Ring Fission Research Articles

Immunomodulatory Effects of Green Tea Catechins and Their Ring Fission Metabolites in a Tumor Microenvironment Perspective.

Green tea is the second most consumed beverage following water, and the health benefits provided by its consumption have been well established from research in recent decades. The main bioactive compounds found in all Camellia sinensis-based teas are catechins, which have been reported to have antioxidant, anticancer, anti-inflammatory, and immunomodulatory properties. Although most of the health benefits are well established, studies show that the intact catechins as found in tea are poorly absorbed in the digestive tract. These compounds are degraded and undergo ring fission by the gut microbiota, increasing their absorption. In this review, we gather knowledge of the health benefits of green tea catechins and their metabolites, with a particular emphasis on the immunomodulatory effects in a cancer microenvironment scenario.

Shatianyu dietary fiber (Citrus grandis L. Osbeck) promotes the production of active metabolites from its flavonoids during in vitro colonic fermentation.

Recent studies reveal that dietary fiber (DF) might play a critical role in the metabolism and bioactivity of flavonoids by regulating gut microbiota. We previously found that Shatianyu (Citrus grandis L. Osbeck) pulp was rich in flavonoids and DF, and Shatianyu pulp flavonoid extracts (SPFEs) were dominated by melitidin, obviously different from other citrus flavonoids dominated by naringin. The effects of Shatianyu pulp DF (SPDF) on the microbial metabolism and bioactivity of SPFEs is unknown. An in vitro colonic fermentation model was used to explore the effects of SPDF on the microbial metabolism and antioxidant activity of SPFEs in the present study. At the beginning of fermentation, SPDF promoted the microbial degradation of SPFEs. After 24 h-fermentation, the supplemented SPFEs were almost all degraded in SPFEs group, and the main metabolites detected were the dehydrogenation, hydroxylation and acetylation products of naringenin, the aglycone of the major SPFEs components. However, when SPFEs fermented with SPDF for 24 h, 60.7% of flavonoid compounds were retained, and SPFEs were mainly transformed to the ring fission metabolites, such as 3-(4-hydroxyphenyl) propionic acid, 3-phenylpropionic acid and 3-(3-hydroxy-phenyl) propionic acid. The fermentation metabolites of SPFEs showed stronger antioxidant activity than the original ones, with a further increase in SPDF supplemented group. Furthermore, SPFEs enriched microbiota participating in the deglycosylation and dehydrogenation of flavonoids, while co-supplementation of SPDF and SPFEs witnessed the bloom of Lactobacillaceae and Lactobacillus, contributing to the deglycosylation and ring fission of flavonoids. SDPF promote SPFEs to transform to active metabolites probably by regulating gut microbiota. © 2023 Society of Chemical Industry.

OH Roaming during the Ozonolysis of α-Pinene: A New Route to Highly Oxygenated Molecules?

The formation of low-volatility organic compounds in the ozonolysis of α-pinene, the dominant atmospheric monoterpene, provides an important route to aerosol formation. In this work, we consider a previously unexplored set of pathways for the formation of highly oxygenated molecules in α-pinene ozonolysis. Pioneering, direct experimental observations of Lester and co-workers have demonstrated a significant production of hydroxycarbonyl products in the dissociation of Criegee intermediates. Theoretical analyses indicate that this production arises from OH roaming-induced pathways during the OO fission of the vinylhydroperoxides (VHPs), which in turn come from internal H transfers in the Criegee intermediates. Ab initio kinetics computations are used here to explore the OH roaming-induced channels that arise from the ozonolysis of α-pinene. For computational reasons, the calculations consider a surrogate for α-pinene, where two spectator methyl groups are replaced with H atoms. Multireference electronic structure calculations are used to illustrate a variety of energetically accessible OH roaming pathways for the four VHPs arising from the ozonolysis of this α-pinene surrogate. Ab initio transition-state theory-based master equation calculations indicate that for the dissociation of stabilized VHPs, these OH roaming pathways are kinetically significant with a branching that generally increases from ∼20% at room temperature up to ∼70% at lower temperatures representative of the troposphere. For one of the VHPs, this branching already exceeds 60% at room temperature. For the overall ozonolysis process, these branching ratios would be greatly reduced by a limited branching to the stabilized VHP, although there would also be some modest roaming fraction for the nonthermal VHP dissociation process. The strong exothermicities of the roaming-induced isomerizations/additions and abstractions suggest new routes to fission of the cyclobutane rings. Such ring fissions would facilitate further autoxidation reactions, thereby providing a new route for producing highly oxygenated nonvolatile precursors to aerosol formation.

Functional analysis of the protocatechuate branch of the β-ketoadipate pathway in Aspergillus niger

Bacteria and fungi catabolize plant-derived aromatic compounds by funneling into one of seven dihydroxylated aromatic intermediates, which then undergo ring fission and conversion to TCA cycle intermediates. Two of these intermediates, protocatechuic acid and catechol, converge on β-ketoadipate which is further cleaved to succinyl-CoA and acetyl-CoA. These β-ketoadipate pathways have been well characterized in bacteria. The corresponding knowledge of these pathways in fungi is incomplete. Characterization of these pathways in fungi would expand our knowledge and improve the valorization of lignin-derived compounds. Here, we used homology to characterized bacterial or fungal genes to predict the genes involved in the β-ketoadipate pathway for protocatechuate utilization in the filamentous fungus Aspergillus niger. We further used the following approaches to refine the assignment of the pathway genes: whole transcriptome sequencing to reveal genes upregulated in the presence of protocatechuic acid; deletion of candidate genes to observe their ability to grow on protocatechuic acid; determination by mass spectrometry of metabolites accumulated by deletion mutants; and enzyme assays of the recombinant proteins encoded by candidate genes. Based on the aggregate experimental evidence, we assigned the genes for the five pathway enzymes as follows: NRRL3_01405 (prcA) encodes protocatechuate 3,4-dioxygenase; NRRL3_02586 (cmcA) encodes 3-carboxy-cis,cis-muconate cyclase; NRRL3_01409 (chdA) encodes 3-carboxymuconolactone hydrolase/decarboxylase; NRRL3_01886 (kstA) encodes β-ketoadipate:succinyl-CoA transferase; and NRRL3_01526 (kctA) encodes β-ketoadipyl-CoA thiolase. Strain carrying ΔNRRL3_00837 could not grow on protocatechuic acid, suggesting that it is essential for protocatechuate catabolism. Its function is unknown as recombinant NRRL3_00837 did not affect the in vitro conversion of protocatechuic acid to β-ketoadipate.

Probiotic Yoghurt Enriched with Mango Peel Powder: Biotransformation of Phenolics and Modulation of Metabolomic Outputs after In Vitro Digestion and Colonic Fermentation.

This study investigated the health-promoting effects and prebiotic functions of mango peel powder (MPP) both as a plain individual ingredient and when incorporated in yoghurt during simulated digestion and fermentation. The treatments included plain MPP, plain yoghurt (YA), yoghurt fortified with MPP (YB), and yoghurt fortified with MPP and lactic acid bacteria (YC), along with a blank (BL). The identification of polyphenols in the extracts of insoluble digesta and phenolic metabolites after the in vitro colonic fermentation were performed employing LC-ESI-QTOF-MS2. These extracts were also subjected to pH, microbial count, production of SCFA, and 16S rRNA analyses. The characterisation of phenolic profiles identified 62 phenolic compounds. Among these compounds, phenolic acids were the major compounds that underwent biotransformation via catabolic pathways such as ring fission, decarboxylation, and dehydroxylation. Changes in pH indicated that YC and MPP reduced the media pH from 6.27 and 6.33 to 4.50 and 4.53, respectively. This decline in pH was associated with significant increases in the LAB counts of these samples. The Bifidobacteria counts were 8.11 ± 0.89 and 8.02 ± 1.01 log CFU/g in YC and MPP, respectively, after 72 h of colonic fermentation. Results also showed that the presence of MPP imparted significant variations in the contents and profiles of individual short chain fatty acids (SCFA) with more predominant production of most SCFA in the MPP and YC treatments. The 16s rRNA sequencing data indicated a highly distinctive microbial population associated with YC in terms of relative abundance. These findings suggested MPP as a promising ingredient for utilisation in functional food formulations aiming to enhance gut health.

Colonic Degradation as Reverse Process to Flavone Biosynthesis in Plants: Similarities and Differences.

For many years, it was thought that the main function of the colon is the reabsorption of water and salt and the elimination of unused food materials. Only very recently, a crucial role of the human intestinal microbiota in the metabolism of different food constituents, including plant foods-derived flavonoids, was discovered. Currently, the knowledge about colonic degradation of ingested flavonoids, involved bacteria and produced catabolites is rapidly increasing. In general, flavonoids unabsorbed in the small intestine reach the colon, where they are exposed to the gut microbiota. In this perspective article, colonic degradation of flavonoids is considered a reverse process to their biosynthesis in plants, with a special focus on the subclass of flavones. According to this approach: what is composed in plants, will be decomposed in the human colon. Several inverse similarities are highlighted, including hydrolysis of flavonoid glycosides as the first step in the gut degradation contrasted with the attachment of sugar moiety as the last reaction of flavonoid biosynthesis in plants, colonic reduction contrasted with plant introduction of C2-C3 double bond in the central heterocyclic ring, or microbial ring fission contrasted with plant ring closure of the heterocyclic ring of flavones. Despite these inverse similarities, precursors of flavonoid pathway in plants are different from the spectrum of gut microbial catabolites in humans. In the human colon, a wide variety of phenolic acids are produced from the ingested flavonoids, due to the diverse enzymatic capacity of intestinal microbiota. The bioactivities and potential health impacts of these catabolites are still largely unknown.

Degradation pathways for organic matter of terrestrial origin are widespread and expressed in Arctic Ocean microbiomes

BackgroundThe Arctic Ocean receives massive freshwater input and a correspondingly large amount of humic-rich organic matter of terrestrial origin. Global warming, permafrost melt, and a changing hydrological cycle will contribute to an intensification of terrestrial organic matter release to the Arctic Ocean. Although considered recalcitrant to degradation due to complex aromatic structures, humic substances can serve as substrate for microbial growth in terrestrial environments. However, the capacity of marine microbiomes to process aromatic-rich humic substances, and how this processing may contribute to carbon and nutrient cycling in a changing Arctic Ocean, is relatively unexplored. Here, we used a combination of metagenomics and metatranscriptomics to assess the prevalence and diversity of metabolic pathways and bacterial taxa involved in aromatic compound degradation in the salinity-stratified summer waters of the Canada Basin in the western Arctic Ocean.ResultsCommunity-scale meta-omics profiling revealed that 22 complete pathways for processing aromatic compounds were present and expressed in the Canada Basin, including those for aromatic ring fission and upstream funneling pathways to access diverse aromatic compounds of terrestrial origin. A phylogenetically diverse set of functional marker genes and transcripts were associated with fluorescent dissolved organic matter, a component of which is of terrestrial origin. Pathways were common throughout global ocean microbiomes but were more abundant in the Canada Basin. Genome-resolved analyses identified 12 clades of Alphaproteobacteria, including Rhodospirillales, as central contributors to aromatic compound processing. These genomes were mostly restricted in their biogeographical distribution to the Arctic Ocean and were enriched in aromatic compound processing genes compared to their closest relatives from other oceans.ConclusionOverall, the detection of a phylogenetically diverse set of genes and transcripts implicated in aromatic compound processing supports the view that Arctic Ocean microbiomes have the capacity to metabolize humic substances of terrestrial origin. In addition, the demonstration that bacterial genomes replete with aromatic compound degradation genes exhibit a limited distribution outside of the Arctic Ocean suggests that processing humic substances is an adaptive trait of the Arctic Ocean microbiome. Future increases in terrestrial organic matter input to the Arctic Ocean may increase the prominence of aromatic compound processing bacteria and their contribution to Arctic carbon and nutrient cycles.6hGoymMH-pRJKwnwbycG8JVideo

Flavonoids' Dual Benefits in Gastrointestinal Cancer and Diabetes: A Potential Treatment on the Horizon?

Diabetes and gastrointestinal cancers (GI) are global health conditions with a massive burden on patients' lives worldwide. The development of both conditions is influenced by several factors, such as diet, genetics, environment, and infection, which shows a potential link between them. Flavonoids are naturally occurring phenolic compounds present in fruits and vegetables. Once ingested, unabsorbed flavonoids reaching the colon undergo enzymatic modification by the gut microbiome to facilitate absorption and produce ring fission products. The metabolized flavonoids exert antidiabetic and anti-GI cancer properties, targeting major impaired pathways such as apoptosis and cellular proliferation in both conditions, suggesting the potentially dual effects of flavonoids on diabetes and GI cancers. This review summarizes the current knowledge on the impact of flavonoids on diabetes and GI cancers in four significant pathways. It also addresses the synergistic effects of selected flavonoids on both conditions. While this is an intriguing approach, more studies are required to better understand the mechanism of how flavonoids can influence the same impaired pathways with different outcomes depending on the disease.

Biochemical characterization of hydroquinone hydroxylase from Phanerochaete chrysosporium

The white-rot fungus Phanerochaete chrysosporium can degrade lignin polymers using extracellular, non-specific, one-electron oxidizing enzymes. This results in the formation of guaiacyl (G), syringyl (S), and hydroxyphenyl (H) units, such as vanillic acid, syringic acid, and p-hydroxybenzoic acid (p-HBA) and the corresponding aldehydes, which are further metabolized intracellularly. Therefore, the aim of this study was to identify proteins involved in the hydroxylation of H-unit fragments such as p-HBA and its decarboxylated product hydroquinone (HQ) in P.chrysosporium. A flavoprotein monooxygenase (FPMO), PcFPMO2, was identified and its activity was characterized. Recombinant PcFPMO2 with an N-terminal polyhistidine tag was produced in Escherichia coli and purified. In the presence of NADPH, PcFPMO2 used six phenolic compounds as substrates. PcFPMO2 catalyzed the hydroxylation of the H-unit fragments such as p-HBA and HQ, and the G-unit derivative methoxyhydroquinone (MHQ). The highest catalytic efficiency (kcat/Km) was observed with HQ, indicating that PcFPMO2 could be involved in HQ hydroxylation invivo. Additionally, PcFPMO2 converted MHQ to 3-, 5-, and 6-methoxy-1,2,4-trihydroxybenzene (3-, 5-, and 6-MTHB), respectively, suggesting that PcFPMO2 might partially be involved in MHQ degradation, following aromatic ring fission, via three MTHBs. FPMOs are divided into eight groups (groups A to H). This is the first study to show MHQ hydroxylase activity of a FPMO-group A superfamily member. These findings highlight the unique substrate spectrum of PcFPMO2, making it an attractive candidate for biotechnological applications.

The Analytical Strategy of "Ion Induction and Deduction Based on Net-Hubs" for the Comprehensive Characterization of Naringenin Metabolites In Vivo and In Vitro Using a UHPLC-Q-Exactive Orbitrap Mass Spectrometer.

Naringenin (5,7,4'-trihydroxyflavanone), belonging to the flavanone subclass, is associated with beneficial effects such as anti-oxidation, anticancer, anti-inflammatory, and anti-diabetic effects. Drug metabolism plays an essential role in drug discovery and clinical safety. However, due to the interference of numerous endogenous substances in metabolic samples, the identification and efficient characterization of drug metabolites are difficult. Here, ultra-high-performance liquid chromatography (UHPLC) coupled with high-resolution mass spectrometry was used to obtain mass spectral information of plasma (processed by three methods), urine, feces, liver tissue, and liver microsome samples. Moreover, a novel analytical strategy named "ion induction and deduction" was proposed to systematically screen and identify naringenin metabolites in vivo and in vitro. The analysis strategy was accomplished by the establishment of multiple "net-hubs" and the induction and deduction of fragmentation behavior. Finally, 78 naringenin metabolites were detected and identified from samples of rat plasma, urine, feces, liver tissue, and liver microsomes, of which 67 were detected in vivo and 13 were detected in vitro. Naringenin primarily underwent glucuronidation, sulfation, oxidation, methylation, ring fission, and conversion into phenolic acid and their composite reactions. The current study provides significant help in extracting target information from complex samples and sets the foundation for other pharmacology and toxicology research.

Characterization of two 1,2,4-trihydroxybenzene 1,2-dioxygenases from Phanerochaete chrysosporium.

Lignin is the most abundant aromatic compound in nature, and it plays an important role in the carbon cycle. White-rot fungi are microbes that are capable of efficiently degrading lignin. Enzymes from these fungi possess exceptional oxidative potential and have gained increasing importance for improving bioprocesses, such as the degradation of organic pollutants. The aim of this study was to identify the enzymes involved in the ring cleavage of the lignin-derived aromatic 1,2,4-trihydroxybenzene (THB) in Phanerochaete chrysosporium, a lignin-degrading basidiomycete. Two intradiol dioxygenases (IDDs), PcIDD1 and PcIDD2, were identified and produced as recombinant proteins in Escherichia coli. In the presence of O2, PcIDD1 and PcIDD2 acted on eight and two THB derivatives, respectively, as substrates. PcIDD1 and PcIDD2 catalyze the ring cleavage of lignin-derived fragments, such as 6-methoxy-1,2,4-trihydroxybenzene (6-MeOTHB) and 3-methoxy-1,2-catechol. The current study also revealed that syringic acid (SA) was converted to 5-hydroxyvanillic acid, 2,6-dimethoxyhydroquinone, and 6-MeOTHB by fungal cells, suggesting that PcIDD1 and PcIDD2 may be involved in aromatic ring fission of 6-MeOTHB for SA degradation. This is the first study to show 6-MeOTHB dioxygenase activity of an IDD superfamily member. These findings highlight the unique and broad substrate spectra of PcIDDs, rendering it an attractive candidate for biotechnological application. KEY POINTS: • Novel intradiol dioxygenases (IDD) in lignin degradation were characterized. • PcIDDs acted on lignin-derived fragments and catechol derivatives. • Dioxygenase activity on 6-MeOTHB was identified in IDD superfamily enzymes.

Systematically Exploring the Chemical Ingredients and Absorbed Constituents of Polygonum capitatum in Hyperuricemia Rat Plasma Using UHPLC-Q-Orbitrap HRMS.

Polygonum capitatum as an ethnic medicine has been used to treat urinary tract infections, pyelonephritis and urinary calculi. In our previous study, P. capitatum was found to have anti-hyperuricemia effects. Nevertheless, the active constituents of P. capitatum for treating hyperuricemia were still unclear. In this study, an ultra-high-performance liquid chromatography coupled to quadrupole/orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) was used to comprehensively detect the chemical ingredients of P. capitatum and its absorbed constituents in the plasma of hyperuricemia rats for the first time. Xcalibur 3.0 and Compound Discoverer 2.0 software coupled to mzCloud and ChemSpider databases were utilized for qualitative analysis. A total of 114 chemical components including phenolics, flavonoids, tannins, phenylpropanoids, amino acids, amides and others were identified or tentatively characterized based on the exact mass, retention time and structural information. Compared to the previous P. capitatum study, an additional 66 different components were detected. Moreover, 68 related xenobiotics including 16 prototype components and 52 metabolites were found in the plasma of hyperuricemia rats. The metabolic pathways included ring fission, hydrolysis, decarboxylation, dehydroxylation, methylation, glucuronidation and sulfation. This work may provide important information for further investigation on the active constituents of P. capitatum and their action mechanisms for anti-hyperuricemia effects.

Influence of different salts of alkali and alkaline earth metals on the pyrolysis of Prosopis juliflora

AbstractThis study explores the effect of acetate, oxide and chloride salts of alkali and alkaline earth metals (AAEMs) on the pyrolysis of lignocellulosic biomass. Prosopis juliflora samples were infused using 2% acetate and chloride salts of potassium (CH3COOK, KCl) and the oxide and chloride salts of magnesium (MgO, MgCl2). Dry impregnation technique was employed for the infusion of salts into the biomass matrix. The AAEM salt‐infused biomass was pyrolyzed using a semi‐batch pyrolysis reactor, and the bio‐oils were characterized for variation in chemical composition using gas chromatography–mass spectroscopy. The AAEM salts significantly influenced the pyrolysis process by catalyzing different degradation pathways. Potassium salts catalyzed the ring fission reactions of carbohydrates, resulting in an increase in carboxylic acid yield. On the other hand, magnesium salts promoted the cyclization of the fragmented radicals of the ring fission, resulting in enhanced furan and cycloketone yield. AAEM salts were most effective in catalyzing carbohydrate degradation pathways over the lignin degradation reactions owing to their ability to easily influence polysaccharide C–C bond cleavage over those of lignin aromatic rings. This study also revealed that the anions of AAEM salts also play a major role in biomass pyrolysis. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd

In Vitro Faecal Fermentation of Monomeric and Oligomeric Flavan-3-ols: Catabolic Pathways and Stoichiometry.

The study evaluates the influence of flavan-3-ol structure on the production of phenolic catabolites, principally phenyl-γ-valerolactones (PVLs), and phenylvaleric acids (PVAs). A set of 12 monomeric flavan-3-ols and proanthocyanidins (degree of polymerization (DP) of 2-5), are fermented in vitro for 24 h using human faecal microbiota, and catabolism is analyzed by UHPLC-ESI-MS/MS. Up to 32 catabolites strictly related to microbial catabolism of parent compounds are detected. (+)-Catechin and (-)-epicatechin have the highest molar mass recoveries, expressed as a percentage with respect to the incubated concentration (75µmol L-1 ) of the parent compound, for total PVLs and PVAs, both at 5 h (about 20%) and 24 h (about 40%) of faecal incubation. Only A-type dimer and B-type procyanidins underwent the ring fission step, and no differences are found in total PVL and PVA production (≃1.5% and 6.0% at 5 and 24 h faecal incubation, respectively) despite the different DPs. The flavan-3-ol structure strongly affects the colonic catabolism of the native compounds, influencing the profile of PVLs and PVAs produced in vitro. This study opens new perspectives to further elucidate the colonic fate of oligomeric flavan-3-ols and their availability in producing bioactive catabolites.

Long-term degradation of toluene and phenol in soil: Identification of transformation products and pathways via HRMS-based suspect and non-target screening

In this study, the long-term fate of toluene and phenol in the soil was investigated, and the transformation products (TPs) and pathways of these compounds were studied by a high resolution mass spectrometry (HRMS)-based suspect and non-target screening approach for the first time, and 9 and 12 transformation products were identified for toluene and phenol, respectively in the lab-exposed soil samples. Salicylaldehyde, 4-hydroxybenzaldehyde, and benzaldehyde were identified in toluene-contaminated field soil samples for the first time, and the main mechanisms involved in the biodegradation and detoxification of toluene and phenol in soil were oxidation, carboxylation, dehydroxylation, and ring fission amongst others. 2-oxoglutarate, TP165-A, TP165-B, TP172, and TP195 were identified as novel phenol transformation products, while salicylaldehyde, 2-oxoglutarate, TP165-A, and TP165-B were identified as novel toluene transformation products, providing new possible evidence for additional degradation pathways, which could give new insights into the fate of toluene and phenol during the natural attenuation process in the environment. Finally, salicylaldehyde, 4-OH-benzaldehyde, and 4-OH-benzoic acid which were detected at Level 1 identification confidence were suggested as indicator chemicals of toluene and phenol exposure in the contaminated field.

Enzymatic Oxidation of Tea Catechins and Its Mechanism.

Tea (Camellia sinensis, Theaceae) is one of the most widely consumed beverages in the world. The three major types of tea, green tea, oolong tea, and black tea, differ in terms of the manufacture and chemical composition. Catechins, theaflavins, and thearubigins have been identified as the major components in tea. Other minor oligomers have also been found in tea. Different kinds of ring fission and formation elucidate the major transformed pathways of tea catechins to their dimers and polymers. The present review summarizes the data concerning the enzymatic oxidation of catechins, their dimers, and thearubigins in tea.

Uptake, translocation, and metabolism of anthracene in tea plants

The origin of 9, 10-anthraquinone (AQ) contamination in tea remains unclear at present. The objective of this study was to test the hypothesis that AQ could be produced from the precursor anthracene in tea plantations. To test this hypothesis, the uptake, translocation, and transformation of anthracene in tea (Camellia sinensis) seedlings using hydroponic experimentation was investigated. Anthracene concentrations in tea tissues rose with increased anthracene exposure, which in the roots were significantly (p < 0.05) higher than those in aboveground parts at the end of the exposure. These results indicated that anthracene tended to be adsorbed into tea seedling via the roots and accumulated largely within roots. The three main pathways of anthracene degradation in tea seedlings were suggested: oxygen was incorporated in the 9th and 10th positions of anthracene resulting in AQ (I) and anthrone (II), and naphthalene was formed by ring fission of anthracene via methylanthracene (III). The principal anthracene metabolites were AQ and anthrone. The concentrations of AQ, like anthrone, were markedly elevated in the roots than those in stems throughout the entire exposure period. Moreover, the translocation factors for anthracene and its primary metabolites AQ and anthrone from roots to stems were persistently lower than 0.1, demonstrating a poor translocation from roots to the aboveground regions. However, tea seedlings could take anthracene up from water and translocate it to the leaves. It was a possible risk for AQ contamination in tea leaves continuously exposed to anthracene for long periods of time because tea plants were perennial crops.

Application of Immobilized Laccase on Polyurethane Foam for Ex-Situ Polycyclic Aromatic Hydrocarbons Bioremediation

There is growing concern about developing treatment technologies for the hazardous Polycyclic Aromatic Hydrocarbons (PAHs), because the rising levels of these compounds in the environment by human activities. The application of laccases has been evaluated as one of the most promising treatments. Thus, laccase immobilization on polyurethane foam (PUF)—low-cost material—was evaluated for bioremediation in batch mode of simulated groundwater using a combination of 16 polycyclic aromatic hydrocarbons as model pollutants. Conditions closer to a real contaminated site (non-optimal) were considered on our experimental design, leading to the formation of new degradation intermediaries, even more degraded than the usual ones. The bioremediation of PAH (mg L−1) using immobilized laccase on PUF reached 92.35% of removal for anthracene (Ant) and 97% for benzo(a)pyrene (BaP). After the treatment, the biodegradation products were identified as diisooctyl phthalate and tetradecane. The biodegradation mechanism was proposed, where PAHs oxidation processes and aromatic ring fission led to quinone and diethyl phthalate formation. Then, through the latter processes besides, polymerization and methylation, lead to the identified biodegradation product formation. The immobilized enzyme improvement in the removal yield of 8 of the other 14 PAHs tested in μg L−1, compared to the free counterpart. Laccase immobilized on PUF achieved final anthracene concentration of 0.95 mg L−1, up to 38 μg L−1 of chrysene (77% removal) and 98 μg L−1 of pyrene (32% removal), under the intervention limits of environmental protection policies. Thus, laccase immobilized on PUF for use in bioreactors can be considered a potential approach for PAHs bioremediation for an ex-situ treatment.

Degradative pathways of polycyclic aromatic hydrocarbons (PAHs) by Phanerochaete chrysosporium under optimum conditions

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) constitute one group of priority environmental contaminants which must be disposed. Phanerochaete chrysosporium is one of the white rot fungi (WRF) used in the present study to investigate different conditions affecting its ability to utilize PAHs as a sole carbon and energy sources. P. chrysosporium was grown under optimum conditions, and its degradation percentage and degradative pathways have been determined by HPLC and GC/MS. The results showed that the optimum condition for the growth of P. chrysosporium was five discs inoculum size at 25°C for 7 days incubation period on 100 mg/L of each PAHs in BSM supplemented with 2000 µM MnSO4 with shaking. Four groups (I–IV) of optimum conditions were used to determine degradation percentage. The results cleared that the best PAHs in degradation was pyrene (Pyr.). P. chrysosporium degraded (100%) Pyr. under the four groups. P. chrysosporium degraded the six PAHs (Acen.; Anth.; Flu.; Naph.; Phen.; and Pyr.) efficiently. The intermediates resulted from degradation indicated that P. chrysosporium first oxidized the middle ring or hetero ring followed by ring fission. P. chrysosporium followed the phthalate route in its degradative pathway. The intermediates finally interred TCA cycle and give CO2 and H2O or short chain aliphatic polymerized to give long chains.

Immunomodulatory Constituents of Conocephalum conicum (Snake Liverwort) and the Relationship of Isolepidozenes to Germacranes and Humulanes.

Structural elucidation of three new sesquiterpenoids, namely, (1Z,4E)-lepidoza-1(10),4-dien-14-ol (1), rel-(1(10)Z,4S,5E,7R)-germacra-1(10),6 diene-11,14-diol (2), and rel-(1(10)Z,4S,5E,7R)-humula-1(10),5-diene-7,14-diol (3), isolated from the liverwort Conocephalum conicum, was accomplished by a combination of extensive NMR experiments, 1H NMR simulation, and other means. Additionally, the change of the identity of bicyclogermacren-14-al, previously reported as a C. conicum constituent, to isolepidozen-14-al is proposed. Compounds 2 and 3 appear to be related to 1 via hydration involving a shared intermediate, a substituted cyclopropylmethyl cation, formed by a highly regio- and stereoselective protonation of 1, followed by a stereospecific fission of the three-membered ring. In other words, an isolepidozene derivative might be a branchpoint to humulanes and germacranes; this transformation could be of, up to now, unknown, biosynthetic and/or synthetic relevance. Multivariate statistical analysis of the compositional data of C. conicum extract constituents was used to probe the hypothesized biochemical relations. The immunomodulatory effect of 1-3 and conocephalenol (4) was evaluated in an in vitro model on both nonstimulated and mitogen-stimulated rat splenocytes. The compounds displayed varying degrees of cytotoxicity to nonstimulated splenocytes, whereas 2 and 3 were found to exert immunosuppressive effects on concanavalin A-stimulated splenocytes while not being cytotoxic at the same concentrations.