Joanna Harasym

Effect of fruit and vegetable antioxidants on total antioxidant capacity of blood plasma

For a long time, the increased consumption of fruits and vegetables was considered critical in protecting humans against a number of diseases, such as cancer, diabetes, neurodegenerative diseases, and heart and brain vascular diseases. Presently, it is thought that the protective properties of these foods result from the presence of low-molecular antioxidants that protect the cells and their structures against oxidative damage. The alleged effect of reducing the risk for many diseases is not only due to the effect of individual antioxidants, such as α-tocopherol, ascorbic acid, or β-carotene, but also may be the result of antioxidant compounds not yet known or synergy of several different antioxidants present in fruits and vegetables. Studies on macromolecules (DNA, nucleotides, proteins) free-radical-related damage showed that diets enriched with extra servings of fruits and vegetables rich in β-carotene, tocopherols, and ascorbic acid had only limited effect on the inhibition of oxidation processes. A number of studies have shown, however, that consuming less common fruits and vegetables contribute much more to the reduction of free-radical processes, most likely because they contain a large amount of non-vitamin antioxidants, such as polyphenols and anthocyanins.

Anticancer properties of low molecular weight oat beta-glucan – An in vitro study.

Anticancer properties of 1-3, 1-4 oat beta glucan are under intensive investigation now. Antitumor characteristic of fungi and yeast beta-glucans have been widely recognized, but those polysaccharides are mostly insoluble which creates several problems especially in topical formulation. Also high molecular weight oat beta-glucans reveal high viscosity which restricts its application. According to those problems in the current study the antitumor activities of low molecular weight beta-glucan derived from oats were investigated in cancer cells: Me45, A431 and normal HaCaT and murine macrophages P388/D1. The low molecular weight beta-glucan from oat significantly deceased cancer cells viability, while for the normal cells it was non-toxic. It was observed that with the increasing incubation time and the beta-glucan concentration the cancer cells viability significantly deceased. Furthermore for the normal cells the low molecular weight beta-glucan from oat was non-toxic. Immunocytochemical ABC analysis showed that beta-glucan induced strong expression of caspase-12 in both cancer cell lines, while in HaCaT cells ABC reaction was significantly lower and in P388/D1 cell line ABC reaction was negative. Our preliminary studies show strong anti-tumor properties of new low molecular weight beta-glucan from oat and at the same time no toxicity for normal cells.

Pro-apoptotic properties of (1,3)(1,4)-β-d-glucan from Avena sativa on human melanoma HTB-140 cells in vitro

In this study, the growth-inhibitory effect of polysaccharide (1,3)(1,4)-β-D-glucan from oat, Avena sativa L. grains was explored on the human skin melanoma HTB-140 cells in vitro. The oat β-D-glucan (OBG) exerted cytotoxic action on HTB-140 cells. After 24h of incubation, LD50 (concentration at which 50% of the cells were found dead) was obtained of 194.6 ± 9.8 μg/mL. The oat β-D-glucan caused a concentration-dependent increase of caspase-3/-7 activation and appearance of phosphatidylserine on the external surface of cellular membranes where it was bound to annexin V-FITC, demonstrating the induction of apoptosis. Intracellular ATP level decreased along with the mitochondrial potential, which suggested a mitochondrial pathway of apoptosis. A cell cycle analysis showed increase in the number of apoptotic cells, increase in the number of cells in G1 phase and decrease in the number of cells in G2/M. Although the detailed mechanism for the anti-tumor activity of the oat β-D-glucan still needs further investigation, this study provides preliminary insights into this direction along with perspectives of developing it as an anti-tumor agent.

Hepato- and gastro- protective activity of purified oat 1-3, 1-4-β-d-glucans of different molecular weight.

Protective and antioxidant properties of highly purified oat β-glucans of high and low molecular weight in liver and stomach were evaluated. The novelty in approach was to determine whether dietary β-glucans affect the parameters of oxidative stress directly in the stomach and indirectly in the liver, especially in inflammation states. Physicochemical properties e.g. viscoelastic was found as strictly dependent from molecular weight of oat β-glucans hence its metabolic activity could also show dependence. Three groups of rats were fed control diet and diet supplemented with low and high molecular weights oat β-glucans. Animals were divided into controls and individuals with experimentally induced intestinal inflammation. Most active in increasing of total antioxidant status was low molecular weight β-glucan. High molecular weight β-glucan supplementation inhibits lipid oxidation the most in LPS treated animals. The results obtained from experiment encourage for dietary intervention with oat β-glucans for stomach and liver protection during existing enteritis.

Comparison of Conventional and Microwave Assisted Heating on Carbohydrate Content, Antioxidant Capacity and Postprandial Glycemic Response in Oat Meals

Minimally processed cereal breakfast products from whole grain entered the market due to consumer demand of more nutritional food with more controlled sugar release. However, the subsequent processing of such products with different cooking methods in the consumer’s kitchen may lead to significant differentiation of their nutritional value. Therefore, the evaluation of the impact of frequently used cooking methods on a final quality of breakfast cereals meal is needed. The present study investigates how the two different methods of heating, conventional and microwave (MW) assisted, affect the carbohydrate content, profile and resulting glycemic index of so prepared food as well as the antioxidant activity of meals. Two products available on the market—oat bran and flakes—were used. The highest starch content in fluid phase of oatmeal was detected in samples heated for 3 min with microwaves, regardless the type. The lowest starch content was obtained for 5 min MW heated flakes sample. The total content of glucose was about 1.5 times lower in bran vs. flakes oatmeal. The highest β-glucan content in fluid fraction was also observed for bran meal but its release was independent of applied conditions.