Phenolic acids inhibit the formation of advanced glycation end products in food simulation systems depending on their reducing powers and structures

Inhibition of Glycation End Products Formation and Antioxidant Activities of Ilex paraguariensis: comparative study of fruit and leaves extracts

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 µg/mL IF = 42 ± 4%, IC = 17 ± 2% and for 10 µg/mL IA = 38 ± 4%, Iβ = 67 ± 7%. For L 0.1 µg/mL IF = 35 ± 2%, IC = 19 ± 2% and for 100 µg/mL IA = 26 ± 3%, Iβ = 63.04 ± 2%. The DPPH IC50 = 134.8 ± 14 µg/mL for F and 34.67 ± 3 µg/mL for L. The ILP IC50 = 512.86 ± 50 µg/mL for F and 154.8 ± 15 µg/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.

Major Depressive Disorder, Inflammation, and Nutrition: A Tricky Pattern?

Major depressive disorder (MDD) is a psychiatric disease associated with inflammation. The Western diet (WD) is a high-fat, high-sugar diet also associated with inflammation. We aimed to show whether the diet of MDD patients was a WD and could act as a risk factor in this context. We conducted a transversal study of MDD patients and controls (CTRLs) without comorbidities. We performed blood analyses including C-reactive protein (CRP), a diet anamnesis, and an advanced glycation end-product assessment. We found that 34.37% of MDD patients had a CRP level above 3 to 10 mg/L, which remained higher than CTRLs after adjustments (sex, BMI, age, smoking status). The MDD patients had an excess of sugar and saturated and trans fatty acids; a deficiency in n-3 polyunsaturated fatty acid, monounsaturated acid, dietary fibers, and antioxidants; a high glycemic load; and aggravating nutritional factors when compared to the CTRLs. We found correlations between nutritional factors and CRP in univariate/multivariate analysis models. Thus, MDD patients showed an elevated CRP level and a WD pattern that could contribute to sustaining an inflammatory state. Further studies are required to confirm this, but the results highlighted the importance of nutrition in the context of MDD.

Comparison of Protective Effects of Phenolic Acids on Protein Glycation of BSA Supported by In Vitro and Docking Studies

Several diabetic complications are associated with forming advanced glycation end products (AGEs). Different chemical and natural compounds are able to prevent the development of these products. In this study, glycosylation was induced as a model by incubating bovine serum albumin (BSA) with glucose. Consequently, BSA was treated with glucose and different concentrations (1.25, 2.5, and 5 μM) of syringic acid, gallic acid, ellagic acid, ferulic acid, paracoumaric acid, and caffeic acid for 4 and 6 weeks. Biochemical experiments comprise measurements of fluorescent AGEs, protein carbonyl contents, total thiol, hemolysis tests, and also malondialdehyde (MDA) levels in RBC. These demonstrated the antiglycating mechanism of these phenolic acids. Most of the phenolic acids used in this study reduced MDA levels and protected thiol residues in protein structures. They also inhibited the formation of fluorescent AGEs and RBC lysis, except gallic acid. Moreover, ferulic acid, paracoumaric acid, and caffeic acid proteins significantly prevent carbonylation. Molecular docking and simulation studies showed that ellagic, caffeic, gallic, and syringic acids could interact with lysine and arginine residues in the active site of BSA and stabilize its structure to inhibit the formation of AGEs. Our results suggest that phenolic acid could be used as a potential phytochemical against protein glycation and related diabetic complications.

Screening and characterization of xenobiotics in rat bio-samples after oral administration of Shen-Wu-Yi-Shen tablet using UPLC-Q-TOF-MS/MS combined with a targeted and non-targeted strategy

Shen-Wu-Yi-Shen tablet (SWYST), a well-known traditional Chinese medicine prescription (TCMP), has been effectively used for treating chronic kidney disease (CKD) in clinically. However, an in-depth study of in vivo metabolism of SWYST is lacking. In this study, a targeted and non-targeted strategy based on ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) was developed to screen and characterize SWYST-related xenobiotics in rats. Based on the in-house library, a chemical database of SWYST including 215 constituents was constructed through "find by formula" and further verified by characteristic fragmentations or the literatures. Then the constructed chemical database was applied for the targeted screening of prototypes. As for metabolites, the non-targeted screening was achieved combined the peak picking using the function "find by auto-MS/MS" and peak filtration of the prototypes and endogenous components, while the targeted screening was performed using Metabolite ID according to the possible metabolic reactions. Furthermore, the potential metabolites were preliminarily identified by comparison of the parent compounds or references to the literatures. As a result, 201 exogenous components (87 prototypes and 121 metabolites) were characterized in rats after administration of SWYST, including 55 (17 prototypes and 38 metabolites) in plasma, 151 (52 prototypes and 99 metabolites) in urine, and 121 (74 prototypes and 47 metabolites) in feces. Finally, their possible metabolic pathways were summarized, and the metabolic reactions mainly involved phase I reactions (hydroxylation, deoxygenation, hydrogenation, methylation, oxidation, hydrolysis and esterification) and phase II reactions (glucuronidation and sulfation). The findings of this research reveal the potential active ingredients of SWYST, providing an important material basis for the pharmacokinetics and pharmacodynamics of SWYST.

Chemical Composition of Hazelnut Skin Food Waste and Protective Role against Advanced Glycation End-Products (AGEs) Damage in THP-1-Derived Macrophages

Glycation and the accumulation of advanced glycation end-products (AGEs) are known to occur during aging, diabetes and neurodegenerative diseases. Increased glucose or methylglyoxal (MGO) levels in the blood of diabetic patients result in increased AGEs. A diet rich in bioactive food compounds, like polyphenols, has a protective effect. The aim of this work is to evaluate the capacity of hazelnut skin polyphenolic extract to protect THP-1-macrophages from damage induced by AGEs. The main polyphenolic subclass was identified and quantified by means of HPLC/MS and the Folin–Ciocalteu method. AGEs derived from incubation of bovine serum albumin (BSA) and MGO were characterized by fluorescence. Cell viability measurement was performed to evaluate the cytotoxic effect of the polyphenolic extract in macrophages. Reactive oxygen species’ (ROS) production was assessed by the H2-DCF-DA assay, the inflammatory response by real-time PCR for gene expression, and the ELISA assay for protein quantification. We have shown that the polyphenolic extract protected cell viability from damage induced by AGEs. After treatment with AGEs, macrophages expressed high levels of pro-inflammatory cytokines and ROS, whereas in co-treatment with polyphenol extract there was a reduction in either case. Our study suggests that hazelnut skin polyphenol-rich extracts have positive effects and could be further investigated for nutraceutical applications.

Phenolic profiles of Atlantic sea cucumber (Cucumaria frondosa) tentacles and their biological properties

Sea cucumber tentacles (aquapharyngeal bulb) are a rich source of biologically active compounds, including phenolics, however they are mainly discarded as processing waste. This study evaluated free, esterified, and insoluble-bound phenolics of Atlantic sea cucumber (Cucumaria frondosa) tentacles and their antioxidant activity for the first time. Biological properties such as inhibitory activities against α-glucosidase, tyrosinase, and the formation of AGEs as well as LDL-cholesterol and DNA oxidation were investigated. The antioxidant activity of the phenolic extracts was also evaluated in a fish model system. In the UHPLC-QTOF-MS/MS analysis, 31 phenolic compounds, mainly phenolic acids and flavonoids, were identified and quantified. Among them, eight compounds were detected for the first time in any species of sea cucumber. The free phenolic fraction was the major form of phenolics, mainly protocatechuic acid, p-coumaric acid, gallic acid, ellagic acid, catechin, and quercetin, exhibiting strong antioxidant and biological activities. Fresh Atlantic salmon treated with sea cucumber phenolics delayed lipid oxidation as measured by the thiobarbituric acid reactive substances (TBARS) assay. Therefore, Atlantic sea cucumber tentacles may serve as a viable source of functional food ingredients with protective antioxidant properties.

Gelling properties and microstructure of the silver carp surimi treated with pomegranate (Punica granatum L.) peel extract

Effects of ethanolic extracts of pomegranate peel (PPE) on the gelling and textural characteristics of silver carp surimi gel was investigated. The peels extracted with 100% ethanol exhibited highest total phenolics, tannin and flavonoid contents. The change of the gelling properties of surimi was explained using infrared spectroscopy, chemical interactions, and scanning electronic microscopy images. Greater number of hydrogen bonds and hydrophobic interactions were found in surimi gel fortified with 0.45% PPE. Amongst all the concentrations of PPE, 0.45% level exhibited the lowest sulfhydryl and primary amino groups and this was concurrent with the highest gel strength. The FT-IR analysis showed a gradual reduction of intensity of the amide I band with the increase of PPE concentration, and also shifting to lower value from control to surimi with PPE 0.90%. Absorption bands like C-N stretching from amide II and N-H deformation from amide III were also detected. The SEM images showed that surimi with 0.45% PPE had most ordered, finest and denser gel network, and was closely integrated with higher breaking force, hardness, and WHC. This study showed the potential of functional components of fruit wastes for improving gelling properties of surimi with additional health benefits for the consumers.

Combination of LC-Q-TOF-MS/MS, network pharmacology, and nanoemulsion approaches identifies active compounds of two Artemisia species responsible for tackling early diabetes-related metabolic complications in the liver

INTRODUCTION

The chronicity of advanced glycation end-products (AGEs) imparts various damages resulting in metabolic dysfunction and diseases involving inflammation and oxidative stress. The use of plant extracts is of high interest in complementary medicine. Yet, extracts are multicomponent mixtures, and difficult to pinpoint their exact mechanism.

OBJECTIVES

We hypothesise that network pharmacology and bioinformatics can help experimental findings depict the exact active components and mechanism of action by which they induce their effects. Additionally, the toxicity and variability can be lowered and standardised with proper encapsulation methods.

METHODOLOGY

Here, we propose the formulation of phytoniosomes encapsulating two Artemisia species (Artemisia dracunculus and Artemisia absinthium) to mitigate AGEs and their induced cell redox dysregulation in the liver. Extracts from different solvents were identified via liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS/MS). Phytoniosomes were explored for their anti-glycating effect and modulation of AGE-induced damages in THLE-2 liver cells. Network pharmacology tools were used to identify possible targets and signalling pathways implicated.

RESULTS

Data demonstrated that A. absinthium phytoniosomes had a significant anti-AGE effect comparable to reference molecules and higher than A. dracunculus. They were able to restore cell dysfunction through the restoration of tumour necrosis alpha (TNF-α), interleukin 6 (IL-6), nitric oxide, and total antioxidant capacity. Phytoniosomes were able to protect cells from apoptosis by decreasing caspase 3 activity. Network pharmacology and bioinformatic analysis confirmed the induction of the effect via Akt-PI3K-MAPK and AGE-RAGE signalling pathways through quercetin and luteolin actions.

CONCLUSION

The current report highlights the potential of Artemisia phytoniosomes as strong contenders in AGE-related disease therapy.

p-Coumaric acid protects against D-galactose induced neurotoxicity by attenuating neuroinflammation and apoptosis in mice brain

D-galactose (D-gal) induced senescence in rodents is a widely used model for assessment of molecules affecting brain ageing. Chronic administration of D-gal causes neuroinflammation leading to cognitive deficit and memory impairment which represent Alzheimer's dementia. In present study, we investigated the neuroprotective effects of the natural phenol, p-Coumaric acid (PCA) and its underlying mechanism in the chronic D-gal treated mice. Subcutaneous administration of D-gal (150 mg/kg) to Swiss albino mice for 42 consecutive days resulted in cognitive impairment as observed in Morris water maize (MWM) and Y maze test, which was ameliorated by concurrent treatment with PCA (80 mg/kg, and 100 mg/kg, p.o.). Importantly, PCA treatment attenuated the D-gal induced oxidative stress and significantly inhibited acetylcholinesterase (AChE) activity in mice brain. Furthermore, PCA treatment significantly lowered levels of inflammatory marker nuclear factor kappa B (NFκB) and reduced levels of proapoptotic enzyme caspase3. We also observed that PCA treatment exhibited β-secretase enzyme (BACE1) inhibitory effect. However, our results revealed that PCA treatment failed to decrease the level of advanced glycation end products both in vitro and in vivo. Taken together, current study demonstrated the significant neuroprotective effect of PCA against D-gal induced oxidative stress, neuroinflammation, cognitive impairment and apoptosis.

Oxygen Radical-Generating Metabolites Secreted by Eutypa and Esca Fungal Consortia: Understanding the Mechanisms Behind Grapevine Wood Deterioration and Pathogenesis

Eutypa dieback and Esca complex are fungal diseases of grape that cause large economic losses in vineyards. These diseases require, or are enhanced by, fungal consortia growth which leads to the deterioration of the wood tissue in the grapevine trunk; however, pathogenesis and the underlying mechanisms involved in the woody tissue degradation are not understood. We examined the role that the consortia fungal metabolome have in generating oxygen radicals that could potentially play a role in trunk decay and pathogenesis. Unique metabolites were isolated from the consortia fungi with some metabolites preferentially reducing iron whereas others were involved in redox cycling to generate hydrogen peroxide. Metabolite suites with different functions were produced when fungi were grown separately vs. when grown in consortia. Chelator-mediated Fenton (CMF) chemistry promoted by metabolites from these fungi allowed for the generation of highly reactive hydroxyl radicals. We hypothesize that this mechanism may be involved in pathogenicity in grapevine tissue as a causal mechanism associated with trunk wood deterioration/necrosis in these two diseases of grape.

Comparative elucidation of bioactive and volatile components in dry mature jujube fruit (Ziziphus jujuba Mill.) subjected to different drying methods

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Convective drying(CD) increased the concentrations of rutin, epicatechin and quercetin in jujube, and the total phenolic content was not significantly different with freeze-drying(FD).

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Six volatile components with OVA >1 were identified in dried jujube, and their concentration changes were related to precursor substances.

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The volatile components expressing “Fruity” aromas increased after CD, and the expression of fruity aromas at CD60 even exceeded that of FD samples.

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CD60 is an efficient drying method with potential to replace FD in terms of bioactivity and aroma.

This study investigated the effects of convective drying(CD) and freeze drying(FD) on bioactive and volatile components in jujube. No significant difference in total phenolic, total flavonoids and antioxidant capacity among CD60, CD70, CD80 and FD samples (P > 0.05). LC-MS/MS analysis showed that this trend mainly originated from the dynamic equilibrium relationships between caffeic acid, chlorogenic acid, p-hydroxybenzoic acid, rutin, epicatechin, and quercetin. HS-SPME-GC–MS identified 31 volatile organic compounds (VOCs) comprising more than 80% aldehydes and acids. Principal component analysis distinguished the VOC characteristics of samples subjected to different drying methods. Six VOCs had an odor activity value (OAV) >1, most of which were fatty acid oxidation or Maillard reaction products. Combined with the precursor components, these reactions were speculated to be the major VOC-producing pathways in dried jujube. Considering the bioactive components and flavor retention, CD at 60 °C was an effective drying method with potential to replace FD.

Dietary polyphenols: regulate the advanced glycation end products-RAGE axis and the microbiota-gut-brain axis to prevent neurodegenerative diseases

Advanced glycation end products (AGEs) are formed in non-enzymatic reaction, oxidation, rearrangement and cross-linking between the active carbonyl groups of reducing sugars and the free amines of amino acids. The Maillard reaction is related to sensory characteristics in thermal processed food, while AGEs are formed in food matrix in this process. AGEs are a key link between carbonyl stress and neurodegenerative disease. AGEs can interact with receptors for AGEs (RAGE), causing oxidative stress, inflammation response and signal pathways activation related to neurodegenerative diseases. Neurodegenerative diseases are closely related to gut microbiota imbalance and intestinal inflammation. Polyphenols with multiple hydroxyl groups showed a powerful ability to scavenge ROS and capture α-dicarbonyl species, which led to the formation of mono- and di- adducts, thereby inhibiting AGEs formation. Neurodegenerative diseases can be effectively prevented by inhibiting AGEs production, and interaction with RAGEs, or regulating the microbiota-gut-brain axis. These strategies include polyphenols multifunctional effects on AGEs inhibition, RAGE-ligand interactions blocking, and regulating the abundance and diversity of gut microbiota, and intestinal inflammation alleviation to delay or prevent neurodegenerative diseases progress. It is a wise and promising strategy to supplement dietary polyphenols for preventing neurodegenerative diseases via AGEs-RAGE axis and microbiota-gut-brain axis regulation.

Evaluation of Sacha Inchi (Plukenetia volubilis L.) By-Products as Valuable and Sustainable Sources of Health Benefits

By-products from sacha inchi (Plukenetia volubilis L.) oil extraction as the husk and shell are used as low value fertilizer or animal feed. The nutritive values, antioxidant activities, phenolics, and in vitro health-related activities of the sacha inchi husk and shell were investigated and compared to increase their economic potential as future food sources. Higher protein, carbohydrates, and total dietary fiber content were detected in the husk, while higher fat content and energy were found in the shell. Several phenolics were also detected in both the husk and shell, with p-coumaric acid being the most abundant phenolic in the shell and caffeic acid in the husk. Total phenolic content was 1.6-fold greater in the shell than in the husk, leading to 1.8–2.7-fold higher antioxidant activity and 1.2-fold higher anti-glycation activity. Various types and quantities of phenolics also led to diverse in vitro enzyme inhibitory activities in the husk and shell. Knowledge received from this research might be useful to maximize the utilization of by-products from sacha inchi oil extraction as future food sources with valuable nutritional compositions, phenolics, and potential health benefits. Further investigations on the health properties of the sacha inchi husk and shell should include toxicity, bioaccessibility, and in vivo experiments.

Preparation of a functional beverage with α-glucosidase inhibitory peptides obtained from ginkgo seeds

To obtain α-glucosidase inhibitory peptides from ginkgo seeds and use it to develop beverages, papain hydrolysis was used to hydrolyze and extract ginkgo seed peptides. Through ultrafiltration and semi-preparative high performance liquid chromatography, peptide fragments which were molecular weight of < 10 KDa with high α-glucosidase inhibition rate were separated and purified to prepare beverages. At the same time, the A1, A2, B1, and B2 peptide fragments purified by semi-preparative high performance liquid chromatography were analyzed for amino acid composition. All four peptide fragments have glutamate. Studies have shown that amino acids such as glutamate can promote postprandial insulin secretion and reduce glucose levels. The result indicates that the amino acid composition may be related to the inhibition rate of α-glucosidase. After orthogonal experiment design, analysis of variance and principal component analysis, when 5% xylitol and 0.3% citric acid were added, and the glycine content was 1.2%, the ginkgo polypeptides beverage had the best flavor.

Influence of In Vitro Human Digestion Simulation on the Phenolics Contents and Biological Activities of the Aqueous Extracts from Turkish Cistus Species

Oxidative stress is one of the significant precursors of various metabolic diseases such as diabetes, Parkinson's disease, cardiovascular diseases, cancer, etc. Various scientific reports have indicated that secondary plant metabolites play an important role in preventing oxidative stress and its harmful effects. In this respect, this study was planned to investigate the phenolic profile and antioxidant and antidiabetic potentials of the aqueous extracts from Turkish Cistus species by employing in vitro methods. In vitro digestion simulation procedure was applied to all extracts to estimate the bioavailability of their phenolic contents. Total phenolic, flavonoid, phenolic acid and proanthocyanidin contents were determined for all phases of digestion. In addition, changes in the quantity of the assigned marker flavonoids (tiliroside, hyperoside and quercitrin) were monitored by High-Performance Thin Layer Chromatography (HPTLC) analysis. The antioxidant activity potentials of the extracts were studied by various methods to reveal their detailed activity profiles. On the other hand, in vitro α-amylase and α-glucosidase enzymes and advanced-glycation end product (AGE) inhibitory activities of the extracts were determined to evaluate the antidiabetic potentials of extracts. The results showed that aqueous extracts obtained from the aerial parts of Turkish Cistus species have rich phenolic contents and potential antioxidant and antidiabetic activities; however, their bioactivity profiles and marker flavonoid concentrations might significantly be affected by human digestion. The results exhibited that total phenolic contents, antioxidant activities and diabetes-related enzyme inhibitions of the bioavailable samples were lower than non-digested samples in all extracts.

Anacardium humile St. Hil as a novel source of antioxidant, antiglycation and α-amylase inhibitors molecules with potential for management of oxidative stress and diabetes

ETHNOPHARMACOLOGICAL RELEVANCE

The substantial increase in diabetes cases worldwide has been a major public health problem, and the use of medicinal plants can be considered an interesting alternative to control the disease and its complications. Anacardium humile St. Hill. (Anacardiaceae) is a typical plant from the Brazilian savanna, popularly known for its antidiarrheal, expectorant, antidiabetic and anti-inflammatory properties, however, few studies have fully described its biological properties. This study aimed to investigate in vitro and ex vivo the antioxidant and antiglycation potential of A. humile ethanolic extract, its organic fractions and three isolated molecules (quercetin, catechin and gallic acid), their capacity to inhibit the glycolytic enzyme α-amylase, as well as their cytotoxic effects against RAW264.7 macrophages.

MATERIAL AND METHODS

The ethanolic extract of A. humile, its organic fractions and three isolated molecules (catechin, quercetin and gallic acid) were tested for their antioxidant (ORAC, FRAP and DPPH) and antiglycation (BSA/Fructose, BSA/Methylglyoxal, Arginine/Methylglyoxal and Lysine/Methylglyoxal) capacities, and also for its potential to inhibit the enzyme α-amylase. Additionally, bioactive compounds present in the A. humile leaves fractions were elucidated by an HPLC-ESIMS/MS analysis.

RESULTS

The analysis showed relevant antioxidant activity of DCM (1264.85 ± 76.90 μM Trolox eq/g ORAC; 216.71 ± 1.04 μM Trolox eq/g FRAP and 3.03 ± 0.08 IC₅₀ μg/mL IC₅₀ DPPH) and EtOAc (1300.11 ± 33.04 ORAC, 236.21 ± 23.86 FRAP and 3.03 ± 0.14 μg/mL IC₅₀ DPPH) fractions and also of the isolated molecules, mainly gallic acid (1291.19 ± 8.41 μM Trolox eq/g ORAC, 1103.52 ± 31.48 μM Trolox eq/g FRAP and 0.78 ± 0.11 μg/mL IC₅₀ DPPH). Concerning the antiglycation activity, all samples inhibited over 88% in the BSA-FRU method. In the BSA-MGO and ARG-MGO methods, the Hex, DCM, EtOAc fractions and the isolated molecule catechin stood out. However, in the LYS-MGO model, only the isolated molecules showed significant results. In α-amylase assay, all fractions, for exception Hex, presented notable inhibition capacity with low IC₅₀ values, especially DCM, EtOAc, ButOH and H₂O (IC₅₀ 0.56 ± 0.10, 0.84 ± 0.01, 0.74 ± 0.03 and 0.79 ± 0.06 μg/mL, respectively). Tests using hepatic tissue showed a notorious capacity of the DCM, AcOEt and ButOH fractions, as well as of the isolated molecules to inhibit lipid peroxidation and ROS production, and also to preserve thiol groups. Molecules of great antioxidant potential were found in our samples, such as kaempferol, quercetin, catechin, gallic acid and luteolin.

CONCLUSION

A. humile extract and its organic fractions showed promising antioxidant and antiglycation potential and a prominent capacity to inhibit the α-amylase enzyme. Hence, this study presents new results and stimulates further research to elucidate the biological properties of A. humile and its capacity to manage DM and its complications.

Antioxidant and Antiglycation Effects of Polyphenol Compounds Extracted from Hazelnut Skin on Advanced Glycation End-Products (AGEs) Formation

The advanced glycation end-products (AGEs) arise from non-enzymatic reactions of sugar with protein side chains, some of which are oxido-reductive in nature. Enhanced production of AGEs plays an important role in the pathogenesis of diabetic complications as well as in natural aging, renal failure, oxidative stress, and chronic inflammation. The aim of this work is to study antiglycation effects of polyphenol compounds extracted by hazelnut skin that represents an example of polyphenols-rich food industry by-product, on AGEs formation. AGEs derived from incubation of bovine serum albumin (BSA) and methylglyoxal (MGO) were characterized by fluorescence. The phenolics identification and total polyphenol content in hazelnut skin extracts were analyzed by HPLC-MS and the Folin–Ciocalteu method, respectively. Antioxidant efficacy was evaluated by monitoring total antioxidant activity to assess the ABTS radical scavenging activity of samples by TEAC assay and oxygen radical absorbance capacity (ORAC) assay, expressed as millimoles of Trolox equivalents per gram of sample. Data here presented suggest that phenolic compounds in hazelnut skin have an inhibitory effect on the BSA-AGEs model in vitro, and this effect is concentration-dependent. The putative role of the hazelnut skin antioxidative properties for hindering AGEs formation is also discussed. Because of AGEs contribution to the pathogenesis of several chronic diseases, foods enriched, or supplements containing natural bioactive molecules able to inhibit their production could be an interesting new strategy for supporting therapeutic approaches with a positive effect on human health.

Advanced glycation end products (AGEs) and other adducts in aging-related diseases and alcohol-mediated tissue injury

Advanced glycation end products (AGEs) are potentially harmful and heterogeneous molecules derived from nonenzymatic glycation. The pathological implications of AGEs are ascribed to their ability to promote oxidative stress, inflammation, and apoptosis. Recent studies in basic and translational research have revealed the contributing roles of AGEs in the development and progression of various aging-related pathological conditions, such as diabetes, cardiovascular complications, gut microbiome-associated illnesses, liver or neurodegenerative diseases, and cancer. Excessive chronic and/or acute binge consumption of alcohol (ethanol), a widely consumed addictive substance, is known to cause more than 200 diseases, including alcohol use disorder (addiction), alcoholic liver disease, and brain damage. However, despite the considerable amount of research in this area, the underlying molecular mechanisms by which alcohol abuse causes cellular toxicity and organ damage remain to be further characterized. In this review, we first briefly describe the properties of AGEs: their formation, accumulation, and receptor interactions. We then focus on the causative functions of AGEs that impact various aging-related diseases. We also highlight the biological connection of AGE-alcohol-adduct formations to alcohol-mediated tissue injury. Finally, we describe the potential translational research opportunities for treatment of various AGE- and/or alcohol-related adduct-associated disorders according to the mechanistic insights presented.

Zinc(II) mineral increased the in vitro, cellular and ex vivo antihyperglycemic and antioxidative pharmacological profile of p-hydroxybenzoic acid upon complexation

In this study, zinc was complexed with p-hydroxybenzoic acid to synthesize a complex with improved pharmacological profile. Proton NMR and FTIR analysis were used to characterize the complex. Several in vitro, cellular and ex vivo antihyperglycemic and antioxidative assays were used to evaluate the potency of the complex, relative to its precursors, while molecular docking was used to investigate interactions with insulin signaling targets (GLUT-4 and PKB). Also, the cytotoxicity of the complex was evaluated in Chang liver cells and L-6 myotubes using MTT assay. Complexation was through a Zn(O₄ ) coordination. This afforded the complex two moieties of p-hydroxybenzoic acid, which influenced its activities. While the complex retained the α-glucosidase and α-amylase inhibitory activity of its phenolic acid precursor, complexation increased in vitro and ex vivo antioxidant activity of the phenolic acid by 1.4 to 10.5-folds. Complexation, further, conferred a potent antiglycation activity and L-6 myotube and psoas muscle glucose uptake properties (2.1 to 3.5-folds more than p-hydroxybenzoic acid) on the phenolic acid, without notably inhibiting or reducing the viability of Chang liver cells (IC₅₀  = 5,120 μM) and L-6 myotubes (IC₅₀  = 2,172 μM). Docking studies showed the complex had better interactions with insulin signaling targets (GLUT-4 and PKB) than p-hydrobenzoic acid, which may influence its glucose uptake effects. Data suggest that Zn(II) complexation improved and/or broadened the pharmacological profile of p-hydroxybenzoic acid, thus, may be further studied as a promising adjuvant for phenolic acids. PRACTICAL APPLICATIONS: Most antidiabetic drugs are used as two or more combinations to achieve better efficacy, which may cause drug interaction and increase the risk of side effects associated with these drugs. This study takes advantage of the glycemic control property of zinc and the antioxidant and/or diabetes-related pharmacological properties of p-hydroxybenzoic acid to form a complex with improved and broader antioxidant and antihyperglycemic profile and minimal toxicity concerns. With appropriate further studies, Zn(II)-phenolic acid complexes may be safe nutraceuticals for diabetes and related oxidative complications.

Inhibitory mechanism of sinensetin on α-glucosidase and non-enzymatic glycation: Insights from spectroscopy and molecular docking analyses

Inhibition of α-glucosidase and non-enzymatic glycation is regarded as an effective method to prevent and treat type 2 diabetes and its complications. In this study, the inhibition of sinensetin on α-glucosidase and non-enzymatic glycation was studied with multi-spectroscopic techniques and molecular docking analysis. The results of fluorescence spectroscopy analysis indicated that sinensetin quenched the endogenous fluorescence of α-glucosidase in static manner. The binding of sinensetin with α-glucosidase was a spontaneous process primarily driven by hydrophobic interaction. At 298 K, the binding constant was (5.70 ± 0.12) × 10⁴ L·mol^-1 and the binding site number was 1. The conformation of α-glucosidase was altered by sinensetin, which was revealed by circular dichroism (CD), FTIR spectra, synchronous fluorescence and three-dimensional (3D) fluorescence spectroscopy methods. Molecular docking analysis demonstrated that sinensetin interacted with the amino acid residues of α-glucosidase, which might prevent the entrance of substrate, leading to the decrease of catalytic efficiency of α-glucosidase. Furthermore, glycation assays showed that sinensetin stabilized the structure of bovine serum albumins (BSA), interacted with BSA, strongly inhibited the formation of dityrosine, N'-formylkynurenine and advanced glycation end products (AGEs). This study provided useful information concerning sinensetin preventing and treating type 2 diabetes and its related complications.

New progress in the pharmacology of protocatechuic acid: A compound ingested in daily foods and herbs frequently and heavily

Protocatechuic acid is a natural phenolic acid, which widely exists in our daily diet and herbs. It is also one of the main metabolites of complex polyphenols, such as anthocyanins and proanthocyanins. In recent years, a large number of studies on the pharmacological activities of protocatechuic acid have emerged. Protocatechuic acid has a wide range of pharmacological activities including antioxidant, anti-inflammatory, neuroprotective, antibacterial, antiviral, anticancer, antiosteoporotic, analgesia, antiaging activties; protection from metabolic syndrome; and preservation of liver, kidneys, and reproductive functions. Pharmacokinetic studies showed that the absorption and elimination rate of protocatechuic acid are faster, with glucuronidation and sulfation being the major metabolic pathways. However, protocatechuic acid displays a dual-directional regulatory effect on some pharmacological activities. When the concentration is very high, it can inhibit cell proliferation and reduce survival rate. This review aims to comprehensively summarize the pharmacology, pharmacokinetics, and toxicity of protocatechuic acid with emphasis on its pharmacological activities discovered in recent 5 years, so as to provide more up-to-date and thorough information for the preclinical and clinical research of protocatechuic acid in the future. Moreover, it is hoped that the clinical application of protocatechuic acid can be broadened, giving full play to its characteristics of rich sources, low toxicity and wide pharmacological activites.

Healthy eating recommendations: good for reducing dietary contribution to the body's advanced glycation/lipoxidation end products pool?

The present review aims to give dietary recommendations to reduce the occurrence of the Maillard reaction in foods and in vivo to reduce the body's advanced glycation/lipoxidation end products (AGE/ALE) pool. A healthy diet, food reformulation and good culinary practices may be feasible for achieving the goal. A varied diet rich in fresh vegetables and fruits, non-added sugar beverages containing inhibitors of the Maillard reaction, and foods prepared by steaming and poaching as culinary techniques is recommended. Intake of supplements and novel foods with low sugars, low fats, enriched in bioactive compounds from food and waste able to modulate carbohydrate metabolism and reduce body's AGE/ALE pool is also recommended. In conclusion, the recommendations made for healthy eating by the Spanish Society of Community Nutrition (SENC) and Harvard University seem to be adequate to reduce dietary AGE/ALE, the body's AGE/ALE pool and to achieve sustainable nutrition and health.

Psiadia punctulata major flavonoids alleviate exaggerated vasoconstriction produced by advanced glycation end products

Exaggerated vasoconstriction plays important roles in vascular complication in aging and many diseases like diabetes. Here, we investigated the protective effect of Psiadia punctulata (PP) on advanced glycation end products (AGEs)-induced aggravated vasoconstriction. The effect of total methanol extract of PP leaves (PPT) on AGE-induced vascular injury was studied through bioassay-guided fractionation procedures in order to find the bioactive fraction and isolate the bioactive compounds. Vascular reactivity was studied using the isolated artery technique by adding cumulative concentrations of phenylephrine (PE) or acetyl choline (ACh). In addition, the antiglycating effect, as well as the effect on AGEs intermediates dityrosine and N`-formylkynurenine and their radical scavenging activity were measured. The results showed that PPT alleviated the AGEs-induced aggravated vasoconstriction in a concentration-dependent manner. The bioassay guided fractionation procedures suggested the chloroform fraction (Fr I) to be responsible for the activity. Chemical investigation of this fraction resulted in isolation of four major bioactive compounds that were identified as: umuhengerin (1), gardenin (2), luteolin-3`,4`-dimethyl ether (3), and 5,3`-dihydroxy-6,7,4`,5`-tetramethoxyflavone (4). The four compounds alleviated the exaggerated vasoconstriction in a dose dependent manner. In search for their mechanism of action, we observed that PPT, Fr. I and the isolated compounds did not improve the impaired vasodilation associated with AGEs exposure. PPT, Fr. I and the isolated compounds 1–4 inhibited AGEs formation and their protein oxidation intermediates. Furthermore, PPT, Fr. I and the isolated compounds 1–4 showed weak radical scavenging activity with compound 4 as the most potent. In conclusion, PPT appears to protect against AGEs-induced exaggerated vasoconstriction through antiglycation and radical scavenging activities.

Insights into the Regulation Effects of Certain Phenolic Acids on 2,3-Dihydro-3,5-dihydroxy-6-methyl-4(H)-pyran-4-one Formation in a Microaqueous Glucose-Proline System

The control of 2,3-dihydro-3,5-dihydroxy-6-methyl-4(H)-pyran-4-one (DDMP) formation in the Maillard reaction is important to improve the thermally treated food quality as a result of its intense bitterness and potential toxicity. In this work, phenolic acids, such as gallic, protocatechuic, caffeic, and ferulic acids, were applied to modulate DDMP formation in a microaqueous glucose-proline model. The formation of DDMP was inhibited at low concentrations (from 0.1 to 5.0 mM) while enhanced at 10.0 mM gallic, protocatechuic, and caffeic acids. Ferulic acid always inhibited DDMP formation as a result of the absence of catechol groups on its benzene ring. The result indicated that the control of DDMP formation depended upon the concentration and chemical structures of phenolic acids, such as the number of hydroxyl groups. Further studies indicated that the hydroxyl distribution of phenolic acids regulated the peroxide formation in the model reaction system and further changed the development of the oxidation reaction, which affected the degradation of glucose via caramel or Maillard reaction, Amadori rearrangement product oxidation, and 1-deoxyglucosone degradation to form the intermediates.

The Modern Western Diet Rich in Advanced Glycation End-Products (AGEs): An Overview of Its Impact on Obesity and Early Progression of Renal Pathology

Advanced glycation end-products (AGEs) are an assorted group of molecules formed through covalent bonds between a reduced sugar and a free amino group of proteins, lipids, and nucleic acids. Glycation alters their structure and function, leading to impaired cell function. They can be originated by physiological processes, when not counterbalanced by detoxification mechanisms, or derive from exogenous sources such as food, cigarette smoke, and air pollution. Their accumulation increases inflammation and oxidative stress through the activation of various mechanisms mainly triggered by binding to their receptors (RAGE). So far, the pathogenic role of AGEs has been evidenced in inflammatory and chronic diseases such as chronic kidney disease, cardiovascular disease, and diabetic nephropathy. This review focuses on the AGE-induced kidney damage, by describing the molecular players involved and investigating its link to the excess of body weight and visceral fat, hallmarks of obesity. Research regarding interventions to reduce AGE accumulation has been of great interest and a nutraceutical approach that would help fighting chronic diseases could be a very useful tool for patients’ everyday lives.

The application of post-translational modification oriented serum proteomics to assess experimental diabetes with complications

Proteome analysis of serum from type 2 diabetics with complications may lead to the discovery of diagnostic or prognostic biomarkers. To circumvent the principal barrier of serum proteomics, our investigation aimed to evaluate whether a study of post-translational modification enriched serum proteins could be valuable for the discovery of biomarkers or metabolic pathways related to type 2 diabetes pathogenesis. Type 2 diabetes was induced from high-fat diet fed Sprague Dawley rats with streptozotocin injection. Once diabetic status was confirmed, serum samples from either fasted healthy or diabetic rats were pooled and profiled by two-dimensional difference gel electrophoresis or comparative 2D electrophoresis after protein enrichments using immobilized metal ion, concanavalin A, and lentil affinity chromatography, respectively. Differential expressed proteins were identified and the associated networks were established by an Ingenuity Pathway Analysis. As a result, induced rats became severe diabetic and accompanied by hyperlipidemia, fatty liver, and glomerular hypertrophy. There were 3 total, 14 phosphorylated and 23 glycosylated protein targets differentially expressed. Proteins could be linked to HNF4A, HNF1A, and NF_κB transcriptional factors and antigen presentation, humoral immune response, and inflammatory response pathways. Predicted organ toxicity in kidney, heart, and liver matched with our histopathological results. In conclusion, post-translational modification based serum protein enrichment could be a valuable approach to enhance the resolution of serum proteomics without depleting potentially valuable abundant proteins. Our results also indicated the potential association of the hepatic secretome and hepatocyte nuclear factors in the pathogenesis of type 2 diabetes and its complications.