• Analytical Science and Technology
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• v.36 no.1
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• pp.12-21
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• 2023

Protein glycation is vital to aging and disease. However, glycated proteins are low-abundant in plasma, rendering them difficult to identify using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Many studies have analyzed glycated peptides with high reproducibility. Here, glycated peptides in human serum were analyzed by LC-MS/MS using data-dependent acquisition (DDA) and parallel reaction monitoring (PRM). Boronic acid (BA) enrichment of in vitro glycated human serum peptides was performed. BA enrichment identified the most glycated peptides, and the glycated peptides of the more diversified proteins, excluding albumin, were analyzed. In PRM, glycated albumin PSMs were the most common, and this method exhibited the best reproducibility. The results of this study could help compare methods for identifying glycation-related biomarkers.

• Biomolecules & Therapeutics
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• v.13 no.3
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• pp.190-197
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• 2005

Advanced glycation end products (AGE) have been implicated in the pathogenesis of diabetic complications including nephropathy. However, the role of AGE in the activation of mesangial cells cultured under high glucose has not been elucidated. The effects of aminoguanidine, which prevents formation of AGE and protein cross-linking, on the synthesis of $TGF-{\beta}1$ and fibronectin by rat mesangial cells cultured under high glucose for 2 weeks were examined and compared with the effects of $N^G$-nitro-L-arginine methyl ester (NAME), a selective nitric oxide synthase inhibitor, because aminoguanidine also inhibits the inducible nitric oxide synthase. Culture of mesangial cells in 30 mM (high) glucose for 2 weeks induced 1.5-fold (ELISA) and 1.9-fold (Western blot analysis) increase in AGE in the culture media compared to 5.6 mM (control) glucose. Northern blot analysis revealed 1.5-fold increase in $TGF-{\beta}1$ and 1.7-fold increase in fibronectin mRNA expression in cells cultured under high glucose compared to control glucose. Increases in mRNA expression were followed by increased protein synthesis. Mink lung epithelial cell growth inhibition assay revealed 1.4-fold increase in $TGF-{\beta}1$ protein in high glucose media compared to control. Fibronectin protein also increased 2.1-fold that of control glucose by Western blot analysis. Administration of aminoguanidine suppressed AGE formation in a dose dependent manner and at the same time suppressed $TGF-{\beta}1$ and fibronectin synthesis by mesangial cells cultured in both control and high glucose. In contrast, NAME did not affect high glucose-induced changes. These findings support a role for AGE in high glucose-induced upregulation of $TGF-{\beta}1$ and fibronectin synthesis by mesangial cells.

• BMB Reports
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• v.32 no.4
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• pp.370-378
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• 1999

The effects of carnosine and related compounds (CRC) including anserine, homocarnosine, histidine, and ${\beta}$-alanine, found in most mammalian tissues, were investigated on in vitro glucose oxidation and glycation of human serum albumin (HSA). Carnosin and anserine were more reactive with D-glucose than with L-lysine. In the presence of $10\;{\mu}M$ Cu (II), although carnosine and anserine at low concentrations effectively inhibited formation of ${\alpha}$-ketoaldehyde from D-glucose, they increased generation of $H_2O_2$ in a dose-dependent manner. Carnosine, homocarnosine, anserine, and histidine effectively inhibited hydroxylation of salicylate and deoxyribose degradation in the presence of glucose and $10\;{\mu}M$ Cu (II). In the presence of 25 mM D-glucose, copper and ascorbic acid stimulated carbonyl formation from HSA. Except for ${\beta}$-alanine, CRC effectively inhibited the copper-catalyzed carbonyl formation from HSA. The addition of 25 mM D-glucose and/or $10\;{\mu}M$ Cu (II) to low density lipoprotein (LDL) increased formation of conjugated dienes. CRC effectively inhibited the glucose and/or copper-catalyzed LDL oxidation. CRC also inhibited glycation of HSA as determined by hydroxymethyl furfural and lysine with free ${\varepsilon}$-amino group. These results suggest that CRC may play an important role in protecting against diabetic complications by reacting with sugars, chelating copper, and scavenging free radicals.

• Food Industry And Nutrition
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• v.10 no.3
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• pp.19-21
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• 2005

• Proceedings of the Korean Biophysical Society Conference
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• 1997.07a
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• pp.36-36
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• 1997

Protein glycation was studied with bovine serum albumin (BSA) as a model protein and methylglyoxal, a 3-carbon ${\alpha}$-ketoaldehyde. Methylglyoxal reacted with BSA, forming a radical as observed in the reaction of methylglyoxal wtih L-alanine or N-acetyl-L-lysine.(omitted)

• Journal of Pharmacopuncture
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• v.26 no.4
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• pp.338-347
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• 2023

Objectives: Ilex paraguariensis (Aquifoleaceae) is cultivated to produce "yerba mate". Due to its nutritional, energizing, hypoglycemic and antioxidant effects, it is used in the elaboration of food, pharmaceuticals, and cosmetics. The oxidative stress related to protein glycation and production of advanced glycation end products (AGEs) leads to the development of several diseases. The objective of this work was to compare the antioxidant and anti-AGEs activity of a decoction of fruits (F) and leaves (L). Methods: The antioxidant activity was assayed by the DPPH assay and the inhibition of egg yolk lipid peroxidation (ILP), and anti-AGEs activity, through the inhibition of the formation of fructosamine (IF), β-amyloid (Iβ), protein carbonylation (IC) and AGEs (IA). Polyphenols were quantified by HPLC. Results: Maximum response ± SEM: For F 0.01 ㎍/mL: IF = 42 ± 4%, IC = 17 ± 2% and for 10 ㎍/mL: IA = 38 ± 4%, Iβ = 67 ± 7%. For L 0.1 ㎍/mL: IF = 35 ± 2%, IC = 19 ± 2% and for 100 ㎍/mL: IA = 26 ± 3%, Iβ = 63.04 ± 2%. The DPPH IC₅₀ = 134.8 ± 14 ㎍/mL for F and 34.67 ± 3 ㎍/mL for L. The ILP IC₅₀ = 512.86 ± 50 ㎍/mL for F and 154.8 ± 15 ㎍/mL for L. By HPLC L presented the highest amounts of flavonoids and caffeoylquinic acids. F and L showed strong anti-AGEs activity, affecting the early stages of glycation at low concentrations and the late stages of glycation at high concentrations. The highest activity for both F and L was seen in the IF and Iβ. F presented the highest anti-AGEs potency. L presented the highest antioxidant potency, which was related to the highest content of polyphenols. Conclusion: The fruits of I. paraguariensis could be a source of antioxidant and anti-AGEs compounds to be used with medicinal purposes or as functional food.

• Journal of Physiology & Pathology in Korean Medicine
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• v.26 no.3
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• pp.273-280
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• 2012

Scutellaria baicalensis Georgi, which has been known to be able to clear away heat and remove dampness, was used for febrile disease. It is now clear that Advanced glycation end products (AGEs) play major roles in the pathogenesis of diabetic complications such as atherosclerosis. In this study, we examined whether Scutellaria baicalensis Georgi suppress the AGE mediated inflammatory responses in the THP-1 cells. AGE treatment increased the gene expression of pro-inflammatory cytokines such as tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$), interleukin-$1{\beta}$ (IL-$1{\beta}$), monocyte chemotactic protein-1 (MCP-1) and cyclooxygenase-2 (COX-2). Reverse transcriptase-polymerase chain reaction and Western blot analysis revealed that S. baicalensis had inhibitory effects on the expression of pro-inflammatory genes and protein levels in AGE-treated THP-1 cells. S. baicalensis had also reduced the production of ROS in the AGE-treated THP-1 cells. These results suggest that S. baicalensis has inhibitory effects for the development of diabetic vascular complication.

• BMB Reports
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• v.39 no.3
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• pp.335-338
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• 2006

Methylglyoxal (MG) is an endogenous physiological metabolite which is present in increased concentrations in diabetics. MG reacts with the amino acids of proteins to form advanced glycation end products. In this in vitro study, we investigated the effect of MG on the structure and function of ceruloplasmin (CP) a serum oxidase carrier of copper ions in the human. When CP was incubated with MG, the protein showed increased electrophoretic mobility which represented the aggregates at a high concentration of MG (100 mM). MG-mediated CP aggregation led to the loss of enzymatic activity and the release of copper ions from the protein. Radical scavengers and copper ion chelators significantly prevented CP aggregation. CP is an important protein that circulates in plasma as a major copper transport protein. It is suggested that oxidative damage of CP by MG may induce perturbations of the copper transport system and subsequently lead to harmful intracellular condition. The proposed mechanism, in part, may provide an explanation for the deterioration of organs in the diabetic patient.

• The Korea Journal of Herbology
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• v.32 no.4
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• pp.53-60
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• 2017

Objectives : Collagen decrease of Skin appears through various path ways. One of causes may be the Advanced glycation endproducts (AGEs) that combine formation of glucose and protein. The aim of this study was to explore the prevent wrinkle formation of Paeoniae radix (PR) and heated Paeoniae radix (HPR) via AGEs path way. Methods : AGEs formation inhibitory activities of PR and HPR measured using bovine serum albumin, glucose, and fructose. To evaluate the protective effects of PR and HPR in diabetic rats induced with streptozotocin (STZ) and methyl glyoxal (MGO), SD rat were distributed into four groups. Normal rats (Nor), AGEs-induced rats (Con), AGEs-induced rats treated with 100 mg/kg PR(PR), AGEs-induced rats treated with 100 mg/kg HPR (HPR). To induce AGEs, streptozotocin (50 mg/kg) was administered intraperitoneally and after 3 days administrated 100mM methyl glyoxal for 3 weeks. Results : The oral administration of HPR inhibited AGEs in skin tissues compared with PR. The increased reactive oxygen species (ROS) levels in the serum were diminished by HPR treatment. The analyses of kidney and skin tissues proteins indicated that HPR treatment effectively reduced AGEs related protein levels as compared to that by PR treatment. Also, HPR decreased anti-oxidant related protein levels in skin tissues such as catalase, glutathione peroxidase. Moreover, it inhibited the reduction of COL1A2 by decreasing MMP-1. Conclusion : Based on these results, it was suggested that PR and HPR could have Improving effects on wrinkle formation. These evidences provide useful information for the development wrinkle formation treated agent.

• Journal of Physiology & Pathology in Korean Medicine
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• v.26 no.2
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• pp.147-154
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• 2012

Hwanggeum-tang (HGT) was recorded in Dongeuibogam as being able to treat Sogal whose concept had been applied to Diabetes Mellitus (DM). Advanced glycation end products (AGEs) play important roles in the development of diabetic complications such as atherosclerosis by eliciting inflammatory responses. In this study, we examined the suppressive effects of HGT against inflammation elicited by AGEs. AGEs treatment increased the expression of pro-inflammatory cytokine gene TNF-${\alpha}$; chemokines MCP-1, IP-10; pro-inflammatory cyclooxygenase COX-2 on the THP-1 cells. HGT had suppressed the expression of pro-inflammatory genes and protein levels in AGE-treated THP-1 cells. HGT had also decreased intracellular ROS production stimulated by AGEs. These results suggest that HGT has beneficial effects for the improvement diabetic vascular complication through suppressing inflammatory responses elicited by AGEs.