Phenolic Profile and Bioactivity Changes of Lotus Seedpod and Litchi Pericarp Procyanidins: Effect of Probiotic Bacteria Biotransformation

Theoretically, lactic acid bacteria (LABs) could degrade polyphenols into small molecular compounds. In this study, the biotransformation of lotus seedpod and litchi pericarp procyanidins by Lactobacillus plantarum 90 (Lp90), Streptococcus thermophilus 81 (ST81), Lactobacillus rhamnosus HN001 (HN001), and Pediococcus pentosus 06 (PP06) were analysed. The growth curve results indicated that procyanidins did not significantly inhibit the proliferation of LABs. Ultra-high-performance liquid chromatography high-resolution mass spectrometry (UPLC-HRMS) revealed that procyanidin B2 and procyanidin B3 in lotus seedpod decreased by 62.85% and 25.45%, respectively, with ST81 metabolised, while kaempferol and syringetin 3-O-glucoside content increased. Although bioconversion did not increase the inhibitory function of procyanidins against glycosylation end-products in vitro, the 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) free radical scavenging capacity and ferric reducing antioxidant power of litchi pericarp procyanidins increased by 157.34% and 6.8%, respectively, after ST81 biotransformation. These findings may inspire further studies of biological metabolism of other polyphenols and their effects on biological activity.

Can grape polyphenols affect glycation markers? A systematic review

Advanced glycation end-products (AGEs) favor inflammation and oxidative stress, playing a role in chronic diseases pathogenesis. Grape polyphenols exert antiglycative and antioxidant effects which may contribute to prevent chronic diseases. However, clinical evidence of grape polyphenols on chronic disease prevention and treatment by glycation markers modulation are limited. Therefore, we aimed to critically analyze studies about that topic to investigate the antiglycative power of dietary grape polyphenol, and to explore the molecular mechanism involved. This systematic review was conducted and reported according to PRISMA guidelines. The following search terms were used: "grape", "extract", "grape seed extract", "grape skin extract", "polyphenol extract", "grape polyphenol(s)", "grape juice", "resveratrol", "quercetin", "catechin", "epicatechin", "procyanidin(s)", and "anthocyanin(s)". Seven studies were included. Glycated hemoglobin was not affected. The interventions duration may not have been enough to detect changes. Grape polyphenols reduced fructosamine and methylglyoxal (MGO) concentrations, and increased endogenous secretory RAGE (esRAGE) gene expression but did not affect the serum concentration. Resveratrol antiglycative effects are mainly due its ability to trap MGO and downregulate RAGE. In conclusion, grape polyphenols may have a positive impact on early glycation products, AGEs and esRAGE. Future studies are needed to explore how they modulate AGEs and receptors in chronic diseases.

Nɛ-(carboxymethyl)lysine, Available Lysine, and Volatile Compound Profile of Biscuits Enriched with Grape by-Product During Storage

We investigated the changes in Nɛ-(carboxymethyl)lysine (CML) and available lysine content, antioxidant properties, volatiles, and oxidation products of biscuits enriched with grape by-product (GP), stored for six months under a modified atmosphere of 0%/30%/70% O₂/CO₂/N₂ and in air. Fresh GP-formulated biscuits showed lower concentrations of CML (89%), available lysine (40%), and pyrazines (75%), but higher antioxidant capacities (~ sixfold), furans (12-fold), and lipid-derived compounds (three-fold) than the control. Although ~ 15% higher losses of Maillard-type volatiles were identified in the air atmosphere during storage, lipid oxidation was ~ 30% less pronounced in the modified atmosphere. A significant correlation of 0.994 between the reduction in CML and the available lysine suggest further CML reactions with the ɛ-NH₂ group of amino acids. Significant correlations (of -0.550 to -0.980) between oxidation products, antioxidant capacities, and changes in CML content during storage suggest that these parameters might be involved in the CML elimination mechanism.

Plant-Derived Chinese Medicine Monomers on Ovarian Cancer via the Wnt/β-Catenin Signaling Pathway: Review of Mechanisms and Prospects

Ovarian cancer (OC) is a common malignant tumor of the female reproductive system and has a high morbidity and mortality rate. The progression and metastasis of OC are complex and involve multiple signaling pathways. The Wnt/β-catenin signaling pathway is closely related to OC, and therefore blocking the activation of the Wnt/β-catenin signaling directly or inhibiting related genes, and molecular targets is of great value in treating OC. Toxicities such as myelotoxicity, cardiotoxicity, genotoxicity, and vasospasm are the major side effects for common anticancer drugs and are well documented. There is, therefore, a need to develop new, effective, safer, and more affordable anticancer drugs from alternative sources. In recent years, plant-derived Chinese medicine monomers have drawn increasing attention due to their high safety, low toxicity, minimal side effects, and antitumor effects. Plant-derived Chinese medicine monomers are effective against multiple targets and can regulate the growth, proliferation, apoptosis, invasion, and migration of OC as well as reverse drug resistance by regulating the Wnt/β-catenin signaling pathway. In this review, we summarize and provide mechanisms and prospects for the use of plant-derived Chinese medicines for the prevention and treatment of OC.

Antiglycoxidative Properties of Extracts and Fractions from Reynoutria Rhizomes

Hyperglycemia, when sustained over a long time in diabetes mellitus (DM), leads to biochemical and cellular abnormalities, primarily through the formation of advanced glycation end-products (AGEs). In the treatment of diabetes, beside blood-sugar-lowering medications, a consumption of herbal products that can inhibit the AGEs’ formation is recommended. This study investigated the in vitro antiglycoxidative potential of extracts and fractions from the rhizomes of Japanese, Giant, and Bohemian knotweeds (Reynoutria japonica (Houtt.), R. sachalinensis (F. Schmidt) Nakai, and R.× bohemica Chrtek et Chrtkova). Their effects on glycooxidation of bovine and human serum albumin were evaluated by incubation of the proteins with a mixture of glucose and fructose (0.5 M) and 150 µg/mL of extract for 28 days at 37 °C, followed by measuring early and late glycation products, albumin oxidation (carbonyl and free thiol groups), and amyloid-β aggregation (thioflavin T and Congo red assays). The highest antiglycoxidative activity, comparable or stronger than the reference drug (aminoguanidine), was observed for ethyl acetate and diethyl ether fractions, enriched in polyphenols (stilbenes, phenylpropanoid disaccharide esters, and free and oligomeric flavan-3-ols). In conclusion, the antiglycoxidative compounds from these three species should be further studied for potential use in the prevention and complementary treatment of DM.

Dietary N-epsilon-carboxymethyllysine as for a major glycotoxin in foods: A review

N-epsilon-carboxymethyllysine (CML), as a potential glycotoxin and general marker for dietary advanced glycation end products (dAGEs), exists in raw food and is formed via various formation routes in food processing such as Maillard reaction between the reducing sugars and amino acids. Although comprehensive cause-effect proof is not available yet, current research suggests a potential risk of chronic diseases such as diabetes is associated with exogenous CML. Thus, CML is causing public health concerns regarding its dietary exposure, but there is a lack of explicit guidance for understanding if it is detrimental to human health. In this review, inconsistent results of dietary CML contributed to chronic disease are discussed, available concentrations of CML in consumed foods are evaluated, measurements for dietary CML and relevant analytic procedures are listed, and the possible mitigation strategies for protecting against CML formation are presented. Finally, the main challenges and future efforts are highlighted. Further studies are needed to extend the dietary CML database in a wide category of foods, apply new identifying methods, elucidate the pathogenic mechanisms, assess its detrimental role in human health, and propose standard guidelines for processed food.

Glycoside Hydrolases and Non-Enzymatic Glycation Inhibitory Potential of Viburnum opulus L. Fruit-In Vitro Studies

Phytochemicals of various origins are of great interest for their antidiabetic potential. In the present study, the inhibitory effects against carbohydrate digestive enzymes and non-enzymatic glycation, antioxidant capacity, and phenolic compounds composition of Viburnum opulus L. fruits have been studied. Crude extract (CE), purified extract (PE), and ethyl acetate (PEAF) and water (PEWF) fractions of PE were used in enzymatic assays to evaluate their inhibitory potential against α-amylase with potato and rice starch as substrate, α-glucosidase using maltose and sucrose as substrate, the antioxidant capacity (ABTS, ORAC and FRAP assays), antiglycation (BSA-fructose and BSA-glucose model) properties. Among four tested samples, PEAF not only had the highest content of total phenolics, but also possessed the strongest α-glucosidase inhibition, antiglycation and antioxidant activities. UPLC analysis revealed that this fraction contained mainly chlorogenic acid, proanthocyanidin oligomers and flavalignans. Contrary, the anti-amylase activity of V. opulus fruits probably occurs due to the presence of proanthocyanidin polymers and chlorogenic acids, especially dicaffeoylquinic acids present in PEWF. All V. opulus samples have an uncompetitive and mixed type inhibition against α-amylase and α-glucosidase, respectively. Considering strong anti-glucosidase, antioxidant and antiglycation activities, V. opulus fruits may find promising applications in nutraceuticals and functional foods with antidiabetic activity.

Development of an Isotope Dilution UHPLC-QqQ-MS/MS-Based Method for Simultaneous Determination of Typical Advanced Glycation End Products and Acrylamide in Baked and Fried Foods

In this work, a stable isotope dilution ultrahigh-performance liquid chromatography triple quadrupole tandem mass spectrometry (UHPLC-QqQ-MS/MS) method was developed and validated for simultaneous determination of N^ε-(carboxymethyl)lysine (CML), N^ε-(carboxyethyl)lysine (CEL), and acrylamide (AA) in baked and fried foods. Ground food samples were extracted with acetone followed by two parallel assays. In assay A, a cleanup procedure based on dispersive solid-phase extraction was conducted for AA, free CML, and CEL analysis using the supernatant. In assay B, a multistep process including reduction, protein precipitation, acid hydrolysis, and solid-phase extraction was conducted for bound CML and CEL analysis using precipitation. The developed method was validated in terms of linearity, sensitivity (limit of detection, LOD; limit of quantitation, LOQ), accuracy, and precision. The results showed that the method had a wide linear range (0.25-500 ng/mL for CML and CEL, 0.5-500 ng/mL for AA), low LOD and LOQ (0.47-0.94 and 1.52-1.91 μg/kg, respectively), and good linearity (R² > 0.999). The recovery test on baby biscuit and French fries samples showed the recovery rates of 90.2-108.3% for CML, 89.0-106.1% for CEL, and 94.5-112.3% for AA with satisfactory precision (relative standard deviation (RSD) < 10%). Finally, the developed method was successfully applied to 11 baked and fried food samples, and total CML, CEL, and AA contents varied in the ranges of 4.07-35.88 mg/kg, 1.99-14.49 mg/kg, and 5.56-506.64 μg/kg, respectively. Therefore, the isotope dilution UHPLC-QqQ-MS/MS method developed herein is promising for routine analysis of CML, CEL, and AA in baked and fried foods.

Spatholobus suberectus Ameliorates Diabetes-Induced Renal Damage by Suppressing Advanced Glycation End Products in db/db Mice

Spatholobus suberectus (SS) is a medicinal herb commonly used in Asia to treat anemia, menoxenia and rheumatism. However, its effect of diabetes-induced renal damage and mechanisms of action against advanced glycation end-products (AGEs) are unclear. In this study, we evaluated the effects of SS on diabetes-induced renal damage and explored the possible underlying mechanisms using db/db type 2 diabetes mice. db/db mice were administered SS extract (50 mg/kg) orally for 6 weeks. SS-treated group did not change body weight, blood glucose and glycated hemoglobin (HbA1c) levels. However, SS treatment reversed diabetes-induced dyslipidemia and urinary albumin/creatinine ratio in db/db mice. Moreover, SS administration showed significantly increased protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2), which is a transcription factor for antioxidant enzyme. SS significantly upregulated glyoxalase 1 (Glo1) and NADPH quinine oxidoreductase 1 (NQO1) expression but reduced CML accumulation and downregulated receptor for AGEs (RAGE). Furthermore, SS showed significant decrease of periodic acid⁻Schiff (PAS)-positive staining and AGEs accumulation in histological and immunohistochemical analyses of kidney tissues. Taken together, we concluded that SS ameliorated the renal damage by inhibiting diabetes-induced glucotoxicity, dyslipidemia and oxidative stress, through the Nrf2/antioxidant responsive element (ARE) stress-response system.

Identification of Antiglycative Compounds in Japanese Red Water Pepper (Red Leaf Variant of the Persicaria hydropiper Sprout)

Glycation, the nonenzymatic reaction between proteins and excess blood sugar, is implicated in multiple disorders and occurs via the formation and accumulation of advanced glycation end products (AGEs). In our previous studies, we demonstrated that the red-leaf variant of the Persicaria hydropiper sprout (Japanese red water pepper, Benitade) is one of the potent plants that inhibit formation of AGEs. In this study, we aimed to identify antiglycative compounds in Benitade. Benitade extracts were prepared with hot water, then fractionated by using high-performance liquid chromatography (HPLC). The antiglycative efficacy of each fraction was evaluated by measuring the formation of fluorescent AGEs (Ex 370 nm/Em 440 nm). Two fractions, which contained peaks at 26.4 min and 31.8 min, showed potent antiglycative efficacy. When we hydrolyzed these peaks, they shifted to 32.5 and 41.4 min, which are the same retention times as cyanidin and quercetin, respectively. Based on thin-layer chromatography, both compounds contained galactose. Finally, ultrahigh-performance liquid chromatography/quadrupole-time of flight mass spectrometry (UHPLC-QqTOF-MS) analyses were performed to determine the structure of those compounds. Overall, we identified two glycosides, cyanidin 3-O-galactoside (idaein) and quercetin 3-O-galactoside (hyperin), as representative antiglycative compounds in Benitade.

Experimental studies on glycolytic enzyme inhibitory and antiglycation potential of Triphala

Introduction:

Imbalance in cellular metabolism of carbohydrates and lipids is observed in diabetes mellitus. Pancreatic α-amylase and α-glucosidases are responsible for the conversion of polysaccharides into glucose that enters in the blood stream. Triphala has shown antidiabetic effects (type 2) in human subjects. However, its effects on glycolytic enzymes and protein glycation have not been studied.

Aim:

To evaluate glycolytic enzyme inhibitory and antiglycation potential of Triphala.

Materials and Methods:

Triphala Churna was extracted with cold water and subjected to phytochemical analysis. Studies on α amylase and α glucosidase inhibition were performed, and its antiglycation potential was determined.

Results:

Triphala extract showed prominent α-amylase inhibitory potential (48.66% at concentration 250 μg/ml). Percent α-glucosidase inhibition increased with increasing concentration of the extract (6.32–40.64%). Extract showed remarkable results for antiglycation potential. Triphala extract showed glycation inhibition by inhibiting fructosamine; fructosamine inhibition was found to be 37.74%, protein carbonyls were inhibited up to 15.23% whereas protein thiols were inhibited up to 84.81%.

Conclusion:

Triphala showed glycolytic enzyme inhibitory and antiglycation potential. Hence, it can be effectively used in the diabetes management.

Recent development of plant products with anti-glycation activity: a review

This review article summarizes the plant natural products that inhibit glycation at different stages leading to the AGEs formation.