Acute and sub-chronic toxicity of aqueous stem-bark extract of Annickia polycarpa

Background and aim The lack of standardization and scientific validation of the use of most plant extracts leads to toxicity problems. The stem bark extract of Annickia polycarpa has been shown to possess antioxidant, antidiabetic, analgesic, and anti-colitis effects. However, nothing is known about the effects of the prolonged use of the extract. Thus, we investigated the acute and sub-chronic toxicity of the aqueous stem bark extract of (APE) in Sprague-Dawley rats. Experimental procedure The LD50 and sub-chronic toxicity of APE (20 mg/kg, 100 mg/kg, and 500 mg/kg) was studied over 3 months in Sprague-Dawley rats. Serum alkaline phosphatase (ALP), alanine transaminase (ALT), direct bilirubin and creatinine were measured after 3 months of treatment. Hematological analysis and urinalysis were also performed. Also, the effect of APE on blood clotting time and pentobarbital-induced sleeping time were determined at the termination of treatment. Finally, histological analysis was done on liver, kidney, lung, and heart after hematoxylin-eosin staining of tissue cross-sections at the termination of treatment. Results and conclusion The LD50 of APE in rats was higher than 5000 mg/kg with no observable signs of toxicity. APE also showed no hematotoxic effect when used consistently for 3 months. Additionally, APE had no adverse effect on the liver and kidney evidenced by a lack of effect on serum biochemical parameters (ALP, ALT, direct bilirubin, and creatinine), urinalysis as well as the tissue morphology of these organs. No adverse morphological effects were also observed with the heart muscle cells. However, APE showed mild selective toxicity to the lung characterized by alveolar space closing and interstitial fibrosis and alveolar septa thickening. These results indicate that APE is generally non-toxic at the tested doses but shows mild selective pneumotoxicity when used over a long period of time.