The aim of the study was to broadly determine the biological activities of purple potato ethanolic extract of the Blue Congo variety (BCE). The antioxidant activity of BCE was determined in relation to liposome membranes, and peroxidation was induced by UVB and AAPH. To clarify the antioxidant activity of BCE, we investigated its interactions with hydrophilic and hydrophobic regions of a membrane using fluorimetric and FTIR methods. Next, we investigated the cytotoxicity and pro-apoptotic activities of BCE in two human colon cancer cell lines (HT-29 and Caco-2) and in normal cells (IPEC-J2). In addition, the ability to inhibit enzymes that are involved in pro-inflammatory reactions was examined. Furthermore, BCE interactions with serum albumin and plasmid DNA were investigated using steady state fluorescence spectroscopy and a single molecule fluorescence technique (TCSPC-FCS). We proved that BCE effectively protects lipid membranes against the process of peroxidation and successfully inhibits the cyclooxygenase and lipoxygenase enzymes. Furthermore, it interacts with the hydrophilic and hydrophobic parts of lipid membranes as well as with albumin and plasmid DNA. It was observed that BCE is more cytotoxic against colon cancer cell lines than normal IPEC-J2 cells; it also induces apoptosis in cancer cell lines, but does not induce cell death in normal cells.

Department of Biochemistry and Molecular Biology Faculty of Veterinary Medicine Wroclaw University of Environmental and Life Sciences C K Norwida 31 50 375 Wrocław Poland

Department of Biophysical Chemistry J Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences Dolejskova 3 18223 Prague 8 Czech Republic

Department of Physics and Biophysics Wrocław University of Environmental and Life Sciences C K Norwida 25 50 375 Wrocław Poland

Department of Physics and Biophysics Wrocław University of Environmental and Life Sciences C K Norwida 25 50 375 Wrocław Poland and Department of Biophysical Chemistry J Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences Dolejskova 3 18223 Prague 8 Czech Republic

Laboratory of Glycobiology Ludwik Hirszfeld Institute of Immunology and Experimental Therapy Polish Academy of Sciences Rudolfa Weigla 12 53 114 Wrocław Poland and Department of Biochemistry and Molecular Biology Faculty of Veterinary Medicine Wroclaw University of Environmental and Life Sciences C K Norwida 31 50 375 Wrocław Poland

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