Thesis Abstract

Diabetes is becoming a pandemic disease despite the recent surge in new drugs to manage the condition. The limitations of currently available oral anti-diabetic agents either in terms of efficacy/safety coupled with the emergence of diabetes into a global epidemic have encouraged a concerted effort to search indigenous, inexpensive botanical sources to manage diabetes more efficiently. Chrysophyllumalbidum (Linn) belongs to Sapotaceae family and is commonly called African star apple. Its various uses as anti-oxidant, antimicrobial and anti-hyperlipidemic agents have been described in the literature. This study aimed at evaluating the nutritive and non-nutritive components and anti-diabetic properties of the edible portions (seed-shell pericarp, pulp and skin) of C. albidum fruit in streptozotocin-induced diabetic male albino rats.

The nutritive and non- nutritive components in seed-shell pericarp, pulp and skin of C. albidum fruit were analyzed using standard methods. In addition, the anti-diabetic capacity in different solvents of seed-shell pericarp, pulp and skin extracts of C. albidum fruit using alpha-amylase and alpha-glucosidase inhibitory assays were investigated. Furthermore, animal studies were conducted, consisting of sixty rats and divided into four groups. Diabetes was induced using 50mg/kg streptozotocin (i.p.), and a 70g/kg C. albidum fruit skin (CAFS) formulated diet was fed to streptozotocin-induced diabetic rats for 28 days to evaluate its anti-diabetic efficacy against glibenclamide (2.5mg/kg b.w.) as standard. Fasting blood glucose levels and body weights of rats were measured on weekly intervals starting with base line until the end of treatment. Other biochemical parameters such as serum insulin, glycosylated haemoglobin, hepatic glycogen, plasma and liver lipid profile contents were evaluated at the end of treatment. Histopathological examinations of liver and pancreatic sections were also carried out.

Results of nutritive composition revealed that CAFS contained the highest content of copper (0.55mg/100g) and manganese (2.25mg/100g). Also the non-nutritive contents of CAFSshowed the highest of saponin (0.41%), pectin (0.44%), cellulose (2.76%), arabinose (4854.79mg/100g) and starch (29.15%), compared with seed-shell pericarp and pulp. Hexane extract of CAFS exhibited the highest inhibitory activities on alpha-amylase (96.70%) and alpha-glucosidase (86.93%) at a concentration of 0.04mg/ml compared with other extracts studied. In vivo studies indicated that CAFS-treated rats had increased body weight from 216.94g to 226.88g and decreased fasting blood glucose from 289.11mg/dl to 122.66mg/dlbefore- and after- treatment respectively. Results of studies at the end of treatment revealed that CAFS-treatment significantly (p<0.05) increased levels of serum insulin (7.40µU/ml) and hepatic glycogen (9.63mg/g wet tissue) while it decreased glycosylated haemoglobin (5.45%), compared with diabetic (untreated) control group. CAFS-treatment reduced plasma and liver lipids except high density lipoprotein-cholesterol compared with diabetic-untreated group. These results were comparable with the standard drug-treated group. Histopathological analysis on liver and pancreas of CAFS-treated group showed regenerative effects.

As a result of anti-hyperglycemic and anti-hyperlipidemic potentials of CAFS, it can be concluded that CAFS may have a considerable impact in preventing the ill effects of diabetes and lipid disorders in experimental diabetes. Thus, CAFS could be used as therapeutic adjunct in the management of diabetes.

Keywords     Chrysophyllumalbidum, Steptozotocin,Glibenclamide, Anti-diabetic-, Anti-hyperlipidemic-properties.

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