Protein–phenolic interactions and inhibition of glycation – combining a systematic review and experimental models for enhanced physiological relevance

Background: While antiglycative capacity has been attributed to (poly)phenols, the exact mechanism of action remains unclear. Studies so far are often relying on supra-physiological concentrations and use of non-bioavailable compounds.<p></p> Methods: To inform the design of a physiologically relevant in-vitro study, we carried out a systematic literature review of dietary interventions reporting plasma concentrations polyphenol metabolites. Bovine Serum Albumin (BSA) was pre-treated prior to in vitro glycation: either no treatment (native), pre-oxidised (incubated with 10nM H2O2, for 8 hours) or incubated with a mixture of phenolic acids at physiologically relevant concentrations, for 8 hours). In-vitro glycation was carried out in presence of i) glucose only (0, 5 or 10mM), ii) glucose (0, 5 or 10mM) plus H2O2 (10nM), or iii) glucose (0, 5 or 10mM) plus phenolic acids (10-160nM). Fructosamine was measured using the nitroblue tetrazolium method.<p></p> Results: Following (high) dietary polyphenol intake, 3-hydroxyphenylacetic acid is the most abundant phenolic acid in peripheral blood (up to 338μM) with concentrations for other phenolic acids ranging from 13nM-200μM. Presence of six phenolic acids with BSA during in-vitro glycation did not lower fructosamine formation. However, when BSA was pre-incubated with phenolic acids, significantly lower concentration of fructosamine was detected under glycoxidative conditions (glucose 5 or 10mM plus H2O2 10nM) (p<0.001 vs. native BSA).<p></p> Conclusion: Protein pre-treatment, either with oxidants or phenolic acids, is an important regulator of subsequent glycation in a physiologically relevant system. High quality in-vitro studies under conditions closer to physiology are feasible and should be employed more frequently.<p></p&gt

Aktivitas Nitrogenase Bintil Akar Dan Kadar Klorofil Daun Kacang Hijau {Phaseolus Radiatus L.) Pada Berbagai Jenis Dan Kadar as Am Fenol at [Nitrogenases Activities in Nodules and Cholorophyll Content of Mungbean {Phaseolus Radiatus L.) on Various Phenolic Acids Concentration]

Phenolic acids are one of the many secondary metabolites causing toxic upon the growth and development of plant. Phenolic acids are produced by plant and subsequently released into soil, and appears to be involved in biochemical interaction between plants and other living organisms in soil. The research was conducted to study the effect of various kinds and doses of phenolic acids on nitrogenases activities and cholorophyll content of mungbean. Research was done in the glass house of Soil Science Departemen, Faculty of Agriculture, Gadjah Mada University (GMU) from April to June 2004. The experiment was arranged by randomized block design in three replications. The treatment consist of four kinds phenolic acid i.e. vanilic, p-coumaric, ferulic and p-1hydroxybenzoic with concentration at 250, 500, 1000 and 1500 mg kg-Â respectively. One treatment was without phenolic acids as control. Result indicated that phenolic acids could reduce nitrogenases activities and chlorophyll content up to 53.35% and 29.98% respectively. The toxicity of p-hydroxybenzoic against both nitrogenases activities and chlorophyll content was higher than other phenolic acids

Composition and content of phenolic acids and avenanthramides in commercial oat products: are oats an important polyphenol source for consumers?

Oats contain a range of phenolic acids and avenanthramides which may have health benefits. Analysis of 22 commercial oat products (oat bran concentrate, oat bran, flaked oats, rolled oats and oatcakes) using HPLC-DAD detected eleven bound and thirteen free + conjugated phenolic acids and avenanthramides. The oat products (excluding concentrate) provided between 15.79 and 25.05 mg total phenolic acids (9.9–19.33 mg bound, 4.96–5.72 mg free + conjugated) and between 1.1 and 2 mg of avenanthramides in a 40 g portion while an 11 g portion of oat concentrate provided 16.7 mg of total phenolic acids (15.17 mg bound, 1.53 mg free + conjugated) and 1.2 mg of avenanthramides. The compositions and concentrations of the components in the different products were broadly similar, with the major component being ferulic acid (58–78.1%). The results show that commercial oat products are a source of phenolic acids and avenanthramides for consumers

The influence of L-phenylalanine, methyl jasmonate and sucrose concentration on the accumulation of phenolic acids in Exacum affine Balf. f. ex Regel shoot culture

Phenolic acids are an important group of plant secondary metabolites with various, valuable therapeutic properties. Apart from plants growing in the open air, tissue cultures can be an alternative source of the secondary metabolites. The yield of their accumulation in in vitro cultures can be increased by different methods, including culture medium supplementation with precursors, elicitors and changing the standard amounts of the medium components. The purpose of this study was to investigate the influence of the precursor (L-phenylalanine), the elicitor (methyl jasmonate) and a higher sucrose concentration on the phenolic acids accumulation in the agitated shoot cultures of Exacum affine Balf. f. ex Regel (Gentianaceae). Qualitative and quantitative analyses of the phenolic acids in methanolic extracts from the biomass were conducted by applying the HPLC method. Fourteen phenolic acids and cinnamic acid were found in all samples. The total content of free phenolic acids increased from approximately 0.242% to 0.635% (2.6-fold) and the total content of the whole phenolic acids (free and bound) - from 0.712% to 1.160% (1.6-fold). The studies show that the best variant for the accumulation of most of the identified phenolic acids contained 6% of sucrose (double the standard amount), L-phenylalanine 1.6 gL-1 of medium and methyl jasmonate 100 μM. The analysis of the results in the experiment presented here showed that it is possible to increase the accumulation of the phenolic acids in Exacum affine shoot cultures - by adding the precursor (L-phenylalanine), the elicitor (methyl jasmonate) and by increasing the sucrose concentration

Hplc analysis of phenolic acids in mountain germander (Teucrium montanum L) extracts

The methanol, petroleum ether, chloroform, ethyl acetate, 1-butanol and water extracts were obtained by extraction of mountain germander (Teucrium montanum L). The total phenolic content in extracts was measured by Folin-Ciocalteu method. The 1-butanol extract had the highest phenolic content (296.00 mg/g). High performance liquid chromatography (HPLC) was employed to define qualitative and quantitative content of phenolic acids in mountain germander extracts. The largest number of phenolic acids were determined in ethyl acetate and 1-butanol extracts, while these acids were not present in petroleum ether extract. The highest content of phenolic acids (28.619 mg/g) had ethyl acetate extract and gentisic acid (14.432 mg/g) was its major component. Despite of a large number of phenolic acids in 1-butanol extract their content was only 3.740 mg/g

Cell membrane damage induced by phenolic acids on wine lactic acid bacteria

The aim of this work was to investigate the effect of phenolic acids on cell membrane permeability of lactic acid bacteria from wine. Several phenolic acids were tested for their effects on the cell membrane of Oenococcus oeni and Lactobacillus hilgardii by measuring potassium and phosphate efflux, proton influx and by assessing culture viability employing a fluorescence technique based on membrane integrity. The experimental results indicate that hydroxycinnamic acids (p-coumaric, caffeic and ferulic acids) induce greater ion leakages and higher proton influx than hydroxybenzoic acids (p-hydroxibenzoic, protocatechuic, gallic, vanillic, and syringic acids). Among the hydroxycinnamic acids, p-coumaric acid showed the strongest effect. Moreover, the exposure of cells to phenolic acids caused a significant decrease in cell culture viability, as measured by the fluorescence assay, in both tested strains. The results agree with previous results obtained in growth experiments with the same strains. Generally, phenolic acids increased the cell membrane permeability in lactic acid bacteria from wine. The different effects of phenolic acids on membrane permeability could be related to differences in their structure and lipophilic character

Response of organically and conventionally produced potatoes to a controlled attack of a pathogen

Organic agricultural products have increasing share of the food market in Europe. The questions related to benefits of organic versus conventionally produced agricultural crops are of increasing meaning. In our paper we have focused on assessment of the reaction of the immunity system of potato tubers from both agricultural systems on an external controlled attack of Phytophthora infestans, a pathogenic microorganism. The reaction of organic and conventional potato tubers was expressed via determination of chlorogenic acid. The content of chlorogenic acid in organic potato tubers increased 1.3 times after an attack, compared to potato tubers without a microbial attack. In conventional potato tubers, the increase was 4 times higher in the same way of comparison. The observed increase in conventional tubers is an evident exaggerated protection reaction to the attack of a natural potato pathogen. It is evident that there is a difference between the reaction of the immunity system of organic versus conventional potato tubers � phytoallergy

Određivanje količine flavonoida i fenolnih kiselina u pet vrsta roda Teucrium L.

The content of flavonoids and phenolic acids in the aerial parts of five Teucrium species (T. botrys, T. chamaedrys, T. halacsyanum, T. hyrcanicum and T. scorodonia) was determined using spectrophotometric methods. Results of quantitative analysis showed significant differences in the quantities of studied compounds. The content of flavonoids ranged from 0.12 to 0.28 %, while the quantity of phenolic acids varied between 1.19 and 9.60 %. Variations in the content of flavonoids and phenolic acids were confirmed using statistical analysis. The content of investigated compounds depended on the plant species and year of collection

The urinary phenolic acid profile varies between younger and older adults after a polyphenol-rich meal despite limited differences in in vitro colonic catabolism

Purpose: To investigate whether age influences colonic polyphenol metabolism. Methods: Healthy participants, younger (n = 8; 23–43 years) and older (n = 13; 51–76 years), followed a 3-day low-polyphenol diet (LPD) and a 3-day high-polyphenol diet (HPD). Urinary phenolic acids (PA), short chain fatty acids (SCFA), pH and gas were monitored, alongside selected colonic bacteria. Human faecal in vitro fermentations of rutin with or without raftiline were used to evaluate the gut microbiota capacity in a subset of both groups. Results: Total urinary PA were higher in the older group after HPD compared to the younger group (1.5-fold; p = 0.04), with no difference between groups in terms of a change between diets (Δ high-low diet). While 17 PA were detected in all younger participants after HPD, a narrower range (n = 8 to 16 PA) was detected in most (n = 9/13) older participants, with lower level of benzoic acid (19-fold; p = 0.03), vanillic acid (4.5-fold; p = 0.04) but higher hippuric acid (2.7-fold; p = 0.03). Faecal SCFA concentration did not change after HPD within group, with similar differential excretion (Δ high-low diet) between groups. There were no differences between groups for faecal pH, total, faecal bacteria including Flavonifractor plautii, bifidobacteria, and bacteroides. In human in vitro faecal fermentations, seven PAs were detected in both groups after 24 h of rutin fermentation, with no quantitative and modest qualitative differences between groups. Total SCFA in faecal fermentation did not differ between groups, except for butyric acid (twofold higher in the older group; p = 0.009) when rutin was fermented with raftiline over 24 h. Conclusions: Urinary phenolic acids were less diverse in older participants despite limited difference in functional capacity of in vitro faecal fermentations

Rapid and comprehensive evaluation of (poly)phenolic compounds in pomegranate (punica granatum L.) juice by UHPLC-MSn

The comprehensive identification of phenolic compounds in food and beverages is a crucial starting point for assessing their biological, nutritional, and technological properties. Pomegranate (Punica granatum L.) has been described as a rich source of (poly)phenolic components, with a broad array of different structures (phenolic acids, flavonoids, and hydrolyzable tannins) and a quick, high throughput, and accurate screening of its complete profile is still lacking. In the present work, a method for UHPLC separation and linear ion trap mass spectrometric (MSn) characterization of pomegranate juice phenolic fraction was optimized by comparing several different analytical conditions. The best solutions for phenolic acids, anthocyanins, flavonoids, and ellagitannins have been delineated and more than 70 compounds have been identified and fully characterized in less than one hour total analysis time. Twenty-one compounds were tentatively detected for the first time in pomegranate juice. The proposed fingerprinting approach could be easily translated to other plant derived food extracts and beverages containing a wide array of phytochemical compounds