Purpose: In a previous work, it was showed that rosmarinic acid is able to break AGE cross-links. This study focuses on the early stage of glycation: the objective is to highlight the ability of rosmarinic acid to deglycate glycated lysozyme and see to what extent the protein is recovered in its original state. Basic procedures: Purified lysozyme is glycated with ribose. After elimination of ribose by purification, glycated lysozyme is treated with rosmarinic acid. Glycation and deglycation are followed over time by ESI-MS analysis. Main findings: After 168 hours, the glycation leads to the binding of at least three molecules of ribose to the amino radicals of lysozyme forming Schiff bases. The deglycation test shows that glycation is a naturally reversible reaction. The presence of rosmarinic acid leads to a faster deglycation reaction. Principal conclusions: This study shows that rosmarinic acid has an important deglycating effect on a glycated protein. Further studies are required to better understand the mechanism behind the deglycation process between glycated lysozyme and rosmarinic acid.

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Glycative stress has drawn attention in recent years as a factor that significantly affects tissues and organs of the human body and is directly related to health maintenance and aging-related diseases. Glycative stress refers to the excessive formations of carbohydrate-derived aldehydes or fatty-acid-derived aldehydes in the body. These aldehydes impact diverse substances such as proteins, lipids, and bases in cells, and subcellular organelles. Proteins in the body are modified by non-enzymatic procedure and abnormal proteins, i.e., carbonylated proteins, advanced glycation end-products (AGEs), are formed and stored intra- and extra-cellularly. AGEs induce endoplasmic reticulum stress, causing the deterioration of cellular functions Although glyceraldehyde-3-phosphate dehydrogenase (GAPDH), glyoxalase, and aldehyde dehydrogenase (ALDH) are prepared for protection in the body as a defensive measure against aldehydes, a co-enzyme, nicotinamide adenine dinucleotide (NAD) is consumed to a large extent through metabolic process. As a result, a tricarboxylic acid cycle (TCA cycle) in mitochondria, where NAD is needed, is unable to function smoothly. Fumaric acid is elevated and important proteins such as GAPDH and adiponectin undergo succinylation, which causes the deterioration of functional proteins. The present study reviewed the involvement of glycative stress in the insulin secretion of pancreatic β cell and Alzheimer's dementia (AD). For AD protectiom, it is important to inhibit peroxidation of lipids which exist abundantly in the brain and inhibit glycative modification of amyloid β (Aβ) and tau proteins. We hope that further extensive research on anti-glycation will be undertaken, and deeper understanding and increased participation will be encouraged. Studies on glycative stress are necessary to lead to a social implementation as a practical science.

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Collagen peptides derived from fish scales and pig skin have a molecular weight of about 1,000, which is a low molecular collagen peptide (CP). We have conducted two RCTs and reported that CP has anti-atherosclerotic effects and improves glucose tolerance. However, the recent finding that CP activates fibroblasts has opened the door to discussing the mechanism of action of CP from a new perspective. This paper introduces the involvement of glycative stress in the mechanism of action of CP. In the first RCT, pulse wave velocity (baPWV) was shown to improve. The results of multivariate analysis of factors involved in the improvement of baPWV indicated that the involvement of improvement in arterial patency, independent of the effect on blood pressure improvement, was important. The 2nd RCT showed that CP intake improved insulin resistance and reduced cutaneous autofluorescence (SAF), a measure of terminal glycation products (AGEs) accumulation in the skin including toxic AGEs (TAGEs), which are highly toxic. One possible mechanism of action is the fibroblast activating and proliferative effects of the CP-derived dipeptides Pro-Hyp (PO) and Hyp-Gly (OG). The production of matrix proteins by fibroblasts is important for maintaining vascular wall homeostasis. In particular, elastic fibers (elastin) are strongly involved in the elasticity of arteries. The second mechanism is aldehyde trapping by CP-derived dipeptides and amino acids. Among the many short-chain aldehydes induced by postprandial hyperglycemia (blood glucose spikes), glyceraldehyde is the most dangerous, generating TAGE. Aldehydes also adversely affect insulin biosynthesis in pancreatic beta cells because they readily cross cell membranes. From the above, it can be inferred that aldehyde trapping is of great significance. In conclusion, since CP has anti-atherosclerotic and anti-glycation effects, it is expected to contribute to the extension of healthy life span through the prevention of cerebro-cardiovascular diseases.

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Purpose: The purpose of this study was to select wines with strong anti-glycation effects based on grape variety, region, and vinification method through basic experiments, and to clarify whether consumption of these wines has an effect on the inhibition of AGE accumulation in human blood. Methods: Study subjects were 60 men and women between the ages of 20 and 65 who were able to consume alcohol. The study design was a prospective crossover open-labeled randomized controlled trial. In the basic study, various wines were added to a human serum albumin (HSA)-glucose glycation model and the effect of glycation inhibition was evaluated by measuring fluorescent AGE production. Study participants consumed 125 mL per day of either wine or mineral water, which has strong anti-glycation effects in basic research and is available for human comparative studies, 6 days per week for 4 continuous weeks. The AGE accumulation level in the body was measured by an AGEs sensor and the stress level by a stress measuring instrument (VM500) before and after ingestion for a total of 4 times. In addition, an email questionnaire regarding lifestyle influences on AGE accumulation was administered weekly. Results: The target wine for intake was a red wine (La Forge Estate Pinot Noir containing 13.5 mL/100 mL of alcohol. The intake was set at 125 mL with the IC50 calculated based on the anti-glycation effect of aminoguanidine. There were 48 research collaborators. Nine persons whose response rate to the questionnaire results was less than 50% and six persons who were absent from at least one measurement session were excluded. A decrease in AGE levels was observed in the wine intake group, and an increase in AGE levels was observed in the mineral water group, Although the difference was not significant (p = 0.16). A comparison of the Week 2-5 group (early June to mid-July) and s Week 8-11 group (late July to early September) groups showed a strong decreasing trend in AGE levels before and after wine consumption (p = 0.06). Women also showed a trend toward lower AGEs after wine consumption (p = 0.07). Overlapping analysis with the time of administration showed a significant decrease in AGEs in women in the Week 8-11 group who consumed wine (p = 0.02). Conclusion: Wine consumption was suggested to inhibit the accumulation of AGEs. In particular, the effect of AGEs due to ultraviolet light was less pronounced in women who used sunscreen on a daily basis, suggesting that the effect of AGE accumulation inhibition was achieved in the latter half of the group, when the amount of ultraviolet light reaches its peak.

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Accumulation of advanced glycation endproducts (AGEs) due to glycative stress in the body leads to tissue stiffening and physiological dysfunction due to protein cross-link formation, and is one of the factors contributing to aging and lifestyle-related diseases. Suppression of glycative stress includes suppression of postprandial hyperglycemia, suppression of glycation reaction, and degradation and excretion of AGEs. Fluorescent AGEs include both cross-linked and non-cross-linked AGEs. Inhibition of fluorescent AGE formation has been reported in various plant materials, one of which is the ginger plant black galingal (Kaempferia parviflora Wall. Ex. Baker; KP), with hydrophilic components and polymethoxy flavonoids (PMF) involved in this effect. On the other hand, there are several types of cross-linked structures of glycated proteins, α-diketone being one of them. The cleavage action of α-diketones is called AGE cross-link cleavage, and phenylpropanedione (1-phenyl-1,2-propanedione; PPD) has been used as a cross-linking model substance. The rate of AGE cross-link cleavage has been evaluated from the rate of free benzoic acid formation. KP rhizome has also been reported to have AGE cross-link-cleaving activity. There have been only a few reports on the effect of AGE formation inhibition and AGE cross-link cleavage on protein cross-linking by glycation. In this study, we examined the inhibition of glycated-protein cross-linking (IGPC) and cleavage of glycated-protein cross-linking (CGPC) of KP extract, which previously has been shown to have effects of fluorescent AGE formation inhibition and AGE cross-linking cleavage.

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