Abstract
Purpose: To determine, in Sprague Dawley rats, the toxicity profile of the methanol extract of Mentha spicata, a plant used in folklore medicine for the treatment of various forms of pain. Methods: The plant extract, at concentrations ranging from 100 - 0.07 mg/ml, was used to determine the median lethal concentration (LC50) based on brine shrimp lethality assay. Artificial sea water served as control. Acute oral toxicity testing was carried out, according to the Organisation for Economic Co-operation and Development (OECD) guidelines, based on serum biochemical analysis and histological investigations of liver, kidney, heart, spleen and lungs. Results: The LC50 value of Mentha spicata was 1701 µg/ml in brine shrimp lethality assay, indicating that the plant extract is non-toxic. For acute toxicity testing, administration of a single dose of 5000 mg/kg extract to the rats did not produce toxicity, in terms of changes in behaviour or mortality. Moreover, the weight of major organs of the animals did not significantly (p > 0.05) differ from those of the control group. No toxicologically significant (p > 0.05) hematological and biochemical changes were noticed between animals treated with the plant extract and control animals. Treatment with plant extract did not cause any morphological changes in the heart, liver, kidney and lung tissues of the rats. Histopathological examination also did not reveal any toxicity evidence in the extract-treated animals. Conclusion: The results obtained suggest that the plant extract can be classified as non-toxic.
Highlights
Plants have been utilized as medicines for thousands of years in the form of crude drugs such as tinctures, teas, poultices, powders, and other herbal formulations [1,2]
The LC50 value for the percentage of mortality brine shrimp treated with Mentha spicata extracts as indicated by the regression equation (R2= 0.8520) was found to be 1701 μg/ml
The value was significantly (p
Summary
Plants have been utilized as medicines for thousands of years in the form of crude drugs such as tinctures, teas, poultices, powders, and other herbal formulations [1,2]. The test was carried out on both control (artificial sea water), plant extract and potassium dichromate at a concentration range of 1.95 – 1000 μg/ml (n = 3), and mortality computed as in Eq 1 [9,10]. Lethality was calculated from the mean survival of larvae in extract-treated tubes and that of control. The animals (n = 6) were treated with a single dose of 5000 mg/kg of Mentha spicata extract by oral gavage (with the volume of 10 ml/kg body weight of the rats) after overnight fast. Surviving animals were weighed daily and visual observations for mortality, behavioral pattern changes such as weakness, aggressiveness, food or water refusal, diarrhea, salivation, discharge from eyes and ears, noisy breathing, changes in locomotor activity, clonic convulsion, coma, injury, pain or any signs of illness in each treated group were monitored carefully on daily basis throughout the experiment period. Confirmation of statistical difference was by Tukey and LSD tests (p < 0.05)
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