Phenolic compounds in beer are derived from grains and hops during processing and production. Thus, the total phenolic content (TPC) of beer extracts, from selected Canadian and foreign commercial, ...and laboratory produced beers were examined and ranged from 3.72 ± 0.23 to 13.73 ± 0.49 mg GAE/100 mL beer. The total flavonoid content (TFC) of the same beer extracts varied from 0.82 ± 0.02 to 5.28 ± 0.04 mg CE/100 mL beer. Of particular interest were the hydroxycinnamic acids (HCAs) and derivatives in beer extracts because of their antioxidant properties. Main HCAs and a key derivative of ferulic acid, 4-vinylguaiacol (4-VG), were identified in beer extracts by high performance liquid chromatography (HPLC). Significant variations in TPC, TFC, HCAs and 4-VG content were observed among the beer extracts. Antioxidant activities of beer extracts, determined by radical scavenging and ferric-reducing assays, were positively correlated (p < 0.05) with TPC, TFC, and 4-VG but observed negative correlation with individual HCAs (p > 0.05). The positive correlation of 4-VG with ABTS radical cation scavenging and reducing power assays is reported first time. These findings suggest that phenolic compounds and a key derivative of the hydroxycinnamic acid, 4-VG, may have the protective role in the beer as an antioxidant.
•Stir stick stout, a local beer, had the highest content of total phenolics and flavonoids.•The major hydroxycinnamic acids were identified and quantified by HPLC-DAD.•4-Vinylguaiacol, (4VG), a derivative of ferulic acid, was identified first time in Canadian beer.•A positive correlation was reported for the first time between 4-VG and radical scavenging assays.•Local Canadian beer showed higher and strong free radical scavenging activities.
Hydroxycinnamic acids (HCAs) are important phytochemicals possessing significant biological properties. Several investigators have studied in vitro antioxidant activity of HCAs in detail. In this ...review, we have gathered the studies focused on the structure-activity relationships (SARs) of these compounds that have used medicinal chemistry to generate more potent antioxidant molecules. Most of the reports indicated that the presence of an unsaturated bond on the side chain of HCAs is vital to their activity. The structural features that were reported to be of importance to the antioxidant activity were categorized as follows: modifications of the aromatic ring, which include alterations in the number and position of hydroxy groups and insertion of electron donating or withdrawing moieties as well as modifications of the carboxylic function that include esterification and amidation process. Furthermore, reports that have addressed the influence of physicochemical properties including redox potential, lipid solubility and dissociation constant on the antioxidant activity were also summarized. Finally, the pro-oxidant effect of HCAs in some test systems was addressed. Most of the investigations concluded that the presence of ortho-dihydroxy phenyl group (catechol moiety) is of significant importance to the antioxidant activity, while, the presence of three hydroxy groups does not necessarily improve the activity. Optimization of the structure of molecular leads is an important task of modern medicinal chemistry and its accomplishment relies on the careful assessment of SARs. SAR studies on HCAs can identify the most successful antioxidants that could be useful for management of oxidative stress-related diseases.
•The isolated lignin was a ρ-hydroxyphenyl-guaiacyl-syringyl lignin and S/G of 0.35.•The major units in the lignin macromolecule are derived from hydroxycinnamic acids.•The antioxidant activity of ...the lignin was due to the ferulic acid subunits.•The lignin is a desirable source of antioxidants guaiacol and 4-vinylguaiacol.
The structure of lignin obtained from the ozone and soaking aqueous ammonia pretreatment of wheat straw has been characterized utilizing chemical analytical methods in order to reveal its antioxidant characteristics, including attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), pyrolysis/tetramethylammonium hydroxide-gas chromatography/mass spectrometry (Py/TMAH-GC/MS), gel permeation chromatography (GPC), ultra violet–visible spectroscopy (UV–vis), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) antioxidant evaluation assay. The results demonstrated that the isolated lignin is a ρ-hydroxyphenyl- guaiacyl-syringyl (H-G-S) lignin, with S/G ratio of 0.35 and significant amounts of phenol 2-methoxy (guaiacol) and phenol 2-methoxy-4-vinyl (4-vinylguaiacol). The Py-GC/MS and Py/TMAH-GC/MS pyrograms indicated that the major units in this lignin are derived from hydroxycinnamic acids. The GPC results revealed the molecular weight of the lignin was considerably low and also the FTIR analysis showed that the lignin possessed hydroxyl and methoxy functional groups; the factors led to the extracted lignin having a comparable antioxidant activity to that of currently used commercial antioxidants. The UV–vis and DPPH antioxidant assay results suggested a percentage of inhibition of the DPPH radicals in the following order: guaiacol (103.6±1.36)>butylated hydroxytoluene (103.3±1)>ferulic acid (102.6±0.79)>pretreated lignin (86.9±0.34).
To better understand the high recalcitrance of bamboo during bioconversion, the fine spatial distribution of polymers in bamboo was studied with Imaging FTIR microscopy under both transmission and ...ATR modes, combined with PCA data processing. The results demonstrated that lignin, xylan and hydroxycinnamic acid (HCA) were more concentrated in the fibers near the xylem conduit, while cellulose was evenly distributed across the whole fiber sheath. PCA processing produced a clear separation between bamboo fibers and parenchyma cells, indicating that the parenchyma cells contains more pectin and HCA than fibers. It also demonstrated that cellulose, xylan and S-lignin were concentrated most heavily in bamboo fiber secondary cell walls, while G-lignin, pectin and HCA were found more in the compound middle lamella. The revealed information regarding polymer distribution is of great significance for better understanding of the inherent design mechanism of plant cell wall and its efficient utilization.
Imaging FTIR with ATR first demonstrated that for bamboo, in similarity with wood species, the spatial distribution of cellulose, xylan and S-lignin were concentrated most heavily in the fiber secondary cell walls, while G-lignin, pectin and hydroxycinnamic acid (HCA) were found more in the compound middle lamella. At the tissue level, imaging FTIR with transmission mode first demonstrated that lignin, xylan and HCA were more concentrated in the fibers near xylem conduit, while cellulose was evenly distributed across the whole fiber sheath. Display omitted
•The polymers distribution in bamboo at both tissue and cellular scale was revealed with Imaging FITR•Xylan and lignin were found to be more concentrated in the fibers near the xylem conduit in bamboo•Cellulose, xylan and S-lignin were more concentrated in the secondary wall
Several herb species classified as oregano have been widely used in folk medicine to alleviate inflammation-related diseases, respiratory and digestive disorders, headaches, rheumatism, diabetes and ...others. These potential health benefits are partially attributed to the phytochemical compounds in oregano such as flavonoids (FL) and phenolic acids (PA). Flavonoids and phenolic acids are among the most abundant and most studied phytochemicals in oregano species. Epidemiological, in vitro and in vivo experiments have related long-term consumption of dietary FL and PA with a decreased risk of incidence of chronic diseases. The aim of this manuscript is to summarize the latest studies on the identification and distribution of flavonoids and phenolic compounds from oregano species and their potential antioxidant, anti-inflammatory and anti-cancer health benefits.
Hairy root (HR) cultures are quickly evolving as a fundamental research tool and as a bio-based production system for secondary metabolites. In this study, an efficient protocol for establishment and ...elicitation of anthocyanin-producing HR cultures from black carrot was established. Taproot and hypocotyl explants of four carrot cultivars were transformed using wild-type Rhizobium rhizogenes. HR growth performance on plates was monitored to identify three fast-growing HR lines, two originating from root explants (lines NB-R and 43-R) and one from a hypocotyl explant (line 43-H). The HR biomass accumulated 25- to 30-fold in liquid media over a 4 week period. Nine anthocyanins and 24 hydroxycinnamic acid derivatives were identified and monitored using UPLC-PDA-TOF during HR growth. Adding ethephon, an ethylene-releasing compound, to the HR culture substantially increased the anthocyanin content by up to 82% in line 43-R and hydroxycinnamic acid concentrations by >20% in line NB-R. Moreover, the activities of superoxide dismutase and glutathione S-transferase increased in the HRs in response to ethephon, which could be related to the functionality and compartmentalization of anthocyanins. These findings present black carrot HR cultures as a platform for the in vitro production of anthocyanins and antioxidants, and provide new insight into the regulation of secondary metabolism in black carrot.
In patients with Alzheimer's disease (AD), elevated levels of butyrylcholinesterase (BChE) are observed. The enzyme hydrolyses acetylcholine, which shows deficiency in these patients. Therefore, BChE ...inhibitors are used in the treatment of Alzheimer's disease, especially synthetic ones, showing side effects with long-term intake. The sources of natural BChE inhibitors are constantly being sought. Coffee brews have been shown to reduce the symptoms of AD in epidemiological studies. However, the ability to inhibit BChE activity has not been investigated, depending on the degree of coffee roasting. The study was aimed at determining the interactions between BChE and the bioactive compounds of coffee and their ability to inhibit the activity of BChE. A comparison of individual bioactive compounds of coffee as well as extracts obtained from two main species, Arabica and Robusta, and additionally from different degrees of roasting was made. Two models were used: isothermal titration calorimetry (ITC) and molecular docking simulation. ITC analysis showed strong interactions of ferulic and dihydrocaffeic acids with BChE. These compounds are the metabolites of the chlorogenic acids, including both mono- and diesters of caffeic acid with quinic acid. Docking simulation showed their strong hydrophobic interaction with BChE, stabilized by hydrogen bonds and pi-pi interactions. After introducing acetylcholine into the model system, the strongest ability to inhibit hydrolytic activity of BChE was again observed for ferulic acid and additionally for 3-caffeoylquinic acid, and among coffee brews the most active were light roasted Arabica and green Robusta. The study was based on the physiological concentrations of coffee components, so the potential therapeutic effect of coffee infusions was proved.
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•Green and roasted coffee showed ability to inhibit activity of butyrylcholinesterase.•Ferulic acid was very effective inhibitor of butyrylcholinesterase.•Caffeine was less effective as the enzyme inhibitor.•Isothermal titration calorimetry allows to determine the degree of inhibition of the hydrolytic activity.•Molecular modeling showed interactions with the active sites of the enzyme.
•Soluble phenolic compounds of perennial ryegrass may benefit ruminant performance.•Soluble phenolic compounds of perennial ryegrass are incompletely profiled.•Environment, endophytes, maturity, and ...genetics affect concentrations.•Differences among studies complicate confirming phenolic composition.
Perennial ryegrass (Lolium perenne L.) contains phenolic compounds esterified to cell walls, and it also contains soluble phenolic compounds in the vacuole. Soluble phenolic compounds of perennial ryegrass may be important to the performance of grazing animals, due to their roles as substrates for polyphenol oxidase and as antioxidants. However, the soluble phenolic compound profile of perennial ryegrass has not been completely identified, making it difficult to determine which compounds could be important for animal performance. This review summarizes information on perennial ryegrass phenolic compound composition and concentration. Chlorogenic acid and its isomers have been characterized in many varieties of perennial ryegrass, as has thesinine rhamnoside. Many glycosides of various flavonoids have been reported, but the glycosidic moieties have not been completely characterized. Condensed tannins have been found in seeds, but their presence in leaf tissue has been variable. Concentration and composition of soluble phenolic compounds of perennial ryegrass are affected by sample preparation, presence of pathogens or endophytes, environmental stresses, time of day, plant maturity, and genetic background. The challenges in characterizing the soluble phenolic compounds of perennial ryegrass lie in the difficulties of comparing results across studies, due to the abovementioned sources of variation, and in the need for consistent extraction methods, separation methods, and adequate amounts of material.
Inhibitors of the shikimate pathway are widely used as herbicides, antibiotics, and anti-infectious drugs. However, the regulation of the shikimic pathway is complex, and little is known about the ...feedback regulation of the shikimate dehydrogenase (SDH, EC 1.1.1.25) in plants. Thus, the aim of this study was to elucidate the kinetic mechanism of SDH purified from the root of Petroselinum crispum (parsley), to determine all possible reaction products and to identify phenylpropanoid compounds that affect its activity. Our results showed that the bisubstrate reaction catalyzed by P. crispum SDH follows a sequential ordered mechanism, except for three dead-end complexes. The main and lateral reactions of SDH were monitored by mass spectrometry, thereby detecting protocatechuic acid as a byproduct. Gallic acid was formed non-enzymatically, whereas quinate was not detected. Several polyphenolic compounds inhibited SDH activity, especially tannic, caffeic and chlorogenic acids, with IC50 0.014 mM, 0.15 mM, and 0.19 mM, respectively. The number of hydroxyl groups influenced their inhibition effect on SDH, and p-coumaric, t-ferulic, sinapic, syringic and salicylic acids were less effective SDH inhibitors. Nevertheless, one branch of the phenylpropanoid pathway may affect SDH activity through feedback regulation.
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•Petroselinum crispum SDH follows an ordered reaction mechanism with three dead-end complexes.•Gallic acid and quinate are not direct bypass products of P. crispum root SDH.•Tannic acid, chlorogenic acid, and caffeic acid effectively inhibit SDH.•P. crispum SDH also forms protocatechuic acid in an irreversible reaction.
•Phenolic acids inhibit the volatilization of ethyl acetate.•The hydroxyl and methoxy groups of phenolic acids affected the inhibition effect.•Hydrophobic effect might drive the spontaneous binding ...of the two compounds.•There was an electron transfer between phenolic acids and ethyl acetate.
Hydroxycinnamic acids and ethyl acetate were assessed in simulated alcohol-free wine solutions to explore the effect of phenolic acids on the aroma volatility of esters. The results showed that the phenolic acids could inhibit the volatilization of ethyl acetate, and the extent of inhibition was influenced by the concentration and structure of the phenolic compounds. The ultraviolet absorption spectra of the phenolic acids and ethyl acetate confirmed the interaction between the two compounds. The thermodynamic parameters of the interaction implied a spontaneous exothermic interaction, driven primarily by hydrophobic effects. Meanwhile, the results of the fluorescence-quenching analysis indicated electron transfer between the reactants. The quantum chemical investigations revealed negative and positive charge density distributions in the structures of ethyl acetate and the phenolic acids, respectively. These results will provide some data reference and theoretical support for further research on the effects of phenolic acid matrix on other structural esters.
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