Physicochemical characteristics of the active fractions of polyphenols from Arctic macrophytes

Brown algae of the Fucaceae family, collected in the western segment of the Arctic, contain a large number of polyphenolic compounds—phlorotannins—with a unique chemical nature, macromolecular structure, and physicochemical properties, exhibiting bioactive properties. The peculiarity of the biopolymers’ properties and structure, which are an element of fundamental scientific research of the cycle, structure—functional nature—properties, determines the priority of the directions of use of polyphenols as effective biologically active pharmaceutical preparations. This work aims to develop methods for selective extraction of phlorotannins from the Arctic brown alga Fucus vesiculosus, characterization of physicochemical properties, and biological activity of these compounds. The efficiency of solid-phase extraction (SPE) on a hydrophobic sorbent with grafted hexadecyl groups was shown for fractionation of the polyphenolic extract: active fractions were obtained, characterized by a high content of polyphenols (yield of polyphenols up to 98% relative to the content of these components in algae) with mass-average molecular weights of 21.4–35.8 kDa and oligomeric components in the mass range 374–994 Da. The IR spectra of the fractions were characterized, and the tendency of phlorotannins to form aggregates at high concentrations of the extract was shown. During hydrodynamic studies, a strong polyelectrolyte swelling of polyphenols (PP) was noted. The obtained polyphenolic fractions differ in physicochemical characteristics (acid-base and redox properties) and antioxidant activity.