Characterization and Biological Activities of Melanin from the Medicinal Fungi .

Melanin is a complex natural pigment that is widely present in fungi. The mushroom has a variety of pharmacological effects. The active substances of have been extensively studied, but few studies have focused on the melanin. In this study, the production of melanin was increased by adding light or oxidative stress, namely, reactive oxygen species (ROS) or reactive nitrogen species (RNS), during liquid fermentation. Subsequently, the structure of the purified melanin was characterized using elemental analysis, ultraviolet-visible absorption spectrum, Fourier transform infrared (FTIR), electron paramagnetic resonance (EPR), and pyrolysis gas chromatography and mass spectrometry (Py-GCMS). Studies have shown that melanin is composed of C (50.59), H (6.18), O (33.90), N (8.19), and S (1.20), with maximum absorbance at 237 nm and typical melanin structures such as benzene, indole, and pyrrole. Additionally, the various biological activities of melanin have been discovered; it can chelate heavy metals and shows a strong ultraviolet-blocking ability. Moreover, melanin can reduce the levels of intracellular reactive oxygen species and counteract the oxidative damage of HO to cells. These results can help us to develop applications of melanin in radiation resistance, heavy metal pollution remediation, and antioxidant use.