Differential effect of schisandrin B and dimethyl diphenyl bicarboxylate (DDB) on hepatic mitochondrial glutathione redox status in carbon tetrachloride intoxicated mice.

The effects of schisandrin B (Sch B), a dibenzocyclooctadiene derivative isolated from the fruit of Schisandra chinensis, and dimethyl diphenyl bicarboxylate (DDB), a synthetic intermediate of schisandrin C (also a dibenzocyclooctadiene derivative), on hepatic mitochondrial glutathione redox status in control and carbon tetrachloride (CCl4)-intoxicated mice were examined. Treating mice with Sch B or DDB at a daily oral dose of 1 mmol/kg for 3 d did not produce any significant alterations in plasma alanine aminotransferase (ALT) and sorbital dehydrogenase (SDH) activities. CCl4 treatment caused drastic increases in both plasma ALT and SDH activities in mice. Pretreating mice with Sch B or DDB at the same dosage regimen significantly suppressed the CCl4-induced increase in plasma ALT activity, with the inhibitory effect of Sch B being much more potent. Sch B, but not DDB, pretreatment could also decrease the plasma SDH activity in CCl4-intoxicated mice. The lowering of plasma SDH activity, indicative of hepatoprotection against CCl4 toxicity, by Sch B pretreatment was associated with an enhancement in hepatic mitochondrial glutathione redox status as well as an increase in mitochondrial glutathione reductase (mtGRD) activity in both non-CCl4 and CCl4-treated mice. DDB pretreatment, though enhancing both hepatic mitochondrial glutathione redox status and mtGRD activity in control animals, did not produce any beneficial effect in CCl4-treated mice. The difference in hepatoprotective action against CCl4 toxicity between Sch B and DDB may therefore be related to their ability to maintain hepatic mitochondrial glutathione redox status under oxidative stress condition.