Tuneable catechin functionalisation of carbohydrate polymers

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Organic Chemistry

Background:

• Natural carbohydrate polymers like dextran, sodium alginate, and chitosan are versatile biomaterials.
• Catechin, a potent antioxidant, has therapeutic potential but limited bioavailability.
• Functionalizing natural polymers can enhance their properties and applications.

Purpose of the Study:

• To develop a facile strategy for functionalizing dextran, sodium alginate, and chitosan with catechin.
• To investigate the impact of polymer charge on the functionalization efficiency and resulting conjugate properties.
• To evaluate the antioxidant activity of the synthesized carbohydrate polymer-catechin conjugates.

Main Methods:

• Oxidation of carbohydrate polymers using sodium periodate to introduce aldehyde groups.
• Acid-catalyzed nucleophilic reaction to conjugate catechin to the aldehyde functionalized polymers.
• Characterization using NMR spectroscopy (¹H, ¹H-¹³C HSQC, DOSY) to confirm structure and assess functionalization degree.
• Measurement of free-radical scavenging activity using established assays.

Main Results:

• Successful functionalization of dextran, sodium alginate, and chitosan with catechin was achieved.
• Catechin loading varied by polymer type, reaching up to 48% for dextran, 35% for chitosan, and 22% for sodium alginate.
• NMR analysis elucidated structural differences and conjugation behavior influenced by polymer charge.
• All synthesized conjugates demonstrated significantly enhanced free-radical scavenging activity compared to unmodified polymers.

Conclusions:

• A versatile method for creating catechin-functionalized carbohydrate polymers was established.
• The degree of functionalization is tunable and dependent on the polymer's chemical nature.
• These novel conjugates represent promising materials with improved antioxidant properties for various applications.