Free radicals are atoms or groups of atoms with an odd (unpaired) number of electrons and can be formed when oxygen interacts with certain molecules. Once formed, these highly reactive radicals can start a chain reaction. Their primary danger comes from the damage they can do when they react with important cellular components such as DNA, or the cell membrane. Cells may function poorly or die if this occurs. To prevent free radical damage human body uses a defence system of antioxidants. An antioxidant is a molecule stable enough to donate an electron to neutralize free radical, thus reducing its capacity to damage.
Karnozin Extra is an antioxidant which stabilizes and protects the cell membrane. As hydro-soluble antioxidant, it prevents lipid peroxidation within the cell (two-layered) membrane (Nagai, Suda, Kawasaki & Yamaguchi, 1990). Karnozin Extra protects the cell wall from lipid peroxidation in a larger extent when compared to carnosine alone. Additionally, it can scavenge hydroxyl radicals and nitroso radicals which you can read on the link.
Free radicals cause the so-called oxidative stress of the organism. Carnosine, in principle, reacts with the reactive forms of oxygen (Reactive Oxygen Species – ROS – Free oxygen radicals) and prevents oxidative stress. Carnosine acts not only protectively – it is also active when harmful components are already formed by the functioning of free radicals such as lipid peroxides and their secondary products. In this way, the tissues are protected from the “second wave” of the harmful effects of these substances. For example, carnosine blocks the very reactive final product of lipid peroxidation – malondialdehyde (MDA). MDA, if not avoided, may cause damage to lipids, enzymes and DNA and plays an important role in the development of atherosclerosis, inflammatory and degenerative changes in the joints, cataracts and all the ageing processes. Carnosine inactivates MDA and thus protects the amino acids in the protein molecule, and where it also gets destroyed. Carnosine is a substance that protects and extends the functional life cycle of the key building units of the organism – proteins, DNA, lipids and justifiably can be called the substance of longevity (Quinn, Boldyrev & Formazuyk, 1992; Yuneva, A. O., Kramarenko, G. G., Vetreshchak, Gallant & Boldyrev, 2002)
References:
Nagai, K., Suda, T., Kawasaki, K., & Yamaguchi, Y. (1990). Effects of L-carnosine on blood cells and biomembrane. Nihon seirigaku zasshi. Journal of the Physiological Society of Japan, 52(10), 339-344.
Quinn, P. J., Boldyrev, A. A., & Formazuyk, V. E. (1992). Carnosine: its properties, functions and potential therapeutic applications. Molecular aspects of Medicine, 13(5), 379-444.
Yuneva, A. O., Kramarenko, G. G., Vetreshchak, T. V., Gallant, S., & Boldyrev, A. A. (2002). Effect of carnosine on Drosophila melanogaster lifespan. Bulletin of experimental biology and medicine, 133(6), 559-561.