Toxicological study on methanol root bark extract of Acacia sieberiana (Fabaceae) in Wistar rats

Background The plant Acacia sieberiana belongs to the family Fabaceae. It has been used in ethnomedical practice to manage bleeding, rheumatism, pain, pyrexia, kidney diseases, gastrointestinal problems, parasitic and infectious diseases, hepatitis, cough, epilepsy, mouth ulcer and many more. Phytochemical compounds such as ellagic acid, quercetin, isoferulic acid, gallic acid, kaempferol, luteolin, apigenin, glucoside dihydroacacipetalin, acacipetalin and many others were isolated from Acacia sieberiana. Previous pharmacological investigations have reported that the plant has anticancer, antimicrobial, antidiarrhoeal and antitrypanosomal effects. Despite the therapeutic properties of this plant, no safety information is available in the literature. Hence, this work intends to investigate the sub-acute toxicity effects of Acacia sieberiana root bark extract (ASE). The phytochemical and oral median lethal dose (LD₅₀) evaluations on the ASE were done in line with the standard protocols. The sub-acute toxic effects of the ASE (250, 750, and 1,500 mg/kg) were investigated following administration of the ASE daily for 28-consecutive days based on the Organization of Economic Cooperation and Development (OECD) 407 protocols in rats. The weekly body weights were monitored and the rats were euthanized on the 29^th day. The blood samples from the animals were obtained for biochemical and haematological determinations. The liver, kidney, lung and heart were removed for histological investigations.

Results The ASE revealed triterpenes, tannins, saponins, cardiac glycosides, flavonoids, and alkaloids. The oral LD₅₀ values was >5,000 mg/kg. The ASE remarkably (p<0.05) declined the body weight of the rats in consideration to the control categories. There was also a remarkable (p<0.05) elevation in ALP, urea and lymphocytes. The cardiac histology revealed no abnormalities. However, the liver produced dose-dependent hepatocellular necrosis and vacuolations. Besides, lymphocyte hyperplasia and glomerular necrosis were observed in the kidneys and alveolar congestion in the lungs.

Conclusions The ASE is relatively non-toxic on acute administration. In contrast, it could pose slight hepatic and renal toxicity on sub-acute administration.