Modification of Chitosan with (-)-Gossypol and (-)-Gossypol Acetic Acid Using Free-Radical Grafting Method

Area of Science:

• Polymer Chemistry
• Materials Science
• Biomedical Engineering

Background:

• Hydrophobic compounds require enhanced bioavailability and stability for therapeutic applications.
• Chitosan (CS) is a versatile biopolymer with potential for drug delivery.
• Gossypol (GS) is a phenolic compound with demonstrated anticancer properties.

Purpose of the Study:

• To modify chitosan by grafting gossypol (GS) to improve its properties.
• To investigate the impact of using pure GS versus gossypol acetate (GSA) on CS modification.
• To evaluate the antioxidant capacity and physical characteristics of the resulting CS-GS derivatives.

Main Methods:

• Free-radical grafting of GS or GSA onto chitosan.
• Characterization using FTIR, Raman, ¹³C ssNMR, elemental analysis, and thermogravimetric analysis.
• Assessment of antioxidant properties via Folin-Ciocalteu (F-C) and DPPH assays; determination of polymer solubility and specific viscosity.

Main Results:

• Successful grafting of GS onto CS, with GS content increasing proportionally to the added amount.
• Gossypol acetate (GSA) resulted in approximately 20% higher grafted GS content compared to pure GS.
• GSA modification led to enhanced antioxidant properties and higher free radical scavenging ability.
• Pure GS grafting resulted in higher CS crosslinking and lower polymer solubility compared to GSA.

Conclusions:

• Chitosan modification with gossypol enhances its properties for potential therapeutic applications.
• Gossypol acetate is more effective than pure gossypol for grafting onto chitosan, yielding improved antioxidant activity.
• The developed CS-GS derivatives show promise for improved drug delivery systems due to enhanced stability and bioavailability.