• YAKHAK HOEJI
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• v.34 no.4
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• pp.267-276
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• 1990

To achieve a better understanding of antioxidant action manifested by malotilate, the dithiol malonates, we monitored the oxy radical-scavenging system against the chronic hepatic damage induced by $CCl_4$ alone or in combination with ethanol. Malotilate was given orally at a dose of 100 mg/kg/day and $CCl_4$ 1.5 ml/kg was injected subcutaneously twice a week for 4 weeks. In each group receiving ethanol, drinking water was replaced by 20% aqueous solution or glucose, isocaloric amounts of ethanol, as a control of ethanol was diluted in its drinking water. Each rat was killed as a starved state at 18 hours after the period of the experiment, four weeks. The results were summarized as follows: 1) Malotilate inhibited the rate of generation of superoxide radicals, the accumulation of lipoperoxides, and promoted the synthesis of glutathione in the liver. 2) Malotilate stimulated the enhancement of activity of superoxide dismutase in hepatic mitochondria. 3) Malotilate had no effects on the hepatic $H_2O_2$ contents. 4) Malotilate showed the increase of catalase activity in the liver poisoned with $CCl_4$, and also gave a tendency to increase it in the liver intoxicated with ethanol. Thus, our data suggested that the activation of hepatic antioxidant system in the presence of malotilate would play a role in protecting liver against the toxic effects of oxy radical and/or lipid peroxides under the hepatotoxic conditions induced by $CCl_4$ with or without ethanol. However, the effects of malotilate against the ethanol-induced hepatotoxicity appear to be insignificant.

• YAKHAK HOEJI
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• v.31 no.6
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• pp.399-401
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• 1987

A gas chromatographic utilizing procedure headspace gas analysis is performed to study effect of malotilate on levels of ethanol and its metabolite acetaldehyde in a blood sample from the rat. The concentrations of ethanol and acetaldehyde were determined simultaneously at 1, 3, and 6h after ethanol administration. Our results would suggest the malotilate could promote clearances of ethanol and acetaldehyde in blood, and could accelerate it, especially, in $CCl_4$ pretreated rats.

• The Korean Journal of Pharmacology
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• v.32 no.3
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• pp.407-416
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• 1996

The reactive intermediates formed during the metabolism of therapeutic agents, toxicants and carcinogens by cytochromes P450 are frequently capable of covalently binding to tissue macromolecules and causing tissue damage. It has been shown that YH439, a congener of malotilate, is effective in suppressing hepatic P450 2E1 expression. The present study was designed to further establish the mechanistic basis of YH439 protection against toxicant by assessing its effects against chemical-mediated potentiated hepatotoxicity. Retinoyl palmitate (Vit-A) pretreatment of rats for 7 days substantially enhanced carbon tetrachloride hepatotoxicity, as supported by an ${\sim}5-fold$ increase in serum alanine aminotransferase (ALT) activity, as compared to $CCl_4$ treatment alone. The elevation of ALT activity due to Vit-A was completely blocked by the treatment of $GdCl_3$ a selective inhibitor of Kupffer cell activity. Concomitant pretreatment of rats with both YH439 and Vit-A resulted in a 94% decrease in Vit-A-potentiated $CCl_4$ hepatotoxicity. YH439 was also effective against propyl sulfide-potentiated $CCl_4-induced$ hepatotoxicity. Whereas propyl sulfide (50 mg/kg, 7d) enhanced $CCl_4-induced$ hepatotoxicity by >5-fold, relative to $CCl_4$ treatment alone, concomitant treatment of animals with both propyl sulfide and YH439 at the doses of 100 and 200 mg/kg prevented propyl sulfide-potentiated $CCl_4$ hepatotoxicity by 35% and 90%, respectively. Allyl sulfide, a suppressant of hepatic P450 2E1 expression, completely blocked the propyl sulfide-enhanced hepatotoxicity, indicating that propyl sulfide potentiation of $CCl_4$ hepatotoxicity was highly associated with the expression of P450 2E1 and that YH439 blocked the propyl sulfide-enhanced hepatotoxicity through modulation of P450 2E1 levels. Propyl sulfide- and $CCl_4-induced$ stimulation of lipid peroxidation was also suppressed by YH439 in a dose-related manner, as supported by decreases in malonedialdehyde production. The role of P450 2E1 induction in the potentiation of $CCl_4$ toxicity and the effects of YH439 were further evaluated using pyridine as a P450 2E1 inducer. Pyridine pretreatment substantially enhanced the $CCl_4$ hepatotoicity by 23-fold, relative to $CCl_4$ alone. YH439, however, failed to reduce the pyridine-potentiated toxicity, suggesting that the other form(s) of cytochroms P450 inducible by pyridine, but not suppressible by YH439 treatment, may play a role in potentiating $CCl_4-induced$ hepatotoxicity. YH439 was capable of blocking cadmium chloride-induced liver toxicity in mice. These results demonstrated that YH439 efficiently blocks Vit-A-enhanced hepatotoxiciy through Kupffer cell inactivation and that the suppression of P450 2E1 expression by YH439 is highly associated with blocking of propyl sulfide-mediated hepatotoxicity.