ABSTRACT
This study was aimed to investigate the biochemical evaluations of aqueous extract of Picralima nitida stem bark on Sprague Dawley rats. Picralima nitida is a West African plant found mostly in the rainforest regions of Nigeria and it belongs to the Apocynaceae family. The study determined the in vitro and in vivo acute and subchronic toxicity study. For the acute toxicity, fifteen (15) male rats with an average weight (172 ± 6.6g) were divided into two phases. In phase 1, twelve rats were divided into four groups of three rats, each group received a single oral dose of (10 mg, 100 mg, 1000 mg/kg body weight) of the extract with group 1 serving as the control. In phase II, three rats were used and administered (1600 mg, 2900 mg, and 5000 mg/kg body weight) of the extract. Behavioural changes and mortality were monitored over 14 days using Lorke method. In subchronic study,thirty (30) male rats with an average weight (187 ± 5.3g), were divided into six groups of five rats each in a cage. Group 1 (control + distilled water), while the test groups (II, III, IV, V, and VI) were given aqueous extract of P. nitida stem bark, at doses of (150 mg, 300 mg, 800 mg, 2000 mg, and 5000 mg/kg body weight/day) for 28 days. The rats were acclimatized for 14 days. The weight of rats and blood glucose levels were determined weekly. On day 28, the animals were fasted for 12hr and euthanized, blood and vital organs, such as the liver, kidney, heart, and pancreas were collected for biochemical and histopathological evaluation. ANOVA was used for statistical comparison. Acute toxicity studies revealed no death or sign of toxicity after an oral administration of the aqueous extract of P. nitida stem bark. The subchronic study revealed an appreciable decrease in blood glucose concentration in all the treated groups with aqueous P. nitida when compared to baseline value of each animal. A significant increase was observed in body weight in all the treated groups. Biochemical analysis shown a significant decrease (P < 0.05) in AST (Aspartate aminotransferase) and triglycerides at 5000 mg/kg respectively. Renal indices, (LDL) low density lipoprotein, (HDL) high density lipoprotein, and insulin remained unchanged in all the treated groups (P > 0.05) when compared to control. The antioxidant enzymes in the liver and kidney shown no significant changes. However, GSH (Reduced glutathione) and GPX (Glutathione peroxidase) in the liver increased significantly at 300 mg/kg and 2000 mg/kg body weight respectively. Histological analysis of the liver revealed inflammation in the portal region which decreased with higher concentrations of the extract. No toxic effects were observed in the heart, kidney, and pancreas, but there was proliferation of the pancreatic duct up to 2000 mg/kg dose. The in vitro study revealed the presences of high moisture content, moderate protein, fat, and low ash content. It also shown the presences of some minerals like, K, Na, Ca, Mg, and heavy metals in low detectable concentrations. Phytochemicals, such as phenols, flavonoids, alkaloids, saponins, and proanthocyanidin, which was screened, for this study implies that the aqueous extract of Picralima nitida may be very efficient in the management of some metabolic diseases.
