High doses of eugenol cause structural and functional damage to the rat liver

Eugenol is a phenolic compound found in clove extract and extensively used in traditional medicine. It is unclear whether its intake can cause positive or negative effects on liver morphology and physiology in healthy individuals. Thus, we aimed to evaluate liver parameters of rats treated with 10, 20, and 40 mg kg^-1 eugenol. After 60 days of treatment, liver samples were collected and analyzed by biometric, histological, biochemical, and oxidative analyses. Our results showed that 10, 20, and 40 mg kg^-1 eugenol did not alter body and liver weights, serum and hepatic ALT levels and catalase, glutathione-s-transferase, total, Ca²⁺, and Mg²⁺ ATPases activities in treated animals. However, 20 and 40 mg kg^-1 eugenol reduced Na⁺/K⁺ ATPase pump activity and blood glucose levels. They also increased hepatic glycogen content, superoxide dismutase activity, ferric reducing antioxidant power, and nitric oxide and malondialdehyde levels. Still, 20 and 40 mg kg^-1 eugenol caused structural and functional damage to the liver tissue of eugenol-treated rats. We concluded that 10 mg kg^-1 eugenol is a safe dose for consumption in long-term treatment for rats. Doses higher than 20 mg kg^-1 lead to hepatic damage that can impair vital processes of liver functionality.