[Oxidative stress and liver disease].

Several papers have been published on the important role of oxidative stress on living cells and cell responses e.g. apoptosis and necrosis, which leads to cell death. At the same time mild oxidative stress can modulate signal transduction cascades and redirect gene expression, and influence many cellular responses, e.g. proliferation, differentiation, reproduction. Regulations of the cell cycle depend on intracellular redox state. Critical steps in the signal transduction cascade are sensitive to oxidative stress and antioxidants. Heavy metal accumulation in higher concentration may inhibit enzyme activities influence the acute phase protein synthesis and gene expression, as well as the pro-oxidant and antioxidant forms of scavenger molecules. Polyphenols and flavonoid type antioxidants may influence the signal transduction routes as well. Ethanol inducible cytochrome P450 2EI isoenzyme oxidise ethanol and acetaldehyde and numerous potentially toxic xenobiotic and produce toxic oxygen free radicals, which are implicated in the pathogenesis of alcoholic liver diseases. Natural preparations, e.g. tea infusions contains trace elements and polyphenol type antioxidants in high concentration, therefore may influence the redox homeostasis, and especially dangerous with interaction of other medicines and alcohol.