Effect of parkia biglobosa seed protein isolate on biochemical and proteomic profiles in streptozotocin-induced diabetes mellitus in male sprague-dawley rats
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Date
2015
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University of Zululand
Abstract
Diabetes mellitus is a metabolic disease characterized by chronic hyperglycemia, the hallmark of diabetic complications and organs damages. Increasing evidence suggests that free radicals play significant role in the beta cell damage. Beta cell destruction in the pancreatic islets results in deficiency and the total loss of insulin secreation. In fact, antioxidant enzymes like catalase and SOD are known to have anti-diabetogenic action. Apparent side effects, huge costs and availability of anti-diabetic medications, coupled with drugs resistance has necessitated the need to search for alternative treatment remedy for this disease. Medicinal plants have attracted a great deal of attention, particularly for their antioxidant activity and presence of bioactive compounds. More so, plant-derived foods which are rich in proteins and antioxidants have been shown to ameliorate various disease conditions and their complications. Parkia biglobosa (Jacq.) is a legume well known for its nutritional and medicinal values. However, there is paucity of knowledge on the anti-diabetic properties of Parkia biglobosa. This study aims to investigate the effect of the protein isolate of Parkia biglobosa on biochemical and proteomic profile of streptozotocin-induced diabetic male rats. Protein isolate was obtained from defatted Parkia biglobosa through a series of water extraction and centrifugation processes. The proximate, functional, minerals and anti-nutrient composition of fermented, defatted and protein isolate were carried out using standard procedures. Diabetes mellitus was induced on the rats by intraperitoneal administration of Streptozotocin, after which the rats were orally fed (200, 400 mg/bw) the protein isolate for 28 days. Blood glucose was daily monitored. At the end of the feeding experiment the rats were sacrificed and the following parameters determined: serum lipid profile (total cholesterol (TC), total triglyceride (TG), high density lipoprotein cholesterol (HLD-c), very low density lipoprotein cholesterol (VLDL-c) and low density lipoprotein cholesterol (LDL-c). Antioxidant status (superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), total glutathione total (GSH) and the level of lipid perioxidation (thiobabituric acid) was determined. Serum testosterone (sTT) level as well as serum activity of asparate aminotransferase (AST), alanine aminotransferase (ALT) and the concentrations of total protein were also measured using commercial kits. Serum interleukin-6 (IL-6) was estimated using the enzyme-linked immunosorbent assay kit. Histopathological analysis of the experimental rats’ liver was assessed by staining with haematoxylin and eosin (H & E). HPLC analysis of the protein isolate was carried out using Beckman HPLC system, while total protein extracted from rat liver was analyzed on one-dimensional polyacrylamide gel electrophoresis (1D SDS-PAGE) system. The results revealed that protein isolate (PI) was high in ash and protein but low in fat and carbohydrate contents which are desirable anti-diabetic properties. PI significantly ameliorated the low activity of antioxidant enzymes (SOD, CAT, GST and total GSH) and high level of lipid perioxidation in the heart tissues of diabetic induced rats. PI attenuated the level of liver AST, ALT, total protein and interleukin-6 (IL-6) in diabetes rats. PI also reversed the low testosterone status in diabetic rats. Histopathology report confirmed the ameliorative effects of PI. The HPLC fingerprint obtained for PI revealed eleven distinct peaks and five minor peaks; this could provide new leads for future identification of the bioactive components in PI. SwissProt database on a ProteinScape 3.0 workstation positively identified 4 differentially expressed proteins which are known to uphold the normal physiological function of organs and tissues. It is apparent that the PI is good source of protein which normalized the hyperglycemia, dyslipidemia, testerosterone, inflammation, oxidative stress and hepatic damage in the experimental rats. Damaged to vital organs as well as reproductive dysfunction are common complications of diabetes. Therefore, these properties of PI could be considered in the treatment and management of diabetic complications.
Description
A thesis submitted to the Faculty of Science and Agriculture in fulfillment of the requirements for the Degree of Doctor of Philosophy in the Department of Biochemistry and Microbiology at the University of Zululand, 2015