Phytochemical and Toxicological Evaluation of Bauhinia Monandra Kurz (Caesalpinaceae) Leaves on Rat

Alade, Gideon Oyewole (2015-04-13)


The study evaluated the acute and subchronic toxicity o f the leaf of Bauhinia monandra Kurz (Caesalpinaceae) methanolic extract and also partitioned the methanolic extract into ethylacetate, butanol and water fractions. A constituent of the ethylacetate fraction using suitable chromatographic techniques was also isolated with a view to justify its traditional use in the management of diabetes. The leaves were extracted at room temperature with methanol. The extract was subjected to phytochemical screening. The acute toxicity of the methanol extract was evaluated using the oral route of administration on adult rats of either sex (N=5) divided into 5 groups. Group 1 which served as normal control was administered with distilled water while the other four groups were administered with 1, 2, 4 and 8 g/kg/day doses of the extract in distilled water. The rats were fasted for 16 hours before and 3 hours after administrations. The animals were then examined at 0, 30, 60 120 minutes and at 4, 6 and 24 hours for gross morphological changes and mortality. In a 28-day sub-chronic toxicity study, male rats (N=5) were divided into three groups. Group 1 served as control and received distilled water while other two groups were administered daily with the extract orally for 28 days at a dose of 2 and 4 g/kg. The animals were then observed daily for any morphological abnormalities. At the end of the 28 days they were fasted overnight after which they were anaesthetized with diethyl ether and sacrificed to obtain blood samples by cardiac puncture. The spleen, testis, lung; liver and kidney tissues were excised for histopathological assessments. The blood was centrifuged at 3000 g for 5 minutes to separate the serum from the plasma, for the biochemical assays. Similarly, a portion of the liver was homogenised and centrifuged for the assay. The ethyl acetate which was previously determined as the hypoglycaemic active fraction was subjected to chromatographic separations. The results showed that the leaf extract contained anthraquinones, flavonoids and saponins with traces of tannins. Quercetin-3-rutinoside was isolated from the ethyl acetate fraction. The result further showed that doses up to 8 g/kg elicited no death or toxicity related signs in the rats. The sub-chronic administration of the extract (2 and 4 g/kg) did not show any morphological change in the key organs investigated. Histopathological examination revealed no observable change in the liver, spleen, testes and kidneys except for focal expansion of the interstitial stroma and lymphoid follicles in the lungs. There was no significant alteration in the total cholesterol, total protein and lactate dehydrogenase (LDH) activity in the serum compared to the control (t = 0.63, p > 0.05). On the other hand, there was a significant increase in the serum triglyceride concentration at 4 g/kg above the control values (t = 0.71, p < 0.05). The extract produced no significant changes in the total protein concentration and LDH activity in the liver of the treated groups when compared with the control (t = 0.51, p > 0.05). In conclusion, the study showed that B. monandra is non toxic to rats at 2 g/kg dose and quercetin-3-rutinoside was isolated from the active ethyl acetate fraction.