Plant polyphenols including flavonoids and tannins are important constituent of our everyday diet and medical herbals. It is broadly accepted that polyphenols may protect us from toxins, carcinogens and pollutants though the mechanisms of the polyphenols action is still not clear. Here we discuss the ability of polyphenols and especially gallate rich compounds like tannins and catechin gallates to interact with proteins and lipids, establish binding between adjacent bilayer surfaces and initiate membrane aggregation. This phenomena discovered in model experiments could also influence lateral segregation and compartmentalization of cell surface compounds and assist the cell-cell interaction and signal transduction. The involvement of plant polyphenols in communication between cells could be an important factor responsible for anticarcinogenic, vascular and cardioprotective activity of these compounds and speculated to be implicated in the evolution of human brain and intelligence.Plant polyphenols including flavonoids and tannins are present on our daily diet. The opinion on their influence on the human health is contradictory and ranges widely from positive to skeptic and even to alarming. [1][2][3] Obviously the processes of their functioning in our body should be studied in more details.The polyphenols are know not only as patent antioxidants but also as cell metabolism regulators. 4 The biological functioning of these compounds begins from their interaction with the cell surface and penetration through the plasma membrane into the cytoplasm. They can influence various physical properties of membrane lipids including diffusion, melting temperature, detergent solubility, osmotic stability, permeability to water soluble compounds 5-7 and general parameters of lipid packing and intrinsic bilayer curvature related to membrane interaction and fusion. Their penetration through the lipid bilayer inversive correlates with the number of hydroxyl groups and accordingly with the hydrophobicity of molecules.The background of polyphenols functioning is attributed to the ability of these compounds to interact with proteins, lipids and polynucleotides through electrostatic, hydrophobic, and even covalent binding. [6][7][8][9] The polyphenolic compounds are generally not very active chemically and only electrostatic and hydrophobic forces are responsible for their interaction within cells. However, after oxidation of catechol and gallate 10 moieties to quinones (Fig. 1) in presence of peroxidases, polyphenol oxidases, alkaline pH, or transition metals they could be involved in reactions with free nucleophilic functional groups such as sulfhydryl, amine, amide, indole and imidazole substituents; 11 and result in covalent binding with different residues including lysine, methionine, cysteine and tryptophane. 8,12 We expect that terminal amino groups of phosphatidylethanolamines or sulfolipids of biological membranes can also participate in covalent binding with quinones. The consequence of chemical derivatization of proteins ma...