ANTIOXIDATIVE AND PROTECTIVE PROPERTIES OF EXTRACTS FROM LEAVES OF THE ARTICHOKE (CYNARA-SCOLYMUS L) AGAINST HYDROPEROXIDE-INDUCED OXIDATIVE STRESS IN CULTURED RAT HEPATOCYTES

Primary rat hepatocyte cultures exposed to tert-butylhydroperoxide (t- BHP) or cumene hydroperoside were used to assess the antioxidative and protective potential of water-soluble extracts of artichoke leaves, B oth hydroperoxides stimulated the production of malondialdehyde (h IDA ), particularly when the cells were pretreated with diethyimaleate (DE M) in order to diminish the level of cellular glutathione (GSH), Addit ion of artichoke extracts did not affect basal MDA production, but pre vented the hydroperoxide-induced increase of MDA formation in a concen tration-dependent manner when presented simultaneously or prior to the peroxides, The effective concentrations (down to 0.001 mg/ml) were we ll below the cytotoxic levels of the extracts which started above 1 mg /ml, The protective potential assessed by the LDH leakage assay and th e MTT assay closely paralleled the reduction in MDA production and lar gely prevented hepatocyte necrosis induced by the hydroperoxides, The artichoke extracts did not affect the cellular level of glutathione (G SH), but diminished the loss of total GSH and the cellular leakage of GSSG resulting from exposure to t-BHP. Chlorogenic acid and cynarin ac counted for only part of the antioxidative principle of the extracts w hich was resistent against tryptic digestion, boiling, acidification, and other treatments, hut was slightly sensitive to alkalinization. Th ese results demonstrate that artichoke extracts have a marked antioxid ative and protective potential, Primary hepatocyte cultures seem suita ble for identifying the constituents responsible for these effects and for elucidating their possible mode of action. (C) 1997 Academic Pres s.