Complex arabinose-containing polysaccharides from cyanobacterium Nostoc sp.: Extraction, structural characterization and antioxidant activity

Amal D Premarathna; Vitalijs Rjabovs; Sanjida Humayun; Clarisa Naa Shormeh Darko; Marju Robal; Tamer A E Ahmed; Maxwell T Hincke; Rando Tuvikene

doi:10.1016/j.ijbiomac.2025.141793

Complex arabinose-containing polysaccharides from cyanobacterium Nostoc sp.: Extraction, structural characterization and antioxidant activity

Int J Biol Macromol. 2025 Mar 7;307(Pt 2):141793. doi: 10.1016/j.ijbiomac.2025.141793. Online ahead of print.

Authors

Amal D Premarathna¹, Vitalijs Rjabovs², Sanjida Humayun³, Clarisa Naa Shormeh Darko³, Marju Robal³, Tamer A E Ahmed⁴, Maxwell T Hincke⁵, Rando Tuvikene⁶

Affiliations

¹ School of Natural Sciences and Health, Tallinn University, Narva mnt 29, 10120 Tallinn, Estonia. Electronic address: amald@tlu.ee.
² National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia; Institute of Chemistry and Chemical Technology, Riga Technical University, Paula Valdena iela 3/7, LV-1048, Riga, Latvia.
³ School of Natural Sciences and Health, Tallinn University, Narva mnt 29, 10120 Tallinn, Estonia.
⁴ Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ontario K1H 8M5, Canada; School of Nutrition Sciences, Faculty of Health Sciences, University of Ottawa, Ontario K1H 8M5, Canada.
⁵ Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ontario K1H 8M5, Canada; Department of Innovation in Medical Education, Faculty of Medicine, University of Ottawa, Ontario K1H 8M5, Canada.
⁶ School of Natural Sciences and Health, Tallinn University, Narva mnt 29, 10120 Tallinn, Estonia. Electronic address: rantuv@tlu.ee.

PMID: 40058433
DOI: 10.1016/j.ijbiomac.2025.141793

Abstract

Freshwater Nostoc sp. polysaccharides (NSPs) have not been extensively studied, particularly regarding their structural and biological characteristics. This study assessed the extracted NSPs through a multi-faceted characterization approach using ¹H and ¹³C NMR, FTIR spectroscopy, HP-SEC and HPAEC-PAD. The study presented novel insights into the extracted polysaccharide composition, extraction efficiency, and antioxidant activities. NSPs were extracted using two different ranges of heating regimes: cold (25 °C) and hot (95 °C), with hot extraction yielding up to 34.9 % of NSPs compared to 27.6 % from cold extraction. The NSPs were non-sulfated and mainly composed of four monosaccharide residues: (1 → 3)-β-d-mannopyranose-(1 → 4)-β-l-arabinopyranose-(1 → 4)-β-d-glucuronic acid-(1 → 4)-β-d-glucopyranose. Some glucose units were 6-O-methylated, and minor sidechain glycosylation by other monosaccharides was observed. β-d-glucuronic acid was present in higher amounts. The polysaccharides from the inner fluid (IF) fraction exhibited a higher molecular weight (up to 480 kDa) compared to outer layer (OL) fractions. The total phenolic content (TPC: 0.2 ± 0.0-2.8 ± 0.0 %), total sugar (9.1 ± 0.8-67.8 ± 0.4 %), and protein (1.2 ± 0.1-25.9 ± 0.6 %) content were determined. NSPs, especially from cold extraction (1B) exhibited the highest antioxidant activity, have potential applications in the skincare, food, pharmaceutical, and biotechnology industries due to their high yield, unique structural features.

Keywords: (1)H and (13)C NMR; FTIR; HPAEC-PAD; HPLC-SEC; Nostoc sp.; Polysaccharides.