Antibacterial activity and mechanisms of depolymerized fucoidans isolated from Laminaria japonica

• Published in: Carbohydrate polymers Vol. 172; pp. 294 - 305
• Main Authors: Liu, Ming, Liu, Yixiang, Cao, Min-Jie, Liu, Guang-Ming, Chen, Qingchou, Sun, Lechang, Chen, Haixiu
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15-09-2017
• Subjects: Anti-Bacterial Agents - isolation & purification; Anti-Bacterial Agents - pharmacology; Antibacterial activity; Brown algae; Escherichia coli - drug effects; Fucoidans; Laminaria - chemistry; Laminaria japonica; Polysaccharides - isolation & purification; Polysaccharides - pharmacology; Staphylococcus aureus - drug effects; Structure-Activity Relationship; Sulfated polysaccharide; Fucoidans; Antibacterial activity; Brown algae; Laminaria japonica; Sulfated polysaccharide
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2017.05.060

•The antibacterial activity of fucoidans from Laminaria japonica was evaluated.•The unprocessed fucoidans did not exhibit obvious antibacterial activity.•The depolymerized fucoidans exhibited excellent antibacterial activity.•Low molecular weight and strong anionic property improve antibacterial activity.•Depolymerized fucoidans inhibit bacterial growth by destroying membrane integrity.
Fucoidans, sulfated polysaccharides in brown algae, were depolymerized though high-pressure hydrolysis, and their antibacterial activity, structural properties, and antibacterial mechanisms were investigated in this work. The fucoidans from Laminaria japonica show no antibacterial activity before depolymerization; however, their depolymerized products can effectively (p<0.05) inhibit the proliferation of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The structure–activity study demonstrated that lower molecular weight and stronger polyanionic property can promote the antibacterial activity. And the depolymerized fucoidans exhibited better antibacterial activity against E. coli than against S. aureus. The results also indicated that the bactericidal pathway of depolymerized fucoidans should be through destruction of the cytomembranes and the target molecules are the membrane proteins, which can result in changed membrane fluidity and/or activated autophagocytosis. Therefore, the depolymerized fucoidans possess potential appliance values in partly or totally replacing antibiotics in our daily life.