Self-assembled nanoparticles of curcuminoids and soluble dietary fibers: Characterization and mechanism

There are interactions between dietary fiber and polyphenols in food, affecting the bioavailability of polyphenols. Soluble dietary fibers (SDF) were extracted from dietary fibers and characterized. The optimal SDF was selected by comparing encapsulation efficiency, hydrodynamic diameter, polydispersity index and ζ-potential of the aggregates formed through interacting with Curcumin (Cur). Finally, the optimized SDF was polymerized with Cur and curcuminoids respectively, and the differences of two aggregates were compared. Among five kinds of dietary fibers, a 60% ethanol-precipitated fenugreek SDF (FS60) belonging to a type of glucan was the best SDF tested for forming Cur-SDF aggregates. However, a better aggregation of FS60 on curcuminoids than Cur was observed. Furthermore, FS60 encapsulated Cur to form spherical nano-aggregates by hydrogen bonding and electrostatic force with ketone and phenolic hydroxyl groups of Cur. Due to the lack of one methoxy, demethoxycurcumin (DMC) had stronger spatial interaction with FS60. Curcuminoids-FS60 aggregates were composed of DMC-FS60 and Cur-FS60 nanoparticles. A small amount of DMC promoted the aggregation of Cur and FS60. The presence of Cur and DMC mutually promoted the hydrogen bond, making the system more stable. The curcuminoids-FS60 aggregates provide an opportunity to improve the solubility and bioavailability of Cur.