Search Results (70)

The polyphenol oxidase (PPO) enzyme leads to undesirable consequences by causing enzymatic browning during the processing of vegetables and fruits. As these browning reactions occur, many phenolic compounds of PPO can lead to significant changes in active metabolites due to substrate utilization. This may cause a loss of appearance and nutritional and commercial value of food. The sickleweed (Falcaria vulgaris Bernh.) plant studied in the current research is considered an edible and medicinal food. In the present research, polyphenol oxidase was purified 15.65-fold with a yield of 23.61% by affinity chromatography. The optimum pH and temperature for catechol, 4-methylcatechol, and 3,4-dihydroxyphenylpropionic acid substrates were determined in separate experiments. For all three substrates, the optimum pH was 7.0, while the optimum temperature was 20 °C. The catalytic efficiency ratio (V_max/K_m) was employed to assess the substrate specificity. Since the highest V_max/K_m ratio reflects the greatest substrate affinity, 4-methylcatechol was identified as the substrate with the highest affinity for sickleweed PPO based on these values. pH stability and thermal stability were examined in the presence of 4-methylcatechol. The inhibitory effects of widely used antibrowning agents, sodium metabisulphite, citric acid, and ascorbic acid, on PPO activity were investigated. The results show that ascorbic acid was the most efficient inhibitor. Full article

Peganum harmala (L.) Schrad., a perennial medicinal plant thriving in arid Moroccan soils, represents a natural reservoir of unexplored bacterial diversity. To uncover its hidden foliar endosphere microbiota, we isolated and characterized two Acinetobacter strains: a novel endophytic bacterium, AGC35, and another strain, AGC59, newly reported from this host. Both are non-halophilic, aerobic, Gram-negative bacteria exhibiting optimal growth at 30–35 °C, pH5, and with 1% NaCl. An integrative genomic, phylogenetic, functional, and phenotypic characterization classified both strains within the genus Acinetobacter (class Gamma-pseudomonadota). However, Average Nucleotide Identity (<96%) and digital DNA-DNA Hybridization (<70%) values distinguished the AGC35 strain as a novel species, for which the name Acinetobacter endophylla sp. nov. is proposed. A comparative genomic and phenotypic analysis with the co-isolated Acinetobacter pittii strain AGC59 revealed extensive genome rearrangements, reflecting distinct evolutionary lineage and ecological strategies. While both genomes share core metabolic pathways, A. endophylla harbors specialized genes for the degradation of plant-derived aromatic compounds (e.g., catechol) but shows reduced capacities in carbohydrate metabolism and osmotic stress tolerance, traits indicative of a metabolic specialist with plant-growth-promotion potential, including phosphorus, potassium, and silicon solubilization and indole-3-acetic acid production. In contrast, A. pittii exhibits a more generalist genome enriched in stress functions. Analysis using the Antibiotics and Secondary Metabolite Analysis Shell revealed multiple biosynthetic gene clusters in both strains, showing ≤26% similarity to known references, suggesting the potential for novel antimicrobial secondary metabolite biosynthesis, including antifungal lipopeptides and thiopeptide antibiotics. Altogether, functional specialization and ecological coherence of these findings support the recognition of A. endophylla sp. nov. as a genomically and functionally distinct species, highlighting niche partitioning and adaptive metabolism within the P. harmala holobiont. These results underscore the plant’s value as a reservoir of untapped microbial diversity with significant ecological and biotechnological relevance. Finally, future work will focus on elucidating the novel metabolites encoded by the biosynthetic gene clusters in both isolates and exploring their applications in crop-improvement strategies and natural-product discovery. Full article

The increasing frequency, duration, and intensity of wildfires over the past decade have raised significant concerns about widespread exposure to wildfire smoke. Inhalation of wildfire smoke poses a substantial risk to human health, with epidemiological studies linking exposure to cardiovascular, respiratory, and neurological dysfunction. Wildfire smoke contains hundreds of chemical compounds across diverse classes, with concentrations varying by fuel type and combustion conditions. Phenolic compounds are prominent constituents of wood smoke, and catechol is especially abundant under smoldering conditions that produce dense smoke. In this study, ¹⁴C-labeled catechol was spiked into smoldering eucalyptus wood smoke extract (WSE) and administered to rats via intranasal instillation. Plasma was collected at 5 min and 2 h post-exposure. Samples were analyzed using parallel accelerator and molecular mass spectrometry (PAMMS). Major catechol-derived metabolites identified included benzene oxide, catechol-cysteine conjugate, and catechol-glutamine conjugate; the parent compound was not detected. These results indicate that inhaled catechol in wood smoke is quickly metabolized upon entry into circulation. PAMMS enabled both identification and relative quantification of circulating catechol metabolites, demonstrating feasibility for biomarker discovery and exposure assessment. Full article

Urinary tract infections (UTIs) are common and create significant clinical challenges. Most UTIs are caused by uropathogenic Escherichia coli (UPEC) and affect 50 to 70% of women at some point in their lives. Of this population, 25% will have a recurrent urinary tract infection (rUTI) within 3 to 12 months of the first episode. High rates of rUTIs may occur because UPEC can enter a non-proliferative or quiescent state within the urothelium of the bladder. This state allows UPEC to evade the host’s immune response and antibiotic treatment. We utilized a library of plant extracts derived from the URI Heber W. Youngken Jr. Medicinal Garden to determine if they reversed UPEC quiescence with a novel in vitro quiescence assay using the classic UPEC endemic lineage ST73 strain CFT073. We found an overall active extract hit rate of 69% (79/114 active) and that active extracts contained high levels of polyphenolic compounds. Further testing showed that polyphenols with adjacent hydroxyl groups on a benzene ring (catechol moiety) were the most effective and potent in reversing quiescence. The ability to reverse quiescence was also linked to the compound’s ability to bind iron (e.g., epigallocatechin gallate and rosmarinic acid were the most potent reversing agents—0.1 mM—and they both had the strongest iron-binding activity as determined via CAS assay). These findings reveal a new class of metabolites that can reverse quiescence in UPEC strains. Full article

Benzene, toluene, ethylbenzene, and xylene (BTEX) are a common class of volatile organic compounds linked to adverse health outcomes. Although BTEX have been shown to have endocrine disrupting properties, their potential impacts on pubertal development in children remain unclear. In this study, for the first time, we investigated the possible association of BTEX exposure with precocious puberty (PP) and early puberty (EP) in children. We conducted a case–control study that included 246 children diagnosed with PP or EP and a controls category matched for sex and age. Urinary concentrations of seven BTEX metabolites and the oxidative DNA damage biomarker 8-hydroxy-2′-deoxyguanosine (8-OHdG) were measured by high-performance liquid chromatography-tandem mass spectrometry. Compared with the control groups, urinary catechol (1,2-DB) levels were significantly higher in both PP (median: 85.3 vs. 42.4 μg/g creatinine) and EP children (median: 62.0 vs. 48.1 μg/g creatinine). Binary logistic regression models showed that 1,2-DB was positively associated with EP (OR = 1.36, 95% CI: 1.10, 1.69), while trans,trans-muconic acid (MU) was negatively correlated with PP (OR = 0.47, 95% CI: 0.24, 0.92), and PGA was negatively correlated with EP (OR = 0.73, 95% CI: 0.56, 0.93) adjusted for confounders. Stratified analyses showed that the relationship between BTEX metabolites and EP varied by parental education level. Our findings revealed that exposure to BTEX, especially benzene, may influence pubertal timing in children, but there was no relationship between oxidative DNA damage and PP or EP. The biological mechanism of BTEX exposure affecting pubertal development requires further investigation. Full article

Terephthalic acid (TPA), a major monomer of polyethylene terephthalate (PET), represents a significant challenge in plastic waste management due to its persistence in the environment. In this study, we report a newly developed bacterial consortium capable of using TPA as the sole carbon source in a defined mineral medium. The consortium achieved stationary phase within five days and metabolized approximately 85% of the available TPA. Metabolite analysis by high-performance liquid chromatography (HPLC) and liquid chromatography tandem mass spectrometry (LC-MS/MS) revealed the activation of the benzoate degradation pathway during TPA catabolism. Additionally, the consortium secreted commercially relevant metabolites such as cis,cis-muconic acid and catechol into the culture medium. Genetic profiling using a reverse transcription quantitative polymerase chain reaction (RT-qPCR) and 16S rRNA sequencing identified Paraburkholderia fungorum as the dominant species, suggesting it plays a key role in TPA degradation. The ability of this microbial community to efficiently convert TPA into high-value by-products offers a promising and potentially economically sustainable approach to addressing plastic pollution. Full article

This study investigates the metabolic responses of the model diatom Phaeodactylum tricornutum under different growth conditions, comparing benthic (adherent) and planktonic states. Using a multiblock metabolomics approach combining LC-HRMS², NMR, and GC-MS techniques, we compared the metabolome of P. tricornutum cultivated on three laboratory substrates (glass, polystyrene, and polydimethylsiloxane) and under planktonic conditions. Our results revealed metabolic differences between adherent and planktonic cultures, particularly concerning the lipid and carbohydrate contents. Adherent cultures showed a metabolic profile with an increase in betaine lipids (DGTA/S), fatty acids (tetradecanoic and octadecenoic acids), and sugars (myo-inositol and ribose), suggesting modifications in membrane composition and lipid remodeling, which play a potential role in adhesion. In contrast, planktonic cultures displayed a higher content of cellobiose, specialized metabolites such as dihydroactinidiolide, quinic acid, catechol, and terpenes like phytol, confirming different membrane composition, energy storage capacity, osmoregulation, and stress adaptation. The adaptative strategies do not only concern adherent and planktonic states, but also different adherent culture conditions, with variations in lipid, amino acid, terpene, and carbohydrate contents depending on the physical properties of the support. Our results highlight the importance of metabolic adaptation in adhesion, which could explain the fouling process. Full article

Urine, which has a high concentration of urea, can be used as a sustainable resource for nutrient recovery and sustainable energy. However, urea undergoes hydrolysis, catalyzed by urease, generating ammonia and carbon dioxide. As ammonia is released during hydrolysis in stored urine, the pH rises progressively until the pK_a of ammonium is reached (i.e., 9.3). At elevated pH levels, struvite and other related precipitates are formed. These reactions lower the efficiency of ammonia and urea nitrogen recovery and often cause scaling, pipe blockage, and odors. Herein, we explore an approach to stabilize urea, using pharmaceuticals and their metabolites that are commonly present in human urine. Based on a survey of the urease inhibitory effects of twenty-three pharmaceuticals and metabolites, we determined that the polyphenolic and disulfide-containing compounds had the highest urease inhibition efficiency. Specifically, outstanding inhibitors include catechol (CAT), hydroquinone (HYD), and disulfiram (DSF). Furthermore, when added to urine, these compounds resulted in the retardation of urease-catalyzed hydrolysis, leading to longer-term urine stabilization upon storage. Reaction mechanisms for urease inhibition by polyphenolics and disulfiram are proposed. Evidence is provided that pharmaceutical metabolites can stabilize urea and thus could lead to a sustainable method for nitrogen nutrient recovery from stored urine. Full article

Background: Cytochromes P450 (CYPs) are heme-containing oxidoreductase enzymes with mono-oxygenase activity. Human CYPs catalyze the oxidation of a great variety of chemicals, including xenobiotics, steroid hormones, vitamins, bile acids, procarcinogens, and drugs. Findings: In our review article, we discuss recent data evidencing that the same CYP isoform can be involved in both bioactivation and detoxification reactions and convert the same substrate to different products. Conversely, different CYP isoforms can convert the same substrate, xenobiotic or procarcinogen, into either a more or less toxic product. These phenomena depend on the type of catalyzed reaction, substrate, tissue type, and biological species. Since the CYPs involved in bioactivation (CYP3A4, CYP1A1, CYP2D6, and CYP2C8) are primarily expressed in the liver, their metabolites can induce hepatotoxicity and hepatocarcinogenesis. Additionally, we discuss the role of drugs as CYP substrates, inducers, and inhibitors as well as the implication of nuclear receptors, efflux transporters, and drug–drug interactions in anticancer drug resistance. We highlight the molecular mechanisms underlying the development of hormone-sensitive cancers, including breast, ovarian, endometrial, and prostate cancers. Key players in these mechanisms are the 2,3- and 3,4-catechols of estrogens, which are formed by CYP1A1, CYP1A2, and CYP1B1. The catechols can also produce quinones, leading to the formation of toxic protein and DNA adducts that contribute to cancer progression. However, 2-hydroxy- and 4-hydroxy-estrogens and their O-methylated derivatives along with conjugated metabolites play cancer-protective roles. CYP17A1 and CYP11A1, which are involved in the biosynthesis of testosterone precursors, contribute to prostate cancer, whereas conversion of testosterone to 5α-dihydrotestosterone as well as sustained activation and mutation of the androgen receptor are implicated in metastatic castration-resistant prostate cancer (CRPC). CYP enzymatic activities are influenced by CYP gene polymorphisms, although a significant portion of them have no effects. However, CYP polymorphisms can determine poor, intermediate, rapid, and ultrarapid metabolizer genotypes, which can affect cancer and drug susceptibility. Despite limited statistically significant data, associations between CYP polymorphisms and cancer risk, tumor size, and metastatic status among various populations have been demonstrated. Conclusions: The metabolic diversity and dual character of biological effects of CYPs underlie their implications in, preliminarily, hormone-sensitive cancers. Variations in CYP activities and CYP gene polymorphisms are implicated in the interindividual variability in cancer and drug susceptibility. The development of CYP inhibitors provides options for personalized anticancer therapy. Full article

In recent years, pharmaceuticals have emerged as pollutants due to their incomplete degradation in sewage treatment plants and their ability to cause physiological problems in humans even at low doses. Understanding the environmental fate of pharmaceutical pollutants and the mechanisms involved in their degradation is crucial for developing strategies to mitigate their impact on ecosystems and human health. In this study, the degradation of pharmaceutical compound ibuprofen was achieved by employing two bacterial strains, Achromobacter spanius strain S11 and Achromobacter piechaudii S18, previously isolated from contaminated water. These strains were capable of degrading ibuprofen as their sole carbon source. The study aimed to identify intermediate metabolites, determine the enzymes involved, and detect specific genes related to ibuprofen degradation. Different concentrations of ibuprofen, temperatures, and pH levels were tested. Both A. spanius S11 and A. piechaudii S18 successfully degraded ibuprofen. A. spanius S11 showed a degradation efficiency of 91.18% after only 72 h and reached 95.7% after 144 h, while A. piechaudii S18 exhibited degradation efficiencies of 72.39% and 73.01% after three and seven days, respectively. The LC-MS technique was used to identify biodegradation metabolites produced by A. spanius S11. The results indicated that the first step was hydroxylation followed by oxidation via the combination of monooxygenases that catalyze the C-H hydroxylation and dehydrogenases. Furthermore, the detection of intermediate metabolites of trihydroxyibuprofen suggested that the biodegradation of ibuprofen by A. spanius S11 can occur through multiple mechanisms. The highest enzyme activities were recorded for catechol 1,2-dioxygenase, 4.230 ± 0.026 U/mg, followed by laccase, 2.001 ± 0.215 U/mg. This study demonstrates the potential of Achromobacter strains, particularly A. spanius (S11), in degrading ibuprofen. These findings provide insights into the ibuprofen degradation process, intermediate metabolites, and relevant genes. Full article

Photosynthesis is initiated when the sun’s light induces electron transfer from chlorophyll to plastoquinone, a para-quinone. While photosynthesis occurs in the intact chloroplasts of living plants, similar photochemical reactions between dietary chlorophyll metabolites and quinones are likely and may affect health outcomes. Herein, we continue our studies of the direct photoreduction of para-quinones and ortho-quinones that were generated by the photo-oxidation of catechols. Chlorophyll metabolites, including pheophorbide A, chlorin e6, and pyropheophorbide A, as well as methylene blue were employed as photosensitizers. We detected hydrogen peroxide using horseradish peroxidase following the photo-oxidation of the catechol dopamine, even in the presence of EDTA, a tertiary amine electron donor. Under ambient oxygen, hydrogen peroxide was also detected after the photoreduction of several para-quinones, including 2,3-dimethoxy-5-methyl-p-benzoquinone (CoQ₀), methoxy-benzoquinone, and methyl-benzoquinone. The combinations of methylene blue and EDTA or pheophorbide A and triethanolamine as the electron donor in 20% dimethylformamide were optimized for photoreduction of the para-quinones. Chlorin e6 and pyropheophorbide A were less effective for the photoreduction of CoQ₀ but were equivalent to pheophorbide A for generating hydrogen peroxide in photo-oxidation reactions with photosensitizers, oxygen, and triethanolamine. We employed dinitrophenylhydrazine to generate intensely colored adducts of methoxy-benzoquinone, methyl-benzoquinone, and 1,4-benzoquinone. Full article

The microsomal metabolism of phenol (11 °C) over an annual reproductive cycle from June to December was studied using fall spawning adult brook trout (Salvelinus fontinalis). Hepatic microsomes were isolated from three male and three female fish each month. Incubations were optimized for time, cofactor concentration, pH, and microsomal protein concentration. The formation of phase I ring-hydroxylation metabolites, i.e., hydroquinone (HQ) and catechol (CAT), was quantified by HPLC with dual-channel electrochemical detection. Sample preparation and chromatographic conditions were optimized to achieve the separation and sensitivity required for the analysis of these labile products. Biotransformation of phenol over a range of substrate concentrations (1 to 150 mM) was quantified for the calculation of Michaelis–Menten constants (Km and Vmax) for each month. Results indicate a nearly equal production of HQ and CAT among males and females in late June. At the peak of maturity in October, there was an approximate ten-fold greater production of ring-hydroxylation metabolites noted in females in comparison with males on a total liver basis. In vitro phase II biotransformation of phenol glucuronidation was assessed by determining the Michaelis–Menten constants (Km, Vmax) using brook trout hepatic microsomes over a range of substrate concentrations (1 to 60 mM). Initially, there were no significant differences in the glucuronide rate of formation (pmol/min/mg protein) or total capacity (nmol/min/liver) between females and males. At the peak of maturation, the maximum rate of glucuronide formation was 4-fold less in females; however, the total capacity was 2-fold less in females due to the increased liver size in the females. The alterations in biotransformation coincided with increases in the hepatic and gonadal somatic indices and with changes in plasma hormone concentrations. These experiments provide insight into the metabolic deactivation of xenobiotics and to provide data for the prediction of altered hepatic biotransformation rates and pathways during the reproductive cycle. Full article

The in vitro biotransformation of phenol at 11 °C was studied using pre-spawn adult rainbow (Oncorhynchus mykiss) (RBT), brook (Salvelinus fontinalis) (BKT), and lake trout (Salvelinus namaycush) (LKT) hepatic microsomal preparations. The incubations were optimized for time, cofactor concentration, pH, and microsomal protein concentration. Formation of Phase I ring-hydroxylation and Phase II glucuronidation metabolites was quantified using HPLC with dual-channel electrochemical and UV detection. The biotransformation of phenol over a range of substrate concentrations (1 to 180 mM) was quantified, and the Michaelis–Menten kinetics constants, Km and Vmax, for the formation of hydroquinone (HQ), catechol (CAT), and phenylglucuronide (PG) were calculated. Species differences were noted in the Km values for Phase I enzyme production of HQ and CAT, with the following rank order of apparent enzyme affinity for substrate: RBT > BKT = LKT. However, no apparent differences in the Km for Phase II metabolism of phenol to PG were detected. Conversely, while there were no apparent differences in Vmax between species for HQ or CAT formation, the apparent maximum capacity for PG formation was significantly less in LKT than that observed for RBT and BKT. These experiments provide a means to quantify metabolic activation and deactivation of xenobiotics in fish, to compare activation and deactivation reactions across species, and to act as a guide for future predictions of new chemical biotransformation pathways and rates in fish. These experiments provided the necessary rate and capacity (Km and Vmax) inputs that are required to parameterize a fish physiologically based toxicokinetic (PB-TK) model for a reactive chemical that is readily biotransformed, such as phenol. In the future, an extensive database of these rate and capacity parameters on important fish species for selected chemical structures will be needed to allow the effective use of predictive models for reactive, biotransformation chemicals in aquatic toxicology and environmental risk assessment. Full article

Nowadays, mycotoxin contamination in cereals and wastewater exposes a safety hazard to consumer health. This work describes the design of a simple, low-cost, and sensitive origami microfluidic paper-based device using electrochemical detection for zearalenone determination. The microfluidic immunosensor was designed on a paper platform by a wax printing process. The graphitized carbon working electrode modified with carbon nanohorns-decorated nanoporous gold showed a higher surface area, sensitivity, and adequate analytical performance. Electrodes were characterized by scanning electron microscopy, energy-dispersive spectroscopy, and cyclic voltammetry. The determination of zearalenone was carried out through a competitive immunoassay using specific antibodies immobilized by a covalent bond on the electrode surface. In the presence of HRP-labeled enzyme conjugate, substrate, and catechol, zearalenone was detected employing the developed immunosensor by applying −0.1 V to the working electrode vs silver as a pseudo-reference electrode. A calibration curve with a linear range between 10 and 1000 µg Kg⁻¹ (R² = 0.998) was obtained, and the limit of detection and quantification for the electrochemical immunosensor were 4.40 and 14.90 µg Kg⁻¹, respectively. The coefficient of variation for intra- and inter-day assays was less than 5%. The selectivity and specificity of the sensor were evaluated, comparing the response against zearalenone metabolites and other mycotoxins that could affect the corn samples. Therefore, origami is a promising approach for paper-based electrochemical microfluidic sensors coupled to smartphones as a rapid and portable tool for in situ mycotoxins detection in real samples. Full article

L-DOPA, the precursor of catecholamines, exerts a pro-locomotor action in several vertebrate species, including newborn rats. Here, we tested the hypothesis that decreasing the degradation of monoamines can promote the pro-locomotor action of a low, subthreshold dose of L-DOPA in five-day-old rats. The activity of the degrading pathways involving monoamine oxidases or catechol-O-methyltransferase was impaired by injecting nialamide or tolcapone, respectively. At this early post-natal stage, the capacity of the drugs to trigger locomotion was investigated by monitoring the air-stepping activity expressed by the animals suspended in a harness above the ground. We show that nialamide (100 mg/kg) or tolcapone (100 mg/kg), without effect on their own promotes maximal expression of air-stepping sequences in the presence of a sub-effective dose of L-DOPA (25 mg/kg). Tissue measurements of monoamines (dopamine, noradrenaline, serotonin and some of their metabolites) in the cervical and lumbar spinal cord confirmed the regional efficacy of each inhibitor toward their respective enzyme. Our experiments support the idea that the raise of monoamines boost L-DOPA’s locomotor action. Considering that both inhibitors differently altered the spinal monoamines levels in response to L-DOPA, our data also suggest that maximal locomotor response can be reached with different monoamines environment. Full article