Phytosterols and γ-Oryzanol as Cholesterol Solid Phase Modifiers during Digestion.

Literature reports that ingestion of phytosterols and γ-oryzanol contributes to cholesterol lowering. Despite in vivo observations, thermodynamic phase equilibria could explain phenomena occurring during digestion leading to such effects. To advance the observations made by previous literature, this study was aimed at describing the complete solid-liquid phase equilibrium diagrams of cholesterol + phytosterol and γ-oryzanol systems by DSC, evaluating them by powder X-ray, microscopy, and thermodynamic modeling. Additionally, this study evaluated the phenomena observed by an in vitro digestibility method. Results confirmed the formation of solid solution in the cholesterol + phytosterols system at any concentration and that cholesterol + γ-oryzanol mixtures formed stable liquid crystalline phases with a significant melting temperature depression. The in vitro protocol supported the idea that the same phenomena can occur during digestion in which mechanochemical forces were probably the mechanisms promoting cholesterol solid phase changes in the presence of such phytocompounds. In this case, these changes could alter cholesterol solubility and possibly its absorption in the gastrointestinal lumen.

Influence of Pluronic F127 microenvironments on the photochemical nitric oxide release from S-nitrosoglutathione.

Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) (F127) hydrogels have been used to deliver nitric oxide (NO) topically in biomedical applications. Here, the effect of F127 microenvironments on the photochemical NO release from S-nitrosoglutathione (GSNO) was investigated in F127 solutions 7.6 wt% 15 wt% and 22.5 wt% at 15 °C and 37 °C. Small-angle X-ray Scattering (SAXS) and Differential Scanning Calorimetry (DSC) measurements, along with proton Nuclear Magnetic Resonance (1H NMR) spectral shifts and T2 relaxation data at six different concentration-temperature conditions, allowed identifying F127 microphases characterized by: a sol phase of unimers; micelles in non-defined periodic order, and a gel phase of cubic packed micelles. Kinetic measurements showed that GSNO photodecompositon proceeds faster in micellized F127 where GSNO is segregated to the intermicellar microenvironment. Real time kinetic monitoring of NO release and T2 relaxation profiles showed that NO is preferentially partitioned into the hydrophobic PPO cores of the F127 micelles, with the consequent decrease in its rate of release to the gas phase. These results show that F127 microphases affect both the kinetics of GSNO photodecomposition and the rate of NO escape and can be used to modulate the photochemical NO delivery from F127/GSNO solutions.

Simultaneous determination of six quality parameters of biodiesel through 1H NMR spectroscopy and partial least squares.

Biodiesel quality is checked by determining several parameters. Considering the large number of analyses in this verification, as well as the disadvantages of the use of toxic solvents and waste generation, multivariate calibration is suggested to reduce the number of tests. In this work, hydrogen nuclear magnetic resonance (1H NMR) spectra were used to build multivariate models, from partial least squares (PLS), in order to perform simultaneous determination of six important quality parameters of biodiesel: density at 20°C, kinematic viscosity at 40°C, iodine value, acid number, oxidative stability, and water content. 1H NMR spectrum reflects the structures of the compounds present in biodiesel and showed suitable correlations with the six parameters. In addition, the models were appropriate to predict all parameters for external samples. Thus, the alliance between 1H NMR spectra and PLS was shown to be applicable to extract a lot of information about biodiesel quality, significantly reducing analysis time, reagent and solvent consumption, and waste generation.

Alternative method to quantify biodiesel and vegetable oil in diesel-biodiesel blends through 1H NMR spectroscopy.

An alternative method is proposed for the quantitative analysis of biodiesel in diesel-biodiesel blends. It is based on hydrogen nuclear magnetic resonance (1H NMR) spectroscopy and applies univariate calibration, in which the integrals of the spectra are considered. Statistical comparisons between the results obtained from the method proposed here and from the infrared (IR) spectrometry method, which is recommended by the European Standard EN 14078, show that the 1H NMR method offers equivalent results compared with standard ones. Furthermore, the proposed 1H NMR method recognizes the difference between biodiesel and vegetable oil, whereas the IR method cannot. Therefore, the 1H NMR method developed to quantify biodiesel in diesel-biodiesel blends is proposed here as a more practical and efficient alternative to the official method, because besides quantifying biodiesel in blends, it indicates adulteration with vegetable oil, either as the intentional and illegal addition of this raw material or because of a low degree of transesterification conversion during biodiesel synthesis.