Preparation of curcumin nanoparticles by protein hydrolysates and Polysaccharids and its stabilization.

Water soluble curcumin nanoparticles (Cur-Ps) were prepared by the simple anti-solvent nanoprecipitation method, using soluble soybean polysaccharide (SSPS) and zein hydrolysate (ZH) as carriers, and the synergistic effect of SSPS and ZH in prepration of Cur-Ps was studied. We expect to provide a new carrier for preparation of Cur-Ps with excellent colloid and oxidation stability. Attributed to poor water solubility of curcumin, the solution of curcumin monomers in deionized water was very turbid. However, the existence of ZH or ZH-SSPS solubilized the curcumin tremendously. The solutions of ZH and ZH-SSPS containing curcumin were yellow and highly transparent. The solubilization results shown that the water solubility of curcumin in ZH solution could reach up to 135, üg/mL when the concentration of ZH was above 2.5 mg/mL, and the addition of SSPS had no effect on the water solubility of curcumin at this concentration. But, when the concentration of ZH was below 2.5 mg/mL, the water solubility of curcumin was enhanced slightly with the addition of SSPS. In pure SSPS solution with a concentration of 3 mg/mL, the solubility of curcumin was only 90, üg/mL, obviously lower than that in ZH solution with the same concentration. These results suggested that ZH plays a leading role in curcumin solubilization in the ZH-SSPS mixture system and this solubiliazation should attributed to the non-covalent interactions between ZH and curcumin, which leading to the formation of ZH-curcumin nanocomplex. Colloidal stability results indicated that at low ionic strength (< 50 mmol/L) or under neutral condition (pH value 7.0), the existence of SSPS had no influence on the particle size distribution of Cur-Ps. However, since SSPS can increase the stability of the protein under acidic and salt-containing solutions, compared with Cur-Ps prepared by ZH only, Cur-Ps fabricated by ZH-SSPS had better colloid stability in solutions with low pH value (4.5 or 2.0) or high ionic strength (>200 mmol/L). Hence, due to the synergistic effect of ZH and SSPS, the curcumin-loaded nanoparticles with small size (< 100 nm) and good colloidal stability can be fabricated. The vitro release study in ethanol-water two-phase system indicated that both Cur-Ps prepared by ZH only and ZH-SSPS solutions had controlled-release effect on curcumin. However, Cur-Ps prepared by ZH-SSPS had better controlled-release effect, and its cumulative release ratio was below 80% in 6 h. The counterpart prepared by ZH only was above 85%. The study on the 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical oxidation stability of curcumin nanoparticles indicated that the stability of the curcumin was significantly (P<0.05) improved after the nano-capsulation by ZH or ZH-SSPS. This result is mainly due to the shielding effect for curcumin nano-canpsulation as well as the strong antioxidant effect of ZH. The lyophilized Cur-Ps powder prepared by ZH-SSPS had a multihole spongy structure in field emission images by scanning electron microscopy (SEM), which resulted in its redispersibility as high as 90%, showing a significant (P<0.05) improvement compared with the Cur-Ps fabricated by ZH only. Besides, using ZH-SSPS to prepare Cur-Ps powder had a more curcumin content compared with the counterpart. In conclusion, owing to the synergistic effect between ZH and SSPS, ZH-SSPS is expected to be a new material for the preparation of water soluble Cur-Ps. Due to the transparent appearance of the Cur-Ps solution, it has a good prospect in preparation of curcumin-enriched functional drinks. [ABSTRACT FROM AUTHOR]