Scleroderma citrinum melanin: isolation, purification, spectroscopic studies with characterization of antioxidant, antibacterial and light barrier properties

The aim of this study was to isolate and evaluate biological properties of raw and purified melanins isolated from Scleroderma citrinum. Native melanin was isolated from the gleba of fresh S. citrinum fruiting bodies by alkaline extraction. Obtained pigment was purifed by acid hydrolysis and washed by organic solvents. Chemical tests, FT-IR and Raman spectroscopy analysis were conducted to determine the melanin nature of the isolated pigments. UV-Vis, transmittance, total polyphenolic content and colour properties were evaluated. Antioxidant activity was determined using ABTS and antibacterial activity by a well diffusion method. The results of the study demonstrated that melanins isolated from S. citrinum had antioxidant, light barrier and antibacterial properties. A purified form of melanin offered better light properties and higher antioxidant activity than the raw form. Both melanins inhibited the growth of E. facealis and P. aeruginosa. This study revealed that S. citrinum may be considered as a promising source of natural melanin. Isolated pigments presented all the physical and chemical properties common to natural and synthetic melanins. Raw and purified melanins showed differences in chemical composition, antioxidant activity and light barrier properties. Results suggest that, melanins from S. citrinum possess remarkable therapeutic action and could be applied in the food, cosmetics and pharmaceutical industries.