Glycation Of Bovine Serum Albumin Research Articles

Monosaccharide-Mediated Glycoxidation of Bovine Serum Albumin and Its Prevention by Nigella sativa.

The substantial rise in metabolic illnesses that has occurred in both developed and developing countries over the last three decades has been linked to an increase in sugar-added foods and sweetened beverage intake. The significance of advanced glycation end products (AGEs) in the pathophysiology of metabolic diseases related to modern nutrition is an emerging issue. Spices and herbs can potentially be potent AGE production inhibitors due to their high polyphenol content. The inhibitory activity of an aqueous extract of Nigella sativa seeds (NS) on glucose- and fructose-mediated glycation of bovine serum albumin (BSA) was investigated. The glycation of proteins and its prevention using NS were assessed using spectrophotometry, spectrofluorometrics, and electrophoretic techniques. Additionally, the NBT assay, DNPH assay, Ellman assay, and thioflavin T assay were used to observe the biochemical alterations caused by glycated BSA. Molecular docking was employed to dock the BSA active site residues with inhibitors. Our data showed that NS protects against glucose- and fructose-mediated glycation and aggregation in vitro by inhibiting the formation of fructosamine, protein carbonyl content, free sulfhydryl groups, and fluorescent AGEs. Furthermore, NS also inhibited the production of β-cross-amyloid aggregates in proteins. It was interesting to note that the inhibition was found to be significantly higher in the Glu-BSA system, although the glycation product formed in the Fru-BSA system was higher compared to the Glu-induced protein system. It can be concluded that, by inhibiting AGE production, oxidation, and aggregation of the protein, NS may be an effective antiglycation drug for the prevention of diabetes complications.

Monascus pigments suppress fructose-mediated BSA glycation by trapping methylglyoxal and covalent binding to proteins

In this study, four Monascus pigments (ankaflavin, AK; monascin MS; rubropunctatin, O1; monascorubrin, O2) were proved to exhibit considerable anti-glycation properties in bovine serum albumin (BSA)-fructose model. AK (40.62 %) and MS (48.38 %) were found to exert lower inhibitory effects on the formation of fluorescent advanced glycation end products (AGEs) than aminoguanidine (59.4 %), while O1 (90.64 %) and O2 (93.82 %) displayed much stronger abilities. AK and MS could trap methylglyoxal (MGO) with maximum capture rates of 85.67 % and 84.90 %, respectively, and only mono-MGO adducts of them were detected. LC-Orbitrap MS/MS analysis revealed that four pigments significantly altered the type and reduced the number of the glycated sites and they all covalently bound to BSA, with O1 and O2 possessing high reactivity. Altogether, AK and MS suppressed fluorescent AGEs formation mainly via trapping MGO and covalently interacting with BSA, and blocking free amino groups was the dominant mechanism for O1 and O2. These findings presented new insights into Monascus pigments as dietary supplement for inhibiting protein glycation.

Investigation on the binding behaviors of two dihydrochalcones to bovine serum albumin and their anti-glycation activities

The interactions of two dihydrochalcones (naringin dihydrochalcone (NGDC) and neohesperidin dihydrochalcone (NHDC)) with bovine serum albumin (BSA) and their anti-glycation effects were studied utilizing multiple spectral methods and molecular simulation technique. The findings proved that NGDC/NHDC could use a static quenching mechanism to reduce the intrinsic fluorescence of BSA, and the interaction between NGDC/NHDC and BSA was a spontaneous behavior with the binding constant ranging from 104 to 105M−1. Furthermore, NGDC and NHDC mainly interacted with the site I (subdomain IIA) of BSA via hydrophobic interactions and hydrogen bonds, endorsed by molecular docking study. A conjoint analysis of circular dichroism, three-dimensional fluorescence, dynamic light scattering, and UV-vis absorption spectra confirmed that NGDC/NHDC could induce some alterations in the spatial conformation and microenvironment of BSA. Additionally, NGDC and NHDC inhibited the non-enzymatic glycation of BSA by decreasing the contents of advanced glycation end products (AGEs), trapping methylglyoxal/glyoxal and maintaining the stability of the natural conformation of the protein. Overall, these findings were highly beneficial in disclosing the interaction mechanisms between dihydrochalcones and BSA and providing valuable information for the application of dihydrochalcones as functional food ingredients.

The Inhibition Mechanisms of Three Structurally Different Salvianolic Acids on the Non-Enzymatic Glycation of Bovine Serum Albumin.

The antiglycation mechanisms of three structurally different salvianolic acids (Sals) including salvianolic acid A (Sal-A), salvianolic acid B (Sal-B) and salvianolic acid C (Sal-C) were investigated using the bovine serum albumin (BSA)-fructose model. The results showed that the three compounds could inhibit the formation of glycation products, maintain protein structural stability, mitigate the development of amyloid fibrils and scavenge radicals. Notably, Sal-A possessed the highest anti-glycated activity compared with Sal-B and Sal-C. This may be related to the fact that Sal-A contained the most molecules of caffeic acid (Sal-A, Sal-B, and Sal-C possessing two, one, and zero caffeic acid units, respectively), and caffeic acid played a leading role in the antiglycation properties relative to Danshensu. Moreover, these compounds quenched the intrinsic fluorescence intensity of BSA in a static mode, with the binding constants in the order of Sal-A > Sal-B > Sal-C. Obviously, Sal-A possessed the strongest binding affinity among these compounds, which may be one of the reasons why it exhibited the optimal antiglycation capability. Furthermore, molecular docking demonstrated that the three Sals exerted protective effects on BSA by preventing glycation modification of lysine and arginine residues. These findings would provide valuable insights into the potential application of Sals for alleviating non-enzymatic glycation of protein.

Effect of glycation-induced concentration-dependent change in albumin structure and alteration in its binding capacity

Reducing sugars causes confirmatory alterations in albumin structure by the nonenzymatic glycation of the amino group of serum albumin. In this study, glucose and its hazardous metabolic products like glyoxal and methylglyoxal were incubated with bovine serum albumin (BSA). The confirmational changes in BSA molecule’s structure by glycating substances was investigated using a variety of spectroscopic methods, including deconvolutionFourier Transform Infra-red (FT-IR) spectroscopy, fluorescence spectroscopy, UV spectroscopy and circular dichroism (CD) spectroscopy. Dynamic fluorescence quenching was observed in the case of glucose, while static quenching was observed in the case of methyl glyoxal and glyoxal. Similarly, employing deconvolution FT-IR spectroscopy and CD spectroscopy for determination of change in secondary structures in terms signature of α-helix, β-turn, β-sheet and random coil modifications. Destabilization or unfolding of the albumin structure, due to the disruption of the hydrogen bonding pattern that stabilizes the albumin manifold, causes a 25-50% reduction in α-helix and a 2-fold increase in β-sheet and turns in glycated BSA. The competitive displacement interaction studies with warfarin were performed using the ultrafiltration technique and quantitative determination of free drug in ultrafiltrate using LC-MS/MS. The binding of carbamazepine (CBZ) or its active metabolite to proteins was unaffected by the glycation of BSA with glucose and methyl glyoxal. Nevertheless, with glyoxal-modified BSA, it changed the binding of selected analytes significantly. Based on in vitro observations and results, it could be anticipated that the serum CBZ concentration variation may be worsened in uncontrolled diabetes circumstances, with an overall variance of 30–40% possible. Communicated by Ramaswamy H. Sarma

Berberis vulgaris L. extract supplementation exerts regulatory effects on the lifespan and healthspan of Drosophila through its antioxidant activity depending on the sex.

Worldwide the aging population continues to increase, so the concept of healthy longevity medicine has become increasingly significant in modern society. Berberis vulgaris L. fruits serve as a functional food supplement with a high concentration of bioactive compounds, which offer numerous health-promoting benefits. The goal of this study was to investigate the geroprotective effect of Berberis vulgaris L. extract. Here we show that extract of Berberis vulgaris L. can, depending on concentrate, increases lifespan up to 6%, promote healthspan (stress resistance up to 35%, locomotor activity up to 25%, integrity of the intestinal barrier up to 12%, metabolic rate up to 5%) of Drosophila melanogaster (in vitro) and exhibits antioxidant (using red blood cell tests) and antiglycation activity (using glycation of bovine serum albumin) (in vitro). In addition to this, the extract does not exhibit cytotoxic properties in vitro, unlike the well-known polyphenolic compound quercetin. qRT-PCR has revealed the involvement of metabolic, heat shock response and lipid metabolism genes in the observed effects.

Attenuation of protein glycation by phenolic compounds of Salvia subg. Perovskia: Insights from experimental and computational studies

Despite the fact that most of the studied activities of plant phenolic compounds rely on their antioxidant properties, few clues about their antiglycation activity are available. Therefore, the aim of this study was to investigate the potential of phenolic compounds to suppress the formation of advanced glycation end products (AGEs) in the leaf and root system of two Salvia subg. perovskia species. The study evaluated the antiglycation activity of the plant species and the main polyphenolic profiles in the bovine serum albumin (BSA)/methylglyoxal (MGO) system. High-performance liquid chromatography (HPLC) analysis also revealed the presence of rosmarinic acid, gallic acid, p-coumaric acid, caffeic acid, quercetin, chlorogenic acid, ferulic acid and rutin. The study found that rosmarinic acid and rutin were the major phenolic compounds in both species. The leaf crude extracts possessed a higher inhibitory effect against BSA glycation than from other parts. The study concluded that rutin can successfully interact with the key residues of Asp108, His145, Tyr147, Arg196, and Arg458. The results of the study can provide new insights into the development of effective molecules for the treatment of conformational protein diseases.

Glycated bovine serum albumin for use in feeding trials with animal models - In vitro methodology and characterization of a glycated substrate for modifying feed pellets.

This study investigated different methods to produce Nε-carboxymethyl-lysine (CML)-enriched bovine serum albumin (BSA) as alternatives to the classical approach using glyoxylic acid (GA) and sodium cyanoborohydride (NaBH3CN) which results in toxic hydrogen cyanide (HCN). The reaction of GA (6mmol/L) and NaBH3CN (21mmol/L) to produce CML remained the most effective with CML yields of 24-35%, followed by 13-24% using 300mmol/L glyoxal (GO). GA promoted specific modification of lysine to CML, and fewer structural modifications of the BSA molecule compared with GO, as evidenced by fluorescence and proteomic analyses. GO promoted greater arginine modification compared with GA (76 vs 23%). Despite structural changes to BSA with GO, murine fecal clearance of CML was similar to literature values. Hence, BSA glycation with 300mmol/L glyoxal is a suitable alternative to GA and NaBH3CN for generating CML-enriched protein free of HCN, but a CML-only fortification model remains to be described.

Experimental and hypothetical appraisal on inhibition of glucose-induced glycation of bovine serum albumin by quercetin

BackgroundThe specificity of protein functions depends on its folding ability into a functional structure. Protein folding is an essential systemic phenomenon that prevents incorrect folding which could result in harmful aggregation. This harmful aggregation of proteins causes neurodegenerative diseases and systemic amyloidosis. Experimental and theoretical approaches were used in this study to explicate the probable mechanisms of action of quercetin in inhibition of glucose-induced glycation through estimations of percentage glycated protein, inhibited induced protein aggregation, and unoxidized bovine serum albumin thiol groups and assessments of molecular interactions of quercetin with the structures of bovine serum albumin, amyloid beta-peptide (1–42) and 3D amyloid-beta (1–42) fibrils retrieved from the protein databank (http://www.rcsb.org). ResultsThe results showed quercetin inhibited the formation of glycated protein, protein aggregation, and thiol oxidation in a concentration-dependent manner where 200 μg/ml showed the highest inhibition while 50 μg/ml depicted the least inhibition in all the studied assessments. From the docking analysis, it was observed that quercetin had a significantly higher binding affinities − 8.67 ± 0.09 kcal/mol, − 5.37 ± 0.05 kcal/mol and − 5.93 ± 0.13 kcal/mol for the bovine serum albumin, amyloid beta-peptide (1–42) and 3D amyloid-beta (1–42) fibrils respectively compared to the glucose, the inducer. Quercetin and glucose interacted with amino acid residues at the BSA subdomain IIA thus providing a clue that quercetin may impose its inhibition through the binding domain. Also, it is important to mention that the phytochemicals shared a similar interaction profile as that of glucose with the amyloid-beta. ConclusionsThese findings established the beneficial effects of quercetin as a potential agent that could alleviate hyperglycaemic-initiated disorders associated with elevated serum glucose levels.

THE INHIBITORY EFFECT OF SILYBUM MARIANUM (MILK THISTLE) SEEDS EXTRACT ON SERUM ALBUMIN GLYCATION BY GLUCOSE, FRUCTOSE AND GALACTOSE

Protein glycation consists of the non-enzymatic attachment of monosaccharides to proteins. This leads to the formation of advanced glycation end products (AGEs) that are held responsible for diabetes complications. There are some drugs that inhibit AGEs, but their usage is limited by side effects. Plant-based therapeutic strategies could be useful in overcoming this limitation. Silybum marianum (Milk thistle), a plant used to treat liver problems, was also proved useful in the treatment of type 2 diabetes. Here we investigated the ability of S. marianum extract to inhibit the in vitro glycation of bovine serum albumin (BSA) by three physiologically relevant monosaccharides, namely glucose, fructose and galactose. BSA was glycated in the absence and in the presence of 0.1 %, 1 % and 5 % S. marianum seeds hydroalcoholic extract. Measurements on fructosamine, AGEs and amyloid cross-β structures formation showed that the plant extract inhibited these processes in the case of the three monosaccharides, especially in the case of glucose and galactose. The inhibition was dose- dependent and time-dependent. Our results demonstrate the ability of the plant extract to inhibit the in vitro glycation of BSA.

Antioxidant and Anti-Glycation Potential of H2 Receptor Antagonists-In Vitro Studies and a Systematic Literature Review.

Background: Histamine H2 receptor antagonists are a group of drugs that inhibit gastric juice secretion in gastrointestinal diseases. However, there is evidence to suggest that H2 blockers have a broader spectrum of activity. The antioxidant properties of H2 blockers have not been fully elucidated, and their anti-glycation potential has not been studied to date. Therefore, this is the first study to compare the antioxidant and antiglycation potentials of the most popular H2 antagonists (ranitidine, cimetidine, and famotidine) on protein glycoxidation in vitro. Methods: Bovine serum albumin (BSA) was glycated using sugars (glucose, fructose, galactose, and ribose) as well as aldehydes (glyoxal and methylglyoxal). Results: In the analyzed group of drugs, ranitidine was the only H2 blocker that significantly inhibited BSA glycation in all tested models. The contents of protein carbonyls, protein glycoxidation products (↓dityrosine, ↓N-formylkynurenine), and early (↓Amadori products) and late-stage (↓AGEs) protein glycation products decreased in samples of glycated BSA with the addition of ranitidine relative to BSA with the addition of the glycating agents. The anti-glycation potential of ranitidine was comparable to those of aminoguanidine and Trolox. In the molecular docking analysis, ranitidine was characterized by the lowest binding energy for BSA sites and could compete with protein amino groups for the addition of carbonyl groups. H2 blockers also scavenge free radicals. The strongest antioxidant properties are found in ranitidine, which additionally has the ability to bind transition metal ions. The systematic literature review also revealed that the anti-glycation effects of ranitidine could be attributed to its antioxidant properties. Conclusions: Ranitidine showed anti-glycation and antioxidant properties. Further research is needed, particularly in patients with diseases that promote protein glycation.

In vitro Antiglycation Activity of Isorhamnetin on Bovine Serum Albumin with different sugars using Sodium Dodecyl Sulphate Polyacrylamide Gel Electrophoresis

Advanced glycation end products (AGEs) resulting from glycation of proteins, lipids and nucleic acids has several pathophysiological manifestations by altering the structure and functions of molecular proteins. Isorhamnetin is a flavonoid with anti-inflammatory, anti-oxidant, anti-obesity, anticancer, antidiabetic and anti-atherosclerosis activity. Based on the structure activity relationship and our insilico antiglycation study of isorhamnetin, we hypothised that isorhamnetin may have antiglycation activity by inhibiting protein glycation on sugar molecules due to its antioxidant and free radical scavenging activity. Hence our aim of the study was to determine the glycation level of bovine serum albumin (BSA) with varying sugar concentration of glucose, fructose and ribose on 14th and 21st day of incubation. Our second objective of the study was to determine the antiglycation activity of isorhamnetin on BSA using all the sugars at 14th and 21st day of incubation using SDS - PAGE. Our study showed that increase in concentration of glucose, fructose and ribose (0 – 50mM) showed a dose dependent decrease in migration of protein implying increased glycation of BSA. Isorhamnetin (100µM) exhibited antiglycation activity for fructose (30mM) at 14th day onwards and for glucose (30mM) was at 21st day onwards. But isorhamnetin did not exert antiglycation activity for ribose (30mM) on both 14th and 21st day of incubation. Our study establishes the antiglycation activity of isorhamnetin however further invivo studies are necessary to warrant this activity.

Antiglycation and antioxidant activity of herbal medicines used in the treatment of climacteric symptoms

ObjectivesThis work had the objective to evaluate the antiglycation and antioxidant potential of Cimicifuga racemosa L., Trifolium pratense L., Humulus lupulus L. and Morus nigra L., commonly used in traditional medicine for the treatment of climacteric symptoms. MethodsAntioxidant activity was evaluated by 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging, ferric reducing antioxidant power, inhibition of lipid peroxidation thiobarbituric acid reactive substances (TBARS), nitric oxide (NO) radical scavenging and inhibition of oxidative haemolysis test. The evaluation of antiglycation activity was performed by the determination of relative electrophoretic mobility of bovine serum albumin (BSA) with ribose and BSA with methylglyoxa in the presence and absence of Cu2+ ion. Total polyphenol and flavonoid contents were determined by spectrophotometric methods. ResultsThe highest antioxidant activity for DPPH and ferric reducing antioxidant power test was detected in Humulus lupulus (83.56% and 46.95 µM TE/g dry extract, respectively). For the inhibition of lipid peroxidation, the lowest percentages of TBARS were found in M. nigra (4.82%) and H. lupulus (18.26%). C. racemosa presented the lowest nitrite formation (34.57 µmol/mL nitrite formed) in nitric oxide test. T. pratense presented the highest polyphenol (24.61 mg GAE/g dry extract) and flavonoid (22.79 mg RE/g dry extract) contents. For the oxidative haemolysis assay, the extracts showed concentration-dependent inhibitory capacity, while for the antiglycation activity all extracts showed antiglycation potential against glycation of BSA promoted by Ribose evaluated by the electrophoretic profile. ConclusionsIn view of the results obtained in this study, it was possible to verify that the dry extracts of herbal medicines used for climacteric symptoms present antioxidant and antiglycation activities, mainly due to the presence of phenols compounds in their composition.

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.

Influence of Nitrosyl Iron Complex with Thiosulfate Ligands on Therapeutically Important Targets Related to Type 2 Diabetes Mellitus.

The high prevalence of type 2 diabetes mellitus (T2DM), and the lack of effective therapy, determine the need for new treatment options. The present study is focused on the NO-donors drug class as effective antidiabetic agents. Since numerous biological systems are involved in the pathogenesis and progression of T2DM, the most promising approach to the development of effective drugs for the treatment of T2DM is the search for pharmacologically active compounds that are selective for a number of therapeutic targets for T2DM and its complications: oxidative stress, non-enzymatic protein glycation, polyol pathway. The nitrosyl iron complex with thiosulfate ligands was studied in this work. Binuclear iron nitrosyl complexes are synthetic analogues of [2Fe-2S] centers in the regulatory protein natural reservoirs of NO. Due to their ability to release NO without additional activation under physiological conditions, these compounds are of considerable interest for the development of potential drugs. The present study explores the effects of tetranitrosyl iron complex with thiosulfate ligands (TNIC-ThS) on T2DM and its complications regarding therapeutic targets in vitro, as well as its ability to bind liposomal membrane, inhibit lipid peroxidation (LPO), and non-enzymatic glycation of bovine serum albumin (BSA), as well as aldose reductase, the enzyme that catalyzes the reduction in glucose to sorbitol in the polyol pathway. Using the fluorescent probe method, it has been shown that TNIC-ThS molecules interact with both hydrophilic and hydrophobic regions of model membranes. TNIC-ThS inhibits lipid peroxidation, exhibiting antiradical activity due to releasing NO (IC50 = 21.5 ± 3.7 µM). TNIC-ThS was found to show non-competitive inhibition of aldose reductase with Ki value of 5.25 × 10-4 M. In addition, TNIC-ThS was shown to be an effective inhibitor of the process of non-enzymatic protein glycation in vitro (IC50 = 47.4 ± 7.6 µM). Thus, TNIC-ThS may be considered to contribute significantly to the treatment of T2DM and diabetic complications.

Glycation Inhibition of Bovine Serum Albumin by Extracts of Momordica charantia L. using Spectroscopic and Computational Methods.

Momordica charantia (M. charantia) has been used in traditional medicine for the management of complications associated with diabetes mellitus. Several phytochemicals with different pharmacological properties have been previously identified from the botanical; however, the mechanisms of actions of this plant vis-à-vis inhibition of non-enzymatic protein glycation are not known. This study aimed at understanding the putative mechanisms underlying the antiglycation properties of M. charantia extracts experimental and theoretical approaches. The antiglycation properties of the plant were evaluated by studying the inhibitory actions of methanol and aqueous extracts on glucose-induced glycation of Bovine Serum Albumin (BSA) and protein aggregation. The mode of binding of identified phenolics of the botanical with BSA, amyloid beta-peptide (1-42) and 3D amyloid beta (1-42) fibrils were also investigated. The in vitro experimental properties of the extracts showed that the extracts could prevent inductions of protein glycation and protein folding. The molecular docking analyses revealed that phenolics had better binding affinities with chlorogenic acid showing the highest binding score (-7.13±0.04 kcal/mol) towards BSA than glucose and their respective interactions with BSA could prevent glucose-induced protein aggregation. Consequently, the results of this study provide insight into the probable mechanisms of actions of the extracts of M. charantia against the inhibition of advanced glycation end products formation.

Effect of macromolecular crowding on the inhibition of non-enzymatic glycation of bovine serum albumin by cichoric acid

The inside of the cell is closely filled with diverse biological macromolecules, which will affect various physiological activities in vivo. It is known that natural products have beneficial effects against the formation of advanced glycation end products (AGEs), but their inhibitory actions in macromolecular crowding environment are still poorly understood. Therefore, to investigate the influence of macromolecular crowding environment, the inhibitory effect of cichoric acid (CA) on the non-enzymatic glycation of bovine serum albumin (BSA) in the absence and presence of crowding reagents (PEG 2000 and PEG 4000) was studied. The results demonstrated that CA could significantly inhibit the formation of AGEs than aminoguanidine in the BSA-fructose model with or without PEG, and the inhibition effect in PBS solution was better than that in macromolecular crowding environment. Moreover, CA presented strong antioxidant capacity and trapping ability of glyoxal, and could stabilize the native structure of BSA caused by the glycation modification, which might be the primary mechanisms for its anti-glycation effect. Additionally, CA tended to bind to site I of BSA mainly through hydrogen bonds and hydrophobic interactions. These findings indicated that CA could be regarded as a high potential anti-glycation inhibitor to prevent the development of diabetic complications.

Luteolin and Vernodalol as Bioactive Compounds of Leaf and Root Vernonia amygdalina Extracts: Effects on α-Glucosidase, Glycation, ROS, Cell Viability, and In Silico ADMET Parameters.

The aqueous decoctions of Vernonia amygdalina (VA) leaves and roots are widely used in traditional African medicine as an antidiabetic remedy. The amount of luteolin and vernodalol in leaf and root extracts was detected, and their role was studied regarding α-glucosidase activity, bovine serum albumin glycation (BSA), reactive oxygen species (ROS) formation, and cell viability, together with in silico absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties. Vernodalol did not affect α-glucosidase activity, whereas luteolin did. Furthermore, luteolin inhibited the formation of advanced glycation end products (AGEs) in a concentration-dependent manner, whereas vernodalol did not reduce it. Additionally, luteolin exhibited high antiradical activity, while vernodalol demonstrated a lower scavenger effect, although similar to that of ascorbic acid. Both luteolin and vernodalol inhibited HT-29 cell viability, showing a half-maximum inhibitory concentration (IC50) of 22.2 µM (-Log IC50 = 4.65 ± 0.05) and 5.7 µM (-Log IC50 = 5.24 ± 0.16), respectively. Finally, an in silico ADMET study showed that both compounds are suitable candidates as drugs, with appropriate pharmacokinetics. This research underlines for the first time the greater presence of vernodalol in VA roots compared to leaves, while luteolin is prevalent in the latter, suggesting that the former could be used as a natural source of vernodalol. Consequently, root extracts could be proposed for vernodalol-dependent antiproliferative activity, while leaf extracts could be suggested for luteolin-dependent effects, such as antioxidant and antidiabetic effects.

Antiglycation and chemopreventive effects of leaf extracts of Ficus palmata Forssk. found in the Hail region of Saudi Arabia

ABSTRACT The antioxidant and antiglycation activities of the Ficus leaf extracts were evaluated using in vitro assays. The antioxidant activity was determined using the α, α-diphenyl-β-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assays. In vitro ferric reducing activity was evaluated using the ferric reducing antioxidant power assay. The antiglycation potential of the extract was evaluated using dinitrophenylhydrazine, thiobarbituric acid and protein thiol assays. The inhibition of the formation of advanced glycation end products (AGEs) was detected using AGE-specific fluorescence with a fluorescence spectrophotometer. This study was aimed at investigating the potential of Ficus palmata Forssk. leaf extracts, which have abundant bioactive constituents, including polyphenols and flavonoids, in inhibiting glycation and cancer. The results show that the aqueous and methanolic Ficus leaf extracts are rich in phenolic and flavonoid compounds. Both extracts showed potent antioxidant activities. Furthermore, the methanolic extract showed antiglycation activities, as assessed using an in vitro model of bovine serum albumin glycation with D-ribose. The polyphenol- and flavonoid-rich Ficus leaf extracts exhibit antiglycation, chemopreventive and antioxidant activities and have potential for use in the treatment of diseases, such as cancer, which involve oxidative and glycative impairment of cellular proteins.

Ethanol Extract of Passiflora cincinnata Seeds Posses Antidiabetic, Antiglycant, and Antioxidant Activities in vitro

This work aimed to investigate the antidiabetic, antiglycation, and antioxidant potentials of the ethanol extract of seeds of Passiflora cincinnata (EPCIN) in vitro. The EPCIN was evaluated from the following assays: total phenolic content (TPC – mg of Gallic Acid Equivalents (GAE)/g of dry extract), Radical Scavenging Assays (DPPH•, HOCl-scavenging assay), and protective effects against glycation of bovine serum albumin (BSA) with methylglyoxal (MGO) or a mixture of reducing sugars, fructose and glucose, as well as the potential for MGO capture by derivatization with ortho-phenylenediamine (OPD). To evaluate the antidiabetic activity of EPCIN in vitro, we used the assays of enzymes α-amylase (4 U/mL), α-glucosidase (0.25 U/mL), and dipeptidyl peptidase-4 (DPP-4 – 3.125 mU). The cell viability of EPCIN-pretreated normal human bronchial epithelial cells (BEAS-2B) alone or in the presence of the carcinogen 4-[(acetoxymethyl)nitrosamine]-1-(3-pyridyl)-1-butanone (NNKOAc) was measured using MTS assay. Quercetin (QCT), piceatannol (PIC), acarbose (ACB), and sitagliptin (STG) were used for comparison purposes. EPCIN had an average of TPC 157.0 ± 1.5 mg of GAE/g of dry extract, exhibited IC50 for DPPH• and HOCl of 11.9 ± 1.8 μg/mL and 6.9 ± 0.9 μg/mL, respectively. EPCIN and AMG inhibited the formation of advanced glycation end-products (AGE) with IC50 of 574 ± 8.7 and 31.9 ± 2.7 μg/mL for the initial stage and 542.6 ± 2.7 and 52.8 ± 8.1 μg/mL for the intermediate stage of glycation, respectively. EPCIN showed IC50 for α-amylase and α-glucosidase of 218.2 ± 15.9 μg/mL (p<0,05) and 242.0 ± 25 μg/mL (p<0,05), respectively. EPCIN did not show cytotoxicity for BEAS-2B cells at 10 and 50 μg/mL concentrations. In addition, it was also able to protect cultured human cells from oxidative stress caused by the NNKOAc at 100 μM. The in vitro evidence of the potential antioxidant, antiglycant, and antidiabetic effects warrants further investigation of the antidiabetic potential of Passiflora cincinnata seeds.