Soluble chitosan-carrageenan polyelectrolyte complexes and their gastroprotective activity

Area of Science:

• Biomaterials Science
• Pharmacology
• Gastroenterology

Background:

• Kappa-carrageenan (κ-CG) and chitosan are natural polysaccharides with potential therapeutic applications.
• Polyelectrolyte complexes (PECs) can be formed between oppositely charged polymers, altering their properties.
• Gastrointestinal ulcers are a significant health concern, often induced by non-steroidal anti-inflammatory drugs (NSAIDs) like indomethacin.

Purpose of the Study:

• To synthesize and characterize soluble polyelectrolyte complexes (PECs) of kappa-carrageenan (κ-CG) and chitosan.
• To investigate the gastroprotective and anti-ulcerogenic effects of these PECs.
• To determine the influence of PEC composition on their therapeutic activity.

Main Methods:

• Formation and characterization of κ-CG:chitosan PECs.
• Determination of binding constants to assess polymer affinity.
• Analysis of supramolecular structure using atomic force microscopy (AFM).
• In vivo study of gastroprotective effects using an indomethacin-induced rat ulcer model.

Main Results:

• High affinity between κ-CG and chitosan was confirmed by a binding constant of 2.11 × 10^7 mol⁻¹.
• Distinct supramolecular structures were observed for κ-CG:chitosan PECs (1:10 and 10:1 w/w) compared to the parent polysaccharides.
• Both PECs demonstrated gastroprotective properties, with the 1:10 w/w complex exhibiting significantly higher activity than the 10:1 w/w complex.
• The gastroprotective effect is potentially mediated by a protective layer formed on the stomach's mucous membrane.

Conclusions:

• Soluble κ-CG:chitosan PECs can be successfully formed with high polymer affinity.
• The composition of κ-CG:chitosan PECs significantly influences their gastroprotective efficacy.
• The 1:10 w/w κ-CG:chitosan complex shows promising anti-ulcerogenic potential, likely through physical protection of the gastric mucosa.