Interfacial characteristics and in vitro digestion of emulsion coated by single or mixed natural emulsifiers: lecithin and/or rice glutelin hydrolysates.

BACKGROUND: The interfacial characteristics and in vitro digestion of emulsion were related to emulsifier type. The mean droplet diameter, ζ-potential, microstructure, interfacial tension, Quartz crystal microbalance with dissipation (QCM-D) and in vitro gastrointestinal fate of emulsions stabilized by soybean lecithin, hydrolyzed rice glutelin (HRG) and their mixture were researched. RESULTS: The value of interfacial tension was much more dramatically declined for the sample containing 20 g kg-1 of HRG. For QCM-D, a rigid layer was formed for all the samples after rinsing. The layer thickness was 0.87 ± 0.20, 2.11 ± 0.31 and 2.63 ± 0.22 nm, and adsorbed mass was 87.17 ± 10.31, 210.56 ± 20.12 and 263.09 ± 23.23 ng cm-2 , for HRG, lecithin and HRG/lecithin, respectively, indicating both HRG and lecithin were adsorbed at the oil-water interface. Structural rearrangements at the interface occurred for HRG/lecithin. The kinetics and final amount of lipid digestion depended on emulsifier type: lecithin > HRG/lecithin > HRG. These differences in digestion rate were primarily due to differences in the aggregation state of the emulsifiers. CONCLUSION: The incorporation of lecithin into HRG emulsions had better interfacial properties comparing with HRG emulsion and facilitated lipid digestibility. These results provide important information for the rational design of plant-based functional food. © 2021 Society of Chemical Industry.

When is the best time to perform external physical vibration lithecbole (EPVL) after retrograde intrarenal surgery (RIRS): a multi-center study based on randomized controlled trials.

To determine the best time to perform EPVL treatment by evaluating the efficacy and safety of active stone extraction in treating residual fragments at different time points after RIRS. All participants had renal or upper ureteral stones preoperatively and still had residual stones after receiving RIRS. They were prospectively randomized into four groups: patients in group A received EPVL 3 days after RIRS; patients in group B received EPVL 7 days after RIRS; patients in group C received EPVL 14 days after RIRS; patients in group D did not receive EPVL after RIRS. Follow-up examinations were performed on all participants. The results, including stone size and location, stone-free rate (SFR) and complications, were compared among the groups. There were 176 patients in total. The SFR in groups A, B, C and D were 62.22%, 40.91%, 14.28% and 11.11%, respectively, 7 days after RIRS. At 14 days after RIRS, the SFR was 80%, 59.09%, 42.86% and 26.67% in groups A, B, C and D, respectively. At 28 days after RIRS, the SFR was 91.11%, 84.09%, 76.19% and 51.11% in groups A, B, C and D, respectively. Group A had the highest SFR from 7 to 28 days, and group C had a higher SFR at 28 days after RIRS than group D (P < 0.05). The side effects were less in groups A and B than in group D 28 days after RIRS (P < 0.05). We recommended that the best time to perform EPVL is 3 days after RIRS, because it could achieve a high SFR at any point in time and reduced complications.

Inhibitory effect of morin on tyrosinase: insights from spectroscopic and molecular docking studies.

Tyrosinase is a key enzyme in the production of melanin in the human body, excessive accumulation of melanin can lead to skin disorders. Morin is an important bioactive flavonoid compound widely distributed in plants and foods of plant origin. In this study, the inhibitory kinetics of morin on tyrosinase and their binding mechanism were determined using spectroscopic and molecular docking techniques. The results indicate that morin reversibly inhibited tyrosinase in a competitive manner through a multi-phase kinetic process. Morin was found to bind to tyrosinase at a single binding site mainly by hydrogen bonds and van der Waals forces. Analysis of circular dichroism spectra revealed that the binding of morin to tyrosinase induced rearrangement and conformational changes of the enzyme. Moreover, molecular docking results suggested that morin competitively bound to the active site of tyrosinase with the substrate levodopa.

Detection of interaction between lysionotin and bovine serum albumin using spectroscopic techniques combined with molecular modeling.

A combination of fluorescence, UV-Vis absorption, circular dichroism (CD), Fourier transform infrared (FT-IR) and molecular modeling approaches were employed to determine the interaction between lysionotin and bovine serum albumin (BSA) at physiological pH. The fluorescence titration suggested that the fluorescence quenching of BSA by lysionotin was a static procedure. The binding constant at 298 K was in the order of 10(5) L mol(-1), indicating that a high affinity existed between lysionotin and BSA. The thermodynamic parameters obtained at different temperatures (292, 298, 304 and 310 K) showed that the binding process was primarily driven by hydrogen bond and van der Waals forces, as the values of the enthalpy change (ΔH°) and entropy change (ΔS°) were found to be -40.81 ± 0.08 kJ mol(-1) and -35.93 ± 0.27 J mol(-1) K(-1), respectively. The surface hydrophobicity of BSA increased upon interaction with lysionotin. The site markers competitive experiments revealed that the binding site of lysionotin was in the sub-domain IIA (site I) of BSA. Furthermore, the molecular docking results corroborated the binding site and clarified the specific binding mode. The results of UV-Vis absorption, CD and FT-IR spectra demonstrated that the secondary structure of BSA was altered in the presence of lysionotin.

α-Glucosidase inhibition by luteolin: kinetics, interaction and molecular docking.

α-Glucosidase is a critical associated enzyme with type 2 diabetes mellitus in humans. Inhibition of α-glucosidase is important due to the potential effect of down regulating glucose absorption in patients. In this study, the inhibitory activity of flavone luteolin on α-glucosidase and their interaction mechanism were investigated by multispectroscopic methods along with molecular docking technique. It was found that luteolin reversibly inhibited α-glucosidase in a noncompetitive manner with an IC50 value of (1.72 ± 0.05) × 10(-4) mol L(-1), and the inhibition followed a multi-phase kinetic process with a first-order reaction. Luteolin had a strong ability to quench the intrinsic fluorescence of α-glucosidase through a static quenching procedure. The positive values of enthalpy and entropy change suggested that the binding of luteolin to α-glucosidase was driven mainly by hydrophobic interactions, and the binding distance was estimated to be 4.56 nm. Analysis of synchronous fluorescence, circular dichroism, and Fourier transform infrared spectra demonstrated that the binding of luteolin to α-glucosidase induced rearrangement and conformational changes of the enzyme. Moreover, the results obtained from molecular docking indicated that luteolin had a high affinity close to the active site pocket of α-glucosidase and indirectly inhibited the catalytic activity of the enzyme.

Effect of luteolin on xanthine oxidase: inhibition kinetics and interaction mechanism merging with docking simulation.

Xanthine oxidase (XO) catalyses hypoxanthine and xanthine to uric acid in human metabolism. Overproduction of uric acid will lead to hyperuricemia and finally cause gout and other diseases. Luteolin is one of the major components of celery and green peppers, its inhibitory activity on XO and their interaction mechanism were evaluated by multispectroscopic methods, coupled with molecular simulation. It was found that luteolin reversibly inhibited XO in a competitive manner with inhibition constant (Ki) value of (2.38±0.05)×10(-6) mol l(-1). Luteolin could bind to XO at a single binding site and the binding was driven mainly by hydrophobic interactions. Analysis of synchronous fluorescence and circular dichroism spectra demonstrated that the microenvironment and secondary structure of XO were altered upon interaction with luteolin. The molecular docking results revealed luteolin actually interacted with the primary amino acid residues located within the active site pocket of XO.