4.

Interactions of Bioactive Quince (Cydonia oblonga Mill.) Extract with Biomolecules

Paulina Strugała, Sylwia Cyboran-Mikołajczyk, Dorota Wyspiańska, Anna Sokół-Łętowska, Narcyz Piórecki and Janina Gabrielska

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

Department of Fruit, Vegetable and Cereal Technology , Wrocław University of Environmental and Life Sciences, Chełmońskiego 37/41, 51-630 Wrocław, Poland

Arboretum and Institute of Physiography in Bolestraszyce, 37-700 Przemyśl, Poland

University of Rzeszów, Towarnickiego 3, 35-959 Rzeszów, Poland

Abstract: The study is concerned with biological activity of quince (Q) fruit extract (Cydonia oblonga Mill.) towards the phosphatidylcholine liposome and the natural lipid-protein erythrocyte membrane, as well as will explaining the 1 way of interaction of the extract with the membrane. The results showed that Q extract protects lipids against oxidation induced by AAPH compound to a similar extent in two models of membrane. Studies with probes (Laurdan and DPH) located at different depths within the membrane lipid bilayer showed that extract caused an increase of the packing order of the polar heads of lipids and a slight decrease in mobility of the acyl chains. Such results suggest that extract molecules associate with the lipid and lipid-protein membrane and can stop the propagation of free radicals within the bilayer by modifying the membrane fluidity. Furthermore, Q extract resulted in the inhibition of the activity of enzymes (cyclooxygenase-1 and cyclooxygenase-2) probably involved in inflammatory reactions in the body. The experimental results proved that extract components can bind to the main plasma protein – human serum albumin, and the quenching mechanism was suggested as static. The obtained quince–albumin binding constants show that the extract probably can be transported from the circulatory system to reach its target organ.