Background: Recently, researchers have shown an increased interest in traditional herbal medicine. The leaves of Mentha longifolia are cultivated all over Iraq. Although, the plants have a wide range of reputed therapeutic properties for treating stomach problems and intestinal disorder, there is insufficient knowledge about this plant makes it difficult to warrant its effectiveness and safety.
Objective: The current study is designed to assess the antioxidant activities and acute oral toxicity of methanol extract from Mentha longifolia leaf in Wistar albino rats.
Materials and Methods: The antioxidant activity of Mentha longifolia leaf was examined using TLC- bioautography assay based 2,2-Diphenyl-1-picrylhydrazyl (DPPH). In acute toxicity evaluation, the mortality, toxicity signs, feeding and water consuming parameters were daily assessed for 14 days. This followed oral single dose administration of Mentha longifolia extract to rats at doses ranging from 10 to 70 mg/kg body weight. The oral single-dose effect of this plant extract on serum level of liver biochemical parameters (AST, ALT, ALP) was also estimated.
Results: The results revealed that the methanolic extracts of Mentha longifolia plant possess good antioxidant activity and free radical scavenging capacity with IC50 value to neutralize the 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH) were 30 mg/ml. Mentha longifolia did not exhibit any toxicity, mortality and significant changes in food/water consumption by rats at 70mg/kg body weight. Furthermore, no significant differences were observed in the serum AST, ALT and ALP activities between the treated groups and control group.
Conclusion: The results suggested that the Mentha longifolia leaves extract shows good antioxidant properties. Therefore, it might be a promising natural source of candidate compounds to develop new drugs. In addition, the acute oral dose administration of Mentha longifolia methanolic leaves extract was nontoxic and safe in single dose.
Key words: Mentha longifolia L., LD50, DPPH, liver enzymes,