Erythorbate Research Articles

Lipase-catalyzed synthesis of erythorbyl oleate and its characterization as a multifunctional emulsifier.

Erythorbyl oleate (EO), a novel emulsifier with multifunctional properties, was synthesized via lipase-catalyzed solvent-free esterification between erythorbic acid and oleic acid. The reaction produced EO of 30.75±1.65mM at 60h, monitored by high-performance liquid chromatography (HPLC) analysis. Purified EO was chemically identified as 6-O-oleoyl-erythorbic acid by HPLC-electrospray ionization/mass spectrometry (ESI-MS), 1H nuclear magnetic resonance (NMR), and 13C NMR analyses, and further investigations on its multifunctionalities were conducted. EO displayed antioxidant activity equivalent to erythorbic acid in 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activities. Investigation of the antibacterial activity of EO against foodborne pathogens showed MICs of 0.27±0.09 and 0.40mM for Bacillus cereus ATCC 10876 and Staphylococcus aureus ATCC 12692, respectively. EO also displayed interfacial properties, lowering interfacial tension between medium-chain triglyceride oil and water to 3.40±0.04 mN/m with a critical micelle concentration of 2.54±0.03mM. Dynamic light scattering analyses of the emulsion stabilized by EO demonstrated a similar polydispersity index (0.15±0.00) to Tween 80-stabilized emulsion (0.28±0.01), with an average droplet size of 173.2±1.8nm. In addition, the EO-stabilized emulsion exhibited a negative surface charge (-56.83±4.30mV) in zeta potential measurements, indicating sufficient electrostatic repulsion between droplets. These results suggest that EO is a multifunctional emulsifier to simultaneously control oxidative rancidification and bacterial spoilage in emulsion-based foods. Practical Application: EO was synthesized via an enzymatic esterification reaction between erythorbic acid and oleic acid. The synthetic process excluded any use of organic solvent, diminishing potential health hazards or environmental pollution associated with chemical reactions. The interfacial properties of the resultant EO, along with excellent antioxidant and antibacterial activities, propose its potential application in emulsion-based foods. Simultaneous control of bacterial spoilage and oxidative rancidification by EO would fulfill the industrial needs for extending shelf life and enhancing consumer safety.

Antifungal and Antioxidant Properties of Some Artificial Antioxidants, Generally Recognized as Safe Compounds and Nano-Oxides

In this study, the usage potential of some artificial antioxidants, generally recognized as safe (GRAS) compounds and nano-oxides solutions in wood preservation industry, was investigated. For this purpose, antifungal and antioxidant properties of solutions were determined. Erythorbic acid, ethoxyquin, potassium disulfide, sodium ascorbate, sodium erythorbate and Enginerring and Nature Sciences Faculty (TBHQ) were selected as artificial antioxidants; dehydroacetic acid, sorbic acid and sodium benzoate were used as GRAS compounds and nano MgO, nano CeO, nano ZnO, nano SiO2 and TiO2 were investigated as nano-oxides in this study. Three different concentrations (0.5%, 1.0% and 1.5% ) were prepared, and anti-fungal test were carried out. The brown rot fungus Coniophora puteana (Schumach.) P. Karst. (BAM Ebw. 15) was used for the anti-fungal test. Then antioxidant activity of the solutions were determined. Iron (III) ion reducing antioxidant power method (FRAP) was used to determine the antioxidant activity of solutions. All solutions at 1.5% concentration completely inhibited the growth of C. puteana fungus. The antioxidant activity of solutions was sorted as artificial antioxidants>GRAS compounds>nano-oxides, respectively. It was concluded that the tested substances can be used as impregnating agents in wood preservation.

Chiral Effect on the Electrochemistry of Magnetic Ferrite Colloidal Nanocrystal Assembly Modified by Amino Acids.

Chirality on the molecular or nanometer scale is particularly significant in chemistry, materials science, and biomedicine. Chiral electrochemical reactions on solid surfaces are currently a hot research topic. Herein, a chiral solid surface is constructed in aqueous solutions by mixing chiral molecules, d- and l-glutamic, with γ-Fe2O3 and Fe3O4 nanoparticles (NPs) and MnFe2O4 colloidal nanocrystal assembly (CNA). Cyclic voltammetry and differential pulse voltammetry measurements are conducted in a phosphate buffer solution (PBS) containing ascorbic acid (AA) or isoascorbic acid (IAA), and a chiral effect appears on the electroreduction of ferric ions of amino acid-modified magnetic samples. A negative or positive potential shift is observed, respectively, for magnetic structures modified by l- and d-glutamic acid in aqueous AA electrolyte, while the opposite is observed for these samples in IAA electrolyte. The reduction peak current increases by 0.8-1.2 times for the electrodes modified with l- and d-glutamate molecules, improving the electron transport efficiency. The chiral effect is absent when the electrolytes contain achiral uric acid or dopamine, or even chiral l-/d-/ld-tartaric acid. The chiral recognition between d-/l-glutamic acid and AA/IAA at the electrochemical interface is suggested to be related to their spinal configurations. These observations will be helpful for the rational design of inorganic functional chiral micro/nanostructures.

The Effects of Cl− and Selected Deoxidizers on the High-Temperature Corrosion Electrochemistry of Alloy 690 in Nuclear Steam Generator Water

The heat transfer tube in a steam generator serves as a critical heat exchange component in the primary and secondary loops of pressurized water reactor (PWR) nuclear power plants. The corrosion resistance of the heat transfer tube material directly influences the longevity of PWR nuclear power plants. This study investigated the electrochemical corrosion properties of 690 alloy (UNS N06690) in a simulated secondary water environment of PWR, focusing on different chloride ion concentrations and combinations of deoxidizers. The findings reveal a gradual decrease in the corrosion potential of 690 alloy, accompanied by an increase in self-corrosion current and a progressive reduction in the passivation range, ultimately leading to its disappearance as chloride ion concentration rises from 0 µg/L to 500 µg/L. Moreover, the impedance value of the inner film exhibits a declining trend with an increase in chloride ion concentration. Conversely, the resistance value of the outer film remains relatively stable while the size and spacing of oxide particles on the surface of the 690 alloy continuously increase. This observation suggests that chloride ions primarily influence the formation of the inner passivation film, which in turn determines the corrosion resistance of the 690 alloy. Notably, the performance of the 690 alloy is similar when the deoxidizer combination is ammonia (NH3) + erythorbic acid (ERA) or NH3 + hydrazine (N2H4), demonstrating the ability to form a relatively complete passivation film and exhibit improved corrosion resistance compared to NH3+N-isopropyl hydroxylamine, additionally, when the deoxidizer combination is NH3+N2H4, the 690 alloy exhibits lower self-corrosion current density across different chloride ion concentrations, indicating enhanced corrosion resistance.

Usporedba sadržaja antioksidansa u različitim mesnim proizvodima s hrvatskog tržišta

Food additives are defined as any substance not normally consumed as a food itself and not normally used as a characteristic ingredient of food, whether or not it has nutritive value. Antioxidants are a class of food additives that can be added to meat products to prevent lipid oxidation, retard development of off-flavours, or improve colour stability. Ascorbic acid (AA) and erythorbic acid (EA) are antioxidants permitted for use in meat preparations and meat products. This study aimed to compare the content of AA and EA in dry and semidry sausages collected on the Croatian market during a 4-year period and to determine their conformity with consumer safety regulations. AA and EA were analysed by a validated UHPLC method with a limit of detection and limit of quantification below 3 and 10 mg/L, respectively. The concentration of AA in dry sausages ranged from 13 to 457 mg/kg and in semi-dry sausages from 170 to 545 mg/kg, while the concentration of EA ranged from 198to 472 mg/kg in dry sausages and from 14 to 400 mg/kg in semi-dry sausages. In total, 12 samples (8.9%) were non-compliant due to an excessive concentration of EA.

UPLC-QTOF/MS-MS Based Profiling Coupled to Antioxidant Activity for Evaluation of Unripe Acerola Fruits from Different Clones

The potential of four commercial clones of unripe acerola fruit was investigated regarding a source of nutraceuticals and functional foods for industrial use. The chemical profiling of the BRS 235-Apodi, BRS 236-Cereja, BRS 237-Roxinha, and BRS 238-Frutacor clones was determined by the ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS-MS) technique coupled to multivariate statistical analysis, which were then correlated to ABTS•+ radical capture (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and ferric reducing antioxidant power (FRAP) assays in order to measure the antioxidant capacity. A total of 24 bioactive compounds were identified, including high amounts of quercetin-O-hexoside, astilbin, and apigenin, which were correlated to three clones (BRS 235, BRS 237, and BRS 238). On the other hand, the BRS 236 clone presented high contents of ascorbic acid, iso-ascorbic acid, citric acid, procyanidin B trimer, rutin, phenolic compounds, and antioxidant activity. These compounds were additionally found to be strongly associated with the antioxidant capacity of unripe acerola fruits. Therefore, the present study revealed that BRS 236 is a promising clone as an antioxidant source to be used as a functional food or ingredient.

Erythorbic Acid and Sodium Erythorbate.

The Expert Panel for Cosmetic Ingredient Safety reviewed newly available studies since their original assessment in 1999, along with updated information regarding product types and concentrations of use, and confirmed that Erythorbic Acid and Sodium Erythorbate are safe as cosmetic ingredients in the practices of use and concentration as described in this report.

Assessment of dietary exposure to food additives used in Polish processed meat products

Dietary exposure assessments have been performed for nitrites, phosphates, erythorbic acid, and sodium erythorbate in processed meat in Poland. The exposure has been estimated based on the maximum level of use of additives contained in Regulation - tier 2 and the concentration of additives in processed meat - tier 3, additionally for nitrites. Daily intake was estimated using 24-h recall, repeated three times. Exposure analyses were correlated with the frequency of occurrence of food additives based on label analysis (tiers 2a and 3a). The mean nitrite intake from processed meat at tier 2 was 0.1 mg/kg bw (143% ADI), 0.08 mg/kg bw (118% - ADI) at tier 2a, 0.03 mg/kg bw (43% - ADI) at tier 3, and 0.026 mg/kg bw (37% - ADI) at tier 3a. The mean intakes of phosphate and erythorbic acid/sodium erythorbate from processed meat were 3.26 and 0.54 mg/kg bw (8.2% and 9% - ADI), respectively at tier 2. None of the respondents exceeded the ADIs for phosphates or erythorbic acid/sodium erythorbate. In contrast, nitrite consumption is of great concern because of significant ADI exceedances, particularly among young children.

Physicochemical properties of in situ microwave-assisted germanium oxide modified nitrogen-doped carbon dots

Preparation of carbon dots (CDs) and nitrogen-doped carbon dots (NCDs) with germanium oxide (GeO2/GeO) using a facile one-step microwave-assisted synthesis procedure is presented. Iso-ascorbic acid, urea and Ge-132 were used as carbon, nitrogen and germanium sources, respectively. Studies have shown that the CDs, NCDs and GeO2/GeO nanoparticles individually have excellent qualities for bio-imaging applications including photoluminescence, biocompatibility, good stability and low toxicity. While CDs have been thoroughly explored in literature, CDs with germanium oxide on their surface are an avenue that has scarce information. Hence the synthesis and physicochemical characterizations of CDs- /NCDs- GeO2/GeO composites were studied using different microscopic and spectroscopic techniques to explore their compatibility for bio-imaging applications. In the presence of Ge, the approximate particle sizes of both the CDs and NCDs increased from 2.5 nm to 5.8 nm and the spherical or quasi-spherical shape was maintained. The X-ray photoelectron spectroscopy survey spectrum showed that the surface of Iso-N-Ge-CDs contained nitrogen and germanium, indicating the successful synthesis of nitrogen-doped carbon dots (NCDs) with germanium oxide (GeO2/GeO). Photoluminescence emissions of longer wavelengths suitable for cell imaging were observed for Iso-N-Ge-CDs (350 nm) and Iso-Ge-CDs (430 nm) and the Iso-N-Ge-CDs are able to fluoresce under the red and blue wavelengths. The Ge-NCDs demonstrated excitation-dependent emission wavelength behaviour, pH sensitivity and Fe3+ sensitivity which may be used as a probe for Fe3+ metal ions and intracellular pH measurements.

Enhancing oxygen scavenging properties of erythorbic acid through transition metal catalysis

The presence of oxygen in pipelines used in power plants and the oil industry requires vigilant attention and utilization of oxygen scavenging to prevent the deleterious effects of corrosion. This study aims to investigate the efficacy of four transition metal catalysts (manganese, copper, nickel, and chromium) on the effectiveness of erythorbic acid as an oxygen scavenger. The experimental approach involved injecting varying concentrations (5 ppm, 10 ppm, and 20 ppm) of transition metal catalyst solutions with erythorbic acid at concentrations of 20 ppm, 50 ppm, and 100 ppm, while maintaining a controlled temperature of 25 °C and a pH of 9.0 at a saturated oxygen concentration. The outcome of the study demonstrated that nickel and chromium did not improve the oxygen removal rate, while copper exhibited notable results compared to the control catalyst (manganese). Specifically, the copper (I) chloride solution proved to be the most efficient in reducing dissolved oxygen content to levels below 20 ppb.

Changes in the firmness and other quality parameters of fresh-cut ‘Maradol’ papaya treated with additives and 1-methylcyclopropene

This study aimed to evaluate the effect of 1-methylcyclopropene (1-MCP) applied as pre-cutting, post-cutting, and double application (before and after cutting) on the changes in the firmness and quality parameters of fresh-cut ripe ‘Maradol’ papaya. Four treatments (T1 T4) were used. T1 (Control treatment): Fresh-cut ‘Maradol’ papaya slices (Control treatment or T1) dipped in 1% CaCl2 for 2 min, then sprayed with 0.1% iso-ascorbic acid and 0.05% sorbic acid. One part of the T1 slices were treated with 1000 nL/L of 1-MCP for 12 h at 10 °C (T2). T3: Fresh-cut papaya slices treated with the same additives from the whole papaya treated 1000 nL/L of 1-MCP for 12 h at 20°C. T4: Fresh-cut papaya with additives treated with 1-MCP before and after cutting. All slices were packed in polypropylene trays with a perforated cover and stored at 4 ºC. T3 and T4 slices exhibited lower firmness loss and decreased activity of pectin methylesterase, polygalacturonase, and beta-galactosidase compared to T1 and T2 slices. Moreover, T3 and T4 slices had low translucency and microbial load, complying with the European Union limit (3 log CFU/g). No significant variations in acidity, pH, and total soluble solids were noted between treatments, but higher color values were obtained in T3 and T4 slices. To the best of our knowledge, this is the first study where the combining effects of additives and 1-MCP application before and after cutting extended the shelf-life of fresh-cut ‘Maradol’ papaya for up to 13 days at 4 °C, twice the duration reported by others. Keywords: Carica papaya, Postharvest, Translucency, Quality, Shelf-life

Pilot-Scale Antioxidant Dipping of Herring (Clupea harengus) Co-products to Allow Their Upgrading to a High-Quality Mince for Food Production.

To enable production of high-quality mince from herring backbones, a scalable antioxidant strategy is needed due to the high susceptibility of herring muscle to lipid oxidation. We here measured the stabilizing effect of lab-/pilot-scale predipping of herring backbones (30-500 kg) in antioxidant solutions prior to production of mechanically separated mince (MSM). The antioxidants were (i) Duralox MANC, a mixture of rosemary extract, ascorbic acid, α-tocopherol, and citric acid, and (ii) rosemary extract with or without isoascorbic acid. Delivery of the key rosemary-derived antioxidant components carnosol and carnosic acid was monitored during the dipping process and ice/frozen storage. Predipping in 2% Duralox MANC gave MSM with 26.7-31.7 mg/kg carnosol + carnosic acid and extended the oxidation lag phase from <1 to 12 days during ice storage and from <1 to 6 months during frozen storage compared to control. Dipping in 0.2% rosemary extract with or without 0.5% isoascorbic acid solution gave MSM with 20.6-28.2 mg/kg carnosol + carnosic acid and extended the lag phase to 6 days and 9 months during ice and frozen storage, respectively. Our results confirmed, in pilot scale, that predipping herring coproducts in antioxidant solutions is a promising strategy to utilize these raw materials for, e.g., mince and burger production rather than for low value products as fish meal.

Elderberry (Sambucus nigra L.) Encapsulated Extracts as Meat Extenders against Lipid and Protein Oxidation during the Shelf-Life of Beef Burgers.

In this work, we studied the impact of encapsulated elderberry extracts as natural meat extenders to preserve both the quality and the oxidative stability of beef burgers. In particular, the comprehensive chemical changes of beef burgers treated with different antioxidants, namely, (a) a control without antioxidants, (b) 0.5 g/kg sodium erythorbate (ERY), (c) 2.5 g/kg encapsulated elderberry extract (EE 2.5), and (d) 5 g/kg encapsulated elderberry extract (EE 5), each one packaged under modified atmosphere (80% O2 and 20% CO2) for 13 days storage at 2 ± 1 °C, were deeply evaluated. Overall, EEs showed a wide array of antioxidant compounds, namely polyphenols like anthocyanins, flavonols, and phenolic acids. Multivariate statistics provided marked chemical differences between burgers manufactured with EEs and synthetic antioxidants (ERY) during 13-days storage in terms of both metabolomic profiles and typical lipid/protein oxidation markers (such as malondialdehyde and total carbonyls). Most of the differences could be attributed to some discriminant compounds, namely glutathione, 4-hydroxy-2-nonenal, hydroxy/peroxy-derivatives of fatty acids, carbonyl compounds (such as 5-nonen-2-one and 1,5-octadien-3-one), and cholesterol. Interestingly, significant correlations (p &lt; 0.01) were observed between malondialdehyde, total carbonyls, and these discriminant metabolites. The combination of spectrophotometric approaches and a high-throughput untargeted metabolomics analysis outlined a strong modulation of both lipid and protein oxidations, likely promoted by the encapsulated meat extender (elderberry), thus confirming its ability to delay oxidative phenomena during the shelf-life of beef burgers.

Lipase-catalyzed synthesis of antibacterial and antioxidative erythorbyl ricinoleate with high emulsifying activity

Erythorbyl ricinoleate (ERO) was synthesized as a novel multi-functional emulsifier with antibacterial and antioxidative activities via lipase-catalyzed esterification between erythorbic acid and ricinoleic acid. Esterification regioselectively produced ERO (6-O-ricinoleoyl-erythorbate) of 238.67 mM at 48 h. ERO effectively reduced interfacial tension to 2.66 mN/m at its critical micelle concentration (0.73 mM), compared with other erythorbyl fatty acid esters (EFEs). Oil-in-water (O/W) emulsion stabilized by ERO remained stable for 15 days with a droplet size of 256.3 nm and polydispersity index of 0.22, whereas the emulsion stabilized by the other EFEs became unstable within six days. ERO had antibacterial activity against Gram-positive bacteria with minimum inhibitory concentrations from 0.2 to 0.6 mM. In O/W emulsion, ERO exhibited higher antioxidative activity than erythorbic acid against lipid oxidation. These findings suggest that ERO has high potential as multi-functional food additive to control lipid oxidation and bacterial contamination for O/W emulsion foods.

Effect of antioxidants on lipid oxidation in herring (Clupea harengus) co-product silage during its production, heat-treatment and storage

Provided high product quality, ensilaging can be used to valorize fish filleting co-products into a silage suitable for food applications. However, a documented challenge for products from hemoglobin-rich fish raw materials is the high susceptibility to lipid oxidation, calling for stabilization by antioxidants. In a comparison among different rosemary-containing antioxidants and isoascorbic acid, we here found that the commercial mixture Duralox MANC-213 (MANC) provided the best protection against peroxide value and 2-thiobarbituric acid reactive substances (TBARS) development during ensilaging of herring filleting co-products (0–7 days, 22 °C), and also during subsequent heat-treatment (30 min, 85 °C). Increasing MANC concentration from 0.25 and 0.75 to 1.25% lowered TBARS values from 43.53 and 25.12 to 18.04 µmole TBARS/Kg silage, respectively, after 7 days of ensilaging. During storage at 4 °C/22 °C in presence of MANC, 1.25% provided the highest protection with 87–90% and 66–73% lower TBARS, at 4 °C and 22 °C, respectively, at 6 months compared to the controls. At this time point, heat-treated silages had lower protein degree of hydrolysis and free amino acids values than the non-heat-treated one. Regardless of antioxidant addition, total volatile basic nitrogen (TVB-N) formation still increased during the storage, but, overall, TVB-N values in silages were below the acceptable limit of 30 mg TVB-N/100 g fish for human consumption. Together with lipid oxidation data, this suggest that herring silage produced in presence of antioxidants can be used both for high quality feed and food applications.

Effects of different concentrations of sodium hypochlorite on dentine adhesion and the recovery application of sodium erythorbate.

Root canal therapy is the most effective and common method for pulpitis and periapical periodontitis. During the root canal preparation, chemical irrigation plays a key role. However, sodium hypochlorite (NaOCl), the widely used irrigation fluid, may impact the bonding strength between dentin and restorative material meanwhile sterilization and dissolving. Therefore, it's important to explore the influence of NaOCl on the adhesion between dentin and restoration materials to ensure clinical efficacy. This study aims to explore the effect of NaOCl on dentine adhesion and evaluate the effect of dentine adhesion induced by sodium erythorbate (ERY), and to provide clinical guidance on dentin bonding after root canal therapy. Seventy freshly complete extracted human third molars aged 18-33 years old, without caries and restorations were selected. A diamond saw was used under running water to achieve dentine fragments which were divided into 10 groups with 14 fragments in each group: 2 control [deionized water (DW)±10% ERY] and 8 experimental groups (0.5%, 1%, 2.5%, and 5.25% NaOCl±10% ERY). The dentine specimens in the control group (treated with DW) and the experimental groups (treated with 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl) were immersed for 20 min using corresponding solutions which were renewed every 5 min. The other 5 groups were immersed in 10% ERY for 5 min after an initial washing with DW for 1 min. Then, we selected 4 dentine fragments from all 14 fragments in each group and the numbers and diameters of opening dentinal tubules were observed under scanning electron microscope (SEM). The other 10 dentine fragments from each group were used to make adhesive samples by using self-etch adhesive wand composite resin. All the above adhesive samples were sectioned perpendicular to the bonded interface into 20 slabs with a cross-sectional area of 1 mm×1 mm using a diamond saw under the cooling water, and then the morphology of 10 slabs in each group's bonding interface was observed from aspects of formation of resin tags, depth of tags in dentin, and formation of hybrid layer under SEM. The other 10 slabs of each group's microtensile bond strength and failure modes were also analyzed. Among the 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl groups, the number and diameter of patent dentinal tubules gradually increased with the rise of concentration of NaOCl solution (all P<0.05). Among the DW, 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl groups, the number and diameter of patent dentinal tubules increased after using ERY, but without significant difference (all P>0.05). Among the DW, 0.5% NaOCl, 1% NaOCl, and 2.5% NaOCl groups, the scores of formation of resin tags under SEM gradually increased with the increase of concentration of NaOCl solution, while the score in the 5.25% NaOCl group decreased significantly compared with the score of the 2.5% NaOCl group (P<0.05). There was no significant difference between using 10% ERY groups and without using 10% ERY groups (all P>0.05). The scores of length of the tags under SEM in the 5.25% NaOCl group was significantly higher than the scores of DW, 0.5% NaOCl, and 1% NaOCl groups (all P<0.05), and it was also higher than the score of the 2.5% NaOCl group, but without significant difference (P>0.05). There was no significant difference between using 10% ERY groups and without using 10% ERY groups (P>0.05). The scores of formation of hybrid layer under SEM in the 2.5% NaOCl and 5.25% NaOCl groups significantly decreased compared with the score of the DW group (all P<0.05). There were significant differences between the 2.5% NaOCl±10% ERY groups and between the 5.25% NaOCl±10% ERY groups (all P<0.05). Microtensile bond strength was greater in the 0.5% NaOCl, 1% NaOCl, and 2.5% NaOCl groups, but lower in the 5.25% NaOCl group than that in the DW group (all P<0.05). There were significant differences between the 2.5% NaOCl±10% ERY groups and between the 5.25% NaOCl±10% ERY groups (all P<0.05). The incidence of type "Adhesive" of failure modes in the 5.25% NaOCl group was significantly higher than that in other groups (all P<0.05), while the incidence of type "Adhesive" in the 5.25% NaOCl+10% ERY group was lower than that in the 5.25% NaOCl group (P<0.05). The bonding strength to dentine increases with the increase of NaOCl concentration when the concentration lower than 2.5%; whereas it is decreased at a higher concentration (such as 5.25%). 10% ERY has a definite recovery effect on attenuated bonding strength to 5.25% NaOCl-treated dentine.

Short communication: Antibacterial and antibiofilm effect of natural substances and their mixtures over Listeria monocytogenes, Staphylococcus aureus and Escherichia coli

Natural antimicrobial agents used as food additives and agents for active food packaging development are a promising way to reduce food-associated microbial risks. We compared the antibacterial and antibiofilm effect of seven natural-origin additives suitable for active food packaging (calcium lactate, citric acid, curcumin, erythorbic acid, garlic extract, hop extract, nisin) against Listeria monocytogenes, Staphylococcus aureus, and Escherichia coli. Minimal inhibitory concentration (MIC) and MIC for biofilm formation (MICBF) were determined. All the tested substances provided a significant antibacterial effect (p ≤ 0.05); among the tested bacteria, E. coli was the most resistant strain to all substances (p ≤ 0.05). Citric acid (MIC and MICBF 0.25–0.5 wt%), garlic extract (MIC and MICBF 2.0–4.0 wt%), and erythorbic acid (MIC 3.0–5.0 wt%; MICBF 2.0–5.0 wt%) were evaluated as the most effective ones. Further, mixtures of garlic extract and i) calcium lactate, ii) curcumin, iii) erythorbic acid, iv) hop extract, v) nisin provided synergy and higher bacterial suppression than the substances alone, even for E. coli (p ≤ 0.05). Thus, this strategy of combining two food additives could prolong the product shelf-life when incorporated, for example, into functionalized food packaging (nano)materials.

A Recyclable Dipping Strategy to Stabilize Herring (Clupea harengus) Co-products During Ice Storage

Applying value-adding techniques to fish filleting co-products is rendered difficult due to their high susceptibility to lipid oxidation, microbial spoilage, and amine formation. In this study, a recyclable dipping strategy was developed and investigated for its ability to stabilize herring (Clupea harengus) co-products (head, backbone, caudal fin, intestines, belly flap, skin, and in some cases roe) against oxidation and microbial spoilage. From initial screening of seven antioxidative components/formulas in minced herring co-products during ice storage, an oil-soluble rosemary extract (RE-B) and isoascorbic acid (IAA) were identified as most promising candidates. These compounds were then formulated to a recyclable solution to be used for dipping of the herring co-products. The commercial Duralox MANC antioxidant mixture was used as a positive control. Dipping in 0.2% RE-B solution ± 0.5% IAA or in 2% Duralox MANC solutions remarkably increased the oxidation lag phase from < 1 day to > 12 days during subsequent storage on ice (0–1 °C) of minced or intact co-products, respectively, even when the antioxidant solutions were re-used up to 10 times. The dipping also reduced microbiological growth and total volatile basic nitrogen, but the effect became weaker with an increased number of re-using cycles. The presented dipping strategies could hereby facilitate more diversified end use of herring co-products from current fish meal to high-quality minces, protein isolates, or oils for the food industry.

Discovery and Biosynthesis of Ascorbylated Securinega Alkaloids

Securinega alkaloids represent a class of plant secondary metabolites with intriguing bridged tetracyclic structures and promising biological activities. Despite extensive synthetic efforts and a number of innovative total syntheses, no relevant biosynthetic genes have been reported to date. In this study, fluesuffine A (1), a C-2 and C-3 functionalized derivative of Securinega alkaloids with a fused 5/5/5/6/5/6/5 congested heptacyclic ring system, was isolated from Flueggea suffruticosa. In the biogenetic study of 1, we found a berberine bridge enzyme (BBE)-like enzyme (FsBBE), which could efficaciously catalyze the condensation of allosecurinine and l-ascorbic acid (l-AA) or dehydroascorbic acid (DHA), resulting in the chemical skeleton of 1. FsBBE also could catalyze the condensation of allosecurinine and isoascorbic acid to form another unnatural Securinega alkaloid fluesuffine B (2), an epimer of 1. Moreover, the catalytic mechanism study of FsBBE revealed the existence of an enamine intermediate (3), which was previously proposed as a key intermediate in the biosynthesis of C-2 and C-3 functionalized derivatives of Securinega alkaloids. The formation of 3 suggested that the epimers were synthesized via an intermolecular enamine-type addition reaction. Hence, our findings provide further insight into the biosynthesis of C-2 and C-3 functionalized derivatives of Securinega alkaloids and expand the diversity of ascorbylated natural product.

Erythorbyl laurate suppresses TNF-α-induced adhesion of monocytes to the vascular endothelium

Abstract Erythorbyl laurate (EL) can be produced via lipase-catalyzed esterification between erythorbic acid and lauric acid. In this study, we evaluate the anti-inflammatory effect of EL in the early stage of atherosclerosis. EL suppressed tumor necrosis factor (TNF)-α-induced monocyte adhesion to vascular endothelial cells and expression of vascular cell adhesion molecule (VCAM)-1 in human umbilical vein endothelial cells (HUVECs). Additionally, EL suppressed TNF-α-induced p65/IκB kinase (IKK)/IκB phosphorylation in HUVECs. Western blot analysis of cytosolic and nuclear cell fractions and immunofluorescence showed that EL suppressed TNF-α-induced translocation of p65 from the cytoplasm to the nucleus. EL also inhibited phosphorylation of extracellular-signal-regulated kinase (ERK) 1/2, p38, and c-Jun N-terminal kinases (JNK) 1/2 in HUVECs. EL suppressed TNF-α-induced phosphorylation of Akt, IRAK1, and TAK1 in HUVECs. Quantitative RT-PCR analysis showed that EL significantly suppressed TNF-α-induced interleukin (IL)1B, IL6, TNFA, and CCL2 mRNA expression in HUVECs. Additionally, oral administration of EL suppressed TNF-α-induced IL6 and TNFA expression in the mouse aorta. EL could represent a promising functional nutrient that can be ingested for the prevention of vascular inflammation via decreased monocyte infiltration to the vascular endothelium and suppression of inflammatory nuclear factor (NF)-κB and mitogen-activated protein kinases (MAPKs) signaling pathways.