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The present study evaluated the priming efficacy of chitosan and chitosan-derived nanoparticles (CNPs) against bacterial wilt of tomato. In the current study, seed-treated CNPs plus pathogen-inoculated tomato seedlings recorded significant protection of 62 % against pathogen-induced wilt disease and subsequently better growth. The induced resistance was witnessed by a prominent increase in lignin, callose and H

Remediation and mitigation processes can recover the ecosystems affected by mining operations. Zygophyllum coccineum L. is a native indigenous xerophyte that grows in Egypt's Western Desert, particularly around the iron mining ore deposits, and accumulates high rates of potentially toxic elements (PTEs) in its succulent leaves. The present study evaluated the genetic variation and molecular responses of Z. coccineum to heavy metal stressful conditions in three sites. Results revealed that Z. coccineum bioaccumulation capacity was greater than unity and varied amongst the three locations. In response to heavy metal toxicity, Z. coccineum plants boosted their antioxidative enzymes activity and glutathione levels as a tolerance strategy. Anatomically, a compact epidermis, a thick spongy mesophyll with water storage cells, and a thicker vascular system were observed. Protein electrophoretic analysis yielded 20 fragments with a polymorphism rate of 85%. The antioxidant genes (CAT: catalase, POD: peroxidase and GST: polyphenol oxidase) showed greater levels of expression. In addition, DNA-based molecular genetic diversity analyses using Start Codon Targeted (SCoT) and Inter Simple Sequence Repeat (ISSR) markers yielded 54 amplified fragments (i.e. 24 monomorphic and 30 polymorphic), with 12 unique fragments and a polymorphism rate of 55.5%. The greatest PIC values were recorded for SCoT-6 (0.36) and for both of the 14 A and 44 B ISSR primers (0.25). Diversity index (DI) of all SCoT and ISSR amplified primers was 0.23. The present findings reveal the distinct heavy metal's adaption attributes of Z. coccineum, indicating its improved survival in severely arid mining environments.

Pearl millet is a nutrient dense and gluten free cereal, however it's flour remains underutilized due to the onset of rancidity during its storage. To the best of our knowledge, processing methods, which could significantly reduce the rancidity of the pearl millet flour during storage, are non-existent. In this study, pearl millet grains were subjected to a preliminary hydro-treatment (HT). Subsequently, the hydrated grain-wet flour have undergone individual and combined thermal treatments viz., hydrothermal (HTh) and thermal near infrared rays (thNIR). Effects of these thermal treatments on the biochemical process of hydrolytic and oxidative rancidity were analyzed in stored flour. A significant (p 0.05) decrease in the enzyme activities of lipase (47.8%), lipoxygenase (84.8%), peroxidase (98.1%) and polyphenol oxidase (100%) in HT-HTh-thNIR treated flour compared to the individual treatments was documented. Upon storage (90 days), decline of 67.84% and 66.4% of free fatty acid and peroxide contents were observed in flour under HT-HTh-thNIR treatment without altering starch and protein digestibility properties. HT-HTh treated flour exhibited the highest (7.6%) rapidly digestible starch, decreased viscosity and increased starch digestibility (67.17%). FTIR analysis of HT-HTh treated flour divulged destabilization of short-range ordered crystalline structure and altered protein structures with decreased in vitro digestibility of protein. Overall, these results demonstrated the effectiveness of combined thermal treatment of HT-HTh-thNIR in reducing rancidity and preserving the functional properties of the stored flour.

Chitosan/montmorillonite (CTS/MMT) and chitosan‑gold nanoparticles/montmorillonite (CTS-Au/MMT) composites were prepared, characterized through Fourier transformed infrared (FT-IR), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM), and utilized as support for immobilization of polyphenol oxidase (PPO). PPO was immobilized on CTS/MMT (IPPO) and CTS-Au/MMT (IPPO-Au) by physical adsorption, respectively. In order to achieve simultaneous maximization of immobilization efficiency and enzyme activity, the immobilization process parameters were optimized by Taguchi-Grey relational analysis (TGRA) approach. Under the optimal immobilization condition, the immobilization efficiency and enzyme activity reached at 50.16% and 1.46 × 104 U/mg for IPPO, and 63.35% and 3.01 × 104 U/mg for IPPO-Au, respectively. The isotherm, kinetic and thermodynamics of PPO adsorption were investigated in detail. The adsorption process was better explained by Toth isotherm and Fractal-like pseudo second order model, respectively. Intra-particle diffusion and film diffusion were involved in the adsorption process and intra-particle diffusion was not the only rate-controlling step. The adsorption of PPO was exothermic, physical and spontaneous at the investigated temperature range. The immobilized PPO were used to oxidize phenolic compounds. All investigated phenolic compounds showed the higher conversion as catalyzed by IPPO-Au. For both IPPO and IPPO-Au, the conversion of substituted phenols was higher than that of phenol.

Tyrosinase (Ty) and catechol oxidase (CO) are members of type-3 copper enzymes. While Ty catalyzes both phenolase and catecholase reactions, CO catalyzes only the latter reaction. In the present study, Ty was found to catalyze the catecholase reaction, but hardly the phenolase reaction in the presence of the metallochaperon called "caddie protein (Cad)". The ability of the substrates to dissociate the motif shielding the active-site pocket seems to contribute critically to the substrate specificity of Ty. In addition, a mutation at the N191 residue, which forms a hydrogen bond with a water molecule near the active center, decreased the inherent ratio of phenolase versus catecholase activity. Unlike the wild-type complex, reaction intermediates were not observed when the catalytic reaction toward the Y98 residue of Cad was progressed in the crystalline state. The increased basicity of the water molecule may be necessary to inhibit the proton transfer from the conjugate acid to a hydroxide ion bridging the two copper ions. The deprotonation of the substrate hydroxyl by the bridging hydroxide seems to be significant for the efficient catalytic cycle of the phenolase reaction.

Vibrio anguillarum is a globally distributed aquatic pathogen, and its flagellin B (FlaB) protein can evoke innate immune responses in hosts. In order to explore the role of FlaB in V. anguillarum infection, we constructed a FlaB-deficient mutant using overlapping PCR and two-step homologous recombination, and gene sequencing confirmed successful knockout of the FlaB gene. Scanning electron microscopy showed no significant differences in the morphological structure of the flagellum between wild-type and FlaB-deficient strains. The mutant was subsequently injected into the freshwater prawn (Macrobrachium rosenbergii) to explore its pathogenicity in the host, and expression of myeloid differentiation factor 88, prophenoloxidase, catalase, superoxide dismutase and glutathione peroxidase was investigated by real-time PCR. The results showed that deletion of FlaB had little effect on V. anguillarum-induced expression of these immune-related genes (p > 0.05). In general, the FlaB mutant displayed similar flagella morphology and immune characteristics to the wild-type strain, hence we speculated that knockout of FlaB might promote the expression and function of other flagellin proteins. Furthermore, this study provides a rapid and simple method for obtaining stable mutants of V. anguillarum free from foreign plasmid DNA.

The effects of three biogenic amines (DA, NE and 5-HT) on the immune signaling pathway and immune response of hemocytes in shrimp were investigated through in vitro experiments. The results showed that the G protein effectors (AC, PLC), the second messengers (cAMP, DAG), Calmodulin (CaM) and protein kinases (PKA, PKC) of DA and NE groups shared a similar trend in which all intracellular signaling factors increased significantly and reached the maximum at 3 h. The concentrations of AC, cAMP and PKA in 5-HT groups decreased significantly compared with the control group, while the concentrations of PLC, CaM, DAG and PKC in 5-HT groups increased markedly. The immune parameters such as total hemocyte count (THC), cell viability, antibacterial activity and bacteriolytic activity, as well as prophenoloxidase (proPO) activity in three biogenic amines groups decreased significantly, while the phenoloxidase (PO) activity increased significantly. The phagocytic activity in DA and NE groups decreased significantly, while that in 5-HT groups increased markedly and reached the highest level at 1 h. Among these three biogenic amines, DA showed the strongest effect on the immune activity of the hemocytes, whereas 5-HT had the least effect. In addition, we speculated that DA and NE might regulate phagocytosis by activating intracellular AC-cAMP-PKA pathway while 5-HT might inhibit intracellular AC-cAMP-PKA pathway. Moreover, the activation of proPO system might be related to PLC-DAG-PKC and PLC-CaM pathway.

Polyphenol oxidase (PPO) was immobilized on chitosan/montmorillonite (CTS/MMT) and chitosan-gold nanoparticles/montmorillonite (CTS-AuNPs/MMT) composites, respectively. Taguchi method was applied to determine the optimal immobilization conditions for achieving the maximum enzyme activity. PPO immobilized on CTS/MMT (IPPO) and CTS-AuNPs/MMT (IPPO-Au) showed the highest enzyme activity at 15.61 × 103 and 29.01 × 103 U/g, respectively. IPPO-Au exhibited the higher stability and reusability than that of IPPO. The bio-catalytic performance of immobilized PPO was evaluated for the removal of phenol (PH), 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) in aqueous solution. The effects of pH, temperature, enzyme/substrate ratio, substrate concentration, reaction time on the phenolic compounds removal were investigated in detail. The results showed that, for both immobilized PPO, the optimal pH was 7, 6 and 5 for PH, 4-CP and 2,4-DCP, respectively, and the optimal temperature was 30 °C for all substrate. The optimal enzyme/substrate ratio and reaction time for IPPO-Au was lower than that of IPPO proved the higher catalytic efficiency. Chlorophenols showed the improved catalytic efficiency in comparison with PH for both immobilized PPO, while the effect of substrate chemical structure on the IPPO-Au properties was limited. The results suggested AuNPs presented in support played an important role on the enzyme activity and stability of immobilized PPO.

Phenoloxidase (PO) is a crucial enzyme in the Arthropods melanization process, in which synthesized melanin rapidly acts at the site of injury and infection. In this study, we observed significant changes in humoral and cellular responses after exposing susceptible and resistant strains to a sub-lethal concentration of Cry1Ah toxin. Based on STRING v 11.0 computational protein-protein interaction analysis, we selected seven immune genes namely Prophenoloxidase PPO1b, PP03, Serpin-3, Serpin-5, Beta-1,3-glucan recognition protein, Immulectin-3 and Serine protease SP105 reported in Asian corn borer. Quantitative real-time PCR gene expression studies showed Cry1Ah resistant strain had higher expression of PPO1b, PP03, Serpin-3, Beta-1,3-glucan recognition protein, Immulectin-3 and Serine protease SP105 genes in midgut and hemocyte samples. This study also investigated and found that the level of prophenoloxidation (proPO) activity in Cry1Ah resistant strains was significantly higher than susceptible strains. Cry1Ah toxin significantly increased the resistant strain's immune responses, the difference was observed through assays of bacterial agglutination and phagocytosis. Additionally, immune response induced by Cry1Ah toxin influences the microbiome composition associated with the host system. These parameters seem to explain the contribution of PO/PO regulating proteins render the host to resist the Cry1Ah toxin.

It has been revealed that slightly acid electrolysed water (SAEW) could delay enzymatic browning and melanin formation in food. In this work, multi-spectroscopic methods and UHPLC-Q-TOF-MS were combined to study the underlying reason. The reversible mixed-type inhibition mode of HOCl (main components in SAEW) was determined. The ground state complex formation quenched the intrinsic fluorescence of polyphenol oxidase (PPO) and it was stable at lower temperature. The PPO conformational change (transformation from α-helix to β-sheet) induced by SAEW was confirmed by 3D fluorescence and Circular dichroism (CD) spectrum. Moreover, the driving force of the interaction between HOCl and PPO was hydrogen bond, which was validated by the molecular docking result. Besides, the formation of melanin related compounds including dihydroxyphenylalanine (DOPA), dopaquinone, dopachrome, 5,6-dihydroxyindole-2-carboxylic acid (DHICA), 5,6-dihydroxyindole (DHI), and 5,6-indolequinone were significantly inhibited by SAEW treatment. These results demonstrated the potential of SAEW as a PPO inhibitor in the food industry.

Enzymatic browning greatly affects the quality of potato products. Polyphenol oxidase (PPO) is the enzyme mainly responsible for potato enzymatic browning. PPO has soluble polyphenol oxidase (sPPO) and membrane-bound polyphenol oxidase (mPPO) forms. In this study, the properties of sPPO and mPPO were investigated in potato tubers. The molecular weight of potato sPPO and mPPO were estimated to be 69 kDa in the form of homodimers in vivo. The mass spectrometry results showed that the purified sPPO and mPPO protein in potato tubers was mainly tr|M1BMR6 (Uniprot). The optimum pH for sPPO and mPPO was 6.5, and the optimum temperatures were 20 and 30 °C, respectively. The Michaelis constant (K

The inhibition mechanisms of soluble PPO (sPPO) by l-cysteine, reduced glutathione and thiourea, and membrane-bound (mPPO) by l-cysteine, reduced glutathione, thiourea, anisaldehyde and cinnamaldehyde were investigated by combining multispectroscopic analysis and computational simulations. Reduced glutathione showed the strongest inhibitory effect, with IC50 of 0.46 and 0.94 mM, respectively. The multispectral results showed that all inhibitors inhibited activity by destroying the secondary and tertiary structure, and the structure of sPPO were more easily affected. Docking showed that hydrogen bond and metal contact were the main driving force for inhibitors binding to sPPO and mPPO, respectively. Simulation showed that sPPO-inhibitor system had more fluctuation than mPPO-inhibitor system, indicating easier inhibition of sPPO activity. This work revealed that the structural differences between sPPO and mPPO led to different inhibition mechanisms of PPOs by inhibitors at the molecular level, which could provide the guidance for the selection of inhibitors in fruit and vegetable processing.

Blue mold decay is a major postharvest disease of apples, causing considerable losses to the apple industry. In the early stage of this research, an antagonistic yeast, Hannaella sinensis, with a good control effect on the blue mold of apples, was selected. On this basis, the main purpose of this work was to study the biocontrol effect of H. sinensis on the blue mold of apples and the mechanisms involved. The results showed that H. sinensis could effectively control the blue mold decay of apples, reduce the rot rate and diameter, and the antagonistic effect strengthened with the increase of H. sinensis concentration (1 × 10

It is still unclear how pH affects the inhibitory effects of phenolic acids and flavonoids on polyphenol oxidase (PPO). In this study, 4-hydroxycinnamic acid and naringenin were selected to investigate their interactions with PPO from pH 6.8 to 5.0. Results showed that acidic pH could enhance the inhibitory effect of inhibitors and a greater enhancement effect was observed in 4-hydroxycinnamic acid. Fluorescence emission spectra indicated that 4-hydroxycinnamic acid and naringenin interacted with PPO and quenched its intrinsic fluorescence, which was also enhanced by acidic pH. Circular dichroism suggested that 4-hydroxycinnamic acid and naringenin could reversibly bind to PPO molecules and transform α-helix into β-sheet. Molecular docking results revealed that 4-hydroxycinnamic acid and naringenin interacted with PPO through hydrogen bond and hydrophobic interaction, and more interactions were observed near the carboxyl group. These results indicated that acidic pH could significantly enhance the inhibitory effect of phenolic acid on PPO.

Cashew (Anacardium occidentale L.) is composed of two distinct parts: the nut (fruit), which represents only 10% of the total weight of the harvested product, and the cashew apple (pseudo-fruit), usually known as cashew. This study aimed to determine the hydrocooling temperature of cashew apples and its effects on quality maintenance. Cashews were hydrocooled (HC) by immersion in chlorinated water at 1, 3, 5 and 7 °C. Fruit were cooled in a refrigerator at 5 °C as controls. After treatments, all the fruit were stored at 5 °C for 15 d, and cooling rate, color, freshness, visual assessment, weight loss, and thermal properties were evaluated. Fruit hydrocooled at 1 and 7 °C had lower visual quality and wilting, and greater weight loss, 3 °C was discarded by did not show evident results. A temperature of 5 °C was selected for further studies. Cashew apples were HC at 5 °C, and control treatment cooled in display cold room (CR) at 5 °C, and then fruit from both treatments were stored for 25 days. Samples were taken for physical, physico-chemical and enzymatic analyses at 5 days intervals. HC fruit showed greater freshness, higher firmness and acidity, and slower losses of fresh weight loss and vitamin C when compared with CR. Total phenolic contents decreased during storage, but little effect of treatment on the rate of decline was detected. However, activities of polyphenol oxidase and peroxidase were generally higher in cashew apples with CR than after HC. Red color loss of the cashew apples was constant during storage, regardless of the cooling method. Our study shows that 5 °C is the minimal temperature for hydrocooling of cashew apples, to decrease the risk of damage by cooling, and that this temperature is the optimal temperature for storage of cashew apples

Proline is one of the amino acids that compose proteins and has various roles under non-stress and stress conditions. In this study, we investigated the effect of proline on the growth and browning of two plants, tobacco and rice, by exogenous application and endogenous increase of proline. Exogenous proline had a different effect on the growth and browning between tobacco and rice: proline affected negatively the growth of tobacco seedlings and favorably that of rice seedlings. In addition, proline prevented browning only in rice cultured cells, consistent with the increase of proline contents, but not in tobacco BY-2 cells. These results might be due to the difference of exogenous proline uptake activity in these cells. From the Lineweaver-Burk plots, proline inhibited polyphenol oxidase activity in vitro, which is a major factor of enzymatic browning in plants, by affecting the enzyme-substrate complex. Proline could suppress the browning of the plant callus by inhibition of PPO activity.

Prophenoloxidase (proPO) is the zymogen form of phenoloxidase (PO), a key enzyme in melanization cascade that has been co-opted in invertebrate immune reactions. There have been reported that proPO plays many essential roles in the crustacean immune system. However, little is known about the function of proPO from red swamp crayfish (Procambarus clarkii) which is an important cultured species worldwide. Here, we cloned and expressed proPO gene from red swamp crayfish (PcproPO). Subsequently, specific antibody against PcproPO was generated. The immune function of PcproPO was further characterized in vitro and in vivo. The results showed that the expression of PcproPO mRNA could be significantly up-regulated during the challenge of Gram-positive-negative (Vibrio parahaemolyticus) and Gram-positive-positive bacterial (Staphylococcus aureus). Furthermore, the purified recombinant PcproPO protein had a strong affinity binding to both bacteria and polysaccharides. In vivo knockdown of PcproPO could significantly reduce the crayfish bacterial clearance ability, resulting in the higher mortality of the crayfish during V. parahaemolyticus infection. In addition, in vitro knockdown of PcproPO in the hemocytes significantly reduced the phenoloxidase (PO) activity and the bacterial clearance ability, indicating that PcproPO might involve in hemocyte-mediated melanization. Our results will shed a new light on the immune function of PcproPO in the crayfish.

Two heteroleptic cobalt(III) complexes, [CoL1(acac)(N3)] (1) and [CoL1(acac)(NCS)] (2) {where HL1 = 1-((2-(dimethylamino)ethylimino)methyl)naphthalen-2-ol and Hacac = acetylacetone} have been synthesized and structurally characterized by several analytical techniques including single crystal X-ray diffraction analysis. Extended supra-molecular assemblies were generated in them through weak noncovalent interactions. Synthesized complexes have also been found to mimic the role of quite a lot of metalloenzymes like catechol oxidase, phenoxazinone synthase and phosphatase efficiently by catalytic areal oxidation of respective substrates. Detailed kinetic studies of catalytic reactions are performed spectrophotometrically, which confirm that catalytic reactions follow Michaelis-Menten enzymatic reaction kinetics. Role of co-ligands in catalytic activity has also been assessed.

Postharvest skin browning of litchi is the major issue which substantially affects its visual quality and market potential. Effect of modified atmosphere packaging (MAP) was studied to manage its surface browning and various quality attributes during storage at 5 ± 1 °C. It was noted that fruits kept under MAP exhibited reduced decay, browning index and loss of fresh weight. MAP storage of fruits markedly suppressed polyphenol oxidase (PPO) activity and delayed production of superoxide anion (O2– ), malondialdehyde (MDA), hydrogen peroxide (H2O2) and relative electrolyte leakage with higher anthocyanin concentrations. Likewise, MAP stored fruits had higher total soluble solids (TSS), ascorbic acid content and titratable acidity (TA) with lower peroxidase (POD) activity. In addition, sensory quality, total phenolic content (TPC), radical scavenging activity, superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activities were also markedly higher in MAP kept fruits. So, litchi fruits storage under MAP packaging was suitable to delay its postharvest browning and to conserve biochemical attributes and antioxidative enzymes during 28 days cold storage.

The performance of calcium nanoparticles (CaNPs) blending in ascorbic acid (AA) to alleviate internal browning symptoms of ‘Hindi Be-Sennara’ mango fruit under cold storage otherwise the impacts of CaNPs-AA on browning enzyme activities such as polyphenol oxidase (PPO, EC: 1.14.18.1) and Phenylalanine ammonia-lyase (PAL, EC: 4.3.1.24) were assessed. The mango fruits were immersed with CaNPs with AA at the diff ;erent concentration (0, 6, and 9 mM) and stored at low temperature (6 °C and 95% RH) for 35 days. Fruit samples were picked every five days interval. The visual measurement of internal browning index (IB-index) was monitored. The chemical analysis, for instance, the total phenol (TP), and flavonoids (FL) content were measured. Moreover, the cell wall degradation enzymes for example lipoxygenase (LOX; EC: 1.13.11), pectinase (PT; EC: 3.2.1.15), cellulase (CEL; EC: 3.2.1.4), and cell membrane leakage percentage were measured. However, the cell wall termination compounds such as lipid peroxidation (malondialdehyde, MDA), and DPPH radical were determined. The CaNPs-AA 9 mM reduced significantly the IB incidence, maintained the phenolic compounds content by preserving cell wall structure and minimizing action of both PPO and PAL activities during cold storage. Moreover, the changes in cell wall degradation enzyme activities were inhibited by CaNPs-AA 9 mM treatment so less leakage percentage. In the same trend, the lowest accumulation of MDA and the highest concentration of DPPH was monitored too. As the main conclusion, using the CaNPs-AA 9 mM treatment for 24 h to fruit exhibited significantly a reduction of internal browning incidences of mango during cold storage.

Ternary copper(II) complexes with the molecular formulae of [CuIILL′]X or [CuIILL′X]; L = l -Valinate; L′ = α, ά-bipyridyl or 1,10 - phenanthroline and X is Cl¯, Br¯, NO3¯, AcO¯, ½SO42− or ClO4¯ were synthesized. Elemental and thermal analysis in addition to electrochemical (molar conductance and cyclic voltammetry), magnetic moment measurements as well spectral (FT-IR, UV–Vis and ESR) techniques were used to characterize the complexes. The spectroscopic results suggested square pyramidal and square planar geometries for the five- and four-coordinate complexes respectively. Powder X-ray diffraction spectral data along with the structure solution program Expo 2014 has been used for structural elucidation of the sulfato complexes 1 and 5. Stopped follow technique was employed to study the substitution of the nonelectrolytic coordinately counter anion ligand by using thiourea (TU) as a function of nucleophile and a biphasic process is proposed. An initial fast reaction is followed by a slower one and the initial one was found to be counter ion dependent. Bio-mimicking the multicopper oxidase enzyme such as catechol oxidase and phenoxazinone synthase is a further goal of the present study. Catalytic examinations displayed that the present complexes are promising candidates as functional mimic of the examined enzymes and the probable mechanistic catalytic sequences are discussed.

Litchi (Litchi chinensis Sonn. cv. ‘Feizixiao’) has a high market value. However, its value declines during postharvest storage because its quality deteriorates, and its pericarp turns brown. Therefore, safe and effective ways of improving litchi quality and inhibiting postharvest browning are required. In this study, 5-aminolaevulinic acid (5-ALA) and thidiazuron (TDZ) were applied to litchi fruit before harvest to determine their relative effects on litchi colour and postharvest storage characteristics. The results showed that preharvest 5-ALA application significantly increased postharvest fruit weight, anthocyanins, total phenol, vitamin C and antioxidant activity relative to those in the untreated fruits. Compared with the control, TDZ significantly increased fruit weight but inhibited anthocyanin accumulation and did not significantly alter antioxidant activity. Both preharvest treatments significantly reduced the browning index, the relative leakage rate and polyphenol oxidase activity after 6 d of storage. A membership function analysis indicated that preharvest 5-ALA application was the most beneficial for postharvest storage whereas TDZ treatment was relatively less effective. Preharvest colour promotion was preferable for improving litchi quality and inhibiting postharvest browning.

The blue mold caused by Penicillium italicum in grapefruit fruit was controlled by the antifungal activities of Carboxymethyl chitosan (CMCS) alone and combined with Cryptococcus laurentii treatments in this study. According to the study results spore germination of P. italicum can be inhibited by both CMSC and C. laurentii treatment. Moreover, the growth of C. laurentii can be maintained by low CMCS concentration in vitro. The blue mold in grapefruit fruit inoculated with P. italicum was decreased in all treatments compared with the control fruit. The combination of CMSC and C. laurentii treatment resulted in a significantly synergistic effects in smallest lesion diameter and decay incidence. The defense enzyme activities, such as phenylalanine ammonia-lyase, polyphenol oxidase, peroxidase and antifungal compounds like total phenolic related to disease resistance can be induced by combined treatment. Furthermore, the commercial quality parameters of the CMCS combined with C. laurentii treatment which were measured by ascorbic acid, titratable acidity, weight loss and total soluble solid, were better than those treated with treatments alone. According to the results, the combination of CMSC and C. laurentii treatment can maintain fruit quality and control postharvest decay more effectively than single treatment, and can be commercially used in grapefruit fruit.

Macadamia nut is rich in monounsaturated fatty acids, which are known to reduce the risk of cardiovascular diseases when included as part of a healthy human diet. On the negative side, high concentrations of unsaturated fatty acids lead to oxidative reactions, which result in rancidity thus decreases the quality of the nut. Drying and roasting are, therefore, needed to reduce moisture content and hence alleviate the above-mentioned problems. This research was conducted to evaluate and compare the quality properties of raw and roasted macadamia nuts during the accelerated storage of 70 days. Two commercially important macadamia cultivars, namely, ‘A4’ and ‘Beaumont’ were used as model cultivars. Nuts were roasted at 125 °C for 15 min using a hot air oven dryer. Roasted kernels of ‘A4’ and ‘Beaumont’ cultivars had significantly lower concentration of peroxide value (PV), high concentration of flavonoids, phenols and antioxidants activity and good sensory quality compared to raw kernels which had a higher concentration of polyphenol oxidase activity, PV, low concentration of flavonoids, phenols and antioxidant activity and poor sensory quality during the accelerated storage of 70 days. These results indicated that roasting significantly improved kernel quality and shelf life of ‘A4’ and ‘Beaumont’ macadamia cultivars.

Hemocytes are the major immune cells of crustaceans. New hemocyte production is required throughout the life cycle of these animals to maintain a functional immune system. The mechanism of crustacean hematopoiesis has just begun to be understood and new methods are needed for the investigation of this process. Here we report the directed differentiation of granular cells (GCs) from the hematopoietic tissue (HPT) cells of Cherax quadricarinatus in vitro. We started by providing the cultured HPT cells with different additives to induce possible differentiation. We found that crayfish muscle extract greatly promoted the physical status of the cells and induced the formation of refractile cytoplasmic granules. The transcription of marker genes and the production of functional prophenoloxidase further confirmed the formation of mature GCs. In our experiments, young GCs usually started to develop in ∼2 weeks post induction and over 60% of the cells became mature within 3-4 weeks. This is the first time that the fully differentiation of crustacean hemocytes is accomplished in vitro. It provides a powerful tool for in-depth study of crustacean hematopoiesis.

Endocrine-disrupting chemicals (EDCs), xenobiotics that interfere with endogenous hormone function, have been studied for their impacts in aquatic environments. However, there is limited information about the potentially hazardous impact of bisphenol A (BPA) and di-(2-ethylhexyl) phthalate (DEHP) on the marine environment. The aim of this study was to investigate the effects of BPA and DEHP on the immune response of the intertidal mud crab, Macrophthalmus japonicus. In order to examine immunological responses involving the prophenoloxidase (proPO) system, mRNA transcript and activity levels of six immune-related genes, including lipopolysaccharide and β-1,3-glucan-binding protein (LGBP), proPO, phenoloxidase (PO), peroxinectin (PE), serine protease inhibitor (Serpin), and trypsin (Tryp), were assessed in M. japonicus hepatopancreas and gills exposed to BPA or DEHP. Expression of immune genes generally decreased in M. japonicus hepatopancreas and gills exposed to all concentrations of BPA by days 4 and 7. However, at day 1, expression of Serpin and Tryp genes was significantly increased in M. japonicus hepatopancreas and gills exposed to BPA. For DEHP exposure, all genes, with the exception of Serpin, were significantly downregulated in M. japonicus gills. In the hepatopancreas, gene expression of PO, proPO, and LGBP increased at day 1, and then decreased by day 7, while mRNA expression of Serpin and Tryp exhibited up-regulation over all exposure periods. In addition, PE gene expression was upregulated in hepatopancreas at day 7 in a dose-dependent manner. Taken together, these results indicated that the crab immune responses were perturbed by exposure to BPA, and, in particular, DEHP.

Trichoderma harzianum T-soybean plays an important role in controlling soybean root rot disease. However, the mechanism by which it improves plant tolerance to salt stress is not clear. In this study, we investigated the possible mechanism of T-soybean in mitigating the damage caused by salt stress in Cucumis sativus L plants. Our results suggest that T-soybean improved salt tolerance of cucumber seedlings by affecting the antioxidant enzymes including peroxidase (POD) (EC 1.11.1.6), polyphenol oxidase (PPO) (EC 1.14.18.1), phenylalanine ammonia-lyase (PAL) (EC 4.3.1.5), catalase (CAT) (EC 1.11.1.6), superoxide dismutase (SOD) (EC 1.15.1.1), ascorbate peroxidase (APX) (EC 1.11.1.11), and glutathione reductase (GR) (EC 1.6.4.2), by increasing the levels of proline, soluble sugars, soluble protein, ascorbic acid (AsA) and chlorophyll as well as improving root activity. Treatment with T-soybean improved the ratio of glutathione (GSH)/oxidized glutathione (GSSG) and AsA/dehydroascorbate (DHA), and up-regulated the expression of CsAPX and CsGR genes involved in the AsA-GSH cycle. In addition, treatment with T-soybean increased the K+ content and K+/Na+ ratio while decreased the Na+ concentration and ethylene level. In summary, the improved salt tolerance of cucumber plants may be due to multiple mechanisms of T-soybean, such as the increase in reactive oxygen species (ROS) scavenging, as well as maintaining osmotic balance and metabolic homeostasis under salt stress.

The use of alfalfa protein in human food is limited by its low quality. Response Surface Methodology was employed to optimise the combined effects of different steam blanching conditions on the enzymatic activity, browning and protein degrading which cause undesirable characteristics. The optimum conditions were: steaming time 4.36 min, particle size 23 mm, time from harvesting to steaming 2 h leading to a residual activity of polyphenol oxidase of 1.31% and a completely inactivation of peroxidase. The Browning Index value was 108.3 and the non-protein nitrogen 170.2 (g kg−1 TN). The browning and protein degradation rates of alfalfa treated under the optimum conditions were much lower than the control alfalfa after 60 days ensiling. This suggests that blanching of fresh whole alfalfa leaves under the optimum conditions was helpful for avoiding the appearance of the dark color and degradation of the extracted protein, improving its quality for human consumption.

Wilt disease, caused by Fusarium oxysporum. f. sp. lycopersici, is a global threat to tomato production that needs to be addressed seriously. The current research envisages the use of two self-compatible Bacillus strains, Bacillus tequilensis PKDN31 and Bacillus licheniformis PKDL10, in a combinatorial approach. The spent supernatant of liquid cultures from strains PKDN31 and PKDL10 showed in vitro antifungal activity against Fusarium sp. attaining an inhibition percentage of 95.33% and 96.54%, respectively. The bacterial isolates lytic activity against Fusarium oxysporum was evaluated by scanning electron microscopic analysis and lytic enzyme production of amylase, lipase, protease and β-1,3 glucanase. Furthermore, PKDN31 and PKDL10 produced siderophores and had root colonizing ability that enhanced the biocontrol efficiency. Combined in vivo inoculation of Bacillus tequilensis PKDN31 and Bacillus licheniformis PKDL10 on tomato seeds revealed that the strains could induce systemic resistance in tomato against Fusarium oxysporum. f. sp. lycopersici by increasing defence enzymes such as β-1,3 glucanase, polyphenol oxidase, peroxidase, phenylalanine ammonia-lyase, chitinase, and total phenol accumulations. Pot culture experiments also proved the biocontrol efficacy of the above dual culture supplementation as this treatment displayed a better growth as well as defense against Fusarium challenge compared to the controls. The obtained results suggest that rhizobacterial isolates could be employed as systemic resistance inducers and biocontrol agents in tomato plants to protect against Fusarium wilt disease.

This work focuses on understanding the action of a novel seaweed extract with anti-browning functionality in fresh-cut apples. Organic fresh-cut apples were coated by immersion in an aqueous Codium tomentosum seaweed extract (0.5 % w/v), packaged under ambient atmospheric conditions in plastic bags, and stored at 4 ˚C for 15 days. Browning-related enzymatic activities, as well as targeted gene expression related to superficial browning, were monitored immediately after coating and followed at five-day intervals, until a final storage period of 15 days. Gene expression was particularly affected one hour after coating application (day 0), with no expression registered for peroxidase (mdPOD) and phenylalanine ammonia-lyase (mdPAL) genes in the coated samples. A reduction in polyphenol oxidase expression levels was also observed. After 15 days of storage, the coated samples developed lower browning levels and presented distinctly lower activities of polyphenol oxidase and peroxidase - the oxidative enzymes predominantly involved in enzymatic browning. The observed post-coating suppression of mdPAL and mdPOD expression, and reduction in mdPPO expression, suggest that the seaweed C. tomentosum extract delays the activation of these genes, and decreases enzymatic activity, which in turn accounts for the coating's anti-browning effect.

Environmental microplastic accumulation can lead to a range of problems and the potential loss of ecosystem services. However, the impacts of microplastics on sediment environmental properties and microbial ecosystems remain unclear. Therefore, this article aimed to better elucidate the effects of microplastics on sediment physicochemical properties, enzymatic activities and the diversity and composition of sediment microbial communities. We conducted a 60-day sediment-incubation experiment using sediments with three concentrations (2%, 5%, and 10%, w/w) and two types (polyethylene (PE) and polyvinyl chloride (PVC)) of microplastics (550 μm) in a climate-controlled chamber. The addition of both PE and PVC microplastics reduced sediment catalase, polyphenol oxidase (PO), and urease activities, and decreased physicochemical indicators, including total organic carbon (TOC), total nitrogen (TN), and pH value. In addition, microplastics reduced bacterial community diversity and inhibited the recovery of community richness, implying that microplastics may compete with sediment microorganisms for niches. Stronger effects were generally detected under a high microplastic concentration (10%), reflecting the influence of the concentration of microplastic exposure on the bacterial community. The dominant bacterial phyla were Chloroflexi, Proteobacteria, Bacteroidota, Firmicutes, and Actinobacteriota, and the relative abundances of Proteobacteria, and Bacteroidota significantly increased in the microplastic treatments during the late incubation period, indicating that microplastic addition may have improved nutritional conditions later in the incubation process. Structural equation modeling indicated that shifts in PO activity had a significant correlation with changes in Proteobacteria abundance (P 0.01), and important drivers affecting the dissimilarity of Bacteroidota abundance were the changes of TN content and catalase activity (P 0.05). These results indicated that microplastics with diverse characteristics affected the environmental properties of the sediment, while the physicochemical properties and enzymatic activity of the sediment could directly or indirectly exert different impacts on the dominant bacteria. This study can provide a theoretical basis for the ecological effects of microplastic contamination.

Melanization is a key immune response mediated by serine protease (SP) cascade in insects. Multiple SP pathways exist in different species and it is unclear how conserved these cascades are. The cotton bollworm Helicoverpa armigera is a major worldwide agricultural pest. We reported a conserved melanization pathway in this species, which consists of SP41, cSP1, and cSP6. In this study, we attempted to identify an insect pathogen that elicits the cascade and test whether or not there are other SP cascades in H. armigera. After Micrococcus luteus, Enterobacter cloacae, Beauveria bassiana, or Helicoverpa armigera nucleopolyhedrovirus were injected into larvae, pathogen-induced hemolymph samples were collected for in vitro biochemical assays, which failed to detect proSP41 or procSP1 activation. In contrast, we found that procSP4, a protein proposed to participate in H. armigera melanization, was activated in M. luteus infected hemolymph. We further revealed that cSP8 was a prophenoloxidase (PPO) activating protease downstream of cSP4, and cSP4 was activated by cSP10. The pathway of cSP10-cSP4-cSP8 activated PPO in vitro. Efficiently cleaved procSPH11 and procSPH50 by cSP8 substantially enhanced phenoloxidase activity, suggesting they work together as a cofactor for cSP8 mediated PPO activation. Hemolymph from larvae challenged with M. luteus or its peptidoglycan effectively activated procSP10. Collectively, these results revealed a new PPO activation cascade specifically triggered by the bacterium. In addition, we found that the PPO activation cascades in H. armigera and Manduca sexta are conserved.

Atmospheric cold plasma (ACP) is a novel nonthermal technology with potential applications in maintaining and improving food quality. The effect of ACP on the activity and structure of mushroom (Agaricus bisporus) polyphenol oxidase (PPO) was evaluated. Results demonstrated that the dielectric barrier discharge (DBD) based plasma technology could inactivate PPO (up to 69%) at 50 kV with the increased concentrations of H

As the dominant microbial strain in Fuzhuan brick tea, Eurotium cristatum (E. cristatum) can biotransform the fermentation substrate during growth and reproduction, and in so doing enhance the tea's health benefits. Green tea contains a large number of bioactive compounds with antihypertensive potential. However, as a nonfermented tea, inactivation of various enzymes (such as polyphenol oxidase) during processing results in a single secondary metabolite with limited health effects. The novel fermented tea we studied was processed by solid-state fermentation (SSF) with E. cristatum, and the substrate was a mixture of green tea and Radix Puerariae (RP). This study was aimed at evaluating the multiple effects by E. cristatum during fermentation. Compared to the unfermented control groups, the sample groups secreted enzymes (such as polyphenol oxidase and α-amylase), and the bioactive compounds content of sample groups changed, as well as significantly higher inhibition of Angiotensin-converting enzyme (ACE) in vitro (which also implies greater antihypertensive potential). These results will help further investigations of the antihypertensive bioactive compounds of green tea and the fermentation potential of E. cristatum.

Although Galla rhois has been used as a traditional medicine in Asian countries, there was no application of it in anti-browning food additives. Here, we tested whether Galla rhois inhibits apple juice browning. Apple juice browning was blocked at 250-1000 µg/ml of Galla rhois for 16 days but the effect of vitamin C did not last until a day. In vitro assays showed that the antioxidant capacity of Galla rhois was stronger than that of vitamin C. Further analysis by UPLC-MS/MS identified 17 phytochemicals containing gallotannin derivatives. Docking simulation and polyphenol oxidase activity assay indicate that the mechanisms underlying Galla rhois-mediated inhibition of the enzymatic browning include but are not limited to the combined effects of multiple compounds including galloylglucose- and gallate-derivates. Although marketability and long-term toxicity of Galla rhois should be tested, it may be applied as a food additive to elevate food quality.

A series of four copper(II) µ-alkoxo-µ-carboxylato double bridged complexes, [{Cu 2 (L)} 2 ][(µ-O 2 C-CO 2 ] 1 , [{Cu 2 (L)} 2 (µ-O 2 C-(CH 2 )CO 2 ] 2 , [{Cu 2 (L)} 2 (µ-O 2 C-CH 2 -CO 2 ] 3 and [{Cu 2 (L)} 2 (µ-O 2 C-C 6 H 4 -CO 2 ] 4 (H 3 L = 4-bromo-2-((E)-((3-(((E)-5-chloro-2-hydroxybenzylidene) amino)-2-hydroxypropyl) imino) methyl)-6-methoxyphenol and µ-dicarboxylate ions = oxalate, malonate, succinate and terephthalate) have been synthesized and characterized using several physicochemical technique. The tridentate nature of H 3 L is interpreted from IR spectra. The Epr spectra of these complexes are characteristic of the quintet state (S = 2) in central features and the triplet state (S = 1) of the tetranuclear complexes. The electrochemical potential of these complexes was investigated using cyclic Voltammetry (CV) and differential pulse Voltammetry (DPV). All complexes exhibited quasi-reversible reduction peaks in the cathodic region. To explore the stability of these complexes, quantum chemical parameters like electronegativity, ionization potential, electron affinity, global hardness and softness and electrophilicity were estimated and discussed. The synthesized complexes have been designed as structural and functional models of the catechol oxidase enzymes to investigate the catecholase activity. Additionally, superoxide dismutase activity data of all complexes have also been evaluated and compared with known SOD mimics.

Melanization mediated by the prophenoloxidase-activating system (proPO) is an important immune response in invertebrates. However, the role of melanization on viral infection has not been wildly revealed in Bombyx mori (B. mori), silkworm. Here, we investigated the extent of melanization of susceptible (871) and resistant (near-isogenic line 871C) B. mori strains. The result showed that the extent of melanization was significantly higher in the susceptible strain than in the resistant strain. A majority of Serpins were up-regulated in the resistant strain through iTRAQ-based quantitative proteomics, comparing with susceptible strain. Our data further identified that Serpin-5, Serpin-9 and Serpin-19 reduced PO activity, indicating that the menlanization pathway was inhibited in the resistant strain. Moreover, our results indicated that the hemolymph of 871 reduced viral infection in the presence of PTU, indicating that melanization of 871 strain hemolymph blocked viral infection. However, viral infection was significantly suppressed in the hemolymph of 871C strain regardless of the presence of PTU or not, which implied that the resistant strain inhibited viral infection independent of the melanization pathway. Taken together, our findings indicated that the melanization pathway was inhibited in resistant strain. These results expend the analysis of melanization pathway in insects and provide insights into understanding the antiviral mechanism.

The extracellular serine protease cascade is an essential component of insect humoral immunity. Serine protease inhibitors (serpins) play an important regulatory role in the process of insect immunity by regulating the serine protease cascade pathway. We aimed to clarify the function of Bmserpin32 in this study. First, we performed homologous sequence alignment and phylogenetic analysis of Bmserpin32. Bmserpin32 was found to share 64% amino acid sequence identity with Manduca sexta serpin7, an immunomodulatory protein. Bmserpin32 cDNA was cloned, and the recombinant Bmserpin32 protein was expressed in Escherichia coli and purified by nickel-nitrilotriacetic acid affinity and gel filtration chromatography. The activity assay showed that Bmserpin32 had significant inhibitory activity against trypsin. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry and site-directed mutagenesis combined with activity assays indicated that the cleavage site of Bmserpin32 is between Arg359 and Ile360. After infection with E. coli or Micrococcus luteus, the expression level of Bmserpin32 in immune-related tissues was significantly upregulated. In addition, Bmserpin32 could delay or inhibit the melanization of hemolymph by inhibiting the activation of prophenoloxidase in larval hemolymph. Furthermore, a physiological target of Bmserpin32 was identified as the clip protease, BmPAP3, an apparent ortholog of M. sexta propenoloxidase-activating protease-3. Our observations enable a better understanding of the physiological role of Bmserpin32 in regulating melanization in silkworm.

In this work it is explored a real applicability of miniaturised and portable biosensing technology for the estimation of total phenolic content in 15 different commercial beers by applying direct amperometry. Gold nanoparticles screen-printed electrodes were thoroughly modified with tyrosinase (Tyr-AuNPS-SPCEs), which was immobilised on the surface by crosslinking with glutaraldehyde. All chemical and instrumental variables involved in the electrochemical method were optimised to develop a reliable and powerful tool to estimate rapidly the content of phenolic compounds in complex beer samples. Catechol, phenol, caffeic acid and tyrosol were analysed individually using the proposed methodology and good analytical and kinetic performances were obtained. Total phenolic content in tested beers (high fermented, low fermented and non-alcoholic) were expressed as mg L−1 of tyrosol, which is one of the major phenolic compound reported in beer. Moreover, the developed amperometric methodology was successfully benchmarked against standardised Folin-Ciocalteau spectrophotometric method with a good Pearson correlation (r = 0.821, p

‘Yali’ pear (Pyrus bretschneideri Rehd. cv. Yali) is susceptible to core browning after a long term of cold storage. In this study, the effects of 1-methylcyclopropene (1-MCP) with different concentrations (0, 0.25, 0.5, 1.0 μL L−1) on the quality and core browning of ‘Yali’ pear fruit were investigated. The results showed that 1-MCP significantly reduced the ethylene production, kept higher firmness and titratable acidity (TA) content, and lowered core browning. Moreover, the most effective concentration of 1-MCP was found at 1.0 μL L−1. Compared with control, 1.0 μL L−1 1-MCP treatment decreased the content of H2O2, while maintained higher levels of ascorbic acid (AsA) and glutathione (GSH) of core, and meanwhile, it reduced phenolics content and polyphenol oxidase (PPO) activity of core. In addition, among the four encoded the enzyme of PPO genes (PbPPO1, PbPPO4, PbPPO5 and PbPPO6), the expressions of PbPPO1 and PbPPO5 were markedly inhibited by 1-MCP. It suggested that 1-MCP could effectively keep fruit quality, and inhibit core browning which was resulted from the inhibition on accumulation of reactive oxygen species, reduction on phenolics content, PPO activity and its associated genes (PbPPO1 and PbPPO5) expression of core in ‘Yali’ pear during cold storage.

The post-harvest ripening of ‘Nanguo’ pears (Pyrus ussuriensis Maxim.) can be effectively postponed by refrigerated storage. However, peel browning (PB) often appears in the pears after refrigerated storage during the shelf life at room temperature. In order to find an effective method to relieve PB of pears, 2% CaCl2 was used to treat the fruit after low temperature. In the study, CaCl2 treatment on the pears has efficiently restrained the appearance of PB. Higher firmness and polyphenol content were detected in CaCl2-treated fruit during the shelf life. Electrolyte leakage and malondialdehyde (MDA) concentration were lowered in CaCl2-treated fruit. Gene expression levels of phospholipase D (PLD) and polyphenol oxidase (PPO) were inhibited by CaCl2 treatment, and the activities of PLD and PPO were lower in CaCl2-treated fruit. The activity and gene expression of superoxide dismutase (SOD) were promoted under CaCl2 treatment. Consequently, CaCl2 treatment effectively alleviated the PB appearance of ‘Nanguo’ pears after refrigerated storage during the shelf life at room temperature and brown-related genes are regulated by CaCl2 to varying degrees, which can help improve the quality of postharvest pears undergoing long term refrigeration and gene modification of brown pears.

The present study compared the nutraceuticals in thirty different genotypes of brinjal, cultivated in the Punjab state of India. Activity of enzyme polyphenol oxidase was studied in selected genotypes of brinjal in correlation with the phenolic compounds. The free radical scavenging capacities were evaluated by three assays viz. 2,2′-azinobis (3-ethylbenzothiazoline-6 sulfonic acid) (ABTS); 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). Study showed wide variation in content of phenolic compounds (total phenols, flavonols, ortho-dihydroxyphenols, quinones and tannins) in different brinjal genotypes. Polyphenol oxidase (PPO) activity was higher in P-71 and SR-305 with different substrates, catechol and caffeic acid respectively. PPO activity had positive correlation with quinone content whereas negatively correlated with phenols. SR-301 genotype had maximum free radical scavenging capacity as studied by different assays: ABTS assay (92.21 ± 2.15 EC50, μg ml−1), DPPH assay (124.58 ± 4.55 EC50, μg ml−1) and FRAP assay (29.92 ± 1.64 μmol TE g−1). The results indicated perspectives for the usage of selected brinjal genotypes with considerable level of nutraceuticals and radical scavenging activity.

In horticulture copper sulphate is utilized for the inhibition of phytopathogenic fungi. However, copper tends to accumulate in soil with a concomitant effect on soil quality and microbial diversity. As part of the biological diversity of soil and the rhizosphere, yeasts have been relatively less characterized than bacteria or filamentous fungi. In this work, we analyzed the presence of yeasts in the rhizosphere of tomato plants and the effect of copper in fungal biological activities of agronomical and ecological interest. Yeasts isolates that were selected for their higher copper resistance were all identified molecularly as Papiliotrema laurentii. Results show that all were capable of auxin production, and that copper has a detrimental effect on it. In contrast, ammonification was mainly increased by the metal. Copper also inhibits the growth of the yeasts on D-xylose, cellobiose and phenolic acids, suggesting a negative consequence on the recycling of lignocellulosic degradation products. Laccase and catechol oxidase activities were increased by the metal in P. laurentii. Altogether, results presented in this report indicate that P. laurentii presents properties of ecological and agronomical interest. The effect of the metal highlights the importance of the analysis of the consequence of copper utilization as fungicide on microbial activities. At the same time, the variability in the yeast response to copper suggests the concern of not only the characterization of biotechnological properties of a specific strain, but also the effect of copper on them. Fil: Leguina, Ana Carolina del Valle. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Barrios, Andrea C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Rosales Soro, Maria del Milagro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Lacosegliaz, Mariano José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Pajot, Hipolito Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Castellanos, Lucia Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Universidad Nacional de Tucumán; Argentina Fil: Nieto Peñalver, Carlos Gabriel. Universidad Nacional de Tucumán; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina

Herein, we investigate the in situ copper(I/II) complexes of pyrazole based on ligand: 5,5'-diphenyl-1H,1'H-3,3'-bipyrazole (H2L) and Its corresponding [C36H28CuN8] (CuL). Copper(I/II) complexes were tested for their reactivity towards the oxidation of catechol to o-quinine with the atmospheric dioxygen by following the appearance of quinone spectrophotometrically at ambient conditions in order to demonstrate the structural parameters essential to the reactivity of the enzyme and to understand the mechanism of action. The reaction rate depends on three parameters: the nature of counter anion, the nature of solvent and the concentration of ligand. We compared the potentialities of the complexes formed in situ as well as the synthesized complex, as a catalyst of the oxidation reaction of catechol to o-quinone.The highest rate activity given by the complex resulting from two equivalents of ligand H2L and one equivalent of [Cu(NO3)2] in MeOH is to 3.10 µmol.L-1.min-1.

To determine the effect of grafting method (hole insertion grafting, HIG; tongue approach grafting, TAG; and spliced grafting, SG) on graft union formation in cucumber grafted onto bottle gourd rootstock, an anatomical and physiological study was carried out during the healing stage. The results showed that the TAG method resulted in an obviously higher daily growth rate than the other grafting methods 7 days after grafting (DAG), with significantly higher values in the scion than in the rootstock. The isolation layer, callus formation, and vascular connection all occurred at the graft junction when using HIG, TAG, and SG. Vascular bridging first occurred between scion and rootstock using HIG or TAG at 5 DAG; this process was delayed with SG. The activities of superoxide dismutase (SOD), POD (peroxidase), CAT (catalase), PAL (Phenylalanine ammonia-lyase), and PPO (polyphenol oxidase) were significantly enhanced in the graft union during the healing process when different grafting methods were used. Compared with HIG and SG, the POD and CAT activities and total phenolic compounds were higher with TAG at 7 DAG; a reduction in PPO activity and lignin content were also overserved at the graft with TAG at 7 DAG. These results suggest that the association of TAG with a higher growth rate during the healing period is linked with the earlier improvement in vascular bundle connection that may be caused by increased antioxidant activities and lower lignin content at the graft junction. These morphological and physiological differences may provide valuable information for revealing the graft union healing process.

The biosynthesis of flavones has drawn considerable attention. However, the presence of flavones and their biosynthesis in tomato (Solanum lycopersicum) remain unclear. Here, we confirmed that flavones are present in MicroTom tomato and unexpectedly found that a tomato polyphenol oxidase (SlPPO F) possesses a flavone synthase-like activity and catalyzes the conversion of eriodictyol to luteolin without the need for any cofactor. SlPPO F showed a similar K

The impact of supercritical carbon dioxide (SCCD) (10-60 MPa/45 °C/30 min) and subsequent 10 weeks storage at 4 °C on polyphenol oxidase (PPO), peroxidase (POD) activities, phenolic profile, vitamin C, sugars, physicochemical properties of cloudy apple juices was investigated. No significant changes in sugars and total polyphenols were observed, whereas significant degradation (≈28%) of vitamin C and individual polyphenols (≈18%) was noted after SCCD treatment. After 4 weeks storage only 34% of vitamin C was retained and no vitamin C was detected after this time. Ten weeks of storage caused hydrolysis of sucrose in 15%, whereas degradation of individual polyphenols ranged from 43 to 50% depending on the pressure applied. The highest pressure was applied the highest retention of polyphenols was observed. The lightness of juice significantly increased by 15% after SCCD and decreased during storage. Moreover, the synergistic effect of both enzymes with chlorogenic acid and catechol was found.

Enzymatic browning is a major industrial problem of fresh-cut vegetables and fruits. Bioactive peptides are safe, nutritive and low-cost sources of antioxidant and antimicrobial agents. However, there has been little research on the effect of random peptides on anti-browning of fresh-cut food. For developing more natural and nutritive anti-browning agents, the effect of the enzymatic hydrolysis of random peptides from cod fish skin on polyphenol oxidase (PPO), peroxidase (POD), phenylalanine ammonia-lyase (PAL), total phenolic content, membrane permeability, malondialdehyde (MDA) content and color changes were investigated during fresh-cut potato storage. The results showed that 0.1% (w/w) cod peptides efficiently blocked enzymatic browning by inhibiting PPO, POD and PAL activities, reducing the total phenol accumulation during the entire 8 d storage at 4 °C. Furthermore, the membrane permeability and MDA content increases were delayed in 0.1% cod peptides treatment compared with the control. Oddly, the browning of fresh-cut potato was aggravated in 1.0% cod peptides treatment, which expressed higher POD and PAL activities. Meanwhile, the functional composition of cod peptides was a random component, which total 1765 peptides were identified by LC–MS/MS and the amino acids length of peptides were 4∼57 in the cod peptides. All the results showed that random peptides might be promising candidates as anti-browning agents for fresh-cut potato slices.

Five Brassicaceae sprouts (white cabbage, kale, broccoli, Chinese cabbage, arugula) were comparatively analyzed based on phytochemicals (polyphenols, glucosinolates, carotenoids, chlorophylls, ascorbic acid) content and accompanying enzymes associated with phytochemical stability and bioavailability (peroxidases, myrosinase, and polyphenol-oxidase) that consequently impact food quality. Significantly high content of polyphenols and glucosinolates, as well as a high antioxidant activity were found in white cabbage, followed by kale sprouts. In addition, white cabbage contained higher amount of fibers and lower polyphenol-oxidase activity which potentially indicates prevention of browning and consequently better sprout quality. Arugula and broccoli showed higher activity of myrosinase that may result in higher bioavailability of active glucosinolates forms. According to our data, sprouts are cheap, easy- and fast-growing source of phytochemicals but also they are characterized by different endogenous enzymes activity. Consequently, this parameter should also be taken into consideration in the studies related to the health benefits of the plant-based food.

Lactic acid bacteria (LAB) are group of beneficial bacteria that have been proposed as relevant probiotics with immunomodulatory functions. In this study, we initially isolated and identified host-derived LAB from the gut of the Pacific white shrimp Litopenaeus vannamei. Analysis of the bacterial 16S rRNA gene sequence revealed two candidate LAB, the Lactobacillus plantarum strain SGLAB01 and the Lactococcus lactis strain SGLAB02, which exhibited 99% identity to the L. plantarum strain LB1-2 and the L. lactis strain R-53658, which were isolated from bee gut, respectively. The two LAB displayed antimicrobial activities against gram-positive and gram-negative bacteria, including the virulent acute hepatopancreatic necrosis disease (AHPND)-causing strain of Vibrio parahaemolyticus (VPAHPND). Viable colony count and SEM analysis showed that the two candidate LAB, administered via oral route as feed supplement, could reside and adhere in the shrimp gut. Double-stranded RNA-mediated gene silencing of LvproPO1 and LvproPO2 revealed a significant role of two LvproPOs in the proPO system as well as in the immune response against VPAHPND infection in L. vannamei shrimp. The effect of LAB supplementation on modulation of the shrimp proPO system was investigated in vivo, and the results showed that administration of the two candidate LAB significantly increased hemolymph PO activity, the relative mRNA expression of LvproPO1 and LvproPO2, and resistance to VPAHPND infection. These findings suggest that administration of L. plantarum and L. lactis could modulate the immune system and increase shrimp resistance to VPAHPND infection presumably via upregulation of the two LvproPO transcripts.