OXYGEN RADICAL SCAVENGERS INHIBIT CLASTOGENIC ACTIVITY-INDUCED BY SONICATION OF HUMAN SERUM

Clastogenic factors (CF) are diffusible molecules that damage DNA. The y are generated within biological media by a variety of physical and c hemical stimuli. Their nature and mechanism of action remain largely u nknown. Clastogenic activity can be experimentally generated by pulsed ultrasound treatment of human serum. To investigate whether oxygen ra dicals are involved in the clastogenic activity induced by sonication of human serum, we examined the effects on such clastogenic activity o f different oxygen radical scavengers added to human serum before and after sonication. Human serum was sonicated for 50 min at 24 mu W/cm(2 ) by pulsed ultrasound. The clastogenic activity of sonicated human se rum was examined in the presence or absence of oxygen radical scavenge rs by measuring the amount of DNA damage induced in autologous human l ymphocytes, assessed with the fluorometric analysis of DNA unwinding ( FADU). Sonication of human serum generated significant DNA damage in a utologous lymphocytes (DNA unwinding averaged 31.79% +/- 2.1 after son ication vs. 12.82% +\- 2.6 in the controls, p < 0.005). Superoxide dis mutase (SOD; 500 LU./ml), catalase (500 LU./ml), mannitol (50 mM), and glutathione (50 mM) completely prevented DNA damage when added before serum sonication, whereas only mannitol (86%) and glutathione (90%) a lmost completely inhibited DNA damage when added after sonication. SOD and catalase had only a partial inhibitory effect when added after so nication (49% and 63%, respectively). The prevention of DNA damage was also obtained by an association of subliminal amounts of glutathione (20 mM) and vitamin E (1 I.U./ml). These results suggest that the clas togenic activity generated by sonication of human serum is mediated by oxygen radicals.