Bimolecular interaction of argpyrimidine (a Maillard reaction product) in in vitro non-enzymatic protein glycation model and its potential role as an antiglycating agent

1. It has been suggested that 2-amino-6-(2-formyl-5-hydroxymethyl-pyrrol-l-yl)-hexanoic acid ('pyrraline') is formed as an advanced glycation end product in the Maillard reaction under physiological conditions. Antibodies were raised to caproyl-pyrraline linked to keyhole-limpet haemocyanin and were used to develop an e.l.i.s.a. and Western blotting system for the specific detection of pyrraline in samples in vivo and in vitro. 2. Human serum albumin was isolated from the serum samples of diabetic and non-diabetic subjects. Pyrraline was not detected (<1.2 pmol) in any of the samples, indicating that it was not a major advanced glycation end product in vivo. 3. BSA was incubated separately with D-glucose and a model fructosamine, N-(l-deoxy-D-fructos-l-yl)-hippuryl-lysine, under physiological conditions for 30 days. Aliquots removed from the incubations at 5 day intervals contained no detectable pyrraline, indicating that pyrraline was not an early-stage product of the Maillard reaction in vitro. 4. The model fructosamine, N>-(1-deoxy-D-fructos-l-yl)-hippuryl-lysine, was incubated at pH 7.4 and 37°C for 25 days during which it degraded to hippuryl-lysine and N>-carboxymethyl-hippuryl-lysine. Aliquots were removed at 5 day intervals and assayed for pyrraline. None was detected (<23 pmol/ml) in the course of the degradation of the fructosamine (400 nmol/ml degraded), indicating that pyrraline was not a major product of the degradation of fructosamine under physiological conditions in vitro. 5. We conclude that pyrraline is not a major intermediate or advanced glycation end product in the Maillard reaction under physiological conditions in vitro and in vivo. A previous report of immunoassay of pyrraline may have given positive results because of non-specific antibodies raised to impure hapten.

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Polyphenols of leaves of Apium graveolens inhibit in vitro protein glycation and protect RINm5F cells against methylglyoxal-induced cytotoxicity

Functional Foods in Health and Disease ◽

10.31989/ffhd.v8i3.399 ◽

2018 ◽

Vol 8 (3) ◽

pp. 193 ◽

Cited By ~ 2

Author(s):

Rosa Martha Perez Gutierrez ◽

Alethia Muñiz-Ramirez ◽

Abraham Heriberto Garcia Campoy ◽

Jose Maria Mota Flores ◽

Sergio Odin Flores

Keyword(s):

Therapeutic Potential ◽

Health Benefits ◽

Protein Glycation ◽

Apium Graveolens ◽

Ionization Mass ◽

Intensity Level ◽

Edible Plants ◽

Rinm5f Cells ◽

Protein Carbonyl Content

Background: The health benefits of edible plants have been widely investigated and disseminated. However, only polyphenols have been found to have sufficient therapeutic potential to be considered in clinical trials. Fewer manuscripts have other applications such as prospective health benefits and disease treatment. Other components of edible plants are responsible for a range of other benefits including antimalarial, burns, flu, cancer, inflammation, diabetes, glycation, antimicrobial, prevention of neurodegeneration, analgesic, antimigraine activity, sedative activities, etc. Accordingly, the public needs to be informed of the potential edible plants have to act on different targets and maintain better control over diabetes compared to commercial drugs which can be toxic, have side effects, do not have the capacity to maintain blood glucose at normal levels, and do not protect the patient from the complications of diabetes over time. Consequently, edible plants, such as Apium graveolen, which have therapeutic targets on AGEs formation, are potentially a better alternative treatment for diabetes.Methods: The leaves of celery were extracted with methanol (CM). Polyphenols contents in CM were investigated by liquid chromatography-electrospray ionization mass. The ability of the compounds to inhibit formation of AGEs was evaluated in vitro models using formation of AGE fluorescence intensity, level of fructosamine, Nε-(carboxymethyl)lysine (CML), methylglyoxal (MG)-derived protein, and formation of amyloid cross β structure. Protein-oxidation was determined by thiol group and protein carbonyl content. Inhibition of MG-derived AGEs and MG-trapping ability were also measured. Additionally, insulin production was determined in methylglyoxal-treated pancreatic RINm5F cells assay. Results: Apigenin, kaempferol, apiin, rutin, caffeic acid, ferulic acid, chlorogenic acid, coumaroylquinic acid, and p-coumaric acid were the major polyphenols contained in CM. In all the model tests CM displayed potent AGE inhibitory activity, suggesting that CM delayed the three stages of glycation. Accordingly, the mechanisms of action of celery involving dicarbonyl trapping and breaking the crosslink structure in the AGEs formed may contribute to the protection of pancreatic RINm5F cells against MG conditions.Conclusion: These findings indicate that CM have an excellent anti-glycation effect which may be beneficial for future development of antiglycating agents for the treatment of diabetes.Keywords: Apium graveolens, anti-glycation, polyphenols methylglyoxal, insulin, pancreatic cells

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Conifers Phytochemicals: A Valuable Forest with Therapeutic Potential

Molecules ◽

10.3390/molecules26103005 ◽

2021 ◽

Vol 26 (10) ◽

pp. 3005

Author(s):

Kanchan Bhardwaj ◽

Ana Sanches Silva ◽

Maria Atanassova ◽

Rohit Sharma ◽

Eugenie Nepovimova ◽

...

Keyword(s):

Experimental Data ◽

Potential Role ◽

Therapeutic Potential ◽

Fungal Infections ◽

Cell Damage ◽

Cancer Growth ◽

Naturally Occurring ◽

Antioxidant Effects

Conifers have long been recognized for their therapeutic potential in different disorders. Alkaloids, terpenes and polyphenols are the most abundant naturally occurring phytochemicals in these plants. Here, we provide an overview of the phytochemistry and related commercial products obtained from conifers. The pharmacological actions of different phytochemicals present in conifers against bacterial and fungal infections, cancer, diabetes and cardiovascular diseases are also reviewed. Data obtained from experimental and clinical studies performed to date clearly underline that such compounds exert promising antioxidant effects, being able to inhibit cell damage, cancer growth, inflammation and the onset of neurodegenerative diseases. Therefore, an attempt has been made with the intent to highlight the importance of conifer-derived extracts for pharmacological purposes, with the support of relevant in vitro and in vivo experimental data. In short, this review comprehends the information published to date related to conifers’ phytochemicals and illustrates their potential role as drugs.

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Molecular and Cellular Mechanisms of Metformin in Cervical Cancer

Cancers ◽

10.3390/cancers13112545 ◽

2021 ◽

Vol 13 (11) ◽

pp. 2545

Author(s):

Ya-Hui Chen ◽

Po-Hui Wang ◽

Pei-Ni Chen ◽

Shun-Fa Yang ◽

Yi-Hsuan Hsiao

Keyword(s):

Cervical Cancer ◽

Potential Role ◽

Treatment Options ◽

Cellular Mechanisms ◽

Anticancer Effects ◽

Clinical Benefits ◽

Underlying Mechanisms

Cervical cancer is one of the major gynecologic malignancies worldwide. Treatment options include chemotherapy, surgical resection, radiotherapy, or a combination of these treatments; however, relapse and recurrence may occur, and the outcome may not be favorable. Metformin is an established, safe, well-tolerated drug used in the treatment of type 2 diabetes; it can be safely combined with other antidiabetic agents. Diabetes, possibly associated with an increased site-specific cancer risk, may relate to the progression or initiation of specific types of cancer. The potential effects of metformin in terms of cancer prevention and therapy have been widely studied, and a number of studies have indicated its potential role in cancer treatment. The most frequently proposed mechanism underlying the diabetes–cancer association is insulin resistance, which leads to secondary hyperinsulinemia; furthermore, insulin may exert mitogenic effects through the insulin-like growth factor 1 (IGF-1) receptor, and hyperglycemia may worsen carcinogenesis through the induction of oxidative stress. Evidence has suggested clinical benefits of metformin in the treatment of gynecologic cancers. Combining current anticancer drugs with metformin may increase their efficacy and diminish adverse drug reactions. Accumulating evidence is indicating that metformin exerts anticancer effects alone or in combination with other agents in cervical cancer in vitro and in vivo. Metformin might thus serve as an adjunct therapeutic agent for cervical cancer. Here, we reviewed the potential anticancer effects of metformin against cervical cancer and discussed possible underlying mechanisms.

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Specificity of the HIV-1 Protease on Substrates Representing the Cleavage Site in the Proximal Zinc-Finger of HIV-1 Nucleocapsid Protein

Viruses ◽

10.3390/v13061092 ◽

2021 ◽

Vol 13 (6) ◽

pp. 1092

Author(s):

János András Mótyán ◽

Márió Miczi ◽

Stephen Oroszlan ◽

József Tőzsér

Keyword(s):

Amino Acid ◽

Zinc Finger ◽

Cleavage Site ◽

Potential Role ◽

Binding Mode ◽

Interaction Energies ◽

Vitro Assay ◽

Hiv 1

To explore the sequence context-dependent nature of the human immunodeficiency virus type 1 (HIV-1) protease’s specificity and to provide a rationale for viral mutagenesis to study the potential role of the nucleocapsid (NC) processing in HIV-1 replication, synthetic oligopeptide substrates representing the wild-type and modified versions of the proximal cleavage site of HIV-1 NC were assayed as substrates of the HIV-1 protease (PR). The S1′ substrate binding site of HIV-1 PR was studied by an in vitro assay using KIVKCF↓NCGK decapeptides having amino acid substitutions of N17 residue of the cleavage site of the first zinc-finger domain, and in silico calculations were also performed to investigate amino acid preferences of S1′ site. Second site substitutions have also been designed to produce “revertant” substrates and convert a non-hydrolysable sequence (having glycine in place of N17) to a substrate. The specificity constants obtained for peptides containing non-charged P1′ substitutions correlated well with the residue volume, while the correlation with the calculated interaction energies showed the importance of hydrophobicity: interaction energies with polar residues were related to substantially lower specificity constants. Cleavable “revertants” showed one residue shift of cleavage position due to an alternative productive binding mode, and surprisingly, a double cleavage of a substrate was also observed. The results revealed the importance of alternative binding possibilities of substrates into the HIV-1 PR. The introduction of the “revertant” mutations into infectious virus clones may provide further insights into the potential role of NC processing in the early phase of the viral life-cycle.

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Inhibitory Effect of Antidesma bunius Fruit Extract on Carbohydrate Digestive Enzymes Activity and Protein Glycation In Vitro

Antioxidants ◽

10.3390/antiox10010032 ◽

2020 ◽

Vol 10 (1) ◽

pp. 32

Author(s):

Pattamaporn Aksornchu ◽

Netima Chamnansilpa ◽

Sirichai Adisakwattana ◽

Thavaree Thilavech ◽

Charoonsri Choosak ◽

...

Keyword(s):

Antioxidant Activity ◽

Radical Scavenging Activity ◽

Digestive Enzyme ◽

Radical Scavenging ◽

Protein Glycation ◽

Trolox Equivalent Antioxidant Capacity ◽

Fruit Extract ◽

Antioxidant Power ◽

Ic50 Values

Antidesma bunius (L.) spreng (Mamao) is widely distributed in Northeastern Thailand. Antidesma bunius has been reported to contain anthocyanins, which possess antioxidant and antihypertensive actions. However, the antidiabetic and antiglycation activity of Antidesma bunius fruit extract has not yet been reported. In this study, we investigated the inhibitory activity of anthocyanin-enriched fraction of Antidesma bunius fruit extract (ABE) against pancreatic α-amylase, intestinal α-glucosidase (maltase and sucrase), protein glycation, as well as antioxidant activity. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) chromatogram revealed that ABE contained phytochemical compounds such as cyanidin-3-glucoside, delphinidin-3-glucoside, ellagic acid, and myricetin-3-galactoside. ABE inhibited intestinal maltase and sucrase activity with the IC50 values of 0.76 ± 0.02 mg/mL and 1.33 ± 0.03 mg/mL, respectively. Furthermore, ABE (0.25 mg/mL) reduced the formation of fluorescent AGEs and the level of Nε-carboxymethyllysine (Nε-CML) in fructose and glucose-induced protein glycation during four weeks of incubation. During the glycation process, the protein carbonyl and β-amyloid cross structure were decreased by ABE (0.25 mg/mL). In addition, ABE exhibited antioxidant activity through DPPH radical scavenging activity and Trolox equivalent antioxidant capacity (TEAC) with the IC50 values 15.84 ± 0.06 µg/mL and 166.1 ± 2.40 µg/mL, respectively. Meanwhile, ferric reducing antioxidant power (FRAP) showed an EC50 value of 182.22 ± 0.64 µg/mL. The findings suggest that ABE may be a promising agent for inhibiting carbohydrate digestive enzyme activity, reducing monosaccharide-induced protein glycation, and antioxidant activity.

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Ginsenoside derivatives inhibit advanced glycation end-product formation and glucose–fructose mediated protein glycation in vitro via a specific structure–activity relationship

Bioorganic Chemistry ◽

10.1016/j.bioorg.2021.104844 ◽

2021 ◽

pp. 104844

Author(s):

Md Yousof Ali ◽

Susoma Jannat ◽

M. Mizanur Rahman

Keyword(s):

Structure Activity Relationship ◽

Product Formation ◽

Protein Glycation ◽

Specific Structure ◽

Activity Relationship ◽

Advanced Glycation ◽

Advanced Glycation End Product ◽

Structure Activity

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Nanoceria Prevents Glucose-Induced Protein Glycation in Eye Lens Cells

Nanomaterials ◽

10.3390/nano11061473 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1473

Author(s):

Belal I. Hanafy ◽

Gareth W. V. Cave ◽

Yvonne Barnett ◽

Barbara K. Pierscionek

Keyword(s):

Protein Glycation ◽

Human Lens ◽

Lens Epithelial Cells ◽

Oxide Nanoparticles ◽

Lens Protein ◽

Oxygen Species ◽

Human Lens Epithelial Cells ◽

Age Related ◽

Age Related Changes

Cerium oxide nanoparticles (nanoceria) are generally known for their recyclable antioxidative properties making them an appealing biomaterial for protecting against physiological and pathological age-related changes that are caused by reactive oxygen species (ROS). Cataract is one such pathology that has been associated with oxidation and glycation of the lens proteins (crystallins) leading to aggregation and opacification. A novel coated nanoceria formulation has been previously shown to enter the human lens epithelial cells (HLECs) and protect them from oxidative stress induced by hydrogen peroxide (H2O2). In this work, the mechanism of nanoceria uptake in HLECs is studied and multiple anti-cataractogenic properties are assessed in vitro. Our results show that the nanoceria provide multiple beneficial actions to delay cataract progression by (1) acting as a catalase mimetic in cells with inhibited catalase, (2) improving reduced to oxidised glutathione ratio (GSH/GSSG) in HLECs, and (3) inhibiting the non-enzymatic glucose-induced glycation of the chaperone lens protein α-crystallin. Given the multifactorial nature of cataract progression, the varied actions of nanoceria render them promising candidates for potential non-surgical therapeutic treatment.

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