Toxicity and Anti-Trypanosomal Studies of Aqueous and Methanol Leaf Extracts of Acacia Nilotica on Trypanosoma Brucei-Induced Infection in Mice

ABSTRACT: African Animal Trypanosomiasis constitutes one of the greatest threats to the health of animals and socioeconomic status of people, particularly in developing countries. Chemotherapy, the main means of controlling the disease is limited due to parasite resistance and toxicity of the current anti-trypanosomal drugs. The development of a vaccine has been thwarted by antigenic variation of the parasite. Thus, plant extracts are one of the strategies being explored to address some of the problems encountered. The main objective of the current study was to investigate the toxicity and anti-trypanosomal activity of methanol and aqueous extracts of Acacia nilotica through in vivo assays against Trypanosoma brucei brucei. The chosen plants' healthy, fresh, matured leaves were air dried under shade, pulverized with mortar and pestle into powder, and passed through a 0.5mm mesh to standardize their particles. The plant samples were extracted using aqueous, methanol solvents. Qualitative and quantitative phytochemical analysis of the active chemical constituents of the extracts was conducted to determine saponins, flavonoids, tannins, terpenoids, steroids, and cardiac glycosides according to standard procedure. It was established that aqueous and methanol leaf extracts of the selected plants were safe in rats at dose levels of 1000, 3000, and 5000 mg/kg body weight for 72 hours. However, Sedation and abnormal movement were observed for both A. nilotica and Z. mucronata as manifestations of clinical toxicity at 5000mg/kg body weight. The fatal dose of all extracts exceeds the maximum dose of 5000mg/kg. Prolonged oral administration of the extracts for 21 days with A. nilotica extracts did not reveal major changes in body and organs weights, liver and kidney functions, the biochemical analysis showed a slight, non-significant increase in Alanine transaminase, Aspatate transaminase, and Alkaline phosphatase at (4000mg/kg) in rats, the average creatinine and urea levels were within the normal range, the relative organ weight and isolated organ are within the normal reference value. The photomicrographs of the liver and kidney sections showed mild histological changes. The in vivo assay showed the aqueous and methanol extracts from A. nilotica at 200mg/kg, 100mg/kg, and positive control (diminazine aceturate 3.5mg) reduced parasitaemia (p < 0.05), improved anaemia (p < 0.05), prevented body weight loss (p < 0.05) compared to the negative control. This study showed that the leaf of A. nilotica is safe and possess antitrypanosomal properties, suggesting that they may be a source of novel drugs for treatment of tropical diseases caused by trypanosomes.