Grapefruit Derived Flavonoid Naringin Improves Ketoacidosis and Lipid Peroxidation in Type 1 Diabetes Rat Model.

BACKGROUND: Hypoglycemic effects of grapefruit juice are well known but the effects of naringin, its main flavonoid on glucose intolerance and metabolic complications in type 1 diabetes are not known. OBJECTIVES: To investigate the effects of naringin on glucose intolerance, oxidative stress and ketonemia in type 1 diabetic rats. METHODS: Sprague-Dawley rats divided into 5 groups (n = 7) were orally treated daily with 3.0 ml/kg body weight (BW)/day of distilled water (group 1) or 50 mg/kg BW of naringin (groups 2 and 4, respectively). Groups 3, 4 and 5 were given a single intra-peritoneal injection of 60 mg/kg BW of streptozotocin to induce diabetes. Group 3 was further treated with subcutaneous insulin (4.0 IU/kg BW) twice daily, respectively. RESULTS: Stretozotocin (STZ) only-treated groups exhibited hyperglycemia, polydipsia, polyuria, weight loss, glucose intolerance, low fasting plasma insulin and reduced hepatic glycogen content compared to the control group. Furthermore they had significantly elevated Malondialdehyde (MDA), acetoacetate, ß-hydroxybutyrate, anion gap and significantly reduced blood pH and plasma bicarbonate compared to the control group. Naringin treatment significantly improved Fasting Plasma Insulin (FPI), hepatic glycogen content, malondialdehyde, ß-hydroxybutyrate, acetoacetate, bicarbonate, blood pH and anion gap but not Fasting Blood Glucose (FBG) compared to the STZ only-treated group. CONCLUSIONS: Naringin is not hypoglycemic but ameliorates ketoacidosis and oxidative stress. Naringin supplements could therefore mitigate complications of diabetic ketoacidosis.

In vitro antihyperlipidemic potential of triterpenes from stem bark of Protorhus longifolia.

Two lanostane triterpenes, 3ß-hydroxylanosta-9,24-dien-21-oic acid (1) and methyl-3ß-hydroxylanosta-9,24-dien-21-oate (2), were isolated from the stem bark of Protorhus longifolia. Their structures were deduced on the basis of spectroscopic analysis (NMR, HRMS, IR). This study investigated the in vitro anti-adipogenic activity of the two triterpenes. Their inhibitory activity was evaluated on selected lipid digestive enzymes (pancreatic lipase and cholesterol esterase). The inhibitory activity of the compounds on hormone-sensitive lipase and their ability to bind bile acids were also evaluated. The effect of the compounds on glucose uptake in C2C12 muscle cells and 3T3-L1 adipocytes, and on triglyceride accumulation in 3T3-L1 adipocytes was investigated. The triterpenes effectively inhibited the activities of the enzymes with IC50 values ranging from 0.04 to 0.31 mg/mL. The compounds showed a high affinity for secondary bile acids. Both compounds stimulated glucose uptake in C2C12 muscle cells and 3T3-L1 adipocytes. Compound 1 significantly reduced triglyceride accumulation in mature differentiated 3T3-L1 adipocytes. It is apparent that these lanostane triterpenes enhance glucose uptake and suppress adipogenesis, which together with their inhibitory effects on lipid digestive enzymes suggests that they have antihyperlipidemic potential.