Biological potential of polysaccharides extracted from Nostoc colonies for film production -  Physical and biological properties.

Cyanobacteria of the Nostoc genus secrete a number of biologically active compounds, including polysaccharides, which may exhibit antioxidant, antimicrobial, anticancer, and anti-inflammatory properties. The aim of the study was to investigate the biological properties of Nostoc polysaccharides (NPs) (antioxidative and antimicrobial) and the possibility of using NPs addition in the production of biofoils. Our results allow to indicate that NPs were compatible with the used biopolymer matrix (furcellaran and chitosan) and showed antioxidant properties. The tested polysaccharide extracts (0.14%) exhibited the ability to neutralize free radicals - 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) at a level of 4.46% and 10.14%, respectively. NP extracts demonstrated reducing properties of 15.35 and 30.07 mg Trolox equivalents (FRAP and CUPRAC methods, respectively) and 2.64 mg chlorogenic acid equivalents (tested with Folin's reagent). NP extracts showed: a growth-stimulating effect (Escherichia coli, Staphylococcus aureus, and Saccharomyces cerevisiae), no effect (Penicillum sp.), or a slight inhibitory effect (Streptomyces sp.) on the tested microorganisms. The enrichment of the film with NPs influenced the physic-chemical properties of the obtained biofoils. The addition of polysaccharides to furcellaran and chitosan films decreased their water solubility (by approximately 40% and 9%, respectively, compared to the control) and, at the same time increased, their water absorption.