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Armoracia rusticana P. G. Gaertner. belongs to the Brassicaceae family and has aroused scientific interest for its anti-inflammatory and anticancer activities. In a continuing investigation to discover bioactive constituents from A. rusticana , we isolated 19 phenolic glycosides including three undescribed flavonol glycosides and one undescribed neolignan glycoside from MeOH extract of this plant. Their structures were elucidated based on NMR spectroscopic analysis (1H, 13C, 1H–1H COSY, HSQC, and HMBC), HRESIMS, and chemical methods. The determination of their absolute configuration was accomplished by ECD and LC-MS analysis. All the compounds were assessed for their potential neurotrophic activity through induction of nerve growth factor in C6 glioma cell lines and for their anti-neuroinflammatory activity based on the measurement of inhibition levels of nitric oxide production and pro-inflammatory cytokines (i.e. , IL-1β, IL-6, and TNF-α) in lipopolysaccharide-activated microglia BV-2 cells. [Display omitted] • Four undescribed glycosides were isolated from the roots of Armoracia rusticana. • The structures were characterized through the 1D and 2D NMR and HRMS analysis. • The stereochemical assignments were carried out using ECD and LC-MS analysis. • Some compounds exhibited powerful NGF secretion activities. [ABSTRACT FROM AUTHOR]

• Low-temperature ball milling (LBM) can increase WHC and OHC of horseradish powder. • LBM helps improve flavor and increase pungent odor of the powder. • LBM helps increase total flavonoids and phenolic contents of the powder. • Flavonoids and phenolic contents are related to antioxidant activity of the powder. • Excessive milling time exhibits adverse effect on quality of the powder. Horseradish is widely used as a seasoning and food additive due to its unique flavor and ability to act as antioxidant, among other favorable characteristics. A dried powdery form of horseradish is desired as it is convenient for either domestic or industrial use. Size reduction time is among the most important parameters that needs to be optimized to produce horseradish powder of higher quality. In this study, dried horseradish was milled either for 15, 30, 60, 120 or 180 min using a low-temperature ball-milling pulverizer to obtain powder of different sizes. Effect of milling time on particle size, microstructure, color, water and oil holding capacities, flavor profiles, isothiocyanates, phenolics and flavonoids contents as well as radical scavenging activities of the powder was determined. Powder milled for 60 min exhibited a more intense pungent flavor, better physicochemical properties and higher flavonoids content, 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity and 2,2′-azino-bis 3-ethylbenzthiazoline-6-sulfonic acid (ABTS) free radical scavenging activity than the powder milled for different other periods of time. [ABSTRACT FROM AUTHOR]

Graphical abstract A nanochip biosensor was modeled in COMSOL Multiphysics and the proposed model was used to determine the phenol concentration in the presence of HRP. Experimental results from phenol measurement in the presence of HRP were in agreement with results of the proposed model. Highlights • A nanochip biosensor was modeled in COMSOL Multiphysics. • The proposed model was used to determine the phenol concentration in presence of HRP. • Cyclic voltammetric and chronoamperometric responses were predicated by the model. • Experimental results from phenol measurement in the presence of HRP were in agreement with the results of the model. • Diffusion layer of phenol enzymatic oxidation product was predicated by the model. Abstract Horseradish peroxidase enzyme selectively oxidizes phenol to o -quinone that can be reduced electrochemically to catechol and generating a current response which is directly proportional to phenol concentration. In order to investigate the o -quinone enzymatic production and its electrochemical behavior, a 2-D model was developed for a nanochip biosensor in COMSOL Multiphysics. The oxidation rate of phenol to o -quinone was predicted by the developed model based on Michaelis-Menten equation. The diffusion coefficient of o -quinone was obtained 2.17 × 10−6 cm2 s-1 based on experimental chronoamperograms. The cathodic and anodic peak potentials for o -quinone/catechol redox couple are obtained experimentally 255 and 310 mV, respectively. The obtained results from simulation were compared with the experimental results to verify the validity of the model. By comparing the cyclic voltammograms from the simulation and experimental results, the heterogeneous rate constant, k°, and the transfer coefficient, α, were calculated 0.02 cm s-1 and 0.5, respectively. Then, using simulation results, chronoamperograms were drawn for the nanochip biosensors with different heights. Also, o -quinone concentration gradients were determined at the electrode surface, which can be used to estimate the thickness of the diffusion layer. Finally, a calibration plot was obtained based on the simulation results of the proposed nanochip as phenol biosensor with the following equation I (nA) = 0.1497 C (μM)–0.3521 and a linear range of 20.0–150.0 μM. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • One-pot polymerization to prepare nanogel-based artificial enzymes, which is facile and scalable. • NAEs are much more stable than the natural HRP in a broad range of temperature and pH. • NAEs have a good enzymatic activity on several azo compounds. • NAEs are temperature-switchable, and have a great potential in controllable catalysis. Abstract Novel artificial enzymes are highly desired to overcome the shortcomings of natural enzymes during industrial or biological applications. Here we designed and prepared nanogel-based artificial enzymes (NAEs) to mimic natural horseradish peroxidase (HRP) using a facile one-pot, scalable method. The poly(N-isopropylacrylamide) (PNIPAM) matrix provided a temperature-responsive and size-controllable scaffold for the NAEs, and 1-vinylimidazole (Vim) moieties stabilized the enzymatic centers (Hemin) through coordination interaction. The feeding ratios of the components to prepare NAEs were subsequently studied and optimized to ensure the NAEs possess the highest catalytic activity and stability. The optimized NAEs were quite stable and can maintain their catalytic activities over a broad range of heat or pH treatments, and a long storage period as well. The NAEs are active to catalytic oxidation of several azo compounds and their activities can easily be switched on/off by changing the surrounding temperature. Taken together, these easily made, highly stable, efficient and activity-switchable NAEs could mimic natural HRP while overcoming their shortcomings and have a potential in wastewater treatment and controllable catalysis. [ABSTRACT FROM AUTHOR]

Based on the signal transduction with a horseradish peroxidase (HRP)-functionalized gold nanoprobe, this work develops a new electrochemical aptasensing method for kanamycin (Kana) detection. The aptasensor was constructed through the hybridization of biotinylated Kana-aptamer at its complementary oligonucleotide strand-modified electrode, followed by intercalating methylene blue (MB) into the formed double-stranded DNA (dsDNA). Then, the streptavidin and high-content HRP functionalized gold nanoparticle probes were bound onto the aptasensor. As the MB-mediated HRP-catalytic reaction could produce sensitive electrochemical signal and the aptamer-biorecognition toward Kana could cause quantitative decrease of MB intercalation and nanoprobe capture, convenient electrochemical signal transduction was achieved. Both the enzymatic reaction and nanoprobe signal amplification greatly enhance the electrochemical signal, offering ultrahigh sensitivity of the method. The MB intercalation into dsDNA not only provides necessary electron mediator for the enzymatic reaction but also simplifies the electrochemical measurement. Under optimal conditions, this method showed a wide linear range over four-order of magnitude with a low detection limit of 0.88 pg/mL. In addition, the aptasensor features high specificity, excellent repeatability and stability as well as satisfactory reliability. Thus it possesses valuable application potentials. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Non-fouling surfaces can be equipped with specific bioactivity. • Terminal click functionality useful for covalent attachment of enzymes on brushes. • Control of immobilized amount by spacer length and brush conformation. • Control of activity by spacer length and immobilized amount. Abstract Thermoresponsive poly(N -isopropylacrylamide) (PNIPAAm) brushes with terminal click functionality can be used to selectively immobilize enzymes. Exploiting their inherent protein-repellent and thus non-fouling properties, surfaces with specific bioactivity can be created in this way. This report describes the functionalization of alkyne-PNIPAAm brushes with two biotin linkers of different poly(ethylene glycol) (PEG) spacer length via click chemistry and the subsequent immobilization of streptavidin-conjugated horseradish peroxidase (SA-HRP) by the strong interaction between biotin and streptavidin. Spectroscopic ellipsometry is used to quantify the biotin and the SA-HRP amount on the PNIPAAm brushes. Enzyme activities are determined by UV‑vis spectroscopy. A better accessibility to the alkyne-functionalized chain ends for the short biotin-PEG 3 linker leads to a higher biotin amount on these PNIPAAm brushes, which in turn results in higher SA‑HRP amounts on biotin-PEG 3 -modified brushes in the swollen (20 °C) and collapsed state (37 °C) compared to biotin-PEG 23 -modified ones. For both linkers, an increased immobilization temperature leads to higher SA-HRP amounts due to an enhanced reaction kinetics and mobility. All immobilized SA-HRP amounts are in range of 81–98% monolayer coverage, except for SA-HRP immobilized on biotin-PEG 23 -modified PNIPAAm brushes at 20 °C, exhibiting only 43% monolayer coverage. A high mobility of the biotin linker combined with a low surface loading of SA-HRP is found to be beneficial for the activity of SA-HRP. Hence, the highest specific activity as measured by HRP-catalyzed 3,3´,5,5´‑tetramethylbenzidine (TMB) oxidation is found for a low SA-HRP amount on biotin-PEG 23 -modified brushes. [ABSTRACT FROM AUTHOR]

In this work, a sandwich-type electrochemical biosensing platform is developed based on carbon sphere-MoS 2 (CS-MoS 2 ) and target recycling amplification of catalyzed hairpin assembly (CHA) strategy for ultrasensitive determination of microRNA (miRNA). The CS-MoS 2 is prepared and used as sensing substrate, which shows high specific surface area, enhanced stability and good dispersibility. The capture probe is first modified on Au nanoparticles/CS-MoS 2 modified glassy carbon electrode through Au-S band, and hairpin DNA1 (H1) then reacts with it and unfolds its loop domain by hybridizing with target miRNA-21. The opened H1 subsequently assembles with biotin labeled hairpin DNA 2 (H2) to displace the target. The liberated miRNA-21 is free and backs to the original solution to proceed next circulation, resulting in the generation of large amounts of H1–H2 duplex. Massive signal indicators horseradish peroxidase are then immobilized on electrode, and catalyze hydrogenperoxide + hydroquinone (H 2 O 2  + HQ) system to produce a strong electrochemical response. The proposed assay benefits from advantages of sandwich-type structure, favorable electrochemical properties of CS-MoS 2 and CHA target recycling amplification strategy. Therefore, it exhibits a wide linear relation between 1 × 10 −16 and 1 × 10 −10  M with a low detection limit of 1.6 × 10 −17  M for miRNA-21 detection. [ABSTRACT FROM AUTHOR]

Background Multidrug-resistant (MDR) bacteria are increasingly causing urinary tract infections (UTI), which has been linked to frequent use of antibiotics. Alternative treatment regimens are urgently needed and natural isothiocyanates (ITC) may represent one. ITCs are natural plant products found in nasturtium ( Tropaeoli majoris herba ) and horseradish ( Armoraciae rusticanae radix ). Purpose The objectives were to (1) assess the antimicrobial effects of nature-identical ITCs for UTI treatment caused by uropathogenic E. coli (UPEC), (2) to evaluate a potential influence of antimicrobial resistance on ITC susceptibility, and (3) to test whether ITCs affect UPEC penetration into human uroepithelial cells. Methods We tested 217 clinical UPEC isolates, 54.5% of which were classified as MDR, for susceptibility against ITCs. ITC susceptibility testing was performed by broth dilution using a mixture of three synthetic ITCs. Internalization was tested using human T-24 bladder carcinoma cells in an internalization assay co-incubated with UPEC ( n  = 5) and ITCs. Results The mean minimal inhibitory concentration (MIC) 90 was 0.17 mg/ml, showing very high susceptibility against ITCs. Interestingly, MDR E. coli were significantly less susceptible than non-MDR strains ( p  = .01). Internalization of UPEC was decreased by 31.9% in the mean when treated with ITCs. Overall, ITCs exerted a strong antimicrobial activity against clinical UPEC isolates and reduced internalization into uroepithelial cells. Conclusion ITCs might present a promising treatment alternative for UTIs, expressing both high antimicrobial activity as well as blocking the pathogenic process of human cell penetration by UPEC. Clinical studies, however, are needed to confirm activity of ITCs in UTIs in vivo . [ABSTRACT FROM AUTHOR]

The cold-pressed horseradish (Armoracia rusticana L.) root juice was used for spray-drying encapsulation within different biopolymeric carriers (maltodextrin/alginate, maltodextrin/guar gum, and maltodextrin/gum Arabic) to ensure easier handling and preservation of its bioactive compounds. The obtained encapsulates were added in mayonnaise formulations as potential substitutes for synthetic antioxidants. Physicochemical, spectrophotometric, and chromatographic analyses of the encapsulates showed the presence of various phenolic compounds and a pronounced antioxidant activity. The encapsulates were stable in terms of total phenolic content retention over 6 months of storage at −18 °C. The determination of the peroxide and p -anisidine values as well as the accelerated oxidation stability analysis showed that the horseradish encapsulates added to the mayonnaise were more potent in maintaining the oxidative stability of the mayonnaise than the synthetic antioxidant. The added encapsulates positively affected the pH and acid values of the mayonnaises. Also, mayonnaises with encapsulates were sensory acceptable. These results suggest that encapsulated horseradish root juice within various carriers could find useful application as a natural antioxidant in food products to prevent oxidation and prolong shelf-life. [Display omitted] • Encapsulated horseradish root juice exhibited desirable physicochemical properties. • Encapsulates contained high amounts of phenols and potent antioxidant activity. • Adding the encapsulates to mayonnaise delayed the formation of oxidation products. • Mayonnaises with the encapsulated horseradish root juice were sensory acceptable. • Horseradish encapsulates could be potential substitutes for synthetic antioxidants. [ABSTRACT FROM AUTHOR]

The plants of the genus Armoracia P. Gaertn., B. Mey. & Scherb. (Brassicaceae) contain glucosinolates, which volatile hydrolysis products are known for their antimicrobial activity. In this work, the composition and antimicrobial activity of the root volatiles of wild-growing Armoracia macrocarpa (Waldst. & Kit.) Kit. ex Baumg., obtained by hydrodistillation, were analysed for the first time. These results were compared with those of widely used horseradish, A. rusticana P. Gaertn., B. Mey. & Scherb. Additionally, the possibility of the propagation of A. macrocarpa from the roots, and impact of its cultivation on the composition and antimicrobial activity of the root volatiles were investigated. The GC-FID and GC–MS analysis revealed that all A. macrocarpa root volatile fractions were dominated by berteroin (55.0–59.0%) and lesquerellin (34.1–36.4%), and were significantly different from horseradish root volatile fraction. In microdilution method, A. macrocarpa volatile fractions exhibited weak/no antibacterial activity, while their effect against standard strain (MICs = 4.8–9.3 μg/mL) and clinical isolates (MICs = 25–119 μg/mL) of Candida albicans was significant. Horseradish volatiles exhibited better antibacterial and slightly weaker anticandidal activity. Armoracia macrocarpa represents a new source of raw materials with potential use in pharmaceutical and food industries, as well as in cookery. Preliminary results indicated the possibility of its cultivation, which is required for its preservation and sustainable usage. [ABSTRACT FROM AUTHOR]

Oxidative stress can cause damage to lipids, proteins and nucleic acids in several biological systems, leading to the functional and structural impairment of individual molecules that may be involved in various diseases. The aim of study was to evaluate the effect of dietary plant extract supplementation, based on Lippia citriodora , horseradish ( Raphanus sativus L.) and lycopene ( Solanum lycopersicum L.), on several blood parameters and plasma oxidative status in growing rabbits. The experiment lasted 80 days and was conducted on 160 weaned-rabbits, divided into four groups of 40 animals each, matched by age (38 ± 2 days) and body weight (1.49 ± 0.07 kg). The control group (CON) received a weaning-fattening feed without any feed additives, while of the other three experimental groups, the first group received a supplement of plant extract based on Lippia citriodora , containing 5 mg of verbascoside/kg feed (VB group), the second group received 5 mg of lycopene/kg feed, tomato fruit extract (LIC group), and the third received 350 mg of Raphanus sativus root extract/kg feed (RAF group). The feed additives, based on verbascoside ( Lippia citriodora ), horseradish ( Raphanus sativus L.) and lycopene ( Solanum lycopersicum L.) resulted in a marked decrease in blood content of low density lipoprotein cholesterol and bilirubin. In addition, only when verbascoside was supplemented, were improvements in high density lipoprotein cholesterol and AST enzyme levels observed. Plasma oxidative markers significantly improved for all three extract groups. There was a significant reduction in ROMs and TBARS values, as well as an increase in the content of retinol and alfa-tocopherol, confirming the strong antioxidant ability of the plant extracts used. A dietary supplementation with phyto-extracts, based on Lippia citriodora , horseradish and lycopene can thus be effectively used in rabbit feeding due to the positive effects observed on the blood parameters and plasma oxidative status, with possible beneficial effects on the welfare of livestock animals. [ABSTRACT FROM AUTHOR]

This work addresses the use of protic ionic liquids (PIL) as adjuvants (5 wt%) in the formation of aqueous two-phase systems (ATPS), based on polyethylene glycol with different molecular weights + ammonium sulfate + water for peroxidase purification from alternatives vegetables as radish peroxidase ( Raphanus sativus L.) from horseradish root peroxidase. Protic ionic liquid as a process adjuvant did not extend the biphasic area in the phase diagram, but the phase behavior was modified according to the hydrophobicity of the PIL used and additional interactions between the enzyme and PIL increased the purification factor of the radish peroxidase from ≈2.5 (no ionic liquid) to ≈ 19.2 fold using 2-hydroxyethylammonium propionate as adjuvant in ATPS. [ABSTRACT FROM AUTHOR]

Horseradish ( Armoracia rusticana ) is a plant well known for its roots’ spicy aroma. The present study investigates the main aroma constituents of horseradish roots in general by analysing the aroma profiles of six different horseradish varieties, with one variety grown in two different soils. Odorants were characterised by means of gas chromatography-olfactometry and identified via their mass spectra, retention indices on two columns with different polarity, and their characteristic odour. A series of new aroma compounds from different substance groups were identified that have hitherto not been described in horseradish. Moreover, several of these constituents were successfully shown to exhibit high odour potency, alongside a high potential to influence the overall aroma of horseradish roots, like (3 S ,3a S ,7a R )-wine lactone and 3-isopropyl-2-methoxypyrazine. [ABSTRACT FROM AUTHOR]

Detailed analyses of horseradish autolysates led to the identification of a new natural product, 5-phenylpentyl isothiocyanate (PhPeITC). The structural assignment was corroborated by synthesis, and the identity unequivocally established by spectral means. The occurrence of PhPeITC is the first direct proof of the existence of a 5-phenylpentyl glucosinolate in the aerial parts of this species as one of the possible “mustard oil” precursors. To verify its possible contribution to the horseradish functional food status, horseradish above- and underground autolysates, together with five ω-phenylalkyl isothiocyanates were tested for their spasmolytic, cytotoxic and antimicrobial activities. Specifically, the cytotoxic effect on Caco-2, HeLa (cancer) and MDCK (non-cancer) cell lines was established. Additionally, the five tested ITCs exerted significant spasmolytic activity (on rat distal colon), with PhPeITC being almost 100 times more potent than papaverine. A non-selective antimicrobial activity of all ITCs was revealed in the case of 6 bacterial and 2 fungal strains. [ABSTRACT FROM AUTHOR]

Nanomaterial-based peroxidase-mimetics are an emerging research field that promises to produce alternatives to horseradish peroxidase for a variety of applications. Generally, some peroxidase-mimetics substrates are used in acidic condition (pH ≤ 7). Then, it is necessary to screen some peroxidase-mimetics substrates suitable for basic condition because that some peroxidase-mimetics leached ions in acidic solution. In this paper, using Ni/Co layered double hydroxides (LDHs) as a nano-peroxidase mimic model, we evaluated three fluorogenic substrates suitable for basic condition though experimental conditions, reaction kinetic and glucose detection assay. And the detection of glucose method based on homovanillic acid (HVA) as fluorescent substrate gave wide linear range (0.02–20 μM) and low detection limit (0.01 μM). We also developed a novel platform that could study the inhibitory effects of ascorbic acid and glutathione based on the system of Ni/Co LDHs-HVA-H 2 O 2 . [ABSTRACT FROM AUTHOR]

Catalase, a heme enzyme, which catalyzes decomposition of hydrogen peroxide to water and molecular oxygen, is one of the main enzymes of the antioxidant defense system of the cell. Nitrite, used as a food preservative has long been regarded as a harmful compound due to its ability to form carcinogenic nitrosamines. Recently, much evidence has been presented that nitrite plays a protective role as a nitric oxide donor under hypoxic conditions. In this work the effect of nitrite on the catalytic reactions of catalase was studied. Catalase was inhibited by nitrite, and this process was pH-dependent. IC 50 values varied from about 1 μM at pH 5.0 to about 150 μM of nitrite at pH 7.4. The presence of chloride significantly enhanced nitrite-induced catalase inhibition, in agreement with earlier observations. The kinetics of the reactions of nitrite with ferric catalase, its redox intermediate, Compound I, and catalase inactive form, Compound II, was also studied. Possible mechanisms of nitrite-induced catalase inhibition are analyzed and the biological consequences of the reactions of catalase with nitrite are discussed. [ABSTRACT FROM AUTHOR]

Porous Co 3 O 4 hexagonal nanosheets (PCHNSs) with a well-defined morphology have been synthesized successfully via a hydrothermal process and followed by calcinations. Co 3 O 4 nanosheets immobilizing horseradish peroxidase (HRP), together with reduced graphene oxide, have been used to modify glassy carbon electrode to fabricate a mediator-free biosensor. The morphology and structure of PCHNSs are studied by XRD, FESEM, and HRTEM techniques. Spectroscopic and electrochemical results reveal that Co 3 O 4 /rGO composite film is an excellent immobilization matrix with biocompatibility for enzymes, affording good enzymes’ bioactivity and stability. Meanwhile, due to the unique structure of the modified electrode, the direct electron transfer of HRP is facilitated and the prepared nitrite biosensors display good performance—a wide linear range of 1–5400 μM, an extremely low limit of detection (LOD) as 0.21 μM and a limit of quantification as (LOQ) as 0.58 μM. This work suggests that Co 3 O 4 /rGO composite film is a potential matrix for enzymes’ immobilization and biosensors’ preparation. [ABSTRACT FROM AUTHOR]

Here, a functionalized organic salt composed of [N k,k,k,k ]+ (k = 1–4) and [MES]- (2-(N-morpholino)ethanesulfonate), i.e., Good's buffer ionic liquid with self-buffering and biocompatible properties, was chosen as electrolyte as well as buffer to construct a H 2 O/AOT/isooctane bicontinuous microemulsion for enzymatic synthesis of polyaniline (PANI). Studies on the effects of the functionalized organic salt on the phase behavior indicate that [N k,k,k,k ][MES] can tune the phase inversion temperature of AOT-stabilized oil-water microemulsion system through changing the cationic alkyl chain length, exhibiting the properties of both inorganic salt and co-alcohol. More interestingly, the stability of horseradish peroxidase (HRP) solubilized in the H 2 O(0.1 M [N 1,1,1,1 ][MES], pH = 4.5)/AOT/isooctane bicontinuous microemulsion is much better than that formulated with mixed surfactants AOT/SB-12 and inorganic salt. Studies on the HRP-catalyzed oxidative polymerization of aniline in the present bicontinuous microemulsion indicates that at low surfactant content and high oil-water ratio, the present microemulsion resulted in a PANI with better conductivity than the counterpart reported elsewhere. This work is of guiding significance for constructing a less-component and enzyme-compatible bicontinuous microemulsion for template-assisted biopolymerization. [Display omitted] [ABSTRACT FROM AUTHOR]

The roots of horseradish (Armoracia rusticana) are used for infections of respiratory airway and for urinary tract infections due to isothiocyanates (ITC), enzymatically formed during fermentation of glucosinolates by myrosinase. The present study aims to present a comprehensive overview on the phytochemical composition of A. rusticana roots, especially concerning isothiocyanates and respective glucosinolates. The complex flavonoid spectrum of the herbal material is reviewed. Published data on in vitro activity of horseradish extracts and isolated compounds are summarized. These data indicate well-established use of horseradish as an antibacterial remedy against bacterial infections of the airway and urinary tract. To answer the question if other compounds from A. rusticana beside ITC contribute to the antibacterial activity, non-targeted LC-MS studies were performed with fermented and non-fermented horseradish extracts, and detailed phytochemical profiles were established. Comparative investigations on the antibacterial activity indicated that only ITC-containing extracts and fractions exert antibacterial activity. The huge variety of non-ITC compounds do not significantly contribute to the antibacterial activity, but can be used for analytical characterisation and quality control of the herbal material. Detailed phytochemical analysis additionally revealed a variety of compounds, not described until now for horseradish roots: the flavonol glycosides kaempferol-3- O - β - d -xylopyranosyl-(1′′′ → 2′′)- β - d -galactopyranoside, kaempferol-3- O - α - l -rhamnopyranosyl-(1′′′ → 6′′)- β - d -glucopyranoside, kaempferol-3- O-β - d -glucopyranoside, Kaempferol-3- O - β - d -xylopyranosyl-7- O - β - d -glucopyranoside, Kaempferol-3- O - β - d -xylopyranosyl-(1′′′′ → 2′′′)- β - d -galactopyranoside-7- O - β - d -glucopyranoside, the oxo-indole derivative spirobrassinin, the phenylthiazole 2-methylsulfanyl-4-phenyl-4,5-dihydro-1,3-thiazole, a series of lysophophatidylethanolamine and 13 different N -phenylpropenoyl-L-amino acids. The antibacterial effects of horseradish are only due to the presence of glucosinolates resp. the corresponding ITC, and the detailed overall composition of horseradish extracts has been reported. [Display omitted] [ABSTRACT FROM AUTHOR]

Atrial switch operations for D-Transposition of the great arteries (D-TGA) were performed until the late 20th century. These patients have substantial rates of re-operation, particularly for baffle related complications. This study sought to analyze the efficacy of percutaneous transcatheter intervention (PTI) for baffle leak and/or stenosis in adult atrial switch patients. Adult patients with a prior atrial switch operation who underwent heart catheterization (2002–2014) at a tertiary adult congenital heart disease referral center were retrospectively analyzed. In 58 adults (30 ± 8 years, 75% men, 14% New York Heart Association (NYHA) functional class ≥ 2) who underwent 79 catheterizations, PTI was attempted in 50 (baffle leak (n = 10, 20%), stenosis (n = 27, 54%), or both (n = 13, 26%)). PTI was successful in 45 and 5 were referred for surgery due to complex anatomy. A total of 40 bare metal stents, 18 covered stents, 16 occlusion devices, 2 angioplasties, and 1 endovascular graft were deployed. In isolated stenosis, there was improvement in NYHA functional class after PTI (8 vs. 0 patients were NYHA FC > 2, p = 0.004), which was matched by improvement in maximal oxygen consumption on exercise testing (VO 2 ) (25.1 ± 5.4 mL/kg/min vs. 27.9 ± 9 mL/kg/min, p = 0.03). There were no procedure-related deaths or emergent surgeries in this cohort. This single-center cohort is the largest reported series of adult atrial switch operation patients who have undergone PTI for baffle stenosis and/or leak. We demonstrate that PTI with an expert multi-disciplinary team is a safe and effective alternative to surgery in adult patients with an atrial switch operation. [ABSTRACT FROM AUTHOR]

Although various supports including nanomaterials have been widely utilized as platforms for enzymes immobilization in order to enhance their catalytic activities, most of immobilized enzymes exhibited reduced activities compared to free enzymes. In this study, for the first time, we used iron ions (Fe 2+ ) and horseradish peroxidase (HRP) enzyme together to synthesize flowerlike hybrid nanostructures with greatly enhanced activity and stability and reported an explanation of the enhancements in both catalytic activity and stability. We demonstrated that Fe 2+ -HRP hybrid nanoflower (HNF) showed catalytic activity of ∼512% and ∼710%, respectively when stored at +4 °C and room temperature (RT = 20 °C) compared to free HRP. In addition, the HNF stored at +4 °C lost only 2.9% of its original activity within 30 days while the HNF stored at RT lost approximately 10% of its original activity. However, under the same conditions, free HRP enzymes stored at +4 °C and RT lost 68% and 91% of their activities, respectively. We claim that the drastic increases in activities of HNF are associated with to high local HRP concentration in nanoscale dimension, appropriate HRP conformation, less mass transfer limitations, and role of Fe 2+ ion as an activator for HRP. Further biosensors studies based on enhanced activity and stability of HNF are currently underway. [ABSTRACT FROM AUTHOR]

Profile and distribution of glucosinolates (GLS) were detected in plant tissues of horseradish at different developmental stages: beginning of vegetative re-growth, flowering and silique formation. The GLS profile varied widely in the different tissues: we identified 17 GLS in roots and sprouts, one of which was not previously characterized in horseradish, i.e. the 2(S)-hydroxy-2-phenylethyl-GLS (glucobarbarin) and/or 2(R)-hydroxy-2-phenylethyl-GLS (epiglucobarbarin), 11 already found in the roots, including the putative 2-methylsulfonyl-oxo-ethyl-GLS, and 5 previously recognized only in the sprouts. Fifteen of those GLS were also identified in young and cauline leaves, 12 in the mature leaves and 13 in the inflorescences. No difference in GLS profile was observed in plant among the phenological stages. Differences in concentrations of GLS, quantified as desulfated, were found in plant. At the beginning of vegetative re-growth, sprouts while showing the same profile of the roots were much richer in GLS having the highest total GLS concentrations (117.5 and 7.7 μmol g −1 dry weight in sprouts and roots, respectively). During flowering and silique forming stages, the roots still maintained lower amount of total GLS (7.4 μmol g −1 of dry weight, on average) with respect to the epigeous tissues, in which mature and young leaves showed the highest total concentrations (70.5 and 73.8 μmol g −1 of dry weight on average, respectively). Regardless of the phenological stages, the aliphatic GLS were always predominant in all tissues (95%) followed by indolic (2.6%) and benzenic (2.4%) GLS. Sinigrin contributed more than 90% of the total GLS concentration. Aliphatic GLS concentrations were much higher in the epigeous tissues, particularly in the mature and young leaves, while benzenic and indolic GLS concentrations were higher in the roots. Through the phenological stages, GLS concentration increased in young and mature leaves and decreased in cauline leaves and inflorescences, while it remained constant over time in roots. [ABSTRACT FROM AUTHOR]

In this paper, a novel label-free G-quadruplex DNAzyme sensor has been proposed for colorimetric identification of GMO using CaMV 35S promoter sequence as the target. The binary probes can fold into G-quadruplex structure in the presence of DNA-T (Target DNA) and then combine with hemin to form a DNAzyme resembling horseradish peroxidase. The detection system consists of two G-rich probes with 2:2 split mode by using the absorbance and color of ABTS2- as signal reporter. Upon the addition of a target sequence, two probes both hybridize with target and then their G-rich sequences combine to form a G-quadruplex DNAzyme, and the DNAzyme can catalyze the reaction of ABTS2- with H2O2. Then the linear range is from 0.05 to 0.5 μM while detection limit is 5 nM. These results demonstrate that the proposed G-quadruplex DNAzyme method could be used as a simple, sensitive and cost-effective approach for assays of GMO. [ABSTRACT FROM AUTHOR]

The glucosinolate (GSL) content is an important quality parameter of crops, such as mustard, horseradish or nasturtium, which are grown for their taste as condiments or for medical purposes. Accordingly, an enhancement of the GSL content should promote the large-scale cultivation of these plants. It is well known that GSLs reveal a high significance in plant defense, and that several stress factors cause an increase in the GSL concentration. The goal of the present study was to evaluate the means to stimulate the GSL biosynthesis during plant growth by applying moderate stress. The impact of different treatments on the GSL content and on growth of Tropaeolum majus L. was investigated in a greenhouse trial. Moderate stress was induced by drought, by the addition of salt, or the application of growth regulators (methyl jasmonate, salicylic acid). Moreover, cell wall lysate was applied to the plants to mimic biotic stress, such as pathogen attack. Evapotranspiration (ETP), biomass development, specific leaf weight (SLW), plant pigments, and thiol contents had been recorded to evaluate physiological changes in response to the treatments. The glucotropaeolin (GT) content, representing the sole GSL of T. majus was measured as target compound. Drought and MeJA application increased the GT concentration on dry weight basis and impacted on ETP, dry matter content, SLW and plant pigments, too. Application of salt, SA and cell wall lysate did not affect the GT concentration in a consistent way. Moderate drought and the application of MeJA are suitable tools to increase the GT concentration in T. majus. However, in case of drought the higher GT concentration was only reached at the expense of biomass production. High GT concentrations together with reasonable yields were only achieved by MeJA application. [ABSTRACT FROM AUTHOR]

Highlights: [•] The root yield, total and individual GLS concentrations differed among accessions. [•] Sinigrin is the predominant GLS in all accessions, contributing up to 87% of total GLS concentration. [•] Wide variability among accessions was found based on root traits and molecular markers. [•] The best root yield are not always associated with the higher GLS concentration. [•] The preservation of local horseradish germplasm is an important task against genetic erosion. [Copyright &y& Elsevier]

A colorimetric microplate-adapted lactose assay was developed to quantify lactose in dairy products. The assay was based on the coupled enzymatic reaction of β-galactosidase-glucose oxidase-horseradish peroxidase using Amplex red as detection probe. The assay showed good linearity in the range of 0.1 to 0.5 mmol of lactose/L, with a limit of detection of 0.0433 mmol/L and a limit of quantification of 0.1313 mmol/L. The lactose assay at optimized conditions (5 U of β-galactosidase/ mL, 5 U of glucose oxidase/mL, 1 U of horseradish peroxidase/mL, and 100 µmol of Amplex red/L for 1 h at 37°C in the dark) showed good correlation with a commercial lactose enzymatic kit with intraassay variation below 10% and interassay variations below 7.6%. The developed lactose microplate assay can be adopted as routine analysis for lactose determination in dairy products due to its relatively low cost compared with a commercial kit, relatively short reaction time, and high sensitivity and reproducibility. [ABSTRACT FROM AUTHOR]

Highlights: [•] ArMY2 is the first MYR II myrosinase gene described in Armoracia rusticana. [•] ArMY2 encodes a myrosinase and is selectively expressed in young horseradish roots. [•] Gluconasturtiin is the dominant glucosinolate in young horseradish roots. [•] Recombinant ArMy2 produced in Pichia pastoris prefers gluconasturtiin as substrate. [•] A specialized glucosinolate-myrosinase defense system may be active in young roots. [ABSTRACT FROM AUTHOR]

[Display omitted] • Br− markedly enhances SMR degradation by HRP depending on Br− concentration. • Some SMR are first formed into Br substituted products and then are degraded rapidly. • H 2 O 2 , pH and HRP level can adjust the formation of Br substitutes and BrO 3 −. • Nether the degradation products nor bromate in the process inhibit bacteria growth. Degradation of sulfonamide antibiotics (SAs) by horseradish peroxidase (HRP) is an eco-friendly and sustainable approach but with relatively low efficiency. In this study, we present bromide (Br−) enhances sulfamerazine (SMR) degradation in the process of HRP/H 2 O 2. The removal rate of SMR is positively related to Br− concentration and increases over three times within 4 h as Br− concentration increases from 0 to 1 mM. The mechanism of promoting SMR degradation is mainly through oxidation and substitution by reactive bromine, which comes from the oxidation of bromide ions by HRP/H 2 O 2. Moreover, structure and kinetics analysis of HRP confirm that Br− altered the hydrophobic structure of HRP and made it accessible to bind with SMR. Furthermore, eight degradation products are determined by ESI-Q-TOF-MS mass spectrometry. SMR transformation mainly involves two pathways: one way is hydrolysis and then breaking up of sulfonamide bond to generate small fragments, and another is demethylation and Smile rearrangement firstly, then through hydroxylation, SO 2 extrusion, and bromine substitution to form other products. Bacteria growth experiments present the fact that neither the degradation products nor bromate formed in the process inhibited bacteria growth, indicating they have no obvious environmental risk. This study first reports Br− could accelerate the degradation of SMR by HRP and proposes the scheme of bromine species changes and SMR transformation pathways. This study not only develops a novel method to enhance the degradation of sulfonamides, but also provides a reference for the environmental risk assessment of sulfonamides. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new activated wool has been prepared using cyanuric chloride. [•] Horseradish peroxidase (HRP) was successfully immobilized on activated wool. [•] The results revealed that the immobilized HRP has enhanced physical and chemical properties. [•] The wool-HRP was more stable to several denaturants. [ABSTRACT FROM AUTHOR]

Abstract: A gel-based non-instrumental immuno-affinity assay was developed for the rapid screening of chloramphenicol (CAP) in food samples with the limit of detection (LOD) of 1μgL−1. The immuno-affinity test column (IATC) consisted of a test layer containing anti-CAP antibody coupled gel, and a control layer with anti-HRP antibody coupled gel. Based on the direct competitive immuno-reaction and the horseradish peroxidase enzymatic reaction, the test results could be evaluated visually. Basically, blue color development represented the negative results, while the absence of color development represented the positive results. In this study, CAP spiked samples of raw milk, pasteurized milk, UHT milk, skimmed milk powder, acacia honey, date honey, fish and shrimp were tested. Little or none sample pretreatment was required for this assay. The whole procedure was completed within 10min. In conclusion, the gel-based immuno-affinity test is a simple, rapid, and promising on-site screening method for CAP residues in food samples, with no instrumental requirement. [Copyright &y& Elsevier]

Abstract: Lanthanum (La) is an important rare earth element in the ecological environment of plant. The proteins on the plasma membrane control the transport of molecules into and out of cell. It is very important to investigate the effect of La(III) on the proteins on the plasma membrane in the plant cell. In the present work, the interaction between La(III) and proteins on the plasma membrane of horseradish was investigated using optimization of the fluorescence microscopy and fluorescence spectroscopy. It is found that the fluorescence of the complex system of protoplasts and 1-aniline Kenai-8-sulfonic acid in horseradish treated with the low concentration of La(III) is increased compared with that of the control horseradish. The opposite effect is observed in horseradish treated with the high concentration of La(III). These results indicated that the low concentration of La(III) can interact with the proteins on the plasma membrane of horseradish, causing the improvement in the structure of proteins on the plasma membrane. The high concentration of La(III) can also interact with the proteins on the plasma membrane of horseradish, leading to the destruction of the structure of proteins on the plasma membrane. We demonstrate that the proteins on the plasma membrane are the targets of La(III) action on plant cell. [Copyright &y& Elsevier]

Abstract: Ni doped SnO2 nanoparticles (0–5wt%) have been prepared by a simple microwave irradiation (2.45GHz) method. Powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies confirmed the formation of rutile structure with space group (P42/mnm) and nanocrystalline nature of the products with spherical morphology. Direct electrochemistry of horseradish peroxidase (HRP)/nano-SnO2 composite has been studied. The immobilized enzyme retained its bioactivity, exhibited a surface confined, reversible one-proton and one-electron transfer reaction, and had good stability, activity and a fast heterogeneous electron transfer rate. A significant enzyme loading (3.374×10−10 molcm−2) has been obtained on nano-Ni doped SnO2 as compared to the bare glassy carbon (GC) and nano-SnO2 modified surfaces. This HRP/nano-Ni–SnO2 film has been used for sensitive detection of H2O2 by differential pulse voltammetry (DPV), which exhibited a wider linearity range from 1.0×10−7 to 3.0×10−4 M (R=0.9897) with a detection limit of 43nM. The apparent Michaelis–Menten constant (K M app ) of HRP on the nano-Ni–SnO2 was estimated as 0.221mM. This excellent performance of the fabricated biosensor is attributed to large surface-to-volume ratio and Ni doping into SnO2 which facilitate the direct electron transfer between the redox enzyme and the surface of electrode. [Copyright &y& Elsevier]

Abstract: Using a full factorial design the optimization of experimental conditions of enhanced chemiluminescence reaction (ECR) catalyzed by horseradish peroxidase (HRP-C) in the presence of 3-(10′-phenothiazinyl)propane-1-sulfonate (SPTZ) and 4-morpholinopyridine (MORP) as enhancers was performed. The effect of concentrations of SPTZ, hydrogen peroxide, MORP, luminol, and Tris on a ratio of peroxidase-catalyzed CL to background was studied. The use of the full 25 factorial design instead of “one-variable-a time” method allowed to increase the sensitivity of HRP-C determination 2355 fold without a change of detection limit. The obtained results open up very promising perspectives for using HRP-C-catalyzed ECR to improve the sensitivity of chemiluminescent enzyme immunoassay. [Copyright &y& Elsevier]

Abstract: Phenolic compounds from virgin olive oil are known to play an antioxidant role in preventing biomolecule damage. One of the most abundant components of olive oil is an oleuropein derivative named oleacein (dialdehydic form of decarboxymethyl elenolic acid linked to hydroxytyrosol; 3,4-DHPEA-EDA). The aim of the study was to establish the antioxidant activity of oleacein for an array of reactive oxygen (superoxide anion, ; hydrogen peroxide, H2O2; hypochlorous acid, HOCl) and nitrogen species (nitric oxide, NO; peroxynitrite, ONOO−) formation, using in vitro non-cellular systems, as well as cellular screening systems (human neutrophil oxidative burst, monocytes’ nitric oxide production). We used a well-known antioxidant, oleuropein, as a reference compound. Oleacein proved to be stronger in the reduction of formyl-met-leu-phenylalanine (f-MLP) and phorbol–myristate–acetate (PMA)-induced oxidative bursts in neutrophils (IC50 =1.8μM, IC50 =1.5μM, respectively) and myeloperoxidase release (IC50 =8.8μM) than was oleuropein (IC50 =2.4μM, IC50 =16.0μM, IC50 =30.7μM, respectively). Both compounds were stronger scavengers of than H2O2. Oleuropein did not scavenge HOCl as opposed to oleacein (IC50 =1.5μM). Both compounds, in a concentration range 1–10μM, significantly decreased nitrogen species formation in cell-free systems and by lipopolysaccharide (LPS)-stimulated monocytes. [Copyright &y& Elsevier]

Abstract: Extensive research has indicated that the electrostatic attraction between polysaccharides and proteins on the oil–water interface can improve the stability of emulsions. However, this electrostatic effect will be weakened or even eliminated as the solution pH or ionic strength of emulsions change, resulting in the shedding of the polysaccharide layer. We prepared primary oil-in-water emulsions at pH 7.0 using whey protein isolate (WPI) as an emulsifier and then beet pectin was added to form secondary emulsions. After the pH of emulsions was adjusted to 4.0 to promote electrostatic attraction between the beet pectin molecules and the protein-coated droplets, horseradish peroxidase was added to generate a cross-linked beet pectin coating. Results show that stable emulsions coated with WPI and cross-linked beet pectin interfaces could be formed. The sensitivity of the emulsions to the environmental stresses of pH changes, ions addition, thermal processing and freezing was also characterized in this work. Our results support the view that cross-linked beet pectin improves the stability of emulsions and is superior to simple deposition on the surface of lipid droplets. The interfacial engineering technology used in this study could be used to create food emulsions with improved stability to environmental stresses. [Copyright &y& Elsevier]

Abstract: A simple bio-conjugation procedure to surround a single horseradish peroxidase (HRP) enzyme molecule with dendritic polyester macromolecules (polyester-32-hydroxyl-1-carboxyl bis-MPA dendron, generation 5) was proposed. The characterization of resultant nanoparticles entitled HRP dendrozyme, was performed by transmission electron microscopy, dynamic light scattering, gel permeation chromatography and Fourier transform infrared spectroscopy. The results showed that HRP nanoparticles were spherical in shape and have an average size of 14±2nm in diameter. Furthermore, bio-conformational characterization of HRP dendrozyme was performed by means of circular dichroism and fluorescence spectroscopy to evaluate the secondary and tertiary structure changes after enzyme modification. These investigations revealed that protein conformation had small changes (in secondary and tertiary structures) after bio-conjugation. We also reported here that dendritic modification did not significantly affect the kinetic parameters of free HRP. The stabilization of HRP with dendron macromolecules as single enzyme nanoparticles resulted in improvement of half-life over 70 days storage at 4°C as well as its tolerance under different elevated temperatures up to 80°C and in the presence of organic solvents for 15min. These significant results promise extensive applications of HRP particularly in harsh environmental conditions. [Copyright &y& Elsevier]

Abstract: Phenolic compounds removal is a very active research field due to occurrence and the toxicity of phenolic pollutants in industrial wastewaters. In order to make an a priori selection of the most efficient removal process for a target structure this contribution reviews and compares some of the mechanistic aspects of the oxidation in the presence of hydrogen peroxide and catalyzed by complexed iron which is the in-common element in Fenton systems, plant peroxidases and biomimetics. Different substrates were considered from the most basic phenol molecule to complex structures such as phenolic dyes and lignins. The reactivity of iron is related to its microenvironment generated by ligands and their electron withdrawing capacity thus conditioning the type of cleavage induced on hydrogen peroxide and the oxidation state change on iron upon reaction. The relative concentrations of organic to inorganic free radicals generated control the main catalytic action; i.e. from degradation up to mineralization in Fenton systems or oligomerization up to polymerization in plant peroxidases systems. Moreover, some reaction conditions as the peroxide concentration, the initial molar ratio of organic compounds to peroxide and the type of reaction solvent are identified as key factors to promote a desired action mechanism by peroxidases (and their biomimetics). [Copyright &y& Elsevier]

Abstract: Titanate nanotubes (TiNT) surface modified with (3-aminopropyl)trimethoxysilane were employed as a support for covalent immobilization of horseradish peroxidase (HRP) by using 1,4-benzoquinone as a coupling agent. Composite film-electrodes consisting of HRP-modified TiNT embedded into the porous carbon powder/Nafion matrix were fabricated and their applicability in direct bioelectrocatalytic reduction of H2O2 and H2O2 biosensing were investigated. An efficient direct electron transfer between the immobilized HRP molecules and the electrode was observed in the presence of H2O2 at potentials lower than 600mV (vs. Hg/Hg2Cl2/3.5M KCl). For the HRP–TiNT-modified electrodes polarized at 0mV, a linear dependence of the bioelectrocatalytic current on the concentration of H2O2 was observed up to the concentration of H2O2 equal to 10μM, with the sensitivity of (1.10±0.01)AM−1 cm−2 and the detection limit of 35nM. [Copyright &y& Elsevier]

Abstract: Background: Serum S-100B has clinical value in monitoring malignant melanoma and in monitoring and predicting outcomes in patients with traumatic brain injury. Methods: Analytical performance characteristic and split-sample method comparison studies for three commercial S-100B immunoassays (CanAg® S100, Sangtec® 100, YK150 Human S-100 β) were performed. Reference intervals (97.5th percentile) for each assay were established by non-parametric analysis of results from healthy volunteers. Results: Linearity results were slope=1.014, intercept=65.1, r2 =0.999 for the Sangtec assay; slope=1.038, intercept=31.1, r2 =0.999 for the CanAg assay; slope=1.123, intercept=−105.4, r2 =0.997 for the YK150 assay. Within-run CVs were ≤5.7, ≤6.3 and ≤10.8 for the Sangtec, CanAg and YK150 ELISAs, respectively. Between-run CVs were ≤11.3, ≤5.9 and ≤9.5, respectively. Upper reference interval limits of 141, 96 and 735ng/l S-100B were established for the Sangtec, CanAg and YK150 ELISAs, respectively. Deming regression generated the following: CanAg vs. Sangtec, slope=0.339, intercept=24.1, r2 =0.932; YK150 vs. Sangtec, slope=0.266, intercept=−140.0, r2 =0.690; YK150 vs. CanAg, slope=1.376, intercept=−13.1, r2 =0.860. Conclusions: The configurations, procedures and performance characteristics of the Sangtec and CanAg S-100B ELISAs are comparable and better than those of the YK150 assay. Poor agreement and large biases prevent interchangeable use of results. [Copyright &y& Elsevier]

Abstract: Neurotoxic organophosphorus (OP) compounds are commonly used as chemical warfare agents and pesticides. Due to their high toxicity, rapid and sensitive field detection of these compounds has been an ongoing topic of interest. Biosensors made with organophosphate hydrolase enzyme (OPH) are generally designed to either amperometrically detect an electroactive leaving group produced following enzymatic cleavage, or to potenitometrically detect the pH change that occurs during cleavage. Since OPs are more likely to have phenolic leaving groups as compared to electroactive leaving groups, we have developed a new amperometric dual enzyme electrochemical assay that enables the detection of a broad class of OP compounds using the OPH enzyme combined with horseradish peroxidase (HRP). The assay has been applied to the detection of dichlofenthion, which does not have an electroactive leaving group and is not a commonly investigated OPH substrate. Using reverse phase HPLC, we have determined the Michaelis–Menten kinetic parameters of an engineered OPH enzyme to be K M =0.11±0.02mM and k cat =0.046±0.003s−1 with dichlofenthion as the substrate. Detection of the phenolic leaving group from the OPH enzyme reaction using the HRP electrode is carried out at −50mV vs. Ag/AgCl where the noise and background are low and interferences are negligible. After optimization of the solution pH, the dual enzyme biosensor was found to have a limit of detection (LOD) of 24μM (7.6ppm), and a sensitivity of 0.095±0.024nA/μM for dichlorofenthion. By detecting the phenolic leaving groups from the OP targets using the HRP electrode, biosensors made using this new platform have the potential to detect a broad range of important OP compounds. [Copyright &y& Elsevier]

Abstract: Traditional covalent immobilization of enzymes was mostly operated within water phase. However, most of enzymes are flexible when they are in water environment, and the covalent reactions generally lead to complete or partial activity losing due to the protein conformational changes. This paper examined enzyme covalent immobilization operated in micro-aqueous organic media, to display the differences between two environments of immobilization within water and micro-aqueous organic solvent by activity and stability determination of the resulting immobilized enzymes. Catalase, trypsin, horseradish peroxidase, laccase and glucose oxidase have been employed as model enzymes. Results showed the thermal, pH and reusable stabilities of the micro-aqueous organic covalently immobilized enzymes were improved when compared with the immobilized enzymes within water. Micro-aqueous covalent immobilization showed a remarkable advantage in remaining the enzymes catalytic activity for all the five enzymes compared with the traditional water phase immobilization. And the optimum pH values for both immobilization within water and micro-aqueous organic media shifted slightly. [Copyright &y& Elsevier]

Abstract: In situ gellable hydrogels are more attractive in many biomedical and biopharmaceutical applications than pre-formed hydrogels because they can be implanted simply by injection and allow homogeneous incorporation of bioactive materials. In this study, the potential suitability of in situ gellable sugar beet pectin (SBP) for biomedical and biopharmaceutical applications was investigated. SBP aqueous solution gelled within 1min after addition of appropriate amounts of horseradish peroxidase (HRP) and H2O2 via HRP-catalyzed oxidative coupling reaction of feruloyl groups on SBP molecules. The resultant gels gradually degraded under simulated physiological condition. L929 fibroblast cells encapsulated in the gels were scarcely damaged during the gelation process. A subcutaneously injected mixture of SBP, HRP and H2O2 solutions successfully gelled, and the gel did not induce necrosis in the surrounding tissue 1week after implantation. These results demonstrate that the in situ gellable SBP gels are useful for biomedical and biopharmaceutical applications. [Copyright &y& Elsevier]

Abstract: Several classes of oxidative enzymes have shown promise for efficient removal of endocrine disrupting compounds (EDCs) that are resistant to conventional wastewater treatments. Although the kinetics of reactions between individual EDCs and selected oxidative enzymes are well documented in the literature, there has been little investigation of reactions with EDC mixtures. This makes it impossible to predict how enzyme-mediated treatment systems will perform since wastewater effluents generally contain multiple EDCs. This paper reports pseudo-first order rate constants for a model oxidative enzyme, horseradish peroxidase (HRP), during single-substrate (k 1) and mixed-substrate (k 1-MIX) reactions. Measured values are compared with literature values of three Michaelis–Menten parameters: half-saturation constant (K M), enzyme turnover number (k CAT), and the ratio k CAT/K M. Published reports had suggested that each of these could be correlated with HRP reactivity towards EDCs in mixtures, and empirical results from this study show that K M can be used to predict the sequence of EDC removal reactions within a particular mixture. We also observed that k 1-MIX values were generally greater than k 1 values and that compounds exhibiting greatest estrogenic toxicities reacted most rapidly in a given mixture. Finally, because K M may be tedious to measure for every EDC of interest, we have constructed a quantitative structure–activity relationship (QSAR) model to predict these values. This model predicts K M quite accurately (R 2 =89%) based on two molecular characteristics: molecular volume and hydration energy. Its accuracy makes this QSAR a useful tool for predicting which EDCs will be removed most efficiently during enzyme treatment of EDC mixtures. [Copyright &y& Elsevier]

Abstract: An anionic peroxidase POIII, molecular weight 56kDa, was purified from the roots of horseradish cv. Balady. The enzyme exhibited high activity towards o-phenylenediamine and guaiacol, while o-dianisidine had moderate peroxidase activity. Pyrogallol and p-aminoantipyrine had low affinity toward POIII. POIII was found to have a temperature optimum at 40°C; the enzyme activity remained stable up to 40°C and retained 87%, 51% and 29% of its activity at 50, 60 and 70°C, respectively. The enzyme exhibited more than 50% of activity in the pH range between 4.0 and 8.0 with its pH optimum at 5.5. Several metal cations had partial inhibitory effects toward POIII. Fe3+ enhanced the activity of the enzyme by 160% at 5mM. All the metal chelators caused partial inhibitory effects toward POIII, except for EDTA at 1mM, which had no effect on the enzyme. [Copyright &y& Elsevier]

Abstract: In this work, a novel label-free amperometric immunosensor has been constructed for detecting α-1-fetoprotein (AFP) based on nanocomposite of horseradish peroxidase (HRP) labeled carbon nanotubes (CNTs). First, the gold nanoparticles (AuNPs) were electrodeposited on the surface of the glass carbon electrode by electrochemical reduction of gold chloride tetrahydrate (HAuCl4) to immobilize horseradish peroxidase labeled carbon nanotubes (HRP-CNTs). Then HRP-CNTs bioconjugate was immobilized on the surface of the electrodeposited AuNPs layer by the combination of forces (coordination and electrostatic force). Subsequently, it was immersed into gold colloidal nanoparticles (GNPs) solution, which was used to immobilize antibody biomolecules (anti-AFP). Enhanced sensitivity was obtained by using bioconjugates featuring HRP labeled (HRP-CNTs), which had lager specific surface area and good electronic catalysis (current response signal) compared to carbon nanotubes. Under optimized conditions, the linear ranges were from 0.2 to 200ngmL−1 with a detection limit of 0.067ngmL−1 (at an S/N of 3). The proposed immunosenor showed good precision, acceptable stability and reproducibility and could be used for the detection AFP in normal human serum, which provided a potential alternative tool for the detection of protein in clinical diagnosis. [Copyright &y& Elsevier]

Abstract: In the present work, we have developed a novel hydrogen peroxide (H2O2) biosensor based on electropolymerization of thiophene-3-boronic acid film (TBA) in ionic liquid via glucosidic bond with glycoprotein horseradish peroxidase (HRP). A thin film of poly (thiophene-3-boronic acid) (PTBA) has been synthesized by electropolymerization using room temperature ionic liquids (RTIL) as the growth medium and the supporting electrolyte. Horseradish peroxidase (HRP) in this study shows affinity interaction with the formed PTBA thin film. With the aid of hydroquinone (H2Q) mediator, the biosensor has a fast response of less than 7s with linear range of 5.0×10−6 to 1.75×10−4 M and a detection limit of 0.5μM. The developed biosensor exhibits fast response, a low detection limit, high stability and very good reproducibility. [Copyright &y& Elsevier]

Abstract: The possibility to afford by a biomimetic reaction ‘unnatural’ products, which could offer a better bioactivity profile than natural analogues, is outlined and the first applications to the synthesis of lignans and related compounds have been reported. Here we describe the synthesis of new heterodimers, having a phenylcoumaran skeleton, by horseradish peroxidase catalyzed cross-coupling reactions of methyl esters of substituted hydroxycinnamic acids. [Copyright &y& Elsevier]

Abstract: A novel chemiluminescence immunosensor using horseradish peroxidase (HRP)-functionalized mesoporous silica nanoparticles (MSN) as labels was developed, which increases the sensitivity of the chemiluminescence immunoassay. The enzyme-functionalized MSN were fabricated by simultaneous coimmobilization of HRP and the carcinoembryonic antigen antibody (anti-CEA) onto the surface of MSN using 3-aminopropyltriethoxysilane (APTES) as the linkage. Because the large surface area of MSN carriers increased the amount of HRP bound per sandwiched immunoreaction, the conjugates provided a much higher signal and increased sensitivity. This is an improvement over the traditional sandwich immunoassay which often has one or two enzyme molecules per antibody. This approach was successfully demonstrated as a simple, cost-effective, specific, and potent method to detect CEA in practical samples. The analysis showed a linear response within the range of 0.1–40ng/mL (r =0.9912). The relative standard deviation (RSD) for 11 parallel measurements of 20ng/mL CEA was 3.9%. The sensitivity of the immunosensor using MSN–HRP–Ab2 as labels was about 10-fold higher than that of traditional labels. These labels for immunosensors may provide many potential applications for detection of different biomolecules. [Copyright &y& Elsevier]

Abstract: Horseradish peroxidase (HRP) was chemically modified using cyanuric chloride (CC) as a linking agent onto a carbon felt (CF), which is a microelectrode ensemble of micro carbon fiber (>7μm, diameter) with a random three-dimensional structure. The resulting HRP-modified CF (HRP-ccCF) exhibited well-defined redox waves based on the HRP heme FeIII/FeII redox couple at −0.23V vs. Ag/AgCl (at pH 7.0), while the HRP-adsorbed CF (HRP-CF) showed no apparent redox couple in the same potential range, indicating that the chemical modification of HRP via CC facilitated the direct electron transfer (DET) between HRP and CF. The apparent heterogeneous electron transfer rate constant k s was estimated to be 35s−1. Cyclic voltammetry and electrochemical impedance spectroscopy revealed that the interfacial properties (i.e., structure, morphology of enzyme-layer) of covalently modified HRP (HRP-ccCF) and physically adsorbed HRP (HRP-CF) are different, resulting in the difference in the electron transfer properties. The HRP-ccCF was successfully used as a working electrode unit in bioelectrocatalytic flow-through detector for highly sensitive amperometric determination of H2O2. Under the optimized conditions (i.e., applied potential, 0V vs. Ag/AgCl; carrier flow rate, 3.25ml/min; and carrier pH 7.0), the cathodic peak current of H2O2 linearly increased up to 3μM (sensitivity, 1.94μA/μM; the detection limit, 0.08μM [S/N=3]) with sample through-put of ca. 90samples/h. [Copyright &y& Elsevier]

Abstract: The molecular weight, degree of deacetylation and the acetic acid concentration of chitosan solutions were modulated to change the structures and properties of the chitosan membranes, including chemical structures, ionic conductivity and hydrophobicity, which were analyzed by FTIR-ATR, electrochemical impedance and water contact angle measurement, respectively. Consequently, the adsorption of horseradish peroxidase (HRP, as a model) was controlled by the structural and natural changes of chitosan membranes, exhibiting different adsorbed amount and activity. A HRP-based electrode coated with the chitosan membrane was further constructed to investigate the influence of the chitosan membrane properties on the electrochemical performance. Therefore, this work offered a fundamental understanding of the control of the enzyme adsorption and performance through changing the chitosan membrane structures and properties for the more extensive applications, especially in the construction of the highly efficient bioelectrodes. [Copyright &y& Elsevier]