The effect of the addition of selected phenolic acids on the rheological properties of heated solutions of whey proteins

This study measured the flow behaviour of whey protein isolate mixtures with cinnamic or ferulic acids. Samples were heated in a vacuum (80 °C, –0.9 atm, 280 r.p.m., 0.5 h). The flow curves of all samples showed a non- Newtonian shear thinning flow and the viscoelastic properties were typical for weak gel systems. At pH 6.0, 6.7, and 8.0, the highest shear stress values were obtained with 20, 40, and 40 mg of cinnamic acid g–1 protein, respectively. At pH 6.0, the use of ferulic acid (20 mg g–1 protein) resulted in the elevation of shear stress values, but at pH 8.0, ferulic acid caused a decrease in shear stress values in comparison to cinnamic acid. The thixotropic area (AT) was increased in mixtures containing 20–40 mg cinnamic acid g–1 protein (at pH 6.7) and 20 mg of cinnamic acid g–1 protein (at pH 6.0). Similarly, the addition of ferulic acid (40 and 20 mg g–1 protein at pH 6.7 and 6.0, respectively) caused a significant increase in AT. At pH 8.0, no significant differences in AT values were observed between samples. Such systems can be applied with reference to health promoting foods such as WPI-based desserts

Anticholinesterase activity of selected phenolic acids and flavonoids – interaction testing in model solutions

[b][/b][b]Introduction[/b]. Alzheimer’s disease is a progressively developing neurodegenerative disorder of the central nervous system. The only present treatment of this disease is the use of acetyl- and butyrylcholinesterase inhibitors. Previously, the neuroprotection of phenolic acids and flavonoids in the brain has been indicated. [b]Materials and method.[/b] This study measured anticholinesterase activities of 9 phenolic acids and 6 flavonoids, singly or in combination. The synergy/antagonism/zero interaction between compounds was evaluated taking into consideration the statistical significance. Ellman’s modified spectrophotometric method was used with the simultaneous measurement of the false-positive effect of compounds. [b]Results[/b]. The anti-acetylcholinesterase activity of phenolic acids was as follows: homogentisic acid > 4-hydroxyphenylpyruvic acid > nordihydroguaiaretic acid > rosmarinic acid > caffeic acid > gallic acid = chlorogenic acid > homovanillic acid > sinapic acid. p-Hydroxyphenylpyruvic, caffeic, chlorogenic, gentisic, homogentisic, nordihydroguaiaretic and rosmarinic acids in pairs exhibited, in most cases, a lower inhibitory activity (at p>0.05), than the sum of the activities of single compounds. Also, phenolic acids in pairs with flavonoids (cyanidin, delphinidin, kaempferol, myricetin, phloridzin, pelargonidin or quercetin) presented, in most cases, a lower inhibitory activity than could be calculated for both compounds singly (at p>0.05). Only in the case of a few samples was the inhibitory activity of two compounds higher than the sum of inhibitions exerted by the same compounds tested singly (either at p>0.05 or p<0.05). The lack of synergy of pairs of inhibitors suggests one small binding site, making impossible to accommodate both inhibitors adjacent to one another

Gentisic Acid, Salicylic Acid, Total Phenolic Content and Cholinesterase Inhibitory Activities of Red Wines Made from Various Grape Varieties

Alzheimer’s disease is characterised by a decrease in acetylcholine (ACh) levels in the brain due to the activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). As a result, disorders in cholinergic transmission are observed, leading to cognitive impairment. In this work, the inhibition of AChE and BChE activities by red wines made of various grape varieties was determined for the first time.  There was no significant difference in the polyphenol content between the grape varieties; nevertheless, there were significant differences in the content of gentisic acid and salicylic acid, and in the inhibition of AChE and BChE between the wine samples. A statistically significant correlation between AChE inhibitory activity and salicylic acid, as well as between BChE inhibitory activity and total phenolic content, was recorded. In model solution studies, it was shown that salicylic acid effectively inhibited BChE activity at concentrations similar to the maximum concentrations found in the test wines. Hierarchical cluster analysis (HCA) revealed that the wines could be divided into three groups. Cabernet Sauvignon and Syrah wines had the highest content of salicylic acid and AChE inhibitory activity, as well as low BChE inhibitory activity. Pinot noir, Tempranillo, Regent and Rondo wines showed the lowest content of salicylic acid and low AChE inhibitory activity. Garnacha tinta, Merlot, Montepulciano and Negroamaro wines had a medium content of salicylic acid, and the highest or medium BChE inhibitory activity. This work is important for both the wine industry and for health protection

Impact of heat treatment and acid gelation on polyphenol enriched milk samples

The effects of heat treatment and the stage of polyphenol addition to milk before or after heat treatment on the total phenolic content (TPC), ferric-ion reducing antioxidant power (FRAP), pH, casein micelle size (CMS) and whey protein denaturation content of milk-polyphenol mixtures were investigated. Four sources of phenolic compounds (green tea, white grape, tannic acid, gallic acid) were incorporated into pasteurized-skim milk. A heat treatment (85 °C for 30 min) was applied to pasteurized-skim milk either before (MhP) or after polyphenols addition (MhPh). Acid milk gels were produced using MhPh samples, and their TPC and FRAP were determined. Heat treatment decreased the TPC and FRAP values of the samples, except for tannic acid, probably due to increased polyphenol-protein interactions. However, MhPh tannic acid sample resulted in significantly higher FRAP value than MhP. The addition of gallic acid before heat treatment (MhPh) significantly increased CMS due to the lower pH of this sample during heating. Acid gelation decreased the extractable polyphenols, however there was no significant different on FRAP between acid gel and MhPh milk samples. This study showed that the properties of phenolic source, particularly pH, and the stage of polyphenol addition to milk had an impact on selected properties

Common and Distant Structural Characteristics of Feruloyl Esterase Families from Aspergillus oryzae

Background: Feruloyl esterases (FAEs) are important biomass degrading accessory enzymes due to their capability of cleaving the ester links between hemicellulose and pectin to aromatic compounds of lignin, thus enhancing the accessibility of plant tissues to cellulolytic and hemicellulolytic enzymes. FAEs have gained increased attention in the area of biocatalytic transformations for the synthesis of value added compounds with medicinal and nutritional applications. Following the increasing attention on these enzymes, a novel descriptor based classification system has been proposed for FAEs resulting into 12 distinct families and pharmacophore models for three FAE sub-families have been developed. Methodology/Principal Findings: The feruloylome of Aspergillus oryzae contains 13 predicted FAEs belonging to six sub-families based on our recently developed descriptor-based classification system. The three-dimensional structures of the 13 FAEs were modeled for structural analysis of the feruloylome. The three genes coding for three enzymes, viz., A.O.2, A.O.8 and A.O.10 from the feruloylome of A. oryzae, representing sub-families with unknown functional features, were heterologously expressed in Pichia pastoris, characterized for substrate specificity and structural characterization through CD spectroscopy. Common feature-based pharamacophore models were developed according to substrate specificity characteristics of the three enzymes. The active site residues were identified for the three expressed FAEs by determining the titration curves of amino acid residues as a function of the pH by applying molecular simulations. Conclusions/Significance: Our findings on the structure-function relationships and substrate specificity of the FAEs of A. oryzae will be instrumental for further understanding of the FAE families in the novel classification system. The developed pharmacophore models could be applied for virtual screening of compound databases for short listing the putative substrates prior to docking studies or for post-processing docking results to remove false positives. Our study exemplifies how computational predictions can complement to the information obtained through experimental methods. © 2012 Udatha et al.published_or_final_versio

Brewer's spent grain from different types of malt: Evaluation of the antioxidant activity and identification of the major phenolic compounds

The antioxidant activity and phenolic composition of brewer's spent grain (BSG) extracts obtained by microwave-assisted extraction from twomalt types (light and darkmalts) were investigated. The total phenolic content (TPC) and antioxidant activity among the light BSG extracts (pilsen, melano, melano 80 and carared)were significantly different (p b 0.05) compared to dark extracts (chocolate and black types), with the pilsen BSG showing higher TPC (20 ± 1 mgGAE/g dry BSG). In addition, the antioxidant activity assessed by 2,2-diphenyl- 1-picrylhydrazyl, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and deoxyribose assays decreased as a result of increasing kilning temperatures in the following order: pilsen N melano N melano 80 N carared N chocolate N black. HPLC-DAD/ESI-MS/MS analysis indicated the presence of phenolic acids, such as ferulic, p-coumaric and syringic acids, as well as several isomeric ferulate dehydrodimers and one dehydrotrimer. Chocolate and black extracts, obtained frommalts submitted to the highest kilning temperatures, showed the lowest levels of ferulic and p-coumaric acids. These results suggested that BSG extracts from pilsen malt might be used as an inexpensive and good natural source of antioxidants with potential interest for the food, pharmaceutical and/or cosmetic industries after purification

Anticholinesterase activity of selected phenolic acids and flavonoids – interaction testing in model solutions

[b][/b][b]Introduction[/b]. Alzheimer’s disease is a progressively developing neurodegenerative disorder of the central nervous system. The only present treatment of this disease is the use of acetyl- and butyrylcholinesterase inhibitors. Previously, the neuroprotection of phenolic acids and flavonoids in the brain has been indicated. [b]Materials and method.[/b] This study measured anticholinesterase activities of 9 phenolic acids and 6 flavonoids, singly or in combination. The synergy/antagonism/zero interaction between compounds was evaluated taking into consideration the statistical significance. Ellman’s modified spectrophotometric method was used with the simultaneous measurement of the false-positive effect of compounds. [b]Results[/b]. The anti-acetylcholinesterase activity of phenolic acids was as follows: homogentisic acid > 4-hydroxyphenylpyruvic acid > nordihydroguaiaretic acid > rosmarinic acid > caffeic acid > gallic acid = chlorogenic acid > homovanillic acid > sinapic acid. p-Hydroxyphenylpyruvic, caffeic, chlorogenic, gentisic, homogentisic, nordihydroguaiaretic and rosmarinic acids in pairs exhibited, in most cases, a lower inhibitory activity (at p>0.05), than the sum of the activities of single compounds. Also, phenolic acids in pairs with flavonoids (cyanidin, delphinidin, kaempferol, myricetin, phloridzin, pelargonidin or quercetin) presented, in most cases, a lower inhibitory activity than could be calculated for both compounds singly (at p>0.05). Only in the case of a few samples was the inhibitory activity of two compounds higher than the sum of inhibitions exerted by the same compounds tested singly (either at p>0.05 or p<0.05). The lack of synergy of pairs of inhibitors suggests one small binding site, making impossible to accommodate both inhibitors adjacent to one another