CYTOKININS, THEIR BIOCHEMICAL ACTIVITY IN DIVISION PROCESS, AGEING AND APOPTOSIS IN HUMAN AND ANIMAL CELLS

Cytokinins are one of the main group of plant hormones. They stimulate anabolic processes and cells growth and divisions. First invented cytokinin was kinetin, N-6-furfuryloadenine. Kinetin is important component of metabolic pathway, which enable cells to release excess free radicals. This is response to oxidative stress. Cytokinin binding proteins (CBP) can be found in plant cells, especially in cytosol, microsomes and thylacoid membranes. Cytokinins combined with CBP cause certain physiological response. Kinetin is a strong inhibitor of proteins and nucleic acids oxidation and glycosylation in vitro. It is a strong antioxidant both in vitro and in vivo. It delays the onset of human cells ageing in cell culture in vitro. Kinetin influences on cell growth and shape, rate of their growth, cytoskeleton structure, macromolecules biosynthesis and lipofuscin content. It acts favorably on skin, enhances barier functions of stratum corneum, decreases TEWL (Transepidermal Water Loss) and improves skin colour. Both kinetin and its ribosides are cytotoxic to melanoma cells. Another cytokinin is N-6-benzyloadenine. It influences mainly on the cell divisions. It can also inhibit some of human kinases, including CDKs (Cyclin Dependent Kinases). It is important especially for cancer cells. Benzyloadenine derivatives stimulate apoptosis in many types of cancer cells. N-9-benzyladenine inhibits phosphodiesterases (PDE) activity. Furthermore, it was shown in fibroblasts culture that N-6-benzyladenine derivatives stimulate cells elongation.. decreasing of their movement and increase of their adhesion to medium.