Chondroitin sulfate deposited on foxtail millet prolamin/caseinate nanoparticles to improve physicochemical properties and enhance cancer therapeutic effects.

In this study, curcumin (Cur)-loaded chondroitin sulfate (CS)-sodium caseinate (NaCas)-stabilized foxtail millet prolamin (FP) composite nanoparticles (NPs) were fabricated via a one-pot process. FP is capable of self-assembly via liquid antisolvent precipitation under neutral and alkaline conditions (pH 7.0-11.0). Under this condition, the microstructures of hydrophobic FP cores, amphiphilic NaCas and hydrophilic CS shells were fabricated readily by a one-pot method. With an optimal FP/NaCas/CS weight ratio of 3 : 2 : 4, FP-NaCas-CS NPs shared globular microstructures at about 145 nm, and hydrophobic interactions, electrostatic forces, and hydrogen bonds were the main driving forces for the formation and maintenance of stable FP-NaCas-CS NPs. CS coating enhanced the pH stability but reduced the ionic strength stability. The formed NPs were stable over a wide pH range from 2.0 to 8.0 and elevated salt concentrations from 0 to 3 mol L-1 NaCl. FP-NaCas-CS NPs exhibited a higher Cur encapsulation efficiency of 93.4% and re-dispersion capability after lyophilization. Moreover, CS coating promoted selective accumulation in CD44-overexpressing HepG2 cells, resulting in higher inhibition of tumor growth compared to free Cur and FP-NaCas NP-encapsulated Cur. As for comparison, encapsulated Cur exhibited reduced cytotoxicity on normal liver cells L-O2. This preclinical study suggests that FP-NaCas-CS NPs could be very beneficial in terms of encapsulating hydrophobic drugs, improving the effectiveness of cancer therapies and reducing side effects on normal tissues.

Foxtail millet prolamin as an effective encapsulant deliver curcumin by fabricating caseinate stabilized composite nanoparticles.

The development of food proteins as effective delivery systems is of great significance for the encapsulation of active compounds. Foxtail millet prolamin (FP) has a high level of hydrophobic amino acids and proline, meets the basic characteristics of delivery system, and was described here for the first time as an effective delivery system for the encapsulation of curcumin. The interaction between FP and curcumin was confirmed by fluorescence spectroscopy, showing the joint driving of hydrophobic forces and hydrogen bonds. Curcumin-loaded caseinate-stabilized FP nanodispersions were prepared by anti-solvent/evaporation method. The mean particle size was about 220-235 nm, sharing features of a spherical shape, uniform particle size, and smooth surfaces. High level of curcumin was encapsulated in the FP-based nanoparticles, exhibiting high particle yield (>88.4%) and encouraging encapsulation efficiency (>71.3%). X-ray diffraction and Fourier transform infrared spectroscopy demonstrated that the encapsulated curcumin was amorphous state and interacted with proteins via non-covalent bonds. The nano-sized particles can effectively prevent the degradation of curcumin during heat treatment, and significantly enhance the antioxidant and anti-tumor properties. This study provides a new encapsulant for effective protection and targeted delivery of hydrophobic active biomolecules.

Effect of steaming process on the structural characteristics and antioxidant activities of polysaccharides from Polygonatum sibiricum rhizomes.

Polygonatum sibiricum (P. sibiricum) rhizomes are widely used as a tonic and functional food, and are often processed to enhance their tonic function by repeated steaming and drying. As the most important constituent, the polysaccharide from P. sibiricum rhizomes (PSP) has demonstrated various activities, but the alteration of structural characteristics and activities of the purified PSPs during steaming process was rarely investigated. To well understand the effect of steaming process on the polysaccharides of P. sibiricum, neutral polysaccharides from P. sibiricum rhizomes (PSP0 ~ PSP9) after steaming were first isolated and purified, and then the chemical properties and antioxidant activities were determined. The results showed that the molar ratios of monosaccharides in PSPs were different. The molecular weights of PSPs were increased significantly after the fourth steaming. Morphological studies showed that the surface of PSPs became much tighter during the steaming process. Fourier transform infrared spectroscopy spectra displayed the polysaccharides had similar backbones and chemical groups. Furthermore, the antioxidant activity of PSPs was measured through radical scavenging tests. It was found that the radical scavenging activity of PSPs was elevated strikingly after steaming, and increased gradually with numbers of steaming process. The biological and chemical variance of PSPs revealed considerable segregation of PSP0, PSP1 ~ PSP4 and PSP5 ~ PSP9. In conclusion, our results proposed the fourth time as the optimal number of steaming to extract functional polysaccharide from P. sibiricum rhizomes.

Structural elucidation and antidiabetic activity of fucosylated chondroitin sulfate from sea cucumber Stichopus japonicas.

A fucosylated chondroitin sulfate was isolated from the body wall of sea cucumber Stichopus japonicus (FCSsj), whose structure was characterized by NMR spectroscopy and HILIC-FTMS. At the ratio of 1.00:0.26:0.65, three fucosyl residues were found: 2,4-disulfated-fucose (Fuc2,4S), 4-sulfated-fucose (Fuc4S) and 3,4-disulfated-fucose (Fuc3,4S), which were only linked to the O-3 of glucuronic acid residues (GlcA). Besides mono-fucosyl moieties, di-fucosyl branches, namely Fuc2,4Sα(1→3)Fuc4S, were also found to be attached to the O-3 of GlcA. The antidiabetic activity of FCSsj was evaluated using glucosamine induced insulin resistant (IR) Hep G2 cells in vitro. It was found that FCSsj significantly promoted the glucose uptake and glucose consumption of IR-Hep G2 cells in a dose-dependent manner, and could alleviate the cell damage. Furthermore, FCSsj could promote the glycogen synthesis in the glucosamine-induced IR-Hep G2 cells. These results provided a supplement for studying the antidiabetic activity of FCSsj.

Release of antidiabetic peptides from Stichopus japonicas by simulated gastrointestinal digestion.

Sea cucumber (Stichopus japonicus) is a high-protein food with the potential to release certain peptides through enzymolysis. This work is to explore the characteristics of peptides released from Stichopus japonicus protein in the process of digestion. Hydrolysates were obtained by gastrointestinal digestion and fractioned to <3, 3-10, 10-30 and >30 kDa fractions. Fifty-eight peptides from <3 kDa fraction were characterized using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Hydrolysates could improve glucose uptake of 3 T3-L1 cells and high insulin-induced insulin-resistant Hep G2 cells. Molecular docking showed that the released peptides had similar binding mode with anagliptin, a dipeptidyl peptidase IV (DPP-IV) inhibitor. The <3 kDa fraction in gastro and intestinal digestion showed the greatest DPP-IV inhibitory potency (IC50 0.51 and 0.52 mg/mL, respectively). The results indicated that sea cucumber could be used as a functional food to release antidiabetic peptides through gastrointestinal digestion.