Physico-Chemical Characteristics and Antioxidant Properties of Melanins Extracted From Leptogium Furfuraceum (Harm.)

Abstract

Melanins are universal biopolymers, the main biological function of which is to protect living organisms from adverse factors. Interest in these dark pigments arises due to the prospects for their use in medicine, cosmeceuticals, bioremediation, bioelectronics, and other fields. In this work, a complex scheme was developed to isolate melanins from the lichen Leptogium furfuraceum (Harm.), which is a symbiotic extremophilic organism. Screening of the conditions for the extraction of melanin, its subsequent precipitation and purification made it possible to isolate three samples of melanin with a total yield of 7.5% of the dry matter of the lichen. It was established that all isolated melanins have a polyaromatic structure, they contain carbohydrates and proteins, the content of which, depending on the conditions for melanin isolation, is 7.3–9.9% and 13.5–32.7%, respectively. Among the isolated melanins, melanin, which is a water-soluble fraction of acid-precipitated melanin, displays the highest antioxidant activity. This melanin, unlike other melanins, is almost fully soluble in distilled water, 95% ethanol, 99% dimethyl sulfoxide, and phosphate buffer (pH 7.4). The differences in solubility, antioxidant activity, and chelating capacity of isolated lichen melanins make it possible to determine potential areas for their practical use.

Neoplaca mirabilis, a new genus and a new epigaeic species containing naphthopyrans from the family Teloschistaceae

“…This pigment discoloured in reaction with oxidizing agents (0.5 М KMnO 4 , 30% H 2 O 2 ) and produced a brown precipitate with 1% FeCl 3 . These characteristics resemble those displayed by the pigment melanin (Khabibrakhmanova et al 2022); however, the solubility of our pigment in the organic solvents is not typical for melanin. Due to the scarcity of the available material, it was not possible to isolate enough brown pigment to obtain the infrared spectra that could confirm its assignment to melanin.…”

Greenhouse Gas Fluxes from the Epiphytic Lichens: Incubation Experiments

“…The melanization of the thalli due to UVB exposure can occur as a result of melanin formation in the phycobiont, which is one of the secondary metabolites that provide a variety of survival purposes in the natural environment [77,78]. In our study, brown spots cannot be the consequence of phycobiont thallus melanization during incubation under UVB radiation conditions (as in our second experiment with a UVB lamp, Figure 4), because thallus melanization does not impede photosynthetic processes in the photobiont due to the photoprotective capacity of melanin [79][80][81]. Furthermore, in the first incubation experiment (Figure 3), we solely employed LED lamps, which do not emit UVB light.…”

Preparation and properties of nanocomposite films based on carboxymethylcellulose and melanin from Cladosporium endophytic fungus

“…The last type, pyomelanin, was discovered in fungi and bacteria. Fungi and bacteria are important sources of melanin [11][12][13][14], and melanin protects them from environmental stresses [15]. Fungal melanin is of signi cant biotechnological interest because it can be produced at a low cost on a large scale, making it economically viable.…”