Decrease of hepatic catalase level by treatment with diallyl sulfide and garlic homogenates in rats and mice

Area of Science:

• Biochemistry
• Toxicology
• Nutritional Science

Background:

• Diallyl sulfide (DAS) is a garlic-derived compound known for inhibiting chemical carcinogenicity in animal models.
• Garlic compounds, including DAS, are investigated for their potential health benefits and biological activities.
• Catalase, glutathione peroxidase, and superoxide dismutase are key antioxidant enzymes involved in cellular defense against oxidative stress.

Purpose of the Study:

• To investigate the impact of Diallyl sulfide (DAS) and garlic homogenates on the activity of hepatic and extrahepatic antioxidant enzymes.
• To determine the effect of DAS treatment duration and dosage on catalase activity.
• To assess the role of diallyl sulfone (DASO2), a metabolite of DAS, on catalase activity.

Main Methods:

• Male Sprague-Dawley rats and A/J mice were administered varying doses of DAS and garlic homogenates via intragastric gavage.
• Enzyme activities of catalase, glutathione peroxidase, and superoxide dismutase were measured in liver and other tissues (kidney, lung, brain, heart, erythrocytes).
• Western blot analysis was used to evaluate liver catalase protein levels following DAS treatment.
• In vitro assays were performed to test the direct inhibitory effects of DAS and DASO2 on catalase activity.

Main Results:

• DAS treatment (50 or 200 mg/kg daily for 8 days) dose-dependently decreased hepatic catalase activity by 55% and 95%, respectively.
• Extended DAS treatment (29 days) and short-term high-dose treatment (200 mg/kg for 1-7 days) also significantly reduced liver catalase activity.
• Western blot confirmed that DAS treatment led to decreased liver catalase protein levels.
• Garlic homogenates (2 or 4 g/kg daily for 7 days) reduced liver catalase activity by 35% in rats.
• Neither DAS nor its metabolite DASO2 inhibited catalase activity in vitro.
• No significant changes in superoxide dismutase and glutathione peroxidase activities were observed in the treated tissues.

Conclusions:

• Diallyl sulfide and garlic homogenates effectively decrease hepatic catalase levels in rats and mice.
• The reduction in catalase activity appears to be mediated by decreased protein expression rather than direct enzyme inhibition.
• The observed effects are specific to hepatic catalase, with minimal impact on other antioxidant enzymes or catalase in other tissues.