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1.
PLoS One ; 19(3): e0294318, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38446779

RESUMO

Enzymatic browning poses a significant challenge that limits in vitro propagation and genetic transformation of plant tissues. This research focuses on investigating how adding antioxidant substances can suppress browning, leading to improved efficiency in transforming plant tissues using Agrobacterium and subsequent plant regeneration from rough lemon (Citrus × jambhiri). When epicotyl segments of rough lemon were exposed to Agrobacterium, they displayed excessive browning and tissue decay. This was notably different from the 'Hamlin' explants, which did not exhibit the same issue. The regeneration process failed completely in rough lemon explants, and they accumulated high levels of total phenolic compounds (TPC) and polyphenol oxidase (PPO), which contribute to browning. To overcome these challenges, several antioxidant and osmoprotectant compounds, including lipoic acid, melatonin, glycine betaine, and proline were added to the tissue culture medium to reduce the oxidation of phenolic compounds and mitigate browning. Treating epicotyl segments with 100 or 200 µM melatonin led to a significant reduction in browning and phenolic compound accumulation. This resulted in enhanced shoot regeneration, increased transformation efficiency, and reduced tissue decay. Importantly, melatonin supplementation effectively lowered the levels of TPC and PPO in the cultured explants. Molecular and physiological analyses also confirmed the successful overexpression of the CcNHX1 transcription factor, which plays a key role in imparting tolerance to salinity stress. This study emphasizes the noteworthy impact of supplementing antioxidants in achieving successful genetic transformation and plant regeneration in rough lemon. These findings provide valuable insights for developing strategies to address enzymatic browning and enhance the effectiveness of plant tissue culture and genetic engineering methods with potential applications across diverse plant species.


Assuntos
Citrus , Melatonina , Plantas Geneticamente Modificadas , Melatonina/farmacologia , Antioxidantes/farmacologia , Citrus/genética , Agrobacterium , Catecol Oxidase , Fenóis/farmacologia , Regeneração , Suplementos Nutricionais
2.
Talanta ; 272: 125842, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38428131

RESUMO

A novel sensor array was developed based on the enzyme/nanozyme hybridization for the identification of tea polyphenols (TPs) and Chinese teas. The enzyme/nanozyme with polyphenol oxidase activity can catalyze the reaction between TPs and 4-aminoantipyrine (4-AAP) to produce differences in color, and the sensor array was thus constructed to accurately identify TPs mixed in different species, concentrations, or ratios. In addition, a machine learning based dual output model was further used to effectively predict the classes and concentrations of unknown samples. Therefore, the qualitative and quantitative detection of TPs can be realized continuously and quickly. Furthermore, the sensor array combining the machine learning based dual output model was also utilized for the identification of Chinese teas. The method can distinguish the six teas series in China, and then precisely differentiate the more specific tea varieties. This study provides an efficient and facile strategy for the identification of teas and tea products.


Assuntos
Camellia sinensis , Polifenóis , Polifenóis/análise , Chá , Catecol Oxidase , Aprendizado de Máquina
3.
Sci Rep ; 14(1): 3057, 2024 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-38321075

RESUMO

The polyphagous pest, Spodoptera littoralis (Boisduval), poses a significant global economic threat by gregariously feeding on over a hundred plant species, causing substantial agricultural losses. Addressing this challenge requires ongoing research to identify environmentally safe control agents. This study aimed to elucidate the insecticidal activity of the metabolite (ES2) from a promising endophytic actinobacterium strain, Streptomyces sp. ES2 EMCC2291. We assessed the activity of ES2 against the eggs and fourth-instar larvae of S. littoralis through spectrophotometric measurements of total soluble protein, α- and ß-esterases, polyphenol oxidase (PPO), and catalase enzyme (CAT). The assessments were compared to commercial Biosad® 22.8% SC. Untargeted metabolomics using LC-QTOF-MS/MS identified 83 metabolic compounds as chemical constituents of ES2. The median lethal concentration (LC50) of ES2 (165 mg/mL) for treated Spodoptera littoralis eggs showed significant differences in polyphenol oxidase and catalase enzymatic activities, while the LC50 of ES2 (695 mg/mL) for treated S. littoralis fourth instar larvae showed lower significance in α- and ß-esterase activities. Molecular docking of ES2 identified seven potent biocidal compounds, showing strong affinity to PPO and catalase CAT proteins in S. littoralis eggs while displaying limited binding to alpha and beta esterase proteins in the larvae. The results contribute to the understanding of ES2 as a promising alternative biopesticide, providing insights for future research and innovative applications in sustainable pest management strategies.


Assuntos
Inseticidas , Animais , Inseticidas/farmacologia , Spodoptera , Catalase/farmacologia , Simulação de Acoplamento Molecular , Espectrometria de Massas em Tandem , Catecol Oxidase , Esterases , Larva
4.
J Agric Food Chem ; 72(6): 3099-3112, 2024 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-38291573

RESUMO

Among fruits susceptible to enzymatic browning, olive polyphenol oxidase (OePPO) stood out as being unisolated from a natural source until this study, wherein we successfully purified and characterized the enzyme. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of heated and nonheated OePPO revealed distinct molecular weights of 35 and 54 kDa, respectively, indicative of its oligomeric nature comprising active and C-terminal subunits. OePPO displayed latency, fully activating with 5 mM SDS under optimal conditions of pH 7.5 and 15 °C. The enzyme demonstrated monophenolase activity and showcased the highest efficiency toward hydroxytyrosol. Despite its low optimal temperature, OePPO exhibited high thermal resistance, maintaining stability up to 90 °C. However, beyond this threshold, the oligomeric enzyme disassociated, yielding a denatured main subunit and C-terminal fragments. Six OePPO genes were found in the fruits. Tryptic digestion identified the enzyme as mature OePPO1 (INSDC OY733096), while mass spectrometry detected the active form mass alongside several C-terminal fragments, revealing potential cleavage sites (Gly407, Tyr408).


Assuntos
Olea , Catecol Oxidase/genética , Catecol Oxidase/química , Temperatura Alta , Eletroforese em Gel de Poliacrilamida
5.
Int J Biol Macromol ; 259(Pt 2): 129285, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38211907

RESUMO

Phenolic acids are promising inhibitors of polyphenol oxidase (PPO), but the effects of carboxyl group and pH on their inhibition effects are still unclear. In this study, methyl cinnamate, cinnamic acid and 4-carboxycinnamic acid were investigated by their inhibitory effects with pH varied from 6.8 to 5.0. Results showed that 4-carboxycinnamic acid had the strongest inhibitory effect on PPO, followed by cinnamic acid and methyl cinnamate. Acidic pH enhanced the inhibitory effects of cinnamic acid and its derivatives on PPO, and the enhancement degree, IC50 and Ki declining degree were followed as 4-carboxycinnamic acid > cinnamic acid > methyl cinnamate. Methyl cinnamate exhibited competitive inhibition on PPO, while cinnamic acid and 4-carboxycinnamic acid exhibited mixed-type inhibition. Inhibitors induced slight changes in the secondary and tertiary structures of PPO, which were enhanced by acidic pH. Molecular docking results showed that 4-carboxycinnamic acid exhibited the strongest binding ability, and the main interaction forces were around carboxyl groups, and acidic pH enhanced the binding effect through more interactions and lower binding energy. This study could provide new insights into industrial application of cinnamic acid and its derivatives for the control of enzymatic browning of fruits and vegetables.


Assuntos
Catecol Oxidase , Cinamatos , Catecol Oxidase/química , Simulação de Acoplamento Molecular , Concentração de Íons de Hidrogênio
6.
Biosens Bioelectron ; 250: 116056, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38271889

RESUMO

Green tea is popular among consumers because of its high nutritional value and unique flavor. There is often a strong correlation among the type of tea, its quality level and the price. Therefore, the rapid identification of tea types and the judgment of tea quality grades are particularly important. In this work, a novel sensor array based on nanozyme with polyphenol oxidase (PPO) activity is proposed for the identification of tea polyphenols (TPs) and Chinese green tea. The absorption spectra changes of the nanozyme and its substrate in the presence of different TPs were first investigated. The feature spectra were scientifically selected using genetic algorithm (GA), and then a sensor array with 15 sensing units (5 wavelengths × 3 time) was constructed. Combined with the support vector machine (SVM) discriminative model, the discriminative rate of this sensor array was 100% for different concentrations of typical TPs in Chinese green tea with a detection limit of 5 µM. In addition, the identification of different concentrations of the same tea polyphenols and mixed tea polyphenols have also been achieved. Based on the above study, we further developed a facile and efficient new method for the category differentiation and adulteration identification of green tea, and the accuracy of this array was 96.88% and 100% for eight types of green teas and different adulteration ratios of Biluochun, respectively. This work has significance for the rapid discrimination of green tea brands and adulteration.


Assuntos
Técnicas Biossensoriais , Camellia sinensis , Chá , Polifenóis , Catecol Oxidase , China
7.
Insect Biochem Mol Biol ; 164: 104048, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38056530

RESUMO

Phenoloxidase (PO) catalyzed melanization and other insect immune responses are mediated by serine proteases (SPs) and their noncatalytic homologs (SPHs). Many of these SP-like proteins have a regulatory clip domain and are called CLIPs. In most insects studied so far, PO precursors are activated by a PAP (i.e., PPO activating protease) and its cofactor of clip-domain SPHs. Although melanotic encapsulation is a well-known refractory mechanism of mosquitoes against malaria parasites, it is unclear if a cofactor is required for PPO activation. In Anopheles gambiae, CLIPA4 is 1:1 orthologous to Manduca sexta SPH2; CLIPs A5-7, A12-14, A26, A31, A32, E6, and E7 are 11:4 orthologous to M. sexta SPH1a, 1b, 4, and 101, SPH2 partners in the cofactors. Here we produced proCLIPs A4, A6, A7Δ, A12, and activated them with CLIPB9 or M. sexta PAP3. A. gambiae PPO2 and PPO7 were expressed in Escherichia coli for use as PAP substrates. CLIPB9 was mutated to CLIPB9Xa by including a Factor Xa cleavage site. CLIPA7Δ was a deletion mutant with a low complexity region removed. After PAP3 or CLIPB9Xa processing, CLIPA4 formed a high Mr complex with CLIPA6, A7Δ or A12, which assisted PPO2 and PPO7 activation. High levels of specific PO activity (55-85 U/µg for PO2 and 1131-1630 U/µg for PO7) were detected in vitro, indicating that cofactor-assisted PPO activation also occurs in this species. The cleavage sites and mechanisms for complex formation and cofactor function are like those reported in M. sexta and Drosophila melanogaster. In conclusion, these data suggest that the three (and perhaps more) SPHI-II pairs may form cofactors for CLIPB9-mediated activation of PPOs for melanotic encapsulation in A. gambiae.


Assuntos
Anopheles , Manduca , Animais , Serina Proteases/metabolismo , Anopheles/metabolismo , Drosophila melanogaster/metabolismo , Serina Endopeptidases , Catecol Oxidase/genética , Catecol Oxidase/metabolismo , Precursores Enzimáticos/genética , Precursores Enzimáticos/metabolismo , Monofenol Mono-Oxigenase , Manduca/metabolismo , Proteínas de Insetos/metabolismo , Hemolinfa
8.
Dev Comp Immunol ; 151: 105088, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37923098

RESUMO

Prophenoloxidase (proPO) activating enzymes, known as PPAEs, are pivotal in activating the proPO system within invertebrate immunity. A cDNA encoding a PPAE derived from the hemocytes of banana shrimp, Fenneropenaeus merguiensis have cloned and analyzed, referred to as FmPPAE1. The open reading frame of FmPPAE1 encompasses 1392 base pairs, encoding a 464-amino acid peptide featuring a presumed 19-amino acid signal peptide. The projected molecular mass and isoelectric point of this protein stand at 50.5 kDa and 7.82, respectively. Structure of FmPPAE1 consists of an N-terminal clip domain and a C-terminal serine proteinase domain, housing a catalytic triad (His272, Asp321, Ser414) and a substrate binding site (Asp408, Ser435, Gly437). Expression of the FmPPAE1 transcript is specific to hemocytes and is heightened upon encountering pathogens like Vibrio parahaemolyticus, Vibrio harveyi, and white spot syndrome virus (WSSV). Using RNA interference to silence the FmPPAE1 gene resulted in reduced hemolymph phenoloxidase (PO) activity and decreased survival rates in shrimp co-injected with pathogenic agents. These findings strongly indicate that FmPPAE1 plays a vital role in regulating the proPO system in shrimp. Furthermore, upon successful production of recombinant FmPPAE1 protein (rFmPPAE1), it became evident that this protein exhibited remarkable abilities in both agglutinating and binding to a wide range of bacterial strains. These interactions were primarily facilitated through the recognition of bacterial lipopolysaccharides (LPS) or peptidoglycans (PGN) found in the cell wall. This agglutination process subsequently triggered melanization, a critical immune response. Furthermore, rFmPPAE1 exhibited the ability to actively impede the growth of pathogenic bacteria harmful to shrimp, including V. harveyi and V. parahaemolyticus. These findings strongly suggest that FmPPAE1 not only plays a pivotal role in activating the proPO system but also possesses inherent antibacterial properties, actively contributing to the suppression of bacterial proliferation. In summary, these results underscore the substantial involvement of FmPPAE1 in activating the proPO system in F. merguiensis and emphasize its crucial role in the shrimp's immune defense against invading pathogens.


Assuntos
Penaeidae , Vibrio parahaemolyticus , Vírus da Síndrome da Mancha Branca 1 , Animais , Hemócitos , Serina Endopeptidases/genética , Catecol Oxidase/genética , Catecol Oxidase/metabolismo , Proteínas Recombinantes/metabolismo , Precursores Enzimáticos/genética , Precursores Enzimáticos/metabolismo , Aminoácidos , Vírus da Síndrome da Mancha Branca 1/metabolismo
9.
Food Chem ; 439: 138178, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38104443

RESUMO

Polyphenol oxidase (PPO) is critical due to enzymatic browning in fruits and vegetables, developing economic impact in fruits industry. Metal-Organic Frameworks (MOF) have shown interesting characteristics such as water stability, low toxicity, and good adsorption yield, making them good candidates for PPO inactivation. Al-based-MOFs, MIL-53(Al), DUT-5, and MIL-110 were tested as PPO inactivators in apple juice by enzyme-MOF interactions at r.t. through two possible mechanisms, i) substrate scavengers (substrates:catechol and 4-methylcatechol) or ii) enzyme activity modifiers. The scavenging behavior of Al-based-MOFs was moderate, in the same magnitude, being catechol adsorption better than 4-methylcatechol. PPO activity was reduced by at least 70% by MIL-53(Al)/DUT-5 in 10/30 min respectively, and MIL-110 inactivated PPO in 50 min with some structural modifications. Enzyme-MOF interactions are major responsible for PPO inactivation. This could be a new applicability of MOFs, as an alternate PPO inactivation process, easily included in juice processing, retaining sensorial/nutritional properties, developed at r.t thus energy-cost-effective.


Assuntos
Malus , Estruturas Metalorgânicas , Malus/química , Frutas/química , Verduras , Estruturas Metalorgânicas/análise , Catecol Oxidase/química , Catecóis/análise
10.
Molecules ; 28(22)2023 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-38005328

RESUMO

Diverse enzymatic reactions taking place after the killing of green vanilla beans are involved in the flavor and color development of the cured beans. The effects of high hydrostatic pressure (HHP) at 50-400 MPa/5 min and blanching as vanilla killing methods were evaluated on the total phenolic content (TPC), polyphenoloxidase (PPO), and peroxidase (POD) activity and the color change at different curing cycles of sweating-drying (C0-C20) of vanilla beans. The rate constants describing the above parameters during the curing cycles were also obtained. The TPC increased from C1 to C6 compared with the untreated green beans after which it started to decrease. The 400 MPa samples showed the highest rate of phenolic increase. Immediately after the killing (C0), the highest increase in PPO activity was observed at 50 MPa (46%), whereas for POD it was at 400 MPa (25%). Both enzymes showed the maximum activity at C1, after which the activity started to decrease. As expected, the L* color parameter decreased during the entire curing for all treatments. An inverse relationship between the rate of TPC decrease and enzymatic activity loss was found, but the relationship with L* was unclear. HHP appears to be an alternative vanilla killing method; nevertheless, more studies are needed to establish its clear advantages over blanching.


Assuntos
Vanilla , Pressão Hidrostática , Manipulação de Alimentos/métodos , Fenóis , Catecol Oxidase
11.
Chem Commun (Camb) ; 59(98): 14540-14543, 2023 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-37987146

RESUMO

DNA is self-assembled with Fmoc-amino acids and Cu2+ to construct a supramolecular catechol oxidase-mimetic catalyst, which exhibits remarkable activity in catalyzing colorimetric reactions. This catalytic system is used for the detection of DNA hybridization with a high selectivity and a low detection limit.


Assuntos
Colorimetria , Oxirredutases , DNA/química , Catecol Oxidase , Aminoácidos , Limite de Detecção
12.
J Food Sci ; 88(12): 5026-5043, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37872831

RESUMO

In this study, a comprehensive approach to advance the inhibitory effect of Hibiscus sabdariffa extract on apple polyphenol oxidase (PPO) was performed. PPO was extracted, purified, and characterized for optimal activity, whereas response surface methodology generated a quadratic polynomial model to fit the experimental results for hibiscus extraction. The optimum conditions allowed to predict a maximum recovery of anthocyanins (256.11 mg delphinidin-3-O-glucoside/g), with a validated value of 272.87 mg delphinidin-3-O-glucoside/g dry weight (DW). The chromatographic methods highlighted the presence of gallic acid (36,812.90 µg/g DW extract), myricetin (141,933.84 µg/g DW extract), caffeic acid (101,394.07 µg/g DW extract), sinapic acid (1157.46 µg/g DW extract), kaempferol (2136.76 µg/g DW extract), and delphinidin 3-O-ß-d-glucoside (226,367.08 µg/g DW extract). The inactivation of PPO followed a first-order kinetic model. A temperature-mediated flexible fit between PPO and anthocyanins was suggested, whereas the molecular docking tests indicated that PPO is a good receptor for cafestol, gallic acid, and catechin, involving hydrophobic and hydrogen bond interactions. PRACTICAL APPLICATION: It is well known that enzymatic browning is one of the most important challenges in the industrial minimal processing of selected fruit and vegetable products. Novel inhibitors for polyphenol oxidase are proposed in this study by using an anthocyanin-enriched extract from Hibiscus sabdariffa L. Based on our results, combining the chemical effect of phytochemicals from hibiscus extract with different functional groups with minimal heating could be an interesting approach for the development of a new strategy to inhibit apple polyphenol oxidase.


Assuntos
Antocianinas , Hibiscus , Antocianinas/análise , Hibiscus/química , Extratos Vegetais/farmacologia , Extratos Vegetais/química , Catecol Oxidase , Simulação de Acoplamento Molecular , Ácido Gálico , Glucosídeos
13.
Front Immunol ; 14: 1244792, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37781370

RESUMO

Insect phenoloxidases (POs) catalyze phenol oxygenation and o-diphenol oxidation to form reactive intermediates that kill invading pathogens and form melanin polymers. To reduce their toxicity to host cells, POs are produced as prophenoloxidases (PPOs) and activated by a serine protease cascade as required. In most insects studied so far, PPO activating proteases (PAPs) generate active POs in the presence of a high Mr cofactor, comprising two serine protease homologs (SPHs) each with a Gly residue replacing the catalytic Ser of an S1A serine protease (SP). These SPHs have a regulatory clip domain at the N-terminus, like most of the SP cascade members including PAPs. In Drosophila, PPO activation and PO-catalyzed melanization have been examined in genetic analyses but it is unclear if a cofactor is required for PPO activation. In this study, we produced the recombinant cSPH35 and cSPH242 precursors, activated them with Manduca sexta PAP3, and confirmed their predicted role as a cofactor for Drosophila PPO1 activation by MP2 (i.e., Sp7). The cleavage sites and mechanisms for complex formation and cofactor function are highly similar to those reported in M. sexta. In the presence of high Mr complexes of the cSPHs, PO at a high specific activity of 260 U/µg was generated in vitro. To complement the in vitro analysis, we measured hemolymph PO activity levels in wild-type flies, cSPH35, and cSPH242 RNAi lines. Compared with the wild-type flies, only 4.4% and 18% of the control PO level (26 U/µl) was detected in the cSPH35 and cSPH242 knockdowns, respectively. Consistently, percentages of adults with a melanin spot at the site of septic pricking were 82% in wild-type, 30% in cSPH35 RNAi, and 53% in cSPH242 RNAi lines; the survival rate of the control (45%) was significantly higher than those (30% and 15%) of the two RNAi lines. These data suggest that Drosophila cSPH35 and cSPH242 are components of a cofactor for MP2-mediated PPO1 activation, which are indispensable for early melanization in adults.


Assuntos
Catecol Oxidase , Proteínas de Drosophila , Precursores Enzimáticos , Serina Proteases , Animais , Drosophila melanogaster , Proteínas de Drosophila/genética , Melaninas , Monofenol Mono-Oxigenase , Serina Endopeptidases , Serina Proteases/genética , Catecol Oxidase/genética , Precursores Enzimáticos/genética
14.
Eur J Immunol ; 53(12): e2350632, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37793051

RESUMO

Drosophila melanogaster relies on an evolutionarily conserved innate immune system to protect itself from a wide range of pathogens, making it a convenient genetic model to study various human pathogenic viruses and host antiviral immunity. Here we explore for the first time the contribution of the Drosophila phenoloxidase (PO) system to host survival and defenses against Zika virus (ZIKV) infection by analyzing the role of mutations in the three prophenoloxidase (PPO) genes in female and male flies. We show that only PPO1 and PPO2 genes contribute to host survival and appear to be upregulated following ZIKV infection in Drosophila. Also, we present data suggesting that a complex regulatory system exists between Drosophila PPOs, potentially allowing for a sex-dependent compensation of PPOs by one another or other immune responses such as the Toll, Imd, and JAK/STAT pathways. Furthermore, we show that PPO1 and PPO2 are essential for melanization in the hemolymph and the wound site in flies upon ZIKV infection. Our results reveal an important role played by the melanization pathway in response to ZIKV infection, hence highlighting the importance of this pathway in insect host defense against viral pathogens and potential vector control strategies to alleviate ZIKV outbreaks.


Assuntos
Infecção por Zika virus , Zika virus , Animais , Masculino , Feminino , Humanos , Drosophila melanogaster/genética , Infecção por Zika virus/genética , Zika virus/metabolismo , Catecol Oxidase/genética , Catecol Oxidase/metabolismo , Imunidade Inata
15.
Anal Chim Acta ; 1279: 341823, 2023 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-37827622

RESUMO

In order to effectively monitor multiple catecholamine (CA) neurotransmitters with extreme similar structures, a rapid, sensitive and selective detection strategy has become an urgent problem to be solved. In this paper, a novel colorimetric sensors array based on CuNCs protected by various ligands such as tannic acid, ascorbic acid and polymethylacrylic acid (CuNCs@TA, CuNCs@AA and CuNCs@PMAA) was constructed. All of these CuNCs could mimic catechol oxidase to selective catalyze catechol-type analogues (such as CAs) to corresponding quinones along with color changes. Furthermore, experiments and theory calculations demonstrated that Cr6+-modification on the surface of CuNCs facilitated the steady-state kinetics of enzymatic activity. Based on these CuNCs as sensing probes, this sensors array can quickly detect different CAs (such as epinephrine (EP), including dopamine (DA), norepinephrine (NE) and l-dopa) with similar structures. When those analogues were added to the CuNC-based colorimetric array sensors, different absorbance changes were produced at 485 nm. Linear discriminant analysis (LDA) showed that the tri-probe colorimetric array sensors could recognize and distinguish these analogues, and corresponding binary and ternary mixtures could be well categorized. The value of Factor 1 of an array with varied CA concentrations had a good linear correlation, and the detection limit (LOD) was as low as 10-8∼10-9 mol/L. Four CA analogues in real samples were identified by CuNCs-based colorimetric array sensors. This work provides a fast and convenient experimental basis for monitoring the complex structure CAs neurotransmitters.


Assuntos
Catecolaminas , Colorimetria , Catecol Oxidase , Ácido Ascórbico/análise , Neurotransmissores
16.
Ying Yong Sheng Tai Xue Bao ; 34(8): 2185-2193, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37681383

RESUMO

Rising atmospheric carbon dioxide (CO2) and ozone (O3) concentrations are the main global change drivers. Soil ectoenzymes play an important role in maintaining soil ecosystem services. Exploring the responses of soil ectoenzymes to elevated CO2 and O3 concentrations is important for combating global climate change. In this study, we simulated elevated CO2 concentrations (+200 µmol·mol-1, eCO2), elevated O3 concentrations (0.04 µmol·mol-1, eO3), and their combination (eCO2+eO3) in open-top chambers (OTCs), and investigated the responses of rhizospheric soil ectoenzyme activities. The results showed that eCO2 significantly increased the ß-D-Glucosidase (ßG) activity by 73.0%, and decreased that of polyphenol oxidase (PHO), peroxidase (PEO), and acid phosphatase (AP) by 48.9%, 46.6% and 72.9% respectively, but did not affect that of cellulose hydrolase (CBH) and ß-N-Acetylglucosaminidase (NAG). eO3 significantly reduced the activities of CBH and AP by 34.2% and 30.4%, respectively. The activities of PHO and AP were reduced by 87.3% and 32.3% under the eCO2+eO3 compared with the control, respectively. Results of the principal coordinate analysis, permutation multivariate analysis of variance and redundancy analysis showed that both elevated CO2 and O3 significantly affected soil ectoenzyme activities, with stronger effects of elevated CO2 than elevated O3. Root nitrogen content, root carbon to nitrogen ratio, soil microbial biomass carbon and nitrate nitrogen were the main drivers of soil ectoenzyme activities under elevated CO2 and O3. Elevated O3 could partially neutralize the effects of elevated CO2 on soil ectoenzyme activities. In conclusion, elevated CO2 and O3 restrained the activities of most soil ectoenzyme, suggesting that climate change would threat soil ecosystem services and functions in the agroecosystem.


Assuntos
Oryza , Ozônio , Dióxido de Carbono , Ecossistema , Catecol Oxidase , Nitrogênio , Solo
17.
Ultrason Sonochem ; 99: 106595, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37699293

RESUMO

The present work explores different conditions of thermosonication (TS) processing that would ensure microbiological and enzymatic safety for guava juice while simultaneously maximizing the preservation of its quality attributes. The guava juice was subjected to TS treatment (frequency: 40 kHz; power: 200 W; Temperature: 40, 60, and 80 °C; Time: 2, 6 and 10 min) and was compared with fresh and pasteurized (90 °C/60 s) juice samples. The objectives of the research work were to determine the effect of thermosonication on the quality attributes such as total soluble solids (TSS), pH, titratable acidity, cloud value, color attributes, total phenolic contents, total flavonoid contents, antioxidant activity, ascorbic acid levels, enzymatic, microbiological, and sensory properties. The thermosonicated and pasteurized samples showed no significant (p > 0.05) changes in pH, total soluble solids, and titratable acidity. TS improved the cloud value and color attributes. Furthermore, TS enhanced total phenols (10 to17%), flavonoids (5 to 25%), antioxidant activity (10.45% to 14.55%) and retention of ascorbic acid (61.98-83.32%) relative to control. Thermosonicated sample at 80 °C/10 min gives the maximum inactivation of Pectin methyl esterase (PME), Peroxidase (POD) and Polyphenol oxidase (PPO) enzymes. While both thermosonication and pasteurization drastically decreased the microbial count to undetectable levels, only TS exhibited modest improvement in sensory qualities. The results demonstrated that TS can enhance the overall safety, quality, and commercial viability of guava juice as a practical substitute to pasteurization.


Assuntos
Antioxidantes , Psidium , Ácido Ascórbico , Catecol Oxidase , Corantes , Flavonoides , Peroxidases/química , Peroxidases/metabolismo , Fenóis
18.
Mar Environ Res ; 190: 106122, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37549560

RESUMO

Herbivores strongly affect the ecological structure and functioning in seagrass bed ecosystems, but may exhibit density-dependent effects on primary producers and carbon sequestration. This study examined the effects of herbivorous snail (Cerithidea rhizophorarum) density on snail intraspecific competition and diet, dominant seagrass (Thalassia hemprichii) and epiphyte growth metrics, and sediment organic carbon (SOC). The growth rates of the herbivorous snail under low density (421 ind m-2) and mid density (842 ind m-2) were almost two times of those at extremely high density (1684 ind m-2), indicating strong intraspecific competition at high density. Herbivorous snails markedly reduced the epiphyte biomass on seagrass leaves. Additionally, the seagrass contribution to herbivorous snail as food source under high density was about 1.5 times of that under low density, while the epiphyte contribution under low density was 3 times of that under high density. A moderate density of herbivorous snails enhanced leaf length, carbon, nitrogen, total phenol and flavonoid contents of seagrasses, as well as surface SOC content and activities of polyphenol oxidase and ß-glucosidase. However, high density of herbivorous snails decreased leaf glucose, fructose, detritus carbon, and total phenols contents of seagrasses, as well as surface SOC content and activities of polyphenol oxidase and ß-glucosidase. Therefore, the effects of herbivorous snail on seagrass, epiphyte and SOC were density-dependent, and moderate density of herbivorous snail could be beneficial for seagrasses to increase productivity. This provided theoretical guidance for enhancing carbon sink in seagrass bed and its better conservation.


Assuntos
Celulases , Ecossistema , Sequestro de Carbono , Sedimentos Geológicos/química , Herbivoria , Carbono , Catecol Oxidase
19.
PLoS One ; 18(8): e0276041, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37624797

RESUMO

Polyphenol oxidases (PPOs), belong to the group of oxidoreductases that are copper containing enzymes and are responsible for plant browning. PPOs are extensively distributed in plant kingdom and can oxidize wide range of aromatic compounds of industrial importance. The aim of this study was purification and characterization of PPO isoforms from the fruit pulp of Golden delicious apple. High performance liquid chromatography was used to purify the two novel isoforms of PPO and further their molecular weights (45 and 28 kDa) were determined using sodium dodecyl sulfate polyacrylamide gel electrophoresis. The purified isoforms have optimum pH (6.5), optimum temperature (40°C), the Vmax (4.45 µM/min) and Km (74.21 mM) with catechol substrate. The N-terminal microsequences of both PPO isoforms were determined using a pulse liquid protein sequencer and found to be AKITFHG (28 kDa) and APGGG (45 kDa). Polyphenol oxidases are efficiently used in the pharmaceutical, paper and pulp, textiles and food industries. Recently, the PPOs have been used for bioremediation and in the development of biosensors.


Assuntos
Anacardiaceae , Malus , Frutas , Catecol Oxidase , Isoformas de Proteínas , Polifenóis
20.
PeerJ ; 11: e15644, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37645014

RESUMO

Maize is one of the major crops in the world and the most productive member of the Gramineae family. Since cold stress affects the germination, growth, and productivity of corn seeds, the present study aimed to investigate the effect of seed biopriming with Trichoderma harzianum on the tolerance of two genotypes of maize seedlings to cold stress. This study was conducted in triplicates in factorial experiment with a complete randomized block design (CRBD). The study was conducted in the greenhouse and laboratory of the University of Mohaghegh Ardabili, Ardabil, Iran. Experimental factors include two cultivars (AR68 cold-resistant and KSC703 cold-sensitive maize cultivars), four pretreatment levels (control, biopriming with T. harzianum, exogenous T. harzianum, and hydropriming), and two levels of cold stress (control and cold at 5 °C) in a hydroponic culture medium. The present study showed that maize leaves' establishment rate and maximum fluorescence (Fm) are affected by triple effects (C*, P*, S). The highest establishment (99.66%) and Fm (994 units) rates were observed in the KP3 control treatment. Moreover, among the pretreatments, the highest (0.476 days) and the lowest (0.182 days) establishment rates were related to P0 and P3 treatments, respectively. Cultivar A showed higher chlorophyll a and b, carotenoid content, and establishment rate compared to cultivar K in both optimal and cold conditions. The highest root dry weight (11.84 units) was obtained in cultivar A with P3 pretreatment. The pretreatments with T. harzianum increased physiological parameters and seedling emergence of maize under cold and optimal stress conditions. Pretreatment and cultivar improved catalase activity in roots and leaves. Higher leaf and root catalase activity was observed in the roots and leaves of cultivar K compared to cultivar A. The cold treatment significantly differed in peroxidase activity from the control treatment. Cultivar K showed higher catalase activity than cultivar A. The main effects of pretreatment and cold on polyphenol oxidase activity and proline content showed the highest polyphenol oxidase activity and proline content in hydropriming (H) treatment. Cold treatment also showed higher polyphenol oxidase activity and proline content than cold-free conditions.


Assuntos
Resposta ao Choque Frio , Zea mays , Catalase , Clorofila A , Catecol Oxidase
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