Reduction of carbon tetrachloride-induced rat liver injury by IRFI 042, a novel dual vitamin E-like antioxidant

Abstract

Carbon tetrachloride (CCl₄)-induced hepatotoxicity is likely the result of a CCl₄-induced free radical production which causes membrane lipid peroxidation and activation of transcription factors regulating both the TNF-α gene and the early-immediate genes involved in tissue regeneration. IRFI 042 is a novel vitamin E-like compound having a masked sulphydryl group in the aliphatic side chain. We studied the effect of IRFI 042 on CCl₄-induced liver injury. Liver damage was induced in male rats by an intraperitoneal injection of CCl₄ (1 ml/kg in vegetal oil). Serum alanine aminotransferase (ALT) activity, liver malondialdehyde (MAL), hydroxyl radical formation (OH·), calculated indirectly by a trapping agent, hepatic reduced glutathione (GSH) concentration, plasma TNF-α, liver histology and hepatic mRNA levels for TNF-α were evaluated 48 h after CCl₄ administration. Hepatic vitamin E (VE) levels were evaluated, in a separate group of animals, 2 h after CCl₄ injection. A control group with vitamin E (100 mg/kg) was also treated in order to evaluate the differences versus the analogue treated groups.

Intraperitoneal injection of carbon tetrachloride produced a marked increase in serum ALT activity (CCl₄= 404.61 ± 10.33 U/L; Controls= 28.54 ± 4.25 U/L), liver MAL (CCl₄= 0.67 ± 0.16 nmol/mg protein; Controls= 0.13 ± 0.06 nmol/mg protein), OH^· levels assayed as 2,3-DHBA (CCl₄= 8.73 ± 1.46 μM; Controls= 0.45 ± 0.15 μM) and 2,5-DHBA (CCl₄= 24.61 ± 3.32 μM; Controls= 2.75 ± 0.93 μM), induced a severe depletion of GSH (CCl₄= 3.26 ± 1.85 μmol/g protein; Controls= 17.82 ± 3.13 μmol/g protein) and a marked decrease in VE levels (CCl₄= 5.67 ± 1.22 nmol/g tissue; Controls= 13.47 ± 3.21 nmol/g tissue), caused liver necrosis, increased plasma TNF-α levels (CCl₄= 57.36 ± 13.24 IU/ml; Controls= 7.26 ± 2.31 IU/ml) and enhanced hepatic mRNA for TNF-α (CCl₄= 19.22 ± 4.38 a.u.; Controls= 0.76 ± 0.36 a.u.).

IRFI 042 (100 mg/kg, 30 min after CCl₄ injection) blunted liver MAL (0.32 ± 0.17 nmol/mg protein), decreased the serum levels of ALT (128.71 ± 13.23 U/L), and restored the hepatic concentrations of VE (9.52 ± 3.21 nmol/g tissue), inhibited OH^· production (2,3-DHBA= 3.54 ± 1.31 μM; 2,5-DHBA= 7.37 ± 2.46 μM), restored the endogenous antioxidant GSH (12.77 ± 3.73 mmol/g protein) and improved histology. Furthermore IRFI 042 treatment suppressed plasma TNF-α concentrations (31.47 ± 18.25 IU/ml) and hepatic TNF-α mRNA levels (11.65 ± 3.21 a.u.). The acute treatment with vitamin E failed to exert any protective effect against CCl₄-induced hepatotoxicity.

These investigations suggest that IRFI 042 treatment may be of benefit during free radical-mediated liver injury.

Keywords:

• Liver injury
• CCl₄
• antioxidants
• IRFI 042
• lipid peroxidation
• free radicals
• gene expression
• vitamin E
• TNF-α