Microscopic Imaging to Visualize the Distribution of Dietary Nucleic Acids in Food Products of Various Origins.

Dietary nucleic acids (dietNAs) are being increasingly recognized as important food components with nutritional value. However, the precise dietary recommendations for dietNAs are limited, because established methods for determining the quantity and nutritional role of dietNAs are still lacking. One of the tools to narrow this gap could be microscopic imaging, as a convenient approach to visualize the abundance and distribution of dietNAs in food products. With the aid of appropriate bioinformatic elaboration, such images may in future enable the direct semiquantitative estimation of these macromolecules in food products. In the presented study, two methods of preparing microscopic sections and staining them with DNA-specific fluorochromes were used for microscopic imaging of dietNAs in food products of plant and animal origin. Procedures for preparing formalin-fixed paraffin-embedded sections and cryosections were compared in terms of their usefulness for routine food analysis. Both methods turned out equally suitable for visualizing dietNA distribution in animal and plant products. However, the use of cryosections allowed a significantly shorter analysis time and reduced the consumption of organic solvents. Both of these advantages make the cryosection method preferable while establishing a dedicated methodology for routine assessment of dietNAs in the food industry.

Effect of oxidation and in vitro intestinal hydrolysis on phospholipid toxicity towards HT29 cell line serving as a model of human intestinal epithelium.

Oxidation of food-derived phospholipids (PLs) can influence nutrient digestion and induce oxidative stress in gastrointestinal epithelium. In this study, hen egg yolk PL fraction was used to evaluate the effect of lipoxygenase (LOX)-induced PL oxidation on the rate of PL hydrolysis catalyzed by pancreatic phospholipase A2 (PLA2) in the presence of bile salts (BSs). Then, PL/BS solutions containing native or oxidized PLs were used in in vitro intestinal digestion to assess the effect of PL oxidation and hydrolysis on the toxicity towards HT29 cell line. Based on the obtained results, we suggest that hexanal and (E)-2-nonenal, formed by the decomposition of PL hydroperoxides, inhibited PLA2 activity. The cell exposure to simulated intestinal fluid (SIF) containing BSs decreased HT29 cell viability and significantly damaged cellular DNA. However, the genotoxic effect was reversed in the presence of all tested PL samples, while the protective effect against the BS-induced cytotoxicity was observed for native non-hydrolyzed PLs, but was not clearly visible for other samples. This can result from an overlap of other toxic effects such as lipotoxicity or disturbance of cellular redox homeostasis. Taking into account the data obtained, it was proposed that the PLA2 activity decline in the presence of PL oxidation products may be a kind of protective mechanism against rapid release of oxidized FAs characterized by high cytotoxic effect towards intestinal epithelium cells.