatitidis and Alternaria alternata was titrated in vivo with the oxidants permanganate, hypochlorite, and H2O2. Melanized strains neutralized more oxidant and withstood higher concentrations of permanganate and hypochlorite than albino strains did. H2O2 killing required 1,000-fold higher concentrations, and melanin did not protect W. dermatitidis against H2O2.
Insights
Melanin in fungi like Wangiella dermatitidis offers protection against oxidants such as permanganate and hypochlorite. However, melanin did not protect against hydrogen peroxide (H2O2) in this study.
Area of Science:
- Mycology
- Biochemistry
- Fungal Pathogenesis
Background:
- 1,8-Dihydroxynaphthalene (DHN) melanin is a key virulence factor in many pathogenic fungi.
- Melanin's role in fungal resistance to environmental stressors, particularly oxidants, is crucial for survival and pathogenesis.
Purpose of the Study:
- To investigate the protective role of DHN melanin against various oxidants in Wangiella dermatitidis and Alternaria alternata.
- To determine the differential efficacy of melanin in neutralizing different types of oxidants.
Main Methods:
- In vivo titration of 1,8-dihydroxynaphthalene melanin in melanized and albino strains of Wangiella dermatitidis and Alternaria alternata.
- Exposure of fungal strains to increasing concentrations of oxidants: potassium permanganate, sodium hypochlorite, and hydrogen peroxide (H2O2).
- Assessment of fungal survival and oxidant neutralization capacity.
Main Results:
- Melanized fungal strains demonstrated enhanced neutralization of permanganate and hypochlorite compared to albino strains.
- Higher concentrations of permanganate and hypochlorite were tolerated by melanized strains.
- Melanin did not confer significant protection against hydrogen peroxide (H2O2); extremely high concentrations were required to observe any killing effect on W. dermatitidis.
Conclusions:
- DHN melanin provides a significant protective barrier against certain oxidants, contributing to fungal resilience.
- The protective efficacy of melanin is oxidant-specific, with limited protection observed against hydrogen peroxide.
- Understanding melanin's role in oxidant resistance is vital for developing targeted antifungal strategies.