GSH turnover may occur in GSH
redox cycle, in which the oxidized glutathione (GSSG)
formed in the reactions of Se-GPX/GST is reduced back to
GSH by glutathione reductase (GR) through utilizing
NADPH supplied by glucose-6-phosphate dehydrogenase
(G6PDH) (Venugopal et al., 1997) or exported from the
cell, like some GSH conjugates, via multi-drug resistance
associated with proteins (Keppler et al., 1997)