2-2--azino-di-(3-ethylbenzothiazoline)-6-sulfonic-acid and kaempferol

Phenolamines and flavonoids are two important components in bee pollen. There are many reports on the bioactivity of flavonoids in bee pollen, but few on phenolamines. This study aims to separate and characterize the flavonoids and phenolamines from rape bee pollen, and compare their antioxidant activities and protective effects against oxidative stress. The rape bee pollen was separated to obtain 35% and 50% fractions, which were characterized by HPLC-ESI-QTOF-MS/MS. The results showed that the compounds in 35% fraction were quercetin and kaempferol glycosides, while the compounds in 50% fraction were phenolamines, including di-p-coumaroyl spermidine, p-coumaroyl caffeoyl hydroxyferuloyl spermine, di-p-coumaroyl hydroxyferuloyl spermine, and tri-p-coumaroyl spermidine. The antioxidant activities of phenolamines and flavonoids were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS), and ferric reducing antioxidant power (FRAP) assays. It was found that the antioxidant activity of phenolamines was significantly higher than that of flavonoids. Moreover, phenolamines showed better protective effects than flavonoids on HepG2 cells injured by AAPH. Furthermore, phenolamines could significantly reduce the reactive oxygen species (ROS), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, and increase the superoxide dismutase (SOD) and glutathione (GSH) levels. This study lays a foundation for the further understanding of phenolamines in rape bee pollen.

Topics: Alanine Transaminase; Amidines; Animals; Antioxidants; Aspartate Aminotransferases; Bees; Benzothiazoles; Biphenyl Compounds; Gene Expression; Glutathione; Glycosides; Hep G2 Cells; Humans; Kaempferols; Oxidants; Oxidative Stress; Picrates; Plant Extracts; Pollen; Quercetin; Reactive Oxygen Species; Spermidine; Spermine; Sulfonic Acids; Superoxide Dismutase

Blueberries (Vaccinium spp.) have great beneficial effects, and their leaves are rich in phenolics. In the present study, the total phenolic, total flavonoid, and proanthocyanidin contents in the leaf extracts from 73 different blueberry cultivars among five categories were investigated. The phenolic composition was analyzed, and the antioxidants were also evaluated. Here, a total of 23 individual phenolic constituents were identified, among which eight predominant phenolics were quantified, including five caffeoylquinic acids, two quercetin glycosides, and one kaempferol glycoside. The different cultivars could be well clustered according to their phenolic compositions and antioxidant capacities. The correlations among the quantified phenolic constituents and the antioxidant capacities were determined using principal component analysis. The results indicated that blueberry leaves may be a potential resource of antioxidant phenolics, and the differences among the cultivars should be considered when blueberry leaves are further developed.

Topics: Antioxidants; Benzothiazoles; Blueberry Plants; China; Chromatography, High Pressure Liquid; Dietary Supplements; Flavonoids; Glycosides; Kaempferols; Phenols; Plant Extracts; Plant Leaves; Proanthocyanidins; Quercetin; Sulfonic Acids

Irvingia gabonensis stem bark is a medicinal plant used in most parts of Africa to manage a number of ailments including neurodegenerative diseases that occur without scientific basis. This work characterized the phenolic composition, evaluated the cholinergic enzymes (acetylcholinesterase, AChE and butyrylcholinesterase, BChE) inhibition, and assessed the antioxidant activity of phenolic extracts from I. gabonensis (Aubry-Lecomte ex O'Rorke) Baill bark.. Total phenol and flavonoids content was evaluated in addition to antioxidant activity as shown by Fe2+ chelation, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability, and 2,2-azino-bis-(3-ethylbenthiazoline-6-sulfonic acid) (ABTS) radical scavenging ability. Inhibitory activities on AChE and BChE were evaluated.. The extract was found to be rich in phenolic acid (ellagic acid) and flavonoids (quercetrin, kaempferol, and apigenin). The phenolic extracts displayed DPPH radical scavenging ability (IC50=19.98 μg/mL), ABTS radical scavenging ability (IC50=18.25 μg/mL), iron chelation (IC50=113.10 μg/mL), and reducing power (Fe3+ to Fe2+) (5.94 mg ascorbic acid equivalent/100 g). Extracts of I. gabonensis inhibited AChE (IC50=32.90 μg/mL) and BChE (IC50=41.50 μg/mL) activities in concentration-dependent manner.. Hence, possible mechanism through which the stem bark executes their anti-Alzheimer's disease activity might be by inhibiting cholinesterase activities in addition to suppressing oxidative-stress-induced neurodegeneration.

Topics: Acetylcholinesterase; Antioxidants; Apigenin; Benzothiazoles; Biphenyl Compounds; Butyrylcholinesterase; Cellulose; Cholinesterase Inhibitors; Flavonoids; Free Radical Scavengers; Kaempferols; Phenols; Picrates; Plant Bark; Plant Extracts; Plants, Medicinal; Quercetin; Sulfonic Acids

"Chimarrão" and "tererê" are maté (dried, toasted and milled Ilex paraguariensis leaves and stemlets) beverages widely consumed in South America. This paper describes the application of HPLC-DAD-ESI/MS method for the identification and quantification of caffeoylquinic acids (CQA), flavonol glycosides and purine alkaloids in these beverages. The beverage samples were prepared from commercial lots of maté from Southern Brazil. The caffeoylquinic acids, 4,5-diCQA, 3-CQA, 5-CQA, and 4-CQA were the major compounds, having 238-289, 153-242, 183-263, and 123-188 μg/mL, respectively, for chimarrão and 206-265, 122-218, 164-209, 103-169 μg/mL, respectively, for tererê. Caffeine also had high amounts while glycosides of quercetin and kaempferol were found at much lower levels. The individual antioxidant activity was also determined by an on-line system that measured their ABTS•+ radical scavenging activity, showing that the antioxidant capacity was not proportional to the concentrations of the phenolic compounds. 3-CQA, quercetina-3-O-ramnosylglucoside, and quercetina-3-O-glucoside were the major contributors to the antioxidant capacity, although the quercetin glycosides had concentrations less than 10 times that of 3-CQA.

Topics: Antioxidants; Benzothiazoles; Beverages; Brazil; Caffeine; Chlorogenic Acid; Chromatography, High Pressure Liquid; Flavonols; Ilex paraguariensis; Kaempferols; Mass Spectrometry; Phenols; Plant Extracts; Plant Leaves; Quercetin; Quinic Acid; Sulfonic Acids

Natural flavonoids are secondary phenolic plant metabolites known for their bioactivity as antioxidants. The evaluation of this property is generally done by the estimation of their direct free radical-scavenging activity as hydrogen or electron donating compounds. This paper reviews experimental results available in the literature for a selection of flavonoids and compares them with calculated quantities characteristic of the hydrogen or electron donation. For that purpose, bond dissociation energies, ionization potentials and electron transfer enthalpies are computed by using DFT methods and the ONIOM procedure implemented in the ab initio program Gaussian. This process has been chosen because it can be extended to the study of large molecules. When acid dissociation and interaction with the solvent are taken into account, the results present very good concordance with experimental results, enlightening the complexity of the processes involved in the classical assays which measure the ability of compounds to scavenge the (2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt) radical cation (ABTS (+)) or the 2,2-diphenyl-1-picryl-hydrazyl radical (DPPH(·)). This study demonstrates the good accuracy of theoretical calculations in obtaining the relative energies involved in free radical scavenging abilities and its capacity for predictive behaviour. It also highlights the necessity to take into account the pK(a) of the compounds and the solvent interaction. The ability of the method to calculate the antioxidant properties of larger molecules are tested on glycosylated flavonoids and the effects of sugar substitution on the antioxidant properties of flavonoids are investigated, pointing out the importance of the charges on the oxygen atoms.

Topics: Antioxidants; Apigenin; Benzothiazoles; Biphenyl Compounds; Electrons; Flavonoids; Free Radical Scavengers; Glycosylation; Hydrogen; Hydrolysis; Kaempferols; Models, Chemical; Models, Molecular; Molecular Structure; Oxidation-Reduction; Picrates; Quercetin; Solvents; Structure-Activity Relationship; Sulfonic Acids; Thermodynamics

The antioxidant activity of kaempferol 3-O-β-isorhamninoside (K3O-ir) and rhamnocitrin 3-O-β-isorhamninoside (R3O-ir), isolated from the leaves of Rhamnus alaternus L., was determined by the ability of each compound to inhibit NBT photoreduction and to scavenge the free radical ABTS(+)(.). Genotoxic and antigenotoxic activities were assessed using the SOS chromotest. At a concentration of 150 μg/assay the two compounds showed the most potent inhibitory activity against superoxide anion by respectively 80.4% and 85.6%. K3O-ir was a very potent radical scavenger with an IC(50) value of 18.75 μg/ml. Moreover, these two compounds exhibit an inhibitory activity against genotoxicity induced by nitrofurantoine and aflatoxine B1 using the SOS chromotest bacterial assay system in the presence of Escherichia coli PQ37 strain. In this study, we have also evaluated correlation between antigenotoxic and antioxidant effects of K3O-ir and R3O-ir. The highest correlation was showed with R3O-ir (r=0.999).

Topics: Aflatoxin B1; Analysis of Variance; Antimutagenic Agents; Antioxidants; Benzothiazoles; Drug Evaluation, Preclinical; Escherichia coli; Flavonols; Kaempferols; Mutagens; Nitrofurantoin; Plant Extracts; Plant Leaves; Rhamnus; Sulfonic Acids; Superoxides; Trisaccharides

Free radicals play a crucial role in the pathophysiology of human diseases such as cancer, atherosclerosis, and neurodegenerative diseases, and considerable attention has been focused on functional foods (or nutraceuticals) that are able to decrease the concentrations of free radicals and consequently protect against these diseases. The present study investigated an improved quantitative assay to measure antioxidant activity using the stable and fast-reacting chromogenic indicator [2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)] (ABTS). The ABTS-radical-scavenging activities of various antioxidants and apple extracts were measured in 96-well plates, and plots thereof were linearly interpolated, with the total radical-scavenging capacity quantified as the area under the curve. The first order of linear regression was obtained in a relationship between the absorbance reduction and various concentrations of the tested sample, and the total radical-scavenging capacity was expressed as the vitamin-C-equivalent antioxidant capacity. The advantages of this quantitative assay are that, first, it is fast, sensitive and confers little variation from experimental errors for single or mixed antioxidants; second, a large number of samples in a low quantity at a time can be run using 96-well plates.

Topics: Antioxidants; Ascorbic Acid; Benzothiazoles; Butylated Hydroxyanisole; Chromogenic Compounds; Colorimetry; Food Analysis; Free Radical Scavengers; Humans; Kaempferols; Malus; Plant Extracts; Quercetin; Sulfonic Acids

Polyphenolic compounds usually showed different antioxidant capacities depending on the assay methods used. To determine the possible chemical cause for this assay-dependence, two flavonols, kaempferol and morin, were selected as the model molecules for the comparative investigation between electrochemical and chemical oxidations. The electro-oxidation of the flavonols was studied using cyclic voltammetry and in situ UV-Vis spectroelectrochemical technique with a long-optical-path thin-layer electrolytic cell. The spectral changes recorded in different potentials were compared with those in the chemical oxidation by H(2)O(2) or ABTS(*+) radical in the same thin-layer cell. The 4'-OH group of either sample was first oxidized at lower potentials or induced by H(2)O(2), and in this case kaempferol was somewhat more active than morin. With an additional 2'-OH group, morin underwent the secondary oxidation in moderately higher potentials or by ABTS(*+), showing antioxidant capacity about twice of that of kaempferol. This study clarified that the chemical oxidation of a polyphenolic compound by the oxidants with different reactivities, which corresponded to its electro-oxidation in different anodic peaks, had a difference in number of oxidizable OH-groups, leading to the difference in antioxidant capacity.

Topics: Antioxidants; Benzothiazoles; Electrochemistry; Flavonoids; Hydrogen Peroxide; Kaempferols; Oxidation-Reduction; Spectrophotometry; Sulfonic Acids