Thavaree Thilavech

Protective effects of cyanidin-3-rutinoside against monosaccharides-induced protein glycation and oxidation

Cyanidin-3-rutinoside (C3R), a naturally occurring anthocyanin, is present in various fruits and vegetables as a colorant. C3R has been well characterized and demonstrated a number of biological activities attributed to its antioxidant properties. The present study compared the effectiveness of C3R against monosaccharide-induced protein glycation and oxidation in vitro using bovine serum albumin (BSA).The results demonstrated that C3R (0.125-1.00 mM) inhibited the formation of fluorescent AGEs in ribose-glycated BSA (2-52%), fructose-glycated BSA (81-93%), glucose-glycated BSA (30-74%) and galactose-glycated BSA (6-79%).Correspondingly, C3R (1.00 mM) decreased the level of N(ɛ)-(carboxymethyl) lysine (56-86%) in monosaccharide-induced glycation in BSA. C3R also reduced the level of fructosamine, β-amyloid cross structure, protein carbonyl content as well as the depletion of thiol in BSA/monosaccharide system. In summary, C3R might offer a new promising antiglycation agent for the prevention of diabetic complications by inhibiting AGE formation and oxidation-dependent protein damage.

Consumption of Mesona chinensis Attenuates Postprandial Glucose and Improves Antioxidant Status Induced by a High Carbohydrate Meal in Overweight Subjects

Edible plants constitute a potential source for controlling postprandial hyperglycemia and oxidative stress. The objective of this study was to investigate in vitro antioxidant and intestinal α-glucosidase inhibitory activities of Mesona chinensis (MC). In addition, the acute effect of MC on postprandial glucose and plasma antioxidant status after the consumption of a high carbohydrate (HC) meal by overweight subjects was also determined. The results showed that total phenolic and flavonoid contents in the extract were 212.37 ± 5.64 mg gallic acid equivalents/g dried extract and 23.44 ± 2.50 mg catechin equivalents/g dried extract, respectively. MC extract markedly inhibited the intestinal maltase and sucrose with the IC50 values of 4.66 ± 0.22 mg/mL and 1.30 ± 0.43 mg/mL, respectively. However, MC extract had no inhibitory activity against pancreatic α-amylase. In addition, MC extract had antioxidant properties including DPPH radical scavenging activity, superoxide radical scavenging activity (SRSA), hydroxyl radical scavenging activity (HRSA), trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), and ferrous ion cheating activity (FICP). The significant decrease in postprandial plasma glucose, triglyceride and malondialdehyde levels, and the increase in plasma antioxidant capacity (FRAP and ORAC) were observed in overweight subjects receiving a HC meal together with MC extract (1 g). The finding supports that MC helps normalize and enhance antioxidant defense induced by a HC meal, suggesting that MC may have the potential for the prevention of chronic conditions and diseases associated with overweight and obesity.

Naturally occurring anthocyanin cyanidin-3-rutinoside possesses inherent vasorelaxant actions and prevents methylglyoxal-induced vascular dysfunction in rat aorta and mesenteric arterial bed

Cyanidin-3-rutinoside (C3R) possesses anti-oxidant, anti-inflammatory and anti-glycation properties. Methylglyoxal (MG), a highly reactive dicarbonyl aldehyde by-product of glycolysis, is a precursor of advanced glycation end products and contributes to vascular dysfunction, particularly during hyperglycemia. We investigated the possible inherent vasoactivity of C3R, and its effectiveness against MG-induced vascular abnormalities in isolated blood vessel preparations from male Wistar Kyoto rat. C3R induced vasorelaxation concentration-dependently in aortic rings (92% maximum relaxation; EC50: 2.43±0.57μM) and in perfused-mesenteric arterial bed (61% maximum relaxation; EC50: 25.0±1.26μM) pre-contracted with noradrenaline (NA). The vasorelaxation actions of C3R were endothelium-dependent and mediated primarily via nitric oxide (NO) as evidenced by the absence of relaxation in endothelium-denuded preparations as well as in the presence of Nω-nitro-l-arginine, an inhibitor of NO synthase. Intravenous administration of C3R (15-25μmol/kg body weight) in anesthetized rats significantly reduced mean arterial blood pressure (11-23%). Pre-treatment with MG (500μM) potentiated the vasoconstriction elicited by NA and impaired vasorelaxation induced by acetylcholine that was fully restored to basal levels in the presence of C3R (3μM). Taken together, C3R exerts multiple benefits on the vasculature, complementing its potential as a candidate anti-glycation agent.

Cyanidin-3-rutinoside reduces insulin fibrillation and attenuates insulin fibrils-induced oxidative hemolysis of human erythrocytes

Insulin is able to form amyloid-like fibrils, a misfolding process by which insulin molecules interact with each other to form aggregates and pathological amyloid deposition. Inhibition of amyloid aggregation using natural products is proposed as a new strategy to prohibit the development of amyloid diseases. Herein, we demonstrated the inhibitory effect of cyanidin-3-rutinoside (C3R), a natural anthocyanin with multiple biological activities, against insulin amyloid fibrillation. The results showed that increased insulin concentration resulted in faster growth and higher amounts of insulin fibrils. C3R (10.6-170μM) concentration dependently decreased insulin fibril growth and increased the duration of lag time of insulin fibril formation. Moreover, C3R directly decreased the secondary structure transition from α-helix to β-sheet structure. C3R (0.31-5μM) attenuated insulin fibrils-induced oxidative hemolysis of human erythrocytes in a concentration-dependent manner. Moreover, C3R reduced insulin fibrils-induced erythrocyte membrane disruption through the inhibition of reactive oxygen species (ROS) generation. The findings also suggest that C3R reduced fibrils-induced membrane lipid peroxidation by maintaining the catalase activity and oxidized/reduced glutathione content (GSH/GSSH) in erythrocytes. These findings suggest that C3R may serve as a potential inhibitory agent against amyloid fibril formation and insulin fibrils-induced oxidative hemolysis.