Alijaniha_2025_Toxicol.Res.(Camb)_14_tfaf114

Chlorpyrifos (CPF) is a widely used pesticide known for its hepatotoxic effects. Melissa officinalis L. is a medicinal herb, recognized in Persian medicine for its diverse biological activities and protective effects against poisons. This study aimed to study the protective effects of M. officinalis against CPF-induced hepatotoxicity in male rats. Experimental groups included control, sham, CPF (10 mg/kg), M. officinalis (500 mg/kg), and combinations of CPF with M. officinalis (100, 250, and 500 mg/kg). M. officinalis dried powder was administered orally for four weeks, with CPF introduced in the third week. Following treatment, biochemical parameters include serum levels of AST, ALT, ALP, LDH, oxidative stress in liver tissue, acetylcholinesterase (AChE) activity and paraoxonase-1 (PON) activity in the serum, and PON1 gene expression in the liver, along with histological alterations in liver tissue were assessed. Results indicated that CPF-treated groups had significantly increased AST, ALT, and LDH levels in serum and induced oxidative stress in liver tissue, while M. officinalis ameliorate these changes in a dose-dependent manner. Histological analysis showed M. officinalis at 250 mg/kg dose prevented CHF-induced inflammation and degeneration in the liver, but the 500 mg/kg dose resulted in cytoplasmic vesicle lesions and inflammatory cell infiltration. AChE activity was significantly inhibited by CPF, and M. officinalis did not mitigate this inhibition. PON activity and gene expression were also unaffected by M. officinalis treatment. In conclusion, M. officinalis effectively mitigated CPF-induced liver damage and oxidative stress at low to medium doses, while higher doses caused tissue damage.