Cytoprotection and iron mobilization in rat hepatocyte cultures by a new synthetic dihydroxamate chelator

The cytoprotection and iron mobilization effect of a new dihydroxamate chel ator 1,1 bis [(11-N-hydroxy)-2,5,11-triaza-1,6,10-trioxo dodecanyl] ethane or KD was studied in primary rat hepatocyte cultures exposed to iron-citrat e. Lactate dehydrogenase (LDH) release and malondialdehyde (MDA) production were measured as indexes of cytotoxicity. Cell viability was evaluated usi ng the [3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyl tetrazolium bromide] (MT T) reduction test. To demonstrate that this chelator was able to decrease i ron uptake or increase iron release from the hepatocytes, labelled cells we re obtained by maintaining the cultures in the presence of 0.02 mu M Fe-55- citrate. The efficacy of KD was compared to desferrioxamine B (DFO) at stoe chiometry concentrations. After 24 h of exposure to 50 mu M of iron-citrate , a significant release of LDH and MDA was observed. Cell viability was als o significantly decreased. When 100 mu M of KD were added at the same time as iron, LDH and MDA release was decreased and cell viability was improved. In the presence of the same chelator concentration, a net decrease of iron uptake by the cells was observed as attested by the low intracellular Fe-5 5 level. Moreover, in the Fe-55 loaded hepatocytes, the chelator increased the iron extracellular level indicating its iron release effect from the ce lls. In all tested experimental conditions, the efficacy of 100 mu M of the dihydroxamate chelator KD was close to that of 50 mu M of the trihydroxama te chelator DFO. In conclusion, KD is effective at a level comparable to DF O in protecting rat hepatocytes against the toxic effect of iron-citrate by decreasing the uptake of the metal and increasing its release from the cel ls. This synthetic compound appears to have some potential therapeutical in terest and the results obtained encourage the synthesis of new hydroxamate ligands. (C) 1999 Published by Elsevier Science Ireland Ltd. All rights res erved.