Therapeutic effect of S-allylmercaptocysteine on acetaminophen-induced liver injury in mice.

S-allylmercaptocysteine is one of the water-soluble organosulfur compounds in ethanol extracts of garlic (Allium sativum L.). We had demonstrated earlier that treatment with S-allylmercaptocysteine before acetaminophen administration protects mice against acetaminophen-induced hepatotoxicity. In this study, we examined the therapeutic effect of S-allylmercaptocysteine treatment after acetaminophen administration. A single dose of S-allylmercaptocysteine (200 mg/kg, p.o.) to mice 0.5 h after acetaminophen administration (500 mg/kg, p.o.) significantly suppressed both the increase in plasma alanine aminotransferase activity and the hepatic necrosis, and also reduced acetaminophen-induced mortality from 43% to 0%. These data indicate that S-allylmercaptocysteine is useful as an antidote for acetaminophen overdose. S-allylmercaptocysteine significantly suppressed hepatic cytochrome P450 2E1 (CYP2E1) activity and induction of inducible 70-kDa heat shock protein, a marker of acetaminophen arylation of protein. These results suggest that S-allylmercaptocysteine exerts its protective effect by inhibition of CYP2E1 activity, which leads to the suppression of acetaminophen arylation of hepatic protein.

Mechanisms of protection by S-allylmercaptocysteine against acetaminophen-induced liver injury in mice.

S-Allylmercaptocysteine (SAMC), one of the water-soluble organosulfur compounds in ethanol extracts of garlic (Allium sativum L.), has been shown to protect mice against acetaminophen (APAP)-induced liver injury. In this study, we examined the mechanisms underlying this hepatoprotection. SAMC (100 mg/kg, p.o.) given 2 and 24 hr before APAP administration (500 mg/kg, p.o.) suppressed the plasma alanine aminotransferase activity increases 3 to 12 hr after APAP administration significantly. The hepatic reduced glutathione levels of vehicle-pretreated mice decreased 1 to 6 hr after APAP administration, but SAMC pretreatment suppressed the reductions 1 to 6 hr after APAP administration significantly. These inhibitory effects of SAMC were dose-dependent (50-200 mg/kg) 6 hr after APAP administration. As SAMC pretreatment (50-200 mg/kg) suppressed hepatic cytochrome P450 2E1-dependent N-nitrosodimethylamine demethylase activity significantly in a dose-dependent manner, we suggest that one of its protective mechanisms is inhibition of cytochrome P450 2E1 activity. SAMC pretreatment also suppressed the increase in hepatic lipid peroxidation and the decrease in hepatic reduced coenzyme Q9 (CoQ9H2) levels 6 hr after APAP administration. The hepatic CoQ9H2 content of the SAMC pretreatment group was maintained at the normal level. Therefore, we suggest that another hepatoprotective mechanism of SAMC may be attributable to its antioxidant activity.

Anti-allergic effects of aged garlic extract.

To examine the effect of Aged Garlic Extract (AGE) on the function of mast cells and activated T lymphocytes, we adopted the in vitro histamine release system, the in vivo IgE mediated skin reaction system and the in vivo late phase reaction system. Consequently, at 1.25, 2.5, and 5.0% (v/v), AGE dose-dependantly inhibited the antigen specific histamine release by mouse anti-TNP monoclonal antibody and TNP-BSA hapten carrier complex against rat basophil cell line RBL-2H3 by 50, 80, and 90 percent, respectively. In the IgE mediated skin reaction system, repeated or single intragastric administration of AGE (10 ml/kg), decreased by 25-45% the antigen specific ear swelling which was induced by a picryl chloride ointment applied to the ear of mice also given an intravenous administration of anti-TNP antibody IgE ascites. In the late phase reaction system, repeated or single intragastric administration of AGE (10 ml/kg) suppressed by 45-55% the antigen specific ear swelling induced by a secondary challenge to the ear of mice given a picryl chloride ointment seven days prior. These results suggest that AGE application could modify, directly or indirectly, the function of mast cells, basophils and activated T lymphocytes which play a leading role in allergic cascade reactions including inflammation.