Rutin inhibits the in vitro formation of advanced glycation products and protein oxidation more efficiently than quercetin

Introduction: The exacerbated generation of advanced glycation end products (AGEs) triggers the onset of diabetic complications associated with hyperglycemia. The search for natural bioactive compounds that can inhibit AGE formation has gained immense interest. Quercetin and its glycoside derivative, rutin, are powerful antioxidants. They have been studied due to their potential to mitigate the disturbances observed in diabetes; however, studies comparing their antiglycation effects are limited. The aim of the present study was to compare the in vitro antiglycation potentials of quercetin and rutin. Methods: The in vitro model system of protein glycation was applied using bovine serum albumin (10 mg/mL) incubated with glucose (0.5 M) in the absence or presence of aminoguanidine (1 mM, prototype anti-AGE agent), metformin (1 mM), quercetin (100, 50, or 12.5 µM), or rutin (100, 50, or 12.5 µM). Before initiating incubations (day 0) and after 10, 20, and 30 days, aliquots were assayed for fluorescent AGEs. Markers of amino acid oxidation (dityrosine, N'-formylkynurenine, kynurenine), protein carbonyl groups (PCO), and protein crosslink formation were assessed after 30 days. Results: Both quercetin and rutin inhibited the formation of AGEs and decreased the PCO levels in a concentration-dependent manner, and moreover, the effect of rutin was more prominent than that of quercetin. Quercetin and rutin also decreased the formation of amino acid oxidation products and protein crosslinks; the best effects were observed in incubations with rutin. Conclusion: Rutin exhibited the most potent antiglycation and antioxidant activities, which may be attributed to the minor occurrence of interactions between albumin and rutin, making rutinnoside more available to exert its effects.

Ethanolic extract of Passiflora edulis Sims leaves inhibits protein glycation and restores the oxidative burst in diabetic rat macrophages after Candida albicans exposure

abstract This study was conducted to evaluate the effects of the ethanolic extract of Passiflora edulis leaves on blood glucose, protein glycation, NADPH oxidase activity and macrophage phagocytic capacity after Candida albicans exposure in diabetic rats. The Passiflora edulis Sims leaves were dried to 40°C, powdered, extracted by maceration in 70% ethanol, evaporated under reduced pressure and lyophilised. The biochemical tests performed were total phenolic content (TP) as determined by the Folin-Ciocalteu assay, trapping potential DPPH assay and total iron-reducing potential. Diabetes was induced by alloxan injection. Protein glycation was determined by AGE and fructosamine serum concentrations. Extract-treated diabetic animals demonstrated lower fructosamine concentrations compared with the diabetic group. Our results suggest that ethanolic Passiflora edulis Sims leaf extraction may have beneficial effects on diabetes and may improve glycaemic control in diabetic rats.

resumo O objetivo deste estudo foi avaliar os efeitos do extrato etanólico de folhas de Passiflora edulis sobre os níveis de glicose sanguínea, glicação protéica, produção de espécies reativas de oxigênio (ERO) e capacidade fagocítica de macrófagos de ratos diabéticos. As folhas de Passiflora edulis Sims foram secas a 40 °C, trituradas e o extrato preparado por maceração em solução hidroetanólica 70% (v/v) etanol foi evaporado sob pressão reduzida e liofilizado. Os testes químicos realizados demonstraram que além da presença de compostos fenólicos, determinada pelo método de Folin-Ciocalteu, o extrato apresentou potencial sequestrante de radicais DPPH e redutor de ferro. Nos animais diabéticos foi observado aumento na glicação protéica, avaliada pela concentração de frutosaminas e de produtos de glicação avançada (AGE), e redução na produção de ERO por macrófagos frente à Candida albicans, quando comparados ao grupo controle. O tratamento dos animais diabéticos com o extrato reduziu as concentrações de frutosaminas e manteve a produção de ERO em níveis semelhantes aos observados no grupo controle. Nossos resultados sugerem que o extrato etanólico de folhas de Passiflora edulis Sims pode apresentar efeitos benéficos sobre o diabetes e melhorar o controle glicêmico em ratos diabéticos.

Inhibitory effect of Piper betle Linn. leaf extract on protein glycation - Quantification and characterization of the antiglycation components.

Piper betle Linn. is a Pan-Asiatic plant having several beneficial properties. Protein glycation and advanced glycation end products (AGEs) formation are associated with different pathophysiological conditions, including diabetes mellitus. Our study aims to find the effect of methanolic extract of P. betle leaves on in vitro protein glycation in bovine serum albumin (BSA)-glucose model. The extract inhibits glucose-induced glycation, thiol group modification and carbonyl formation in BSA in dose-dependent manner. It inhibits different stages of protein glycation, as demonstrated by using glycation models: hemoglobin-d-gluconolactone (for early stage, Amadori product formation), BSA-methylglyoxal (for middle stage, formation of oxidative cleavage products) and BSA-glucose (for last stage, formation of AGEs) systems. Several phenolic compounds are isolated from the extract. Considering their relative amounts present in the extract, rutin appears to be the most active antiglycating agent. The extract of P. betle leaf may thus have beneficial effect in preventing protein glycation and associated complications in pathological conditions.

Antioxidant, Antliglycation and Antimicrobial Activities of Ziziphus oxyphylla and Cedrela serrata Extracts.

Aims: To determine the antioxidant, antiglycation and antibacterial activity of two selected plants found wild in Pakistan (Ziziphus oxyphylla and Cedrela serrata). Study Design: In vitro assessment of antioxidant assays, phenolic and flavonoid content, protein-glycation inhibition and antibacterial study. Place and Duration of Study: Department of Pharmaceutical Sciences, University of Antwerp Belgium (February - April 2013; Antioxidant, Protein glycation). Department of Pharmacognosy, University of Karachi, Pakistan (March – June, 2012; antibacterial). Methodology: In vitro laboratory experimental tests; preparation of plant extracts, antioxidant assays (ABTS.+, PMS-NADH radicals), total phenol, total flavonoid; protein glycation (fluorescence); susceptibility tests (zones of inhibition). Results: The bark of C. serrata contained the highest amount of total phenol (0.35 ± 0.04 mg GAE/g extract) and exhibited significantly superior ABTS.+ and PMS superoxide radical scavenging activity with IC50 values of 0.043 ± 0.001 mg/ml and 0.18 ± 0.01 mg/ml, respectively (P=0.05). Similarly, the protein-glycation assay revealed that the bark of C. serrata had the best inhibitory property with a low IC50 value of 0.61 ± 0.02 mg/ml (P=0.05), probably due to the presence of high amounts of total phenol. Furthermore, the various extracts showed considerable inhibition against both Gram–positive and – negative bacterial growth when compared against two standard drugs neomycin and doxycycline. Conclusion: The results of this study substantiate a probable role for these plants to be utilized as a natural source of antioxidant having a wide range of bioactivities.

Investigation of antioxidant and anti-glycation properties of essential oils from fruits and branchlets of Juniperus oblonga

Plants represent the best and most extensively studied source of natural antioxidants. The present study investigated the antioxidant and anti-glycation properties of different concentrations of essential oils obtained from fruits and branchlets of Juniperus oblonga M. Bieb., Cupressaceae, using different assays. The essential oils were obtained by steam distillation of the branchlets of male tree (BMT), branchlets of female tree (BFT) and fruits of J. oblonga. Compositional analysis of oils was performed using a gas chromatography-mass method. Antioxidant activity was assessed using linoleic acid peroxidation, peroxyl radical mediated hemolysis of red blood cells (RBC) and low-density lipoprotein (LDL) oxidation assays. Anti-glycation properties of oils were evaluated using hemoglobin and insulin glycation assays. Seventeen, eighteen and fifteen compounds were identified in the BMT, BFT and fruit oil, which represented 82.51, 55.69 and 96.89% of the total oils, respectively. α-Pinene was the major component of all three oils. All three oils possessed antioxidant effects against LDL oxidation, linoleic acid peroxidation and peroxyl radical mediated RBC hemolysis. Anti-glycation activities against hemoglobin and insulin glycation were also observed from all tested oils. Overall, there was no unique pattern of dose-dependence for the antioxidant properties of oils in different employed systems. The findings of this study suggest that essential oils from fruits and branchlets of J. oblonga possess antioxidant and anti-glycation properties. Therefore, these oils might be of therapeutic efficacy against diabetes and cardiovascular disease.

Effect Donglian Capsule on Nonenzymatic Protein Glycation in Diabetes Melitus Rat / 国际中医中药杂志

Objective To observe the effect of Donglian capsule on nonenzymadc protein glycation.Methods An animal model of DM was established by injecting a little dosage of STZ in high fat-fed rats.When the models were established successfully,corresponding medicines were supplied for 12 weeks and then the blood glucose,glycosylation serum protein(GSP)and aldose reductase(AR)in rats semm were measured.Results Comparing with the model group,the levels of blood glucose,GSP and AR in Metformin Hydrochloride tablets group and Chinese medicine group were decreased markedly (P＜0.05).Conclusion Donglian capsule Can restrain nonenzymatic protein glycation and so thus prevent and treat DM.