Digestion and bioavailability of bioactive phytochemicals

There are many scientific reports on determination of the content and biological activity of compounds found in food. However, these analyses are not sufficient to determine their effect on the human body. During digestion of food ingredients, many changes can modify their structure and this may affect their absorption and bioactivity. Many phenolic aglycones are hydrophilic and can be absorbed through biological membranes by diffusion. However, most polyphenols occur in the glycosidic form, which undoubtedly affects their absorption in the intestine. Oligopeptides are also absorbable via secondary active transport but based on the hydrogen ion gradient or with transporter PepT1. The bioavailability of phytochemicals is determined by their molecular weight or chemical structure and the food matrix. Accordingly, the aim of this work was to present the novel scientific reports related to the influence the many factors on digestibility, bioaccessibility and activity of selected bioactive compounds of plant origin.     

Perovskite-type Sr(Mn1−xNix)O3 materials and their chemical-looping oxygen transfer properties

This paper contains the results of research on chemical-looping combustion (CLC). CLC is one of the most promising combustion technologies and has the main advantage of producing a concentrated CO₂ stream, which is obtained after water condensation and without any energy penalty for CO₂ separation. The objective of this work was to study the chemical-looping reaction performance of novel perovskite-type oxygen carriers. The Sr(Mn_1−xNi_x)O₃ family was tested for its suitability as an oxygen carrier in hydrogen (syngas component) combustion for power generation. Sr(Mn_1−xNi_x)O₃ perovskite-type oxides with x = 0, 0.2, 0.5, 0.8, and 1.0 were prepared. Thermogravimetric measurements were performed to investigate the oxidation/reduction of the obtained materials. Reactivity tests were performed under isothermal conditions during multiple redox cycles using a thermogravimetric analyzer (TGA). For the reduction reaction, 3% H₂ in Ar was used, and air was used for the oxidation cycle. The effect of reaction temperature (600–800 °C) and the number of reducing/oxidizing cycles (up to 5 cycles) on the performance of the oxygen-carrier samples developed in this study were evaluated. The stability, oxygen transport capacity, and reaction rates were analyzed on the basis of thermogravimetric TG results. The Sr(Mn_1−xNi_x)O₃ oxides showed stable chemical-looping performance with rapid changes in their oxygen content (2–3 min) while maintaining their chemical properties. The cyclic redox reaction revealed that Sr(Mn_1−xNi_x)O₃ exhibits excellent structural stability and provides a continuous oxygen supply during redox reactions. Good oxygen capacity was maintained during the cycling hydrogen combustion tests. These new perovskite-type materials were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements and by surface area (BET), particle size distribution (PSD) and melting behavior analyses. The Sr(Mn_1−xNi_x)O₃ oxides exhibited high melting temperatures and small surface areas. The promising results obtained from chemical-looping combustion experiments indicate that the Sr(Mn_1−xNi_x)O₃ oxides are potentially useful oxygen carriers for chemical-looping combustion processes where hydrogen is one of the fuel components.     

Zn2+ complexes of di- and tri-nucleating azacrown ligands as base-moiety-selective cleaving agents of RNA 3',5'-phosphodiester bonds: binding to guanine base

The ability of the dinuclear Zn2+ complex of 1,4-bis[(1,5,9-triazacyclododecan-3-yloxy)methyl]benzene (L(1)) to promote the cleavage of the phosphodiester bond of dinucleoside-3',5'-monophosphates that contain a guanine base has been studied over a narrow pH range from pH 5.8 to 7.2 at 90 degrees C. Comparative measurements have been carried out by using the trinuclear Zn2+ complex of 1,3,5-tris[(1,5,9-triazacyclododecan-3-yloxy)methyl]benzene (L(2)) as a cleaving agent and guanylyl-3',5'-guanosine (5'-GpG-3') as a substrate. The strength of the interaction between the cleaving agent and the starting material has been elucidated by UV spectrophotometric titrations. The speciation and binding mode have been clarified by potentiometric titrations with hydrolytically stable 2'-O-methylguanylyl-3',5'-guanosine and 1H NMR spectroscopic measurements with guanylyl-3',5'-guanosine. The results show that the guanine base is able to serve as a site for anchoring for the Zn2+-azacrown moieties of the cleaving agents L(1) and L(2), analogously to uracil base. The interaction is, however, weaker than with the uracil base and, hence, only the 5'-GpG-3' site (in addition to 5'-GpU-3' and 5'-UpG-3' sites) is able to markedly modulate the phosphodiester cleavage by the Zn2+ complexes of di- and trinucleating azacrown ligands containing an ether oxygen as a potential H-bond-acceptor site.     

Dietary Flavonoids Sensitize HeLa Cells to Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL)

TRAIL is a promising candidate for cancer therapeutics that preferentially induces apoptosis in cancer cells. The combined treatment flavonoids with TRAIL might be promising as a chemoprevention and/or new therapy against malignant tumors. We examined the cytotoxic effect of dietary flavonoids in combination with TRAIL on HeLa cells. It was found that treatment with noncytotoxic concentration of some flavonoids significantly sensititizes to TRAIL induced death in HeLa cells. Our study demonstrated that flavone, apigenin and genistein markedly augmented TRAIL mediated cytotoxicity against HeLa, whereas kaempferol and quercetin produced no effect.     

Chalcones Enhance TRAIL-Induced Apoptosis in Prostate Cancer Cells

Chalcones exhibit chemopreventive and antitumor effects. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a naturally occurring anticancer agent that induces apoptosis in cancer cells and is not toxic to normal cells. We examined the cytotoxic and apoptotic effect of five chalcones in combination with TRAIL on prostate cancer cells. The cytotoxicity was evaluated by the MTT and LDH assays. The apoptosis was determined using flow cytometry with annexin V-FITC. Our study showed that all five tested chalcones: chalcone, licochalcone-A, isobavachalcone, xanthohumol, butein markedly augmented TRAIL-mediated apoptosis and cytotoxicity in prostate cancer cells and confirmed the significant role of chalcones in chemoprevention of prostate cancer.     

Comparison of quality and microstructure of chokeberry powders prepared by different drying methods,including innovative fluidised bed jet milling and drying

Food Science and Biotechnology - The study assessed the functional properties, microstructural features and sensory characteristics of chokeberry powders obtained by the new fluidised bed jet...     

Physico-chemical, Biochemical and Microbiological Properties of Traditional Polish Pork Fermented Products During Ripening

The physico-chemical and biochemical properties of the raw pork products, spontaneously fermented as entire primal cuts of ham hock (raw smoked ham hock (RSR)) and loin (raw smoked loin (RSL)), were estimated during the 4-week ripening period. A decrease in water content (4 % in RSR and 7 % in RSL) and an increase in protein (2 and 4.5 %, respectively), fat and salt content (1–2 % for both products) were associated with the phenomena of slight drying. An almost 2.5-fold increase of free amino groups dissolved in water, from 480 to 1,100 μMGly/100 g and from 490 to 1,200 μMGly/100 g, accompanied by a gradual increase of total free fatty acids, from 250 to 530 mg/kg and from 270 to 460 mg/kg, was indicated in the RSR and RSL, respectively. The fermentation and accumulation of free fatty acids affected the pH decrease in the RSL, particularly with a low fat content. The increase of tyramine, tryptamine, putrescine and spermine amounts confirm the activity of bacteria strains in the RSR and RSL during ripening. The considerable part of the “house microflora” included the species fermenting in the presence of air or in anaerobic conditions—in the presence of nitrogen. The presence of volatile cell metabolism products (3-hydroxy-2-butanone, 3-methyl-1-butanol and butanoic acid) confirmed a greater amino acid transformation and saccharide fermentation activity of microflora in the RSR. Similarly, products of free fatty acid degradation (pentanal, hexanal and butanoic acid) as well as products of lipid oxidation (e.g. 3-methyl-3-buten-1-ol and 3-methyl-1-butanol) confirmed the far advanced ripening in the RSR with a greater fat content.