Protection of Erythrocytes and Microvascular Endothelial Cells against Oxidative Damage by Fragaria vesca L. and Rubus idaeus L. Leaves Extracts-The Mechanism of Action.

The aim of this work is to determine the biological activity of ellagitannins rich extracts from leaves of raspberry (Rubus idaeus L.) and wild strawberry (Fragaria vesca L.) in relation to cells and cell membranes. Detailed qualitative and quantitative analysis of phenolic compounds of the extract was made using chromatographic methods. Cytotoxic and antioxidant activities of tested extracts in relation to erythrocytes and human vascular endothelial cells (HMEC-1) were determined by using fluorimetric and spectrophotometric methods. In order to establish the influence of the extracts on the physical properties of the membrane, such as osmotic resistance and erythrocytes shapes, mobility and/or hydration of polar heads and fluidity of hydrocarbon chains of membrane lipids, microscopic and spectroscopic methods were used. The results showed that the extracts are non-toxic for erythrocytes and HMEC-1 cells (up to concentration of 50 µg/mL), but they effectively protect cells and their membranes against oxidative damage. The increase in osmotic resistance of erythrocytes, formation of echinocytes and changes only in the polar part of the membrane caused by the extracts demonstrate their location mainly in the hydrophilic part of the membrane. The results indicate that tested extracts have high biological activities and may be potentially used in delaying the ageing process of organisms and prevention of many diseases, especially those associated with oxidative stress.

POLYPHENOL CONTENT AND BIOACTIVITY OF SASKATOON (AMELANCHIER ALNIFOLIA NUTT.) LEAVES AND BERRIES.

The studies were designed to determine the polyphenolic composition and biological activity of extracts from fruits (SFE) and leaves (SLE) of Saskatoon (Amelanchier alnifolia Nutt.) in relation to erythrocyte membranes. A detailed quantitative and qualitative analysis of extracts was conducted, using the chro- matographic (UPLC-DAD, UPLC-ESI-MS) and spectrophotometric (Folin-Ciocalteu) methods. The biological activity of the extracts was investigated in relation to erythrocytes and isolated membranes of erythrocytes by using spectrophotometric, fluorimetric and microscopic methods and determined on the basis of hemolytic and antioxidant activity of the extracts and their impact on physical properties of the membrane such as: osmotic resistance, shape of erythrocytes, packing order of the polar head of lipids and fluidity of the membrane. The results showed that the tested extracts are rich sources of polyphenols, primarily from the group of flavonoids; in leaves dominating flavonols and anthocyanins in fruits. The SFE and SLE extracts to varying degree modify the physical properties of the erythrocyte membrane, causing formation of echinocytes, an increase in osmotic resistance and changes in the polar part of the membrane. Furthermore, the substances markedly protect erythrocytes and their membranes against oxidation induced by different physico-chemical factors. The findings indicate that the polyphenolic compounds contained in extracts of Saskatoon do not destroy biological membranes but effectively protect them against oxidation by way of interacting with the membrane surface. The extracts could effectively protect the organism and food products from the harmful effects of free radicals.

Biological Activity of Japanese Quince Extract and Its Interactions with Lipids, Erythrocyte Membrane, and Human Albumin.

The aim of the study was to determine in vitro biological activity of fruit ethanol extract from Chaenomeles speciosa (Sweet) Nakai (Japanese quince, JQ) and its important constituents (-)-epicatechin (EC) and chlorogenic acid (CA). The study also investigated the structural changes in phosphatidylcholine (PC) liposomes, dipalmitoylphosphatidylcholine liposomes, and erythrocyte membranes (RBC) induced by the extract. It was found that the extract effectively inhibits oxidation of RBC, induced by 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH), and PC liposomes, induced by UVB radiation and AAPH. Furthermore, JQ extract to a significant degree inhibited the activity of the enzymes COX-1 and COX-2, involved in inflammatory reactions. The extract has more than 2 times greater activity in relation to COX-2 than COX-1 (selectivity ratio 0.48). JQ extract stimulated growth of the beneficial intestinal bacteria Lactobacillus casei and Lactobacillus plantarum. In the fluorimetric method by means of the probes Laurdan, DPH and TMA-DPH, and (1)H-NMR, we examined the structural changes induced by JQ and its EC and CA components. The results show that JQ and its components induce a considerable increase of the packing order of the polar heads of lipids with a slight decrease in mobility of the acyl chains. Lipid membrane rigidification could hinder the diffusion of free radicals, resulting in inhibition of oxidative damage induced by physicochemical agents. JQ extract has the ability to quench the intrinsic fluorescence of human serum albumin through static quenching. This report thus could be of huge significance in the food industry, pharmacology, and clinical medicine.