Results depicted in Fig. 4 indicate that complex I inhibition by Ebs, (PhSe)2 and (PhTe)2 was not modified by the addition of SOD (Fig. 4A), CAT (Fig. 4B) or SOD + CAT (Fig. PARP inhibitor 4C). In order to test the hypothesis that organochalcogens-induced complex I inhibition is mediated by oxidation of thiol groups, we investigated the efficacy of GSH

to reverse the organochalcogens-induced inhibition of complex I. Fig. 5 shows that GSH (500 μM) completely reversed the organochalcogens-induced complex I inhibition in hepatic (Fig. 5A) and in renal (Fig. 5B) membranes. In order to check the inhibitory effect of different organochalcogens in mitochondria complex II activity, we carried out experiments at two different conditions. In brief, in condition 1 the membranes were incubated with the organocompounds (at different concentrations) in the presence of succinate

5 mM for 10 min. The reaction was stopped 3 min after MTT by addition of ethanol. In condition 2, the mitochondrial membranes see more were incubated with various concentrations of organocompounds in the absence of succinate for 10 min. Succinate (5 mM) and MTT were then added and the reaction stopped after 3 min by the addition of ethanol. Statistical analysis indicates that Ebs and (PhTe)2 significantly inhibited both hepatic and renal complex II activity in both conditions (Fig. 6). In contrast, (PhSe)2 did not change the mitochondrial complex II activity from liver (Fig. 6A and B), but inhibited renal complex II activity under condition 6-phosphogluconolactonase 1 (Fig. 6C), without inhibiting it under experimental condition 2 (Fig. 6D). The IC50 (μM) values for inhibition by organochalcogens of mitochondrial complex II activity, in both conditions, are showed in Table 1. Malonate (8 mM) caused a significant inhibition of the mitochondrial complex II activity that varied from 40% to 70% inhibition (see Fig. 6A–D). GSH (500 μM) completely reversed the organochalcogens-induced complex II inhibition both in hepatic (Fig.

7A) and renal (Fig. 7B) membranes. Ebs and (PhTe)2 inhibited the mitochondrial complexes II–III activity from liver (Fig. 8A) and kidney (Fig. 8B). (PhSe)2 did not inhibit hepatic complexes II–III activity (Fig. 8A), but significantly inhibited renal complexes II–III activity (Fig. 8B). The IC50 (μM) values for inhibition by organochalcogens of mitochondrial complexes II–III activity are showed in Table 1. Statistical analysis revealed that Ebs did not modify the hepatic (Fig. 9A) or renal (Fig. 9B) complex IV activity. (PhSe)2 slightly inhibited complex IV activity from liver and kidney (Fig. 9A and B), whereas (PhTe)2 did not change the renal complex IV activity (Fig. 9B); but it inhibited hepatic complex IV activity at 50 μM (Fig. 9A). The IC50 (μM) value for inhibition by (PhSe)2 of mitochondrial complex IV activity is showed in Table 1.