Determination of advanced glycation endproducts in cooked meat products

Improved Methods for the Rapid Formation and Prevention of Advanced Glycation End Products (AGEs) In Vitro by Coupling to the Hypoxanthine/Xanthine Oxidase Assay System

Advanced glycation end products (AGEs) represent a set of molecules that contribute directly to the initiation and aggravation of diseases associated with ageing. AGEs are produced by the reaction between reducing sugars (or α-dicarbonyl compounds), proteins, and amino acid residues. Previous in vitro methods using non-enzymatic procedures described in the literature require an incubation period of 1–3 weeks to generate AGEs. In this study, the reaction time for the formation of AGEs (48 and 3 h) was significantly reduced by adaptation of methods previously described in the literature and coupling them to the free radical generation system termed hypoxanthine/xanthine oxidase assay. The incorporation of this assay into the experimental system accelerated the production of AGEs as a result of the formation of reactive oxygen species (ROS), as shown by increased fluorescence. The capacity of different classes of chemical compounds (aminoguanidine, chlorogenic acid, rutin, and methanol extracts of Hancornia speciosa Gomes) to inhibit protein glycation by acting as scavenging agents of α-dicarbonyl species was evaluated. Aminoguanidine and, especially, rutin identified in the leaf extracts of H. speciosa Gomes showed a high capacity to act as scavengers of reactive carbonyl species RCS-trapping, resulting in the inhibition of AGEs formation.

Effect of lipid oxidation on the formation of Nε-carboxymethyl-lysine and Nε-carboxyethyl-lysine in Chinese-style sausage during storage

This work aimed to investigate the effects of lipid oxidation on N^ε-carboxymethyllysine (CML) and N^ε-carboxyethyllysine (CEL) formation in three types of Chinese-style sausages during storage. Medium-high temperature dried sausage, naturally dehydrated sausage and smoke-dried sausage were prepared, and CML/CEL contents were measured. The result showed that CML and CEL levels increased with the increasing storage time, and an exponential correlation was found between thiobarbituric acid reactive substances (TBARs) and either CML (r² = 0.922) or CEL (r² = 0.921) in medium-high temperature dried sausages and smoke-dried sausage, which suggested that lipid oxidation could facilitate CML/CEL formation during storage. Furthermore, lipid oxidation and the Maillard reaction might have a synergistic effect on CML formation in Chinese-style sausages, as evidence by the results of model system during incubation. These findings indicated that lipid oxidation played a key role in CML/CEL formation during the storage of Chinese-style sausages.

Advanced glycation end products and risk of hypertension in Iranian adults: Tehran lipid and glucose study

Background:

Elevated blood pressure is still one of the major risk factors for diseases and disabilities and also a public health challenge worldwide. In the present longitudinal study, we aimed to evaluate the association between risk of hypertension and dietary advanced glycation end products (AGEs) as a recently discussed potential risk factor.

Materials and Methods:

Dietary assessment of 1775 participants in the third phase of Tehran lipid and glucose study to obtain dietary intake of AGEs was performed using a validated semi-quantitative food frequency questionnaire, and they were followed up for a mean duration of approximately 6 years. To determine the incidence of hypertension across quartiles of AGEs intake, logistic regression models with adjustment for potential confounding variables were used. All statistical analyses were conducted using SPSS, and P < 0.05 was considered statistically significant.

Results:

Higher hypertension occurrence risk was generally attributed to higher AGEs intake quartiles after adjusting for age in men (odds ratio [OR] = 1.48, 95% confidence interval [CI] = 1.11–1.52, P = 0.038) and additional adjustment for smoking, drugs, and physical activity in women (OR = 1.38%–95% CI = 1.09–1.42, P = 0.042). Moreover, across the increasing trend of dietary AGEs intake, the percentage of fat intake increased and that of carbohydrate significantly decreased (P < 0.0001).

Conclusion:

In conclusion, it is highly recommended to limit dietary AGEs consumption to prevent and manage hypertension and its complications.

Effects of Highland Barley Bran Extract Rich in Phenolic Acids on the Formation of Nε-Carboxymethyllysine in a Biscuit Model

Highland barley, a staple food in northwest China, is a well-known source of bioactive phytochemicals, including phenolic compounds. This study evaluated the inhibitory effects of highland barley bran extract (HBBE) on the advanced glycation end product (AGE) levels in a biscuit model, as measured by N^ε-carboxymethyllysine (CML) content. CML was detected in all inhibition models using HBBE extracted with different solvents. Under optimal conditions, CML formation in the heated model system composed of glucose/lysine/linoleic acid was effectively inhibited by HBBE. This inhibition effect using extracts from 60% acetone solution was 45.58%. Five major phenolic acids from HBBE (ferulic, syringic, sinapic, p-coumaric, and caffeic acids) were further tested for their trapping and scavenging abilities of glyoxal, a reactive carbonyl species and a key intermediate compound for forming CML. This study has demonstrated that HBBE can potentially control CML formation during food processing, therefore effectively reducing glycation in foods and benefiting those with chronic diseases.

In vitromembrane damage induced by half-fin anchovy hydrolysates/glucose Maillard reaction products and the effects on oxidative statusin vivo

Through induced H₂O₂generationin vitro, HAHp(9.0)-G MRPs increased the antioxidant status in normal mice after short-term intake.

Factors Generating Glucose Degradation Products In Sterile Glucose Solutions For Infusion: Statistical Relevance Determination Of Their Impacts

Sterilising glucose solutions by heat promotes the generation of a large number of glucose degradation products (GDPs). It has been shown that high levels of GDPs may result in Advanced Glycation End products that have an impact on cellular homeostasis and health in general. If data is available for peritoneal dialysis solutions, little has been published for glucose infusion fluids. It is essential to identify the parameters causing the formation of GDPs and so limit the risk of exposing patients to them. After quantifying both 5-hydroxymethyl-2-furfural, considered as an important indicator of degradation, and 2-furaldehyde, an ultimate GDP of one degradation pathway, in marketed solutions, the aim of this work is to build a model integrating all the parameters involved in the formation rates of these two GDPs: supplier, glucose amount, container material, oxygen permeability coefficient and time-lapse since manufacture. Our results show a good logarithmic relationship between GDP formation rates and time-lapse since manufacture for both GDPs. The amount of GDPs in the glucose solutions for infusion depends on the initial glucose amount, the polymer of the container, the time elapsed since manufacturing and the supplier.

Comparative evaluation of three different ELISA assays and HPLC-ESI-ITMS/MS for the analysis of Nε-carboxymethyl lysine in food samples

N^ε-carboxymethyl-lysine (CML) is measured in food, but there is a controversy concerning the most convenient yet reliable method(s) for this task. This work compares three different ELISA assays and HPLC-ESI-ITMS/MS for the analysis of CML in several food items. The four methods showed the same decreasing order of CML concentration: beef, bacon>chicken > fish>dairy products>grain products>fruits/vegetables. HPLC-ESI-ITMS/MS results highly correlated with those obtained by ELISA performed with monoclonal CML-antibody (β=0.98, p<0.0001) whereas My Bio Source® kit results were not correlated with those provided by Lamider®. Small differences of CML concentrations in food items prepared by different culinary treatment were clearly distinguished by HPLC-ESI-ITMS/MS, but could not always be detected by ELISA. This work demonstrates a reasonable relationship between CM determined by ELISA and HPLC-ESI-ITMS/MS and therefore supports the implementation of ELISA in food CML/AGEs screening.

Control of Maillard Reactions in Foods: Strategies and Chemical Mechanisms

Maillard reactions lead to changes in food color, organoleptic properties, protein functionality, and protein digestibility. Numerous different strategies for controlling Maillard reactions in foods have been attempted during the past decades. In this paper, recent advances in strategies for controlling the Maillard reaction and subsequent downstream reaction products in food systems are critically reviewed. The underlying mechanisms at play are presented, strengths and weaknesses of each strategy are discussed, and reasonable reaction mechanisms are proposed to reinforce the evaluations. The review includes strategies involving addition of functional ingredients, such as plant polyphenols and vitamins, as well as enzymes. The resulting trapping or modification of Maillard targets, reactive intermediates, and advanced glycation endproducts (AGEs) are presented with their potential unwanted side effects. Finally, recent advances in processing for control of Maillard reactions are discussed.

Effects of raw meat and process procedure on Nε-carboxymethyllysine and Nε-carboxyethyl-lysine formation in meat products

This work aimed to investigate the effects of stored raw meat and process procedures on N^ε-carboxymethyl-lysine (CML) and N^ε-carboxyethyl-lysine (CEL) generation in meat products. Meat products of raw pork were sterilized and pasteurized at different storage times (0-4 months) and the CML/CEL contents were determined. The results showed that the extent of lipid and protein oxidation of raw pork increased with increasing storage time. A linear correlation was found between thiobarbituric acid-reactive substances value/carbonyl content and CML/CEL in sterilized meat products, indicating that stored raw pork could promote CML/CEL formation under high temperature processing. Furthermore, mild heating temperatures seemed to favor CML formation, while high temperature could accelerate CEL generation. Therefore, formation kinetics of CML and CEL might be different for different process procedures. These results suggested that stored raw meat and processing temperature could significantly affect CML and CEL generation in meat products.

Advanced Glycation End-Products Enhance Lung Cancer Cell Invasion and Migration

Effects of carboxymethyllysine (CML) and pentosidine, two advanced glycation end-products (AGEs), upon invasion and migration in A549 and Calu-6 cells, two non-small cell lung cancer (NSCLC) cell lines were examined. CML or pentosidine at 1, 2, 4, 8 or 16 μmol/L were added into cells. Proliferation, invasion and migration were measured. CML or pentosidine at 4-16 μmol/L promoted invasion and migration in both cell lines, and increased the production of reactive oxygen species, tumor necrosis factor-α, interleukin-6 and transforming growth factor-β1. CML or pentosidine at 2-16 μmol/L up-regulated the protein expression of AGE receptor, p47(phox), intercellular adhesion molecule-1 and fibronectin in test NSCLC cells. Matrix metalloproteinase-2 protein expression in A549 and Calu-6 cells was increased by CML or pentosidine at 4-16 μmol/L. These two AGEs at 2-16 μmol/L enhanced nuclear factor κ-B (NF-κ B) p65 protein expression and p38 phosphorylation in A549 cells. However, CML or pentosidine at 4-16 μmol/L up-regulated NF-κB p65 and p-p38 protein expression in Calu-6 cells. These findings suggest that CML and pentosidine, by promoting the invasion, migration and production of associated factors, benefit NSCLC metastasis.

Long-term intake of animal flesh and risk of developing hypertension in three prospective cohort studies

OBJECTIVE

Prospective data are scarce on the relation of red meat, seafood, and poultry consumption with hypertension risk. Although red and processed meats are generally considered to have adverse cardiovascular consequences, seafood is believed to be protective and poultry's effect is controversial.

METHODS

We prospectively examined the independent association of long-term intake of animal flesh with incident hypertension in three longitudinal cohort studies of nonhypertensive individuals: Nurses' Health Study (NHS, n = 62 273 women), Nurses' Health Study II (NHS II, n = 88 831 women), and Health Professionals Follow-Up Study (HPFS, n = 37 414 men). We used multivariable Cox proportional hazards regression to study the associations of different types of animal flesh with the risk of developing hypertension while controlling for other hypertension risk factors. We then used fixed-effects meta-analysis to derive pooled estimates of effect.

RESULTS

Compared with participants whose consumption was less than 1 serving/month, the pooled hazard ratios among those whose intake was at least 1 serving/day were 1.30 (95% confidence interval 1.23-1.39) for total meat (a combination of processed and unprocessed red meat), 1.22 (1.12-1.34) for poultry, and 1.05 (0.98-1.13) for seafood. Seafood was associated with an increased risk of hypertension in HPFS and NHS II, but not NHS. Consumption of any animal flesh at least 1 serving/day was associated with an increased hypertension risk [pooled hazard ratio = 1.30 (1.16-1.47)].

CONCLUSION

Long-term intake of meat and poultry were associated with increased risk of hypertension. In contrast to our hypothesis, we found a weak but significant trend toward an increased risk of hypertension with increasing seafood consumption.

Commercial processed soy-based food product contains glycated and glycoxidated lunasin proteoforms

Nutraceuticals have been proposed to exert positive effects on human health and confer protection against many chronic diseases. A major bioactive component of soy-based foods is lunasin peptide, which has potential to exert a major impact on the health of human consumers worldwide, but the biochemical features of dietary lunasin still remain poorly characterized. In this study, lunasin was purified from a soy-based food product via strong anion exchange solid phase extraction and then subjected to top-down mass spectrometry analysis that revealed in detail the molecular diversity of lunasin in processed soybean foods. We detected multiple glycated proteoforms together with potentially toxic advanced glycation end products (AGEs) derived from lunasin. In both cases, modification sites were Lys24 and Lys29 located at the helical region that shows structural homology with a conserved region of chromatin-binding proteins. The identified post-translational modifications may have an important repercussion on lunasin epigenetic regulatory capacity. Taking together, our results demonstrate the importance of proper chemical characterization of commercial processed food products to assess their impact on consumer's health and risk of chronic diseases.

Dietary consumption of advanced glycation end products and risk of metabolic syndrome

Metabolic syndrome (MetS) is a complex disorder which has become one of the major public health challenges worldwide. This study was conducted to evaluate the association between dietary advanced glycation end products (AGEs) and risk of MetS and its components. This cross-sectional study was conducted in a representative sample of 5848 adults, aged 19-70 years. Daily consumption of carboxymethyl lysine, a major type of AGEs, was determined using a validated semi-quantitative food frequency questionnaire. Across increasing trend of AGEs consumption, the percentage of fat intake increased and that of carbohydrate significantly decreased (p < 0.001). Subjects in the highest (>10,506 kU/d) compared to the lowest (<6673 kU/d) quartile category of AGEs had higher risk of abdominal obesity (OR: 1.19, 95% CI: 1.01-1.39) and hypertriglyceridemia (OR: 1.26, 95% CI: 1.07-1.49). Therefore, recommendation on restriction of AGEs intake could be a practical approach to prevent metabolic abnormalities.

Influence of home cooking conditions on Maillard reaction products in beef

The influence of home cooking methods on the generation of Maillard reaction products (MRP) in beef was investigated. Grilling and frying hamburgers to an internal temperature below 90 °C mainly generated furosine. When the temperature reached 90 °C and 100 °C, furosine content decreased by 36% and fluorescent compounds increased by up to 98%. Baking meat at 300 °C, the most severe heat treatment studied, resulted in the formation of carboxymethyllysine. Boiling in water caused very low MRP formation. Acrylamide concentrations in grilled, fried or baked meat were extremely low. Home cooking conditions leading to low MRP generation and pleasant colours were obtained and could be used to guide diabetic and chronic renal patients on how to reduce their carboxymethyllysine intake.