Acute and sub-chronic toxicity studies of an aqueous extract of the leaves of Macaranga heterophylla Müll. Arg. (Euphorbiaceae) in Sprague-Dawley rats

Ethnopharmacological Relevance. In Côte d'Ivoire, Macaranga heterophylla is traditionally used to treat snakebites, coughs, amenorrhoea, and gonorrhoea. To the best of our knowledge, no toxicity studies on this plant have been reported in the literature, despite its medicinal use. Aim of the Study. This study aimed to evaluate the acute and sub-chronic toxicity of an aqueous extract of the leaves of M. heterophylla (MH extract) in Sprague-Dawley rats and assess its heavy metal content. Materials and methods: Acute toxicity was assessed by administering single oral doses of MH extract (1600, 3200, and 6400 mg/kg) to rats, followed by observations over 13 days for signs of toxicity or mortality. Sub-chronic toxicity was evaluated through daily oral administration of MH extract (100, 300, and 1000 mg/kg) for 90 days. In both the acute and sub-chronic toxicity studies, haematological and biochemical analyses were performed using blood samples collected at the end of the observation periods. Additionally, histopathological examination of major organs (heart, liver, kidneys, lungs, and spleen) was conducted to assess any structural abnormalities. Heavy metals in the raw leaf powder and the aqueous extract were quantified using atomic absorption spectroscopy. Results: Acute toxicity tests revealed no observable signs of toxicity, no significant changes in body weight, and no mortality, with the LD₅₀ estimated to be higher than 6400 mg/kg. Haematological parameters showed no significant differences between treated and control groups. However, total protein levels increased significantly (p < 0.05) at 3200 mg/kg, and LDL cholesterol levels increased significantly (p < 0.01) at 6400 mg/kg. Sub-chronic toxicity findings indicated dose-dependent effects, including piloerection at 300 mg/kg and lethargy and mortality at 1000 mg/kg. Significant decreases in lymphocyte percentages (p < 0.001), increases in neutrophil percentages (p < 0.001), and elevated neutrophil-to-lymphocyte ratios (p < 0.0002) were observed at 300 mg/kg. Total bilirubin levels decreased significantly (p < 0.001) at 100 mg/kg and increased significantly (p < 0.001) at 300 mg/kg. Histopathological analysis in both the studies showed no observable abnormalities in major organs. Heavy metals quantified in the leaves included arsenic (0.45–19.89 ppm), lead (Pb), and cadmium (Cd). In the MH extract, Pb and Cd were detected at 0.43 ppm and 0.63 ppm, respectively. Pb was within internationally accepted safety limits, while Cd was slightly above. Conclusion: The aqueous extract of M. heterophylla leaves demonstrated a high safety margin in acute toxicity tests. However, sub-chronic administration revealed dose-dependent toxic effects, including lethargy, mortality, and haematological and biochemical changes at higher doses. The observed toxicological effects suggest caution in its prolonged use. Further studies on chronic toxicity and the mechanisms underlying these findings are necessary to ensure its safe medicinal application.