Structural characterization and binding interaction of rice glutelin fibrils complexing with curcumin

Area of Science:

• Food Science
• Biochemistry
• Materials Science

Background:

• Curcumin, a potent antioxidant, suffers from poor solubility and bioavailability.
• Protein-based delivery systems offer a promising approach to enhance curcumin's properties.
• Rice glutelin fibrils (RGFs) are explored as novel carriers for bioactive compounds.

Purpose of the Study:

• To evaluate rice glutelin (RG), total glutelin fibrils (TGFs), retentate (RGFs), and filtrate (FGFs) fractions as carriers for curcumin.
• To investigate the impact of these carriers on curcumin's solubility, antioxidant activity, and release profile.
• To elucidate the interaction mechanisms and structural changes upon complexation.

Main Methods:

• Preparation and fractionation of rice glutelin fibrils.
• Complexation of curcumin with RG, TGFs, RGFs, and FGFs.
• Solubility and antioxidant activity assays.
• Thermodynamic analysis of interactions.
• Structural analysis using circular dichroism (CD) spectroscopy.

Main Results:

• Curcumin complexation with RG, TGFs, RGFs, and FGFs significantly improved its solubility and antioxidant activity.
• The RGFs-curcumin complex demonstrated the highest curcumin solubility (48.05%) and superior sustained release.
• Complexes were stabilized by hydrogen bonds and van der Waals forces (RG/TGFs/RGFs) or electrostatic interactions (FGFs).
• Curcumin interaction induced fibril aggregation and altered secondary structures (increased α-helix and β-sheet content).

Conclusions:

• Rice glutelin fibrils, particularly the RGFs fraction, serve as effective carriers for curcumin.
• RGFs enhance curcumin's solubility and provide sustained release properties.
• These findings suggest RGFs are a viable alternative for curcumin delivery in the food industry.