Antioxidant activity and protection of pancreatic β-cells by embelin in streptozotocin-induced diabetes.
ABSTRACT The aim of the present study was to evaluate the antioxidant potential of embelin in streptozotocin-induced diabetes.
Diabetes was induced in rats fasted overnight by the administration of a single dose of streptozotocin, and analyzed for blood, serum, and biological and histological pancreatic tissue parameters in intact control, diabetic, and embelin-treated diabetic rats (n = 9) at the dose levels of 15, 25, and 30 mg/kg/day for 21 days.
Diabetes caused highly significant abnormalities in blood, serum, and pancreatic tissue biochemical parameters. Embelin and glibenclamide administration to diabetic rats caused a highly significant decline in the blood glycated hemoglobin and serum glucose levels and nitric oxide activity, with a concomitant increase in the serum insulin level (P < 0.001). Furthermore, embelin and glibenclamide treatment increased the pancreatic antioxidant enzyme status (superoxide dismutase, catalase, reduced glutathione, glutathione peroxidase, glutathione S-transferase, and ascorbic acid), and also decreased the thiobarbituric acid reactive oxygen species contents (P < 0.001). The histoarchitecture of the diabetic rats typically showed a degenerated pancreas with reduced β-cell counts, while embelin treatment was shown to significantly regenerate islet cells.
The study proves the potent antioxidant activity of embelin, which has been found to be effective in managing severe hyperglycemia.
Article: Catalase in vitro.Methods in Enzymology 02/1984; 105:121-6. · 2.00 Impact Factor
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ABSTRACT: The degradation of fructosamines, formed from the non-enzymic glycation of proteins under physiological conditions, to advanced glycation end products was investigated by studying the model peptide fructosamine N epsilon-(1-deoxy-D-fructos-1-yl)hippuryl-lysine (DHL). At pH 7.4 and 37 degrees C in aerobic phosphate buffer, DHL degraded to form N epsilon-carboxymethyl-hippuryl-lysine, and hippuryl-lysine over a 29-day incubation period. The expected N epsilon-(3-lactato)hippuryl-lysine and 'hippuryl-lysylpyrraline' derivatives were not found. Superoxide radicals and hydrogen peroxide were formed during the degradation of DHL but were also both consumed during the degradation reaction. Reversal of the Amadori rearrangement was not a major fate of the fructosamine. The formation of N epsilon-carboxymethyl-hippuryl-lysine was decreased by desferrioxamine, catalase, superoxide dismutase, catalase with superoxide dismutase, anaerobic conditions and aminoguanidine. The formation of hippuryl-lysine was decreased by desferrioxamine, catalase and catalase with superoxide dismutase, but was increased by the addition of aminoguanidine. N epsilon-Carboxymethyl-serine and unmodified lysine residues are major peptide-based end products in the degradation of lysyl-fructosamine under physiological conditions. Oxygen, redox-active metal ions, catalase, superoxide dismutase and the pharmacological agent aminoguanidine are expected to be influential on the rate and fate of fructosamine degradation.European Journal of Biochemistry 01/1993; 210(3):729-39. · 3.58 Impact Factor
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ABSTRACT: Considerable evidence indicates that the maintenance of protein redox status is of fundamental importance for cell function, whereas structural changes in proteins are considered to be among the molecular mechanisms leading to diabetic complications. In this study, protein redox status and antioxidant activity were investigated in the lens and vitreous of diabetic and nondiabetic subjects. A significantly lower content of sulphydryl proteins was found in lens and vitreous of diabetic patients than in those of non-diabetic and control subjects. Moreover, an increased formation of protein-bound free sulphydryls and carbonyl proteins, indices of oxidative damage to proteins, was noted in diabetic patients. All these parameters were shown to be altered particularly when diabetes was complicated with retinal alterations. In addition, glutathione peroxidase activity and ascorbic acid levels, known to exert important antioxidant functions in the eye compartment, were found to be significantly decreased in the lens of diabetic patients, especially in the presence of retinal damage. This study indicates an alteration of protein redox status in subjects affected by diabetes mellitus; lens and vitreous proteins were found to be oxidized to a greater extent in the presence of retinal disease, together with a marked decrease of eye antioxidant systems. These results suggest that oxidative events are involved in the onset of diabetic eye complications, in which the decrease in free radical scavengers was shown to be associated with the oxidation of vitreous and lens proteins. Protein oxidation may, therefore, represent an important mechanism in the onset of eye complications in diabetic patients.European Journal of Clinical Investigation 03/1997; 27(2):141-7. · 3.37 Impact Factor