COMPLEX FORMATION OF IRON IONS WITH FUNGAL MELANINS

Abstract

The paper presents and discusses the results of experimental studies of the complex formation of iron ions with melanins isolated from forest beech chaga (faqus sylvatica) and birch chaga (betula), which exhibit high antioxidant activity. Melanins were isolated by alkaline extraction and precipitation in an acidic medium. To identify the isolated pigments, their IR and EPR spectra were recorded. The complex formation of iron ions with these melanins was studied by the method of gamma-resonance spectroscopy (GRS). It has been established that fungal melanins are able to effectively bind iron ions both in their two- and three-valence states. It is significant that fungal melanins, like melanins of animal and plant origin, are able to directly bind prooxidant Fe2+ ions and oxidize them to prooxidant inactive Fe3+ with subsequent complexation. The activity of these processes increases as the pH of the reaction medium increases and the suspension is illuminated with visible light.