Peptide Supramolecular Self-Assembly: Regulatory Mechanism, Functional Properties, and Its Application in Foods.

Peptide self-assembly, due to its diverse supramolecular nanostructures, excellent biocompatibility, and bright application prospects, has received wide interest from researchers in the fields of biomedicine and green life technology and the food industry. Driven by thermodynamics and regulated by dynamics, peptides spontaneously assemble into supramolecular structures with different functional properties. According to the functional properties derived from peptide self-assembly, applications and development directions in foods can be found and explored. Therefore, in this review, the regulatory mechanism is elucidated from the perspective of self-assembly thermodynamics and dynamics, and the functional properties and application progress of peptide self-assembly in foods are summarized, with a view to more adaptive application scenarios of peptide self-assembly in the food industry.

Effect of chemical modification of κ-carrageenan on its inhibitory effect against heterocyclic amine (HAs) formation in roasted tilapia fish patties.

Sulfated κ-carrageenan (S-KC), carboxymethylated κ-carrageenan (C-KC), acetylated κ-carrageenan (A-KC) and phosphorylated κ-carrageenan (P-KC) were synthesized and tested for their inhibitory effect on heterocyclic amine (HAs) formation in roasted tilapia fish patties. Fish patties with 1 % of each hydrocolloid prepared by 90 % of fish and 10 % of an aqueous hydrocolloid dispersion were determined for HAs-levels after roasting. P-KC showed the strongest inhibitory effect against total HAs formation (20.95 %). Moreover, P-KC increased the content of creatinine and glucose but decreased the content of free amino acids in fish patties, indicating that P-KC may compete with creatinine and glucose to react with amino acids to suppress HAs generation. In addition, P-KC plus naringenin had a stronger inhibitory effect against HAs formation than P-KC or naringenin alone. P-KC at 1 % (w/w) and P-KC (0.5 %, w/w) plus naringenin (0.5 %, w/w) showed no significant effects on the color and textural properties compared to the control group (100 % fish), and had less impact on food quality than 1 % (w/w) KC. Therefore, our results suggest that chemical modification could enhance the inhibitory effect of some hydrocolloids on HAs formation, and an appropriate combination of hydrocolloids and flavonoids contributes to the attenuation of dietary exposure to genotoxic HAs.

Interaction mechanism between hydroxychloroquine sulfate and collagen: Insights from multi-spectroscopy, molecular docking, and molecular dynamic simulation methods.

Hydroxychloroquine sulfate (HCQ) can be used to treat various connective tissue diseases. Collagen, which is not only an important drug delivery carrier but also the main component in the connective tissue, is the focus of this study. Here, the interaction mechanism of HCQ with collagen was investigated through various spectroscopic and computational methods. It is found that HCQ binds to collagen spontaneously, primarily via hydrophobic interactions and some hydrogen bonds. The findings of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) verified that formation of HCQ-collagen complex and the amorphous structure, secondary structures, and microstructure of collagen were changed after HCQ binding. A decrease in the relaxation time of free water was observed in the collagen system when HCQ was added. Molecular docking demonstrated that HCQ was almost buried in the cavity of collagen via some hydrophobic interactions with one hydrogen bond, which conforms to the findings of the fluorescence and FTIR analyses. Molecular dynamic (MD) simulations further revealed the structural change information in the docking process. Hopefully, the information generated in this study can provide some useful insights for the research on the pharmacological mechanisms of HCQ in the treatment of the connective tissue diseases and the application of collagen as a drug carrier.

Inhibition of acrylamide toxicity in vivo by arginine-glucose maillard reaction products.

Acrylamide has a variety of toxicities, including carcinogenicity, and can be present in food via the Maillard reaction in processing of certain foods. Previous studies have demonstrated that co-existing Maillard reaction products (MRPs) ameliorated acrylamide-induced abnormal physiological status in mice. This study is focused on the effects on hematological parameters, erythrocyte osmotic fragility, oxidative stress in plasma and liver, and contents of 8-hydroxy-2-deoxyguanosine (8-OHdG) in mice exposed to acrylamide and to acrylamide and MRPs derived from arginine and glucose. Acrylamide alone caused significant increases in liver indexes, erythrocyte osmotic fragility, malonaldehyde level in liver and 8-OHdG level in testis, and significant decreases in weight gain, hematological parameters, levels of glutathione, glutathione peroxidase and total superoxide dismutase in plasma. Whether MRPs and acrylamide were physically mixed or when the solution is prepared from heating the mixture of arginine, glucose and acrylamide, the presence of MRPs effectively reduced the adverse changes caused by acrylamide. These results suggest that the toxicity of acrylamide to mice can be ameliorated by MRPs, the common compositions simultaneously generated with acrylamide in food matrix.

Simultaneous extraction and determination of free and conjugated phytosterols in tobacco.

Acid hydrolysis and alkaline saponification were incorporated into a microwave-assisted extraction process for the simultaneous extraction of free and conjugated phytosterols from tobacco. The crude extract of the microwave-assisted extraction was purified by C18 solid-phase extraction and then determined by high-performance liquid chromatography. Phytosterols of cholesterol, ergosterol, stigmasterol, campesterol, and ß-sitosterol were determined by chromatographic quantification. The multiple parameters of microwave-assisted extraction were optimized by a uniform design method. The optimal ratio of extraction ethanol solvent to tobacco mass was 30 mL/g. The microwave-assisted extraction acid hydrolysis was carried out in sulfuric acid medium by heating for 10 min at 55°C. The microwave-assisted extraction alkaline saponification was performed after adding excessive sodium hydroxide by heating another 10 min. The repeatability of the proposed method was acceptable with recoveries from 69.68 to 88.17% for the phytosterols. Five target phytosterols were all found in the tobacco samples, and the contents were significantly different in samples from different producing areas.

Determination of gouty arthritis' biomarkers in human urine using reversed-phase high-performance liquid chromatography.

Creatinine, uric acid, hypoxanthine and xanthine are important diagnostic biomarkers in human urine for gouty arthritis or renal disease diacrisis. A simple method for simultaneous determination of these biomarkers in urine based on reversed-phase high-performance liquid chromatography (RP-HPLC) with ultraviolet (UV) detector was proposed. After pretreatment by dilution, centrifugation and filtration, the biomarkers in urine samples were separated by ODS-BP column by elution with methanol/50 mM NaH2PO4 buffer solution at pH 5.26 (5:95). Good linearity between peak areas and concentrations of standards was obtained for the biomarkers with correlation coefficients in the range of 0.9957-0.9993. The proposed analytical method has satisfactory repeatability (the recovery of data in a range of creatinine, uric acid, hypoxanthine and xanthine was 93.49-97.90%, 95.38-96.45%, 112.46-115.78% and 90.82-97.13% with standard deviation of <5%, respectively) and the limits of detection (LODs, S/N≥3) for creatinine, uric acid, hypoxanthine, and xanthine were 0.010, 0.025, 0.050 and 0.025 mg/L, respectively. The established method was proved to be simple, accurate, sensitive and reliable for the quantitation of gouty arthritis' biomarkers in human urine samples. The ratio of creatinine to uric acid was found to be a possible factor for assessment of gouty arthritis.

The reparative effects of Momordica Charantia Linn. extract on HIT-T15 pancreatic beta-cells.

The aim of this study is to investigate the cell reparative effects of Mormordical Charantia Linn. boiling water extract (MCE) on the HIT-T15 Hamster Pancreatic beta-cells. Furthermore, the superoxide dismutase (SOD) activity of MCE was determined. 0.02% MCE (w/v) achieved the highest cell proliferation rate of 45.6% (p<0.01) on alloxan damaged HIT-T15 cells while 0.2% MCE increased the proliferation of the normal cells by 35.4% (p<0.05). The high molecular weight fraction of MCE (MHMF, MW>3 kDa) showed the stronger effects in repairing alloxan damaged cells (cell proliferation rate=32.1%, p<0.05) than that of the low molecular weight fraction (MLMF, MW< or =3 kDa), while the latter showed the higher activity on increasing insulin secretion of normal or damaged cells. 2%MCE and MLMF showed the highest SOD activities, 19.74 NU/mL and 19.84 NU/mL, but they failed to improve the proliferation rate of alloxan damaged cells. These results indicated MCE has significant repairing effects on HIT-T15 cells against superoxide anion radicals, which did not correlate to MCEfs SOD activity. It was hypothesized that the different fractions of MCE may make different contributions to MCE's cell repairing activity and its ability of stimulating insulin secretion.