ANTI-DIABETIC PROPERTIES OF N-HEXANE FRUIT EXTRACT OF DACRYODES EDULIS ON ALLOXAN-INDUCED DIABETIC RATS (RATTUS NOVERGICUS)
The present study was undertaken to investigate the anti-diabetic properties of n-hexane extract of Dacryodes edulis on alloxan-induced diabetic rats. A total of 24 and 72 adult albino rats were used for the acute (24 hours) and sub-chronic (15 days) studies respectively. In the acute study, the rats were divided into 6 groups, (A- F) comprising of 4 rats each without replicates. For the sub-chronic study, the rats were divided into 6 groups (A – F) comprising of 12 rats each and the groups were further replicated three times, with 4 rats each. Diabetes was induced in rats of groups B to F, by a single intraperitoneal injection of alloxan, at a dose of 150mg/kg. The extract which was obtained by standard methods was screened phytochemically. The rats in the normal control (group A) and diabetic control (group B) were given water and food only, while the rats in the standard control (group C) received 2.5prmg/kg of Glibenclamide (GB) by oral inturbation. Furthermore, rats in groups D, E and F were administered graded doses (400mg/kg, 800mg/kg and 1600mg/kg) of the extract respectively. The behavioural activities of the rats were observed on an hourly basis during the acute studies. The fasting blood glucose levels (FBGLs) of the rats used for the acute anti-diabetic testing were ascertained an hour after the treatments and subsequently on the 3rd, 6th, 12th, and 24th hours respectively. The body weights of the rats in the sub-chronic study were determined before the commencement of treatment (Day 0) and subsequently on a 5 days interval. Blood samples were obtained from the orbital sinus of each rat for the various analyses. Blood samples from the rats in the sub-chronic anti-diabetic testing group were used to ascertain such biochemical parameters as; Total cholesterol level (TCL), High Density Lipoprotein Cholesterol (HDL-C), Low Density Lipoprotein Cholesterol (LDL-C), Total Triglyceride (TG), Creatinine, Blood Urea (BU), Alkaline Phosphatase (ALP), Aspartate Aminotransferase (AST) and Alanine Aminotransferase (ALT) respectively. In addition, post sub-chronic histopathological analysis of the pancreas was carried out in the control and treated rats respectively. The acute fasting blood glucose levels obtained over a 24 hour period showed a significant decrease (P < 0.05) in the animals treated with Glibenclamide drug, while, in the extract treatment groups (D – F), FBGLs decreased insignificantly (P > 0.05). Also, during the acute study, rats in the normal control group displayed agility and lacked the symptoms of diabetes displayed in the other rats induced with diabetes. In group D however, agility was restored in the rats from the 12th to 24th hour. Durinmg the sub-chronic treatment, the body weights of the rats didn’t change significantly in groups A, C, D, E and F, while, that of group B increased significantly (P < 0.05). The sub-chronic treatment with D. edulis decreased FBGLs, TCL, TG, LDL-C, AST, ALT and ALP levels significantly (P < 0.05), while the HDL-C, creatinine and BU serum levels increased significantly (P < 0.05). The post sub-chronic histopathological examination of the pancreatic tissues showed that Glibenclamide drug and 1600mg/kg of the extract almost normalised damaged pancreatic architecture, while other diabetes-induced groups showed abnormal pancreatic architecture. This study therefore demonstrates that D. edulis n-hexane fruit extract possesses hypoglycaemic, hypolipidaemic and hepatoprotective effects mediated through restoration of the functions of the pancreatic tissues and even insulinotropic effects.