Influence of the Physico-Chemical Properties of Model Compounds on the Mean Sizes and Retention Rate of Gliadin Nanoparticles

Vegetal proteins have emerged as appealing starting materials for the development of various drug delivery systems, and their use for obtaining polymeric nanoparticles has been profitably exploited in multidisciplinary fields. Wheat gliadin, the water-insoluble storage protein of gluten, is characterized by a great amount of hydrophobic amino acid residues and notable mucoadhesive features. This biopolymer can be easily manipulated to form colloidal carriers, films and fibers by means of bio-acceptable solvents and easy preparation procedures. In this investigation, four model compounds characterized by different octanol/water partition coefficient (logP) values were encapsulated in gliadin nanoparticles, with the aim of investigating the influence of their physico-chemical properties on the cargo features and technological characteristics of the protein nanocarriers. The results demonstrate that the chemical structure, solubility and molecular weight of the compounds used are able to dramatically modulate the mean sizes and the entrapment efficiency of gliadin nanoparticles. This demonstrates the importance of a preformulation investigation when a molecule needs to be encapsulated in this type of polymeric carrier.

FT-Raman Spectroscopy as a Tool to Study the Secondary Structures of Wheat Gliadin Proteins

Raman spectroscopy is a useful method in biological, biomedical, food, and agricultural studies, allowing the simultaneous examination of various chemical compounds and evaluation of molecular changes occurring in tested objects. The purpose of our research was to explain how the elimination of ω-fractions from the wheat gliadin complex influences the secondary structures of the remaining αβγ-gliadins. To this aim, we analyzed the endosperm of wheat kernels as well as gliadin proteins extracted from two winter wheat genotypes: wasko.gl+ (control genotype containing the full set of gliadins) and wasko.gl− (modified genotype lacking all ω-gliadins). Based on the decomposition of the amide I band, we observed a moderate increase in β-forms (sheets and turns) at the expense of α-helical and random coil structures for gliadins isolated from the flour of the wasko.gl− line. Since ω-gliadins contain no cysteine residues, they do not participate in the formation of the disulfide bridges that stabilize the protein structure. However, they can interact with other proteins via weak, low-energetic hydrogen bonds. We conclude that the elimination of ω-fractions from the gliadin complex causes minor modifications in secondary structures of the remaining gliadin proteins. In our opinion, these small, structural changes of proteins may lead to alterations in gliadin allergenicity.

Curcumin Resuscitate Gliadin Induced Oxidative Damage And Altered Cellular Responses In Human Intestinal Cells Via Cross-Talk Between The Transcription Factor Nrf-2 And Multifunctional Protein APE1

An imbalance between the production of oxygen and nitrogen free radicals and their degradation by the antioxidant system are the major causative factors for the wheat intolerance diseases. In the present study, we have examined the wheat gliadin protein-induced oxidative and nitrosative stress and downstream responses in the human intestinal cell lines viz. HCT-116 and HT-29. The role of phytochemical curcumin was investigated to alleviate the gliadin associated cellular damages. The focus of the study was to identify the role of key DNA repair enzyme apurinic/apyrimidinic endonuclease 1 (APE1) in gliadin protein-induced toxicity in the intestine, which may be crucial for establishing the gut-associated diseases. Reactive oxygen species (ROS); reactive nitrogen species (RNS); mitochondrial ROS; mitochondrial trans-membrane potential; protein carbonylation; lipid peroxidation; and the oxidized DNA base damage was estimated in HCT-116 and HT-29 cells after 24 h treatment of 160 µg/ml of gliadin, 10 µM of curcumin and its combination. In addition, the transcriptional expression and enzymatic activities of antioxidants (SOD; Catalase; and GSH) were measured in the in these cells. Furthermore, the cross-talk between the nuclear factor erythroid 2-related factor-2 (Nrf-2) and the multifunctional enzyme APE1 was analyzed by the immunofluorescent based imaging and co-immunoprecipitation assays. The endonuclease activity of APE1 and the DNA-protein interaction of NRF-2 with ARE was analyzed by using electrophoretic mobility shift assay (EMSA) with the nuclear lysates of HCT-116 and HT-29 cells. Results suggest that 3 h pre-treatment of curcumin followed by the treatment of gliadin protein for 24 h time protect the HCT-116 and HT-29 cells via (1) decreasing the ROS, RNS, oxidative stress, mitochondrial ROS, recuperate mitochondrial trans-membrane potential; (2) reestablishing the cellular antioxidant defence systems; (3) enhancing the DNA-repair via APE1 and which further activates the ARE elements via activation of Nrf-2. In conclusion, wheat gliadin induces the oxidative/nitrosative stress, mitochondrial damage and damages the cellular biomolecules; hence is associated with the disease pathogenesis and tissue damage in wheat intolerance diseases. The gliadin induced stress and its consequences are significantly reduced by the pre-treatment of curcumin via DNA repair pathways and oxidative stress which is evident through the interaction between two essential proteins of these pathways APE1 and Nrf-2 hence suggesting the role of curcumin based management of wheat intolerance diseases like celiac disease.

Gliadin-mediated green preparation of Hybrid Zinc Oxide Nanospheres With Antibacterial Activity and Low Toxicity

The development of inorganic antibacterial agents that impart antibacterial properties to biomaterials has attracted widely attention. The paper introduced a kind of hybrid nanosphere antibacterial agent composed of wheat gliadin (WG) and zinc oxide (ZnO), with antibacterial effecacy and low toxicity. The ZnO/WG hybrid nanospheres were environment-friendly integrated by molecular self-assembly co-precipitating and freeze-drying transformating, and were characterized using X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM), Atomic absorption spectroscopy (AAS), bacteriostasis test and safety evaluation. It was found that the prepared hybrid nanospheres were composed of two components, ZnO and wheat gliadin, with a diameter scope of 100~200 nm. The content of ZnO in the hybrid nanospheres can reach 46.9~70.2% (w/w); The anti-bacteria tests proved that the prepared ZnO/WG nanospheres (containing 70% ZnO) have an significant inhibitory effect on E. coli (E.C.) and Staphylococcus aureus(S.A.) while the suspension concentration of the nanospheres was above 5 mg/mL. Furthermore, the ZnO/WG nanospheres are relatively safe and highly effective in cells and mice. Therefore, the prepared novel ZnO/WG hybrid nanospheres were supposed to apply in the preparation of anti-infective wound dressings, tissue engineering skin scaffold materials, food and cosmetics preservatives, and so on.

Structural Study of Wheat Gliadin in Different Solvents by Spectroscopic Techniques

Physicochemical properties of gliadin in different solvents (dimethyl sulfoxide (DMSO), H2O, and aqueous ethanol) and pH (9.8, 6.8, and 1.2) were investigated using dynamic light scattering (DLS), zeta potential (ZP), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Gliadin-DMSO and gliadin-deionized water (H2O) (pH 9.8) showed a lower size distribution, whereas samples solubilized in 60% aqueous ethanol presented a lower size distribution only at pH 1.2. ZP analysis showed that gliadin-H2O (pH 9.8) was the most stable evaluated system. ZP results of gliadin-DMSO indicated an unstable system, with the coexistence of several protein conformations. ATR-FTIR analysis showed that, in H2O, most protein conformations were β-sheets, while in DMSO a band at 1660 cm−1 appeared to be related to protein unfolding. The techniques proved to be effective in monitoring conformation and stability of all gliadin/solvent systems. Such information can be used in the development of new gliadin-based materials.