Antimicrobial activity of phenolic compounds of wine against Campylobacter jejuni

Campylobacter jejuni is a food pathogen which causes gastrointestinal conditions with an ever-increasing incidence at a global level. The antimicrobial power of wine and its components has been studied. Wines having 11.5% ethanol significantly reduced the viability of C. jejuni when they were diluted to 25% in water. The microbicidal power of red wine was higher than that of white wine. While pH does not seem to affect the viability of this pathogen, different phenolic compounds have an effect on it when tested at concentrations from 0 to 1000 mg/L. Gallic acid and p-hydroxybenzoic acid reduced the viability of C. jejuni at concentrations as low as 1 mg/L, but quercetin and catechin did not even affect it at concentrations of 1000 mg/L. Methyl gallate, epicatechin, synaptic acid, vanillic acid, and caffeic acid were microbicidal at concentrations starting at 10 mg/L. Tryptophol, ferulic acid, and cumaric acid were effective starting at 100 mg/L. According to this, wine constitutes an adverse environment for the survival of this pathogen. Furthermore, it would be interesting to study the possible use of phenolic compounds in wine as an alternative to the use of antimicrobial growth promoters against these bacteria in broilers.     

Antibacterial effect of phenolic compounds from different wines

The antimicrobial properties of pure phenolic compounds and polyphenols of different wines against pathogens were investigated. It was observed that bacterial species exhibited different sensitivities towards the different concentrations of phenolic compounds. Escherichia coli was the most sensitive bacterium and Flavobacterium sp. was resistant against all phenolic compounds tested. All wine samples showed antimicrobial properties and the inhibition increased when the polyphenols concentration of wines increased. Clarified wines were inactive against all bacteria, indicating that polyphenolic compounds present in red wines, are responsible for the antimicrobial effects observed. The different concentrations of polyphenols in wines could have an important impact on consumers with the consequent increase in wine commercialization.     

络合萃取法回收高浓度含酚废水中的酚类化合物 I．炼油厂汽油洗涤废碱渣中高浓度酚的回收

以磷酸三丁酯（TBP）为萃取剂和环己烷为稀释剂,对含高浓度酚的废碱液进行了络合萃取处理,并用氢氧化钠溶液为反萃取剂对负载有机相进行了反萃取实验。分别研究了TBP浓度等因素对萃取及氢氧化钠溶液浓度等因素对反萃取的影响,并对萃取剂的重复使用问题、萃取机理进行了初步探讨。实验结果证实,采用20％～30％TBP-环己烷溶液对酚的络合萃取率达到98％以上;用10％的氢氧化钠溶液在反萃温度50℃、反萃比为1：1的情况下,反萃率可达90％左右。萃取剂能在萃取和反萃的过程中多次重复使用,有利于工程化应用。     

Release of phenolic compounds from cork stoppers and its effect on protein-haze

Cork stoppers contain low molecular weight phenols, mainly as ellagic tannin, whose role in the protein stability of white wine has been not elucidated. The release of cork phenols from cork granules, disks and stoppers of different quality classes (A and D) in synthetic wine was investigated as well as its effect on animal gelatin, lysozyme and wine protein. Amounts of cork phenolic compounds up to 115 and 179 µg/cm² were released within two weeks for best and worst quality cork disks, respectively, indicating the cork quality can strongly affect the phenolic compounds release. Similar trend was found for cork stoppers even if the concentration of phenolic compounds was lower (68 µg/cm²). Protein-haze was observed in presence of both animal gelatin and lysozyme (50 mg/l) when the phenol level exceeded 30 and 9 mg/l, respectively, whereas no effect on wine protein was observed. This research suggests that even if the overall amount of phenolic compounds released from cork stoppers is low, protein-haze can be achieved when the bottle is stored horizontally and motionless due to the high phenols concentration close to the cork stopper.     

新型酚酯型抗氧剂的合成及性能研究

以β-（3,5-二叔丁基-4-羟基苯基）丙酸甲酯（MPC）、亚磷酸二乙酯和十八碳醇为原料,通过两步酯交换反应,合成了一种新型酚酯型抗氧剂。采用红外光谱、熔点测定、元素分析和差示扫描量热法对产物的结构、组成及抗氧化性能进行了分析评定。结果表明：该抗氧剂具有较好的抗热氧化性能。     

Influence of phenolic compounds from wines on the growth of Listeria monocytogenes

The anti-microbial properties against Listeria monocytogenes of pure flavonoids rutin, catechin and quercetin; non-flavonoids gallic, vanillic, protocatechuic and caffeic acids and total polyphenols of three Argentinean wines, Cabernet Sauvignon, Malbec and Merlot varieties were investigated. The non-flavonoid caffeic acid and the flavonoids rutin and quercetin were the compounds with higher inhibitory activities on L. monocytogenes growth. The knowledge of the anti-listerial effect of different wines varieties could be the basis to demonstrate if the wine consumption with a meal may collaborate in the health protection against some foodborne organisms such as L. monocytogenes.     

Putrescine production from agmatine by Lactobacillus hilgardii: Effect of phenolic compounds

The influence of phenolic compounds on the growth of Lactobacillus hilgardii X₁B and putrescine formation was assayed at concentrations normally present in wine. Agmatine degradation increased growth and survival of the microorganism and the alkalinity of the media. Bacterial growth was stimulated by phenolic compounds, except for gallic acid and quercetin. Putrescine formation from agmatine diminished in the presence of protocatechuic, vanillic and caffeic acids, and the flavonoids catechin and rutin. The concentration of phenolic compounds decreased after five days of incubation of L hilgardii X₁B, except for gallic acid and quercetin. The results indicate that phenolic compounds, besides their already known beneficial properties to human health, seem to be a natural way of diminishing putrescine formation.     

Studies on antibacterial activity and antibacterial mechanism of a novel polysaccharide from Streptomyces virginia H03

A novel polysaccharide isolated from the broth of Streptomyces virginia H03 exhibited strong antibacterial activities on food spoilage and food poisoning microorganisms such as Staphylococcus aureus, Bacillus subtilis, Listeria monocytogenes, Escherichia coli, Zygosaccharomyces bailii and Candida utilis. The minimal inhibitory concentrations of the polysaccharide determined by the double broth dilution method were 15.6, 31.3, 31.3, 31.3, 125 and 125 (μg/ml) against the microorganisms mentioned above, respectively. The possible targets of the polysaccharide in bacteria might be cell wall, cytoplasmic membrane and DNA as indicated by electron microscopy, leakage of protein, cytoplasmic membrane permeability and DNA binding, respectively. Moreover, the antibacterial activity remained unchanged after being treated at 100 °C for 10 min, which indicated that the polysaccharide had a good heat-stability. In addition, it was safe according to mouse toxicity. All of these suggested that the polysaccharide might be used as a potential antimicrobial in food.     

Assessment of antibacterial activity of fractions from burdock leaf against food-related bacteria

The chemical composition and antibacterial activities of burdock leaves fractions against six food-related bacteria (Staphylococcus aureus, Streptococcus pneumoniae, Bacillus subtilis, Escherichia coli, Shigella dysenteriae and Salmonella typhimurium) were first investigated. The burdock leaves extract was fractioned with ethyl acetate, n-butanol and water, named as EF, BF and WF. The data from minimum inhibitory concentration (MIC) values showed that EF and other fractions effectively inhibited the growth of all test bacterial pathogens, the antibacterial activity of EF being much greater than BF and WF. The time–kill study indicated that EF exhibited significant bactericidal activity against all the six pathogens. At 12 h, EF was bactericidal for 4/6, 6/6 and 6/6 strains at 1× MIC, 3× MIC and 5× MIC, respectively. For all the fractions, the antibacterial capacity had a significant correlation with total phenolic content, suggesting that the activities were probably due to the combined action of phenolic compounds. The phenolic compounds of the fractions were then identified for the first time. After activity-guide fractionation and separation by flash chromatogram, two purified active compounds (chlorogenic acid, rutin) were obtained, and identified by UPLC–MS/MS. The ethyl acetate fraction based on its lower MIC values, concentration and time-dependent antibacterial and bactericidal activities could be useful in control of foodborne bacterial pathogens.     

Analysis of lignin-derived phenolic compounds and their transformations in aged wine distillates

Aromatic aldehydes and acids derived from lignin were studied by capillary zone electrophoresis in barrel matured wine distillates used in brandy production. Different conditions of analysis were applied to set up the best separation and reproducibility. The optimal separation was performed using 25 mM borate buffer containing 8% v/v ethanol as modifier. Total amount of guaiacol-type compounds (coniferaldehyde, vanillin, and vanillic acid) and syringol-type compounds (sinapaldehyde, syringaldehyde, and syringic acid) increased with increasing ageing time for distillates aged from 1 to 25 years. Sum of concentrations of syringic and vanillic acids can be also used for characterizing aged distillates according to their ageing level. The developed analysis method is simple, precise and cost efficient. It provides good separation efficiency, and it is ideally suited for the analysis of aged wine distillates for determination of their overall quality, approximate ageing time and signs of counterfeiting.     

宝明页岩油酚类化合物的富集分离与鉴定

以新疆宝明页岩油为原料,经过糠醛溶剂精制,初步得到浓缩酚类化合物的抽出油。切取抽出油不高于280℃的馏分作为酚类化合物深度富集的原料,采用柱色谱等分离方法分离得到酚类化合物。采用FTIR和GC-MS等技术分别对富集的酚类化合物进行官能团检测和定性、定量分析。实验结果表明,新疆宝明页岩油中酚类化合物主要富集在抽出油不高于260℃和260~280℃两段馏分中,分别占各馏分质量的38.6%和25.4%。通过柱色谱等过程富集分离了抽出油不高于280℃馏分中的酚类化合物,并在富集分离的产物中检测出22种酚类化合物,其中主要为C_(1~3)苯酚类化合物。     

Total antioxidant capacity of plant infusions: Assessment using electrochemical DNA-based biosensor and spectrophotometric methods

Nine plant infusions were assessed in terms of their polyphenolic compounds and antioxidant capacity properties by performing a “battery” of assays. Bioactive compounds (total phenolic and flavonoid content) were measured using spectrophotometric procedures and the total antioxidant capacity was determined by DPPH-RSA, FRAP and DNA-based biosensor against the reactive oxygen species: HO and H₂O₂. Although the optical methods are based on the donation of hydrogen or electrons between antioxidants and radicals, the DNA-based biosensor intends to simulate an in vivo assay by exposing DNA layer to biological ROS and antioxidants. In general, green and black tea showed higher polyphenolic content and antioxidant capacity evaluated by the described methods. All the analysed plant beverages showed to be a good source of bioactive compounds, particularly the green and black tea, peppermint and senna.     

Antibacterial activity of lactic acid bacteria against spoilage and pathogenic bacteria isolated from the same meat small-scale facility: 1—Screening and characterization of the antibacterial compounds

A total of 87 lactic acid bacteria (LAB) (36 Lactobacillus sakei, 22 Enterococcus faecium, 16 Lactococcus garvieae, 11 Vagococcus carniphilus and 2 Enterococcus sp.) isolated from a small-scale facility producing traditional dry sausages were screened for antagonistic activity against other LAB and some spoilage and pathogenic microorganisms, also isolated from the same processing facility, except Listeria innocua (in lieu of Listeria monocytogenes) and Escherichia coli. The final goal was to investigate LAB antibacterial activity within the facility microbial ecosystem and to select interesting strains for the role of bio-preservatives.Twenty-one Ec. faecium, 6 Vc. carniphilus, 4 Lc. garvieae, 3 Lb. sakei and 2 Enterococcus sp. were shown to inhibit the growth of some indicator microorganisms in an agar well diffusion assay. Except 2 Lb. sakei and an Enterococcus sp., all these isolates exhibited antibacterial activity against L. innocua, but only 3 Ec. faecium, 5 Vc. carniphilus and 3 Lc. garvieae displayed also antagonistic activity against Staphylococcus aureus. The 5 Vc. carniphilus isolates were also found to be inhibitory for the Gram-negative bacterium Hafnia alvei.Isolates displaying antibacterial activity against L. innocua and/or Sc. aureus were investigated for the nature of antibacterial compounds synthesized against these indicator microorganisms. Bacteriocin-like production could be detected only on agar plated in overlay assays, and was unsuccessfully researched in cell-free culture supernatant fluids under conditions that eliminate acid and hydrogen peroxide inhibition. Results also showed that a Lb. sakei isolate displayed an additional inhibitory effect by H₂O₂ against L. innocua. These isolates will be investigated for their ability to repress the growth of undesirable bacteria in biofilms, i.e., the real mode of bacterial attachment.This is the first report on bacteriocin-like from Vc. carniphilus and on bacteriocin-like from Lc. garvieae active against both L. innocua and Sc. aureus species.     

低共熔法在萃取酚类化合物中的应用进展

利用酚与氢键受体形成氢键的低共熔法萃取煤焦油中的酚具有能耗低、污染小和效率高等优点。综述了近年来低共熔法萃取分离酚的研究进展,对影响萃取效率的主要因素、萃取剂的回收、萃取分离机理和理论发展进行了分析总结。指出低共熔法萃取分离酚存在的主要问题,并对该方法的发展趋势进行了展望。     

Potential of phenolic compounds for controlling lactic acid bacteria growth in wine

Lactic acid bacteria are important in enology since they undergo the malolactic fermentation, a process which main effect is the reduction of wine acidity and is almost indispensable in red wine-making. However, if this process is not well controlled during the elaboration of wine, alterations in wine quality due to bacteria metabolic activity can happen. Polyphenols are wine natural components in must and wine that can potentially affect the growth of lactic acid bacteria and the malolactic fermentation. In this paper, after describing the main features of the malolactic fermentation in wine, we review the use of different chemical substances to control growth of lactic acid bacteria in enology. Special attention is given to phenolic compounds, being revised the recent studies about the effect of polyphenols on the growth and metabolism of lactic acid bacteria in wine in order to establish the extent to which these compounds are involved in malolactic fermentation during wine-making. Finally, the potential use of phenolic extracts as new antimicrobial agents during wine-making, as a total or partial alternative to traditional treatments mainly using sulphur dioxide (SO₂) is discussed.     

Plant aqueous extracts: Antioxidant capacity via haemolysis and bacteriophage P22 protection

The bacteriophage P22/Salmonella Typhimurium system, as well as human erythrocytes have been used to assay for protection, against forced oxidation caused by hydrogen peroxide, brought about by several aqueous extracts of selected adventitious plants grown in Portugal.This study proved, for the first time, that the aforementioned bacteriophage-based system is a suitable method to assess the antioxidant activity of plant extracts; among the 12 plants tested, raspberry (Rubus idaeus), sage (Salvia sp.), savory (Satureja montana) and yarrow (Achillea millefolium) were found to effectively protect against oxidative damage caused by H₂O₂. Haemolysis was inhibited via pre-treatment with every plant extract tested, except heath at 0.1% (w/v).The two analytical methods produced different results – and for some plants, there was a dependence (either direct or inverse) of the quantitative protection effect on extract concentration, whereas for others no significant dependence was found at all. Savory yielded the most promising results, using either method.Therefore, the P22/Salmonella system can be used as a suitable in vivo assay, and human erythrocytes as a suitable in vitro assay to confirm (or not) the antioxidant capacity of plant extracts in biological matrices.