Effect of ascorbic acid esters on hepatic glutathione levels in mice treated with a hepatotoxic dose of acetaminophen

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Abstract
Acetaminophen (APAP) with or without ascorbyl stearate (AS) or ascorbyl palmitate (AP) was administered by gavage to male Swiss-Webster mice at a dose of 600 mg/kg for each chemical. The biochemical markers of hepatotoxicity, serum transaminases (serum glutamate pyruvate transaminase [SGPT], serum glutamate oxaloacetic transaminase [SGOT]) and serum isocitrate dehydrogenase (SICD) activities were monitored after APAP and APAP + AP or AS dosing. There were significant reductions in serum transaminase and SICD activities in the APAP- + ascorbate ester-treated animals as compared to APAP-positive controls. Oral coadministration of APAP with AP or AS did not prevent the initial hepatic GSH depletion (15 min-4 hr postdosing). However, hepatic GSH content began to rise in the APAP + AS or AP-treated animals at 4 hr and reached control values within 12 hr postdosing. Urinary mercapturate conjugates were also significantly higher in the APAP + AP or AS-treated animals as compared to APAP alone when measured over a 60-min postdosing period. Plasma sulfobromophthalein (BSP) retention was approximately eight times higher in APAP-treated animals as compared to the APAP + ascorbate ester treatments indicating maintenance of hepatic excretory functions in presence of AP or AS. Prior depletion of hepatic GSH by diethyl maleate (DEM) did not alter hepatoprotective effects of AP or AS in the presence of APAP. Hepatic ascorbate levels also peaked at 4 hours after APAP + AP or AS treatments. The possible role of L-ascorbic acid esters in GSH regeneration following co-administration of a hepatotoxic dose and APAP is discussed.