Addition Of Gallic Acid Research Articles

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.

Enhancing oxidative stability of walnuts by using gallic acid loaded lentil flour based electrospun nanofibers as active packaging material

The objective of this study was to enhance oxidative stability of walnuts present in active packages produced by electrospinning technology. Gallic acid was encapsulated into lentil flour/polyethylene oxide (PEO) nanofibers. To promote the solubility of lentil proteins, pH of solutions was adjusted to pH 1 and pH 10 which were far away from isoelectric point of lentil proteins. While acidic solutions had lower viscosity values than alkaline solutions, their electrical conductivity values were significantly higher. When the scanning electron microscopy (SEM) images were examined, it should be noted that alkaline nanofibers showed homogenous structure. Although gallic acid was not so stable at alkaline conditions, gallic acid loaded nanofibers prepared at alkaline pH still showed antioxidant activity after electrospinning. The physical and thermal properties of encapsulated gallic acid and nanofibers were examined by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA) and differential scanning calorimeter (DSC) analyses. FTIR results indicated the effect of pH on chemical properties of nanofibers and the interaction between gallic acid and lentil flour-based nanofibers. Gallic acid addition reduced onset temperature and thermal stability. Therefore, it could be taken as evidence of incorporation of gallic acid. Disappearance of enthalpic peak related to melting of crystalline structure of gallic acid in DSC thermal curves confirmed successful encapsulation of gallic acid. Fabricated gallic acid loaded nanofibers were used to pack walnuts and the reduction in oxidation of walnuts with lower peroxide, p-anisidine and Totox values was observed. This would make these packaging materials substantially preferable for packing of foods being highly susceptible to oxidation.

Chickpea flour‐based biofilms containing gallic acid to be used as active edible films

ABSTRACTChickpea is an easily accessible nutritious legume. Besides, gallic acid is a widespread phenolic found in various plants. In this study, it is aimed to investigate the effects of pH (9 and 11), glycerol concentration (1 and 3% w/v of film solution) and gallic acid concentration (5 and 10% w/w of total solid) on color, opacity, mechanical strength, water vapor permeability (WVP), microstructure, chemical characteristic, antioxidant activity, and phenolic content of films. At pH 11, films are stronger, darker and have higher antioxidant activity. Higher glycerol concentration makes the films more flexible but less strong and more hydrophilic. Higher gallic acid concentration makes great contribution to the films by decreasing WVP but by increasing opacity, antioxidant activity, phenolic content, lightness, and elongation. Film containing glycerol of 1% and gallic acid of 10% and prepared at pH 11 was found to be a great combination for obtaining antioxidant rich edible composite films.HIGHLIGHTS Chickpea flour‐based active films were successfully obtained with addition of gallic acid. Higher gallic acid concentration decreased WVP, increased opacity, antioxidant activity, phenolic content, lightness, and elongation. Higher pH provided stronger mechanical properties, low lightness, and higher antioxidant activity. Lower glycerol concentration resulted lower WVP and stronger tensile properties. Chickpea flour‐based active films at pH 11 with 1% glycerol and 10% gallic acid can be used as active packaging material in especially highly oxidative food products. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47704.

Unraveling the effects of gallic acid on Sb(III) adsorption and oxidation on goethite

Natural organic matter (NOM) profoundly influences the metal(loid)s immobilization by iron (Fe) minerals, which, in turn, are the host phase for Sb that control its mobilization and bioavailability. However, the potential effect of the redox-active phenolic acids derived from NOM on this process has rarely been explored. Therefore, the adsorption of Sb(III) on goethite and Sb(III) oxidation in the presence of a common phenolic acid—gallic acid (GA)—was systematically investigated. The reaction mechanisms were unraveled by the combination of wet chemistry, electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), and X-ray absorption fine structure (XAFS) spectroscopy. Our results showed the addition of GA significantly inhibited Sb adsorption on goethite as the pH increased. Except for the competitive adsorption by GA, the inhibition also resulted from the extensive Sb(III) oxidation in the suspension and the lower Sb(V) sorption capacity of goethite at higher pH. The alkaline condition facilitated the generation of reactive oxygen species (hydrogen peroxide) and quinone species (semiquinone radical (SQ−) and oxidized GA), accounting for the significant Sb(III) oxidation in the solution and on the goethite surface. Besides, the edge-sharing inner-sphere complexes were formed between Sb and goethite regardless of the presence of GA. Our findings demonstrated the remarkable role of the phenolic groups in NOM on the adsorption of Sb(III) on goethite.

Effects of gallic acid on in vitro rumen fermentation and methane production using rumen simulation (Rusitec) and batch-culture techniques

Two experiments were conducted to investigate the effects of adding gallic acid (GA) to ruminant diets on long- and short-term in vitro rumen fermentation and methane (CH4) production, and to test possible interactions between GA and ethanol on fermentation. The first experiment was conducted using the rumen simulation technique (Rusitec), as a completely randomised block design with four replications and the following four doses of GA: 0, 5, 10 and 20 mg GA/g dry matter (DM). Ethanol was used in all treatments to increase the solubilisation of GA in rumen fluid. The experimental period lasted 16 days, of which the first 7 days were for adaptation and the subsequent 9 days were for sampling. The second experiment was a 48-h batch-culture incubation conducted as a completely randomised design with a 4 (GA dose; 0, 10, 20, and 40 mg GA/g DM) × 2 (with or without ethanol) arrangement of treatments. In the Rusitec experiment, addition of GA up to 20 mg/g DM did not affect DM disappearance (DMD), organic matter (OM) disappearance, neutral detergent-fibre disappearance (NDFD), acid detergent-fibre disappearance (ADFD) or starch disappearance (P > 0.05), but crude protein disappearance was linearly decreased (P = 0.04) from 78.3% to 72.0%. Daily gas production and CH4 production expressed as mL/g DM and mL/g DMD were not affected by addition of GA (P > 0.05). Addition of GA up to 20 mg/g DM increased butyrate and isovalerate production (P < 0.05) and tended to increase isobutyrate (P = 0.09) and decrease heptanoate production (P = 0.07). In the batch-culture experiment, adding GA up to 40 mg/g DM linearly increased 48-h DMD, NDFD and ADFD (P < 0.05) and decreased (P < 0.05) CH4 expressed as mL/g DMD, mL/g NDFD and mL/g ADFD. Methane production was decreased after 24 h and 48 h only when GA was added at 10 mg/g DM without ethanol. Fermentation liquid pH and concentration of ammonia-nitrogen (ammonia-N) were also reduced (P < 0.05) with an increasing concentration of GA. Treatments with ethanol notably enhanced 48-h DMD, NDFD, ADFD, gas production (mL/g DM, mL/g OM or mL/g DMD), CH4 production (mL/g DM, mL/g DMD or mL/g NDFD), total volatile fatty acid concentration, the acetate:propionate ratio, acetate, valerate, isovalerate and caproate molar proportions (P < 0.01) and decreased propionate, butyrate and isobutyrate molar proportions (P < 0.01). Significant dose of GA × ethanol interaction was observed only for acetate molar proportion (P = 0.03). In conclusion, our study suggests that the beneficial effects of GA on feed digestion and CH4 production may be short term, while improvements in N metabolism may be sustained over the long term. It may be useful to conduct long-term in vivo studies using a range of diets and doses to verify whether GA can be used as a feed additive to mitigate enteric CH4 production and improve N metabolism of ruminants.

The effect of prefermentative addition of gallic acid and ellagic acid on the red wine color, copigmentation and phenolic profiles during wine aging

Though non-anthocyanin phenolics normally do not have red color, they affect the red color expression in the copigmentation of red wines. In this study, the influence of prefermentative addition of 300mg/L gallic acid and ellagic acid, as cofactors, on aging dry red wines had been systematically evaluated at the industrial scales from the perspectives of color, phenolic profiles and copigmentation effects of anthocyanins. Red wines made with these two compounds exhibited better color properties than the control, having better CIELAB chromatic parameters. Additionally, significantly higher levels of detectable anthocyanins and copigmented anthocyanin ratio had been observed. Wines with ellagic acid showed better chromatic properties and phenolic profiles than wines with gallic acid, as shown in previous theoretical results. Anti-copigmentation phenomenon was noticed and elucidated. These practical results confirmed that ellagic acid was the better cofactor, and would give more additional guidance for the production of high quality wine. Chemical compoundsMalvidin-3-O-glucoside (PubChem CID: 443,652); Petunidin-3-O-glucoside (PubChem CID: 443,651); Delphinidin-3-O-glucoside (PubChem CID: 443,650); Peonidin-3-O-glucoside (PubChem CID: 443,654); Ellagic acid (PubChem CID: 5,281,855); Gallic acid (PubChem CID: 370); Quercetin (PubChem CID: 443,654); Caffeic acid (PubChem CID: 689,043); (+)-catechin (PubChem CID: 9064); Vanillic acid (PubChem CID: 8468).

Characterization of binding interaction between rice glutelin and gallic acid: Multi-spectroscopic analyses and computational docking simulation

Many foods contain mixtures of plant dietary proteins and polyphenols, but there is currently a relatively poor understanding of the nature of the interactions between these components. In this study, the interaction of rice glutelin (RG) and gallic acid (GA) was characterized by spectroscopic and molecular docking techniques. The intrinsic fluorescence of RG quenched after the addition of GA, indicating that an interaction occurred. Thermodynamic analyses indicated that the binding process was spontaneous and the main driving forces were hydrogen bonds and van der Waals forces. The surface hydrophobicity of RG decreased with increasing GA. Furthermore, synchronous fluorescence and circular dichroism spectra provided insights into micro-environmental and conformational changes of RG. In particular, there was a reduction of α-helix structure and an increase of β-sheet structure present in RG after the binding interaction. Finally, molecular docking analysis provided a visual representation of a single binding site where GA interacted with specific amino acid residues located in the active site of the RG.

Short-term microbial respiration in an arid zone mangrove soil is limited by availability of gallic acid, phosphorus and ammonium

Microbial activity in soils of oligotrophic, arid zone mangroves is likely strongly limited by carbon (C) and nutrient availability, where even small changes in microbial activity could result in significant shifts in ecosystem functioning. We hypothesised that microbial respiration in arid mangrove ecosystems is primarily limited by supply of labile C sources. We measured short-term respiration responses to addition of glucose, citric acid, gallic acid, phosphate, ammonium (NH4+), nitrate (NO3−), urea and glutamic acid to mangrove soils from different tidal positions and soil depths in the laboratory using an adaptation of the MicroResp™ procedure (μg CO2-C g soil−1 hr−1). We also measured short-term respiration responses to added glucose, gallic acid, phosphate, ammonium and urea in the field using an infrared gas analyser (g CO2 m−2 hr−1). Both laboratory and field measurements indicated microbial communities were limited by gallic acid, phosphate and ammonium. Respiration rates were enhanced in both the laboratory and the field after addition of gallic acid but not glucose, suggesting adaptations of the arid microbial community to more complex C sources. Addition of phosphate alone and in combination with other substrates enhanced respiration more than ten-fold in the laboratory. In the field, nutrient addition (ammonium and/or phosphate) generally induced greater respiration responses in the surface soils (0–1 cm) compared to subsurface (>1 cm), which we attribute to more nutrient-limited autotrophic microbes in the surface soils. Addition of phosphate also induced slightly higher activity in the low intertidal fringing forests compared to high intertidal scrub forests. Our results contrast with studies of more productive tropical mangrove systems and demonstrate the critical role of microorganisms in maintaining organic matter turnover and nutrient supply in a relatively pristine and water-limited environment.

Effects of dietary gallic acid supplementation on performance, antioxidant status, and jejunum intestinal morphology in broiler chicks

Gallic acid (GA), widely distributed in plants and feeds, is known to have a diverse range of activities such as anti-oxidant, anti-inflammatory, antibacterial, anti-allergic, anti-mutagenic, and anti-carcinogenic. The purpose of this study was to investigate the efficacy of inclusion of dietary GA at levels 0, 25, 50, 75, 100, or 150mg/kg on growth performance, antioxidant status, and jejunum intestinal morphology of broiler chicks. In total, 630 one-day-old Arbor Acres (AA) male broiler chicks were randomly allotted to 6 treatment groups for a period of 6 weeks. The results indicate that dietary addition of GA at 75 to 100mg/kg improved feed conversion efficiency in both the grower (d 21 to 42, P = 0.045) and overall (d 1 to 42, P = 0.026) periods. Dietary addition of GA at a concentration ≥100mg/kg was able to exhibit higher breast muscle ratio at 42 d (P= 0.043). Interestingly, dietary GA inclusion level from 50 to 100mg/kg reduced the crypt depth (P = 0.009) and increased the villus height:crypt depth ratio (VCR) of the birds (P = 0.006). Dietary supplementation of GA at 100mg/kg decreased plasma malondialdehyde (MDA) content at 42 d of age (P = 0.030). Moreover, dietary addition of GA linearly increased plasma total antioxidant capacity (P = 0.039) and plasma total superoxide dismutase activities (P = 0.049) at 21 d of age. However, analysis of plasma biochemical markers revealed that dietary supplementation of GA did not exhibit beneficial health effects. Overall, we conclude that 75 to 100mg/kg of GA are suitable for enhanced growth performance and health benefits in a broiler diet.

Effects of low molecular weight organic acids and fulvic acid on 2,4,4′-trichlorobiphenyl degradation and hydroxyl radical formation in a goethite-catalyzed Fenton-like reaction

The effects of different organic acids on 2,4,4′-trichlorobiphenyl (PCB28) degradation, H2O2 decomposition and OH formation in a goethite-catalyzed Fenton-like reaction were investigated at different pH and initial organic acid concentrations. In general, organic acid addition had a similar effect on PCB28 degradation and OH formation, but there was a significant difference between its effect on PCB28 degradation and H2O2 decomposition. This indicates that OH was responsible for PCB28 degradation in the heterogeneous Fenton reaction. Oxalic, citric, malic and succinic acid addition decreased PCB28 degradation, H2O2 decomposition and OH formation. Their inhibitory effect followed the order oxalic acid>citric acid>malic acid>succinic acid, according to their sorption affinity for a goethite surface. Catechol and gallic acid addition had a considerable inhibitory effect on PCB28 degradation and OH formation, and the opposite effect was observed with 2,6-dimethoxylphenol and caffeic acid addition, although the addition decreased the H2O2 decomposition. The addition of low-concentration fulvic acid (FA) could promote PCB28 degradation and OH formation at pH 3 and pH 7, but an inhibitory effect was observed with increasing concentrations of FA. The inhibitory effect of added FA on H2O2 decomposition increased with decreasing pH and with increasing FA concentrations.

Gallic acid inhibits the release of ADAMTS4 in nucleus pulposus cells by inhibiting p65 phosphorylation and acetylation of the NF-κB signaling pathway.

This study investigated the inhibitory effect of gallic acid (GA) on the release of A Disintegrin and Metalloproteinase with Thrombospondin motifs 4 (ADAMTS4) through the regulation of the NF-κB signaling pathway, which is closely related to the matrix metalloproteinases in nucleus pulposus cells. Different concentrations of GA were added to TNF-α-induced human nucleus pulposus cells (hNPCs) and intervertebral disc degeneration rat model. ADAMTS-4 expression increased both in the TNF-α-induced nucleus pulposus cells and intervertebral disc degeneration rat model. By contrast, the release of ADAMTS-4 was reduced, and the TNF-α-induced apoptosis of nucleus pulposus cells was significantly inhibited after addition of GA at different concentrations. Further study found that the levels of phosphorylated p65 (p-p65) was increased and the classical NF-κB signal pathway was activated after the nucleus pulposus cells were stimulated by TNF-α. Meanwhile, GA suppressed the p65 phosphorylation and inceased p65 deacetylation levels. As a consequence, GA can decrease the expression of ADAMTS-4 in nucleus pulposus cells by regulating the phosphorylation and acetylation of p65 in NF-κB signaling pathways.

Palliative effects of extra virgin olive oil, gallic acid, and lemongrass oil dietary supplementation on growth performance, digestibility, carcass traits, and antioxidant status of heat-stressed growing New Zealand White rabbits.

This study explored the effects of supplemental dietary extra virgin olive oil (EVOO), gallic acid (GA), or lemongrass essential oil (LGEO) on growth performance, nutrient digestibility, carcass traits, lipid peroxidation, hematological, and antioxidative status in growing rabbits under heat stress conditions. A total of 48 male growing New Zealand White rabbits were randomly divided into four equal groups, which received a basal diet without any supplementation or supplemented with 15g EVOO, 500mg GA, or 400mgLGEO/kg of diet, for eight consecutive weeks. Results revealed that the overall mean of temperature humidity index was 84.67±0.35, reflecting a state of severe heat stress. Moreover, dietary supplementation with EVOO, GA, or LGEO significantly increased live body weight and daily body weight gain but decreased both feed conversion ratio and daily water consumption. Additionally, a significant increase in both organic matter and crude protein digestibility besides a remarkable elevation in the nutritive values of digestible crude protein, total digestible nutrients, and digestible energy, as well as an increase in the numbers of WBCs, lymphocytes, and heterophils was significant in EVOO-supplemented rabbits. Supplementation with EVOO, GA, or LGEO in the heat-stressed growing rabbit's diet enhanced catalase activity and reduced glutathione content, whereas EVOO-treated rabbits had the highest values. Also, malondialdehyde activity was reduced in response to all tested additives. In conclusion, these findings suggested that addition of EVOO, GA, or LGEO in growing rabbit's diet could be used effectively to alleviate negative impacts of heat stress load on performance, nutrient digestibility, oxidative status, and hemato-biochemical features. Furthermore, among these additives, EVOO achieved the best effects.

The Influence of Prefermentative Addition of Gallic Acid on the Phenolic Composition and Chromatic Characteristics of Cabernet Sauvignon Wines.

In this study, the prefermentative addition of gallic acid in Cabernet Sauvignon red winemaking was performed. The influence of gallic acid addition on wine phenolic composition, the ratio of copigmentation, and the color parameters were monitored throughout the winemaking process. The results showed that the prefermentative addition of gallic acid enhanced the extraction of total anthocyanins and the copigmentation effect, producing wines with more darkness, redness, yellowness, and saturation. Moreover, the addition of gallic acid contributed to the concentration of total phenolic acids. However, it had a negative effect on the concentrations of flavonols and flavan-3-ols in the final wines. Thus, the prefermentative addition of gallic acid at appropriate levels might be a promising enological technology to obtain wines with high color quality and aging potential.

Change in major fatty acid composition of vegetable oil depending on phenolic incorporation and storage period

In the present study, response surface methodology was conducted for the determination of effects of some phenolics (gallic acid, ellagic acid and quercetin) on the major fatty acid composition of vegetable oil prepared by mixing of sunflower and hazelnut oil (50:50, v/v) during storage at a constant temperature (50 °C). In this respect, major fatty acid composition (palmitic, stearic, oleic and linoleic acid) of vegetable oil was determined. Predictive regression equations were constructed for the estimation of each studied parameter (R2>0.735). Storage period caused a significant increase in palmitic acid, stearic acid and oleic acid content of oil while it caused a decrease in the linoleic acid content of the oil (P<0.01) because of the reactions that occurred in the structure of the oil during storage. In general, gallic acid and quercetin were found to be effective on the preservation of oil against oxidation and addition of gallic acid that retarded the change of major fatty acids composition due to...

Production of secondary metabolite E2.2 from Phaleria macrocarpa endophytic fungus

ObjectiveTo isolate new endophytic fungus from Phaleria macrocarpa (P. macrocarpa) that is able to produce E2.2 compound. MethodsEndophytic fungi were isolated from P. macrocarpa. Morphological and molecular identification was done to determine the species of the endophytic fungus. High performance liquid chromatography was used to determine the ability of this fungus to produce E2.2 compound and to quantify the total yield of E2.2 from fungal fermentation. Fermentation process was optimized by observing suitable medium, pH and length of fermentation process. Phloroglucinol and gallic acid addition were examined to determine the effect of each compound on E2.2 production. ResultsOne endophytic fungus was successfully isolated from P. macrocarpa plant. Morphological and molecular identification showed that it was a Colletotrichum gloeosporioides which belonged to Glomerellaceae family. This fungus showed highest production of E2.2 when incubated in potato dextrose broth with initial pH value of the medium at 5, and was incubated for 15 days. Phloroglucinol was found to better enhance E2.2 production. ConclusionsColletotrichum gloeosporioides found in P. macrocarpa plant is promising as a potential alternative source of E2.2.

Influence of Selected Factors on Anthocyanin Stability in Colored Potato Extracts

Color is considered as an important quality trait of food products. The blue, purple or red colors of several fruits and vegetables are due to the presence of anthocyanins. Scientific evidence suggests that these pigments are health-promoting compounds and there is some research focused on the development of anthocyanin-based natural colorants. However, anthocyanins levels can be altered through the action of several factors during food processing and storage. In this study, prevention of degradation of anthocyanins in potato extracts through combining the addition of gallic acid as copigment and the presence or absence of light with different temperatures was investigated. The four studied factors were statistically significant (P ≤ 0.01), but genotype showed the major effect, followed by light, temperature and gallic acid addition. The stability of anthocyanins can be increased throughout the combination of low temperature (T = 4C), absence of light and gallic acid addition (pigment : copigment molar ratio 1:50). Practical Applications Besides having important biological roles, such as antioxidant activity, anti-inflammatory and anticarcinogenic properties, anthocyanin-rich plant extracts might have potential as food colorants. In fact, colored potatoes have been suggested to be a great source of anthocyanins and a potential source of natural colorants. The major problem of anthocyanin-based natural colorants is their instability under nonacidic normal processing and storage conditions. With the aim of preventing the degradation of anthocyanins to colorless phenolics and insoluble brown compounds, there have been several studies conducted through the addition of different additives. In the present study, the stability effect of gallic acid as a copigment was investigated in different conditions, considering two important factors that influence the preservation of anthocyanins (temperature and light) in purple and red-fleshed potato extracts. Our results contribute to the development of preparation processes of food products and colorants derived from colored potatoes with increased anthocyanin content and color intensity.

α-Tocopherol/Gallic Acid Cooperation in the Protection of Galactolipids Against Ozone-Induced Oxidation.

The protective ability of α-tocopherol (TOH) and gallic acid (GA) acting simultaneously at the moment of oxidizer application was evaluated by determination of galactolipid layers’ oxidation degree. Addition of GA resulted in a significant decrease of ozone-derived radicals shifting the threshold of lipid sensitivity by an amount approximately corresponding to the GA intake in bulk reaction with ozone. TOH presence in lipid layers results in a change of the role of GA which additionally may be involved in the reduction of tocopheroxyl radical formed during oxidation. This leads to a decrease in effectiveness of GA in diminishing the amount of ozone radicals. Such an effect was not observed for mixed layers containing galactolipid and pre-oxidized tocopherol where the ozone threshold level was associated with a stoichiometry of GA + O3 reaction. It was concluded that probably subsequent transformations of tocopheroxyl radical to less reactive forms prevent its reaction with GA the entire quantity of which is used for radicals scavenging. This result shows the role of time parameter in systems where substrates are engaged in various reactions taking place simultaneously. The inactivation of 1,1-diphenyl-2-picrylhydrazyl radical by studied antioxidants in homogeneous system confirmed observations made on the basis of lipid layer properties indicating their antagonistic action (at least at studied conditions). Formation of layers in post-oxidation situation did not depend whether tocopherol was oxidized during oxidation of lipid/tocopherol mixture or was introduced as pre-oxidized. This may be interpreted as indication that products of tocopherol oxidation may stabilize lipid layers.

Molecular adaptation of Lactobacillus plantarum WCFS1 to gallic acid revealed by genome-scale transcriptomic signature and physiological analysis.

BackgroundGallic acid (GA) is a model hydroxybenzoic acid that occurs esterified in the lignocellulosic biomass of higher plants. GA displays relevant biological activities including anticancer properties. Owing to its antimicrobial and cellulase-inhibiting activities, GA also imposes constraints to the fermentability of lignocellulosic hydrolysates. In depth-knowledge of the mechanisms used by tolerant microorganisms to adapt to hydroxybenzoic acids would be a step forward to improve the bioavailability of GA or select/engineer production hosts with improved metabolic traits for the bioconversion of pretreated lignocellulosic biomass.ResultsWhole genome transcriptional profiling using DNA microarrays was used to characterize the molecular response of Lactobacillus plantarum WCFS1 to GA. Expression levels of 14 and 40 genes were differentially regulated at 1.5 and 15 mM GA, respectively. The transcriptomic analysis identified a marked induction of genes with confirmed or related roles to gastrointestinal survival, the repression of genes coding for certain ABC-type transporters and modulation of genes involved in the control of intracellular ammonia levels, among other responses. Most notably, a core set of genes dedicated to produce GA from polyphenols (tanBLp), decarboxylate GA to pyrogallol (lpdB, lpdC and lpdD) and transport functions (lp_2943) was highly overexpressed at both GA concentrations. Correspondingly, resting cells of strain WCFS1 induced by GA, but not their non-induced controls, produced pyrogallol. Gene expression and organization of genes involved in GA metabolism suggested a chemiosmotic mechanism of energy generation. Resting cells of L. plantarum induced by GA generated a membrane potential and a pH gradient across the membrane immediately upon addition of GA. Altogether, transcriptome profiling correlated with physiological observations indicating that a proton motive force could be generated during GA metabolism as a result of electrogenic GA uptake coupled with proton consumption by the intracellular gallate decarboxylase.ConclusionsThe combination of transcriptome and physiological analyses revealed versatile molecular mechanisms involved in the adaptation of L. plantarum to GA. These data provide a platform to improve the survival of Lactobacillus in the gut. Our data may also guide the selection/engineering of microorganisms that better tolerate phenolic inhibitors present in pretreated lignocellulosic feedstocks.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-015-0345-y) contains supplementary material, which is available to authorized users.

Photocatalytic Treatment of Cork Wastewater Pollutants. Degradation of Gallic Acid and Trichloroanisole using Triphenyl(thia)pyrylium salts

The photocatalytic degradation of two typical pollutants present at the wastewaters of cork industry, namely gallic acid (GA) and 2,4,6-trichloroanisole (TCA) has been investigated using triphenylpyrylium (TPP+) and triphenylthiapyrylium (TPTP+) salts as organic photocatalysts. Fast removal of GA and slow but efficient degradation of the reluctant TCA were observed. The role of the transient species involved in the photodegradation has been investigated by means of photophysical experiments. Participation of singlet excited states was safely disregarded since lifetimes of both photocatalysts remained invariable upon addition of GA or TCA. Formation of photoactive ground state complexes was observed, and the complexation constants were estimated as KTPP-GA=468.4M−1, KTPP-TCA=528.0M−1 and KTPTP-TCA=657.1M−1. Moreover participation of the triplet excited states in the electron transfer oxidation of GA was very efficient, while no reaction occurred from the triplet excited states in the case of TCA. In addition, thermodynamic calculations support the participation of the triplet excited state in the case of GA, while the lack of triplet quenching in the case of TCA is associated with a thermodynamically disfavored process. Overall, photophysical experiments indicate that for GA, oxidative electron transfer occurs mainly from the triplet excited state with marginal contribution of the ground state complexes, while for TCA formation of ground state complexes constitutes the only mechanistic pathway.

A response surface methodology study on the effects of some phenolics and storage period length on vegetable oil quality: change in oxidation stability parameters

In the present study, response surface methodology was conducted for the determination of effects of some phenolics (gallic acid, ellagic acid, and quercetin) on some stability parameters of mixed oil prepared with sunflower and hazelnut oils (50:50, v/v). In this respect, peroxide value (PV), free fatty acids (FFAs), p-anisidine value, induction period, and refractive index of mixed oil were investigated. Predictive regression equations were constructed for the estimation of each studied parameter (R^2 > 0.861). The storage period caused a significant increase in the peroxide value, FFAs, p-anisidine, and refractive index values of the mixed oil, while it decreased the induction period value of oil (P < 0.01). The addition of gallic acid significantly retarded oxidation (P < 0.05), and in general gallic acid and quercetin were found to be effective for preserving oil against oxidation.