Search

Danshen, the dried roots and rhizomes of Salvia miltiorrhiza Bunge (S. miltiorrhiza), is widely used in the treatment of cardiovascular and cerebrovascular diseases. Tanshinones, the bioactive compounds from Danshen, exhibit a wide spectrum of pharmacological properties, suggesting their potential for future therapeutic applications. Tanshinone biosynthesis is a complex process involving at least six P450 enzymes that have been identified and characterized, most of which belong to the CYP76 and CYP71 families. In this study, CYP81C16, a member of the CYP71 clan, was identified in S. miltiorrhiza. An in vitro assay revealed that it could catalyze the hydroxylation of four para -quinone-type tanshinones, namely neocryptotanshinone, deoxyneocryptotanshinone, and danshenxinkuns A and B. SmCYP81C16 emerged as a potential broad-spectrum oxidase targeting the C-18 position of para -quinone-type tanshinones with an impressive relative conversion rate exceeding 90%. Kinetic evaluations and in vivo assays underscored its highest affinity towards neocryptotanshinone among the tested substrates. The overexpression of SmCYP81C16 promoted the accumulation of (iso)tanshinone in hairy root lines. The characterization of SmCYP81C16 in this study accentuates its potential as a pivotal tool in the biotechnological production of tanshinones, either through microbial or plant metabolic engineering. [ABSTRACT FROM AUTHOR]

Ubiquinone (UQ) is a lipophilic electron carrier that functions in the respiratory and photosynthetic electron transfer chains of proteobacteria and eukaryotes. Bacterial UQ biosynthesis is well studied in the gammaproteobacterium Escherichia coli, in which most bacterial UQ‐biosynthetic enzymes have been identified. However, these enzymes are not always conserved among UQ‐containing bacteria. In particular, the alphaproteobacterial UQ biosynthesis pathways contain many uncharacterized steps with unknown features. In this work, we identified in the alphaproteobacterium Rhodobacter capsulatus a new decarboxylative hydroxylase and named it UbiN. Remarkably, the UbiN sequence is more similar to a salicylate hydroxylase than the conventional flavin‐containing UQ‐biosynthetic monooxygenases. Under aerobic conditions, R. capsulatus ΔubiN mutant cells accumulate 3‐decaprenylphenol, which is a UQ‐biosynthetic intermediate. In addition, 3‐decaprenyl‐4‐hydroxybenzoic acid, which is the substrate of UQ‐biosynthetic decarboxylase UbiD, also accumulates in ΔubiN cells under aerobic conditions. Considering that the R. capsulatus ΔubiD‐X double mutant strain (UbiX produces a prenylated FMN required for UbiD) grows as a wild‐type strain under aerobic conditions, these results indicate that UbiN catalyzes the aerobic decarboxylative hydroxylation of 3‐decaprenyl‐4‐hydroxybenzoic acid. This is the first example of the involvement of decarboxylative hydroxylation in ubiquinone biosynthesis. This finding suggests that the C1 hydroxylation reaction is, at least in R. capsulatus, the first step among the three hydroxylation steps involved in UQ biosynthesis. Although the C5 hydroxylation reaction is often considered to be the first hydroxylation step in bacterial UQ biosynthesis, it appears that the R. capsulatus pathway is more similar to that found in mammalians. [ABSTRACT FROM AUTHOR]

Stereospecific hydroxylation of chiral tertiary alkyl halides using silver salt as Lewis acid catalyst has been developed. A series of α-hydroxy carboxamides were obtained in high yield (up to 90%) and with high enantiospecificity (es; up to 99%). The reaction proceeded in a retentive manner. Control experiments showed that the reaction proceeds via an ionic reaction and that the hydroxide source comes from both water and DMSO. [ABSTRACT FROM AUTHOR]

[Display omitted] • The polar ZnO (0001) surface exhibits excellent adsorption and activation properties for SF 6. • The O vacancies on ZnO (10 1 ¯ 0) surfaces promote SF 6 activation and bond breaking. • The Zn vacancies on ZnO surfaces impair the adsorption capabilities of SF 6. • Hydroxylation enhances ZnO (10 1 ¯ 0) surfaces' chemical activation and decomposition capabilities towards SF 6. The emission of SF 6 is a worldwide concern. ZnO-based catalysts, featuring high specific surface area and abundant active sites, are potential catalysts for converting waste SF 6. This study, based on density functional theory (DFT), investigates the adsorption behavior of SF 6 on clean and modified ZnO surfaces with different polarities. The results show that polar ZnO (0001) exhibits better adsorption and activation of SF 6. The O vacancy on ZnO (10 1 ¯ 0) surfaces promotes SF 6 activation and bond breaking, while the Zn vacancy inhibits SF 6 adsorption on both ZnO facets. Among various modification treatments, hydroxylated ZnO surfaces exhibit the most significant SF 6 adsorption and activation properties. Due to the orbital hybridization between F-2p and Zn-3d, the hydroxylated ZnO (10 1 ¯ 0) surface demonstrates 46 times higher average adsorption energy and 30 times higher average charge transfer of SF 6 compared to clean surfaces. This paper elucidates the key role of ZnO hydroxylated surfaces in SF 6 activation and decomposition. [ABSTRACT FROM AUTHOR]

Quercetin (QU) and its derivatives exhibited good potential in exerting xanthine oxidase (XO) inhibitory activity. Herein, this study comprehensively investigated the interaction mechanism of QU and its derivatives in inhibiting XO activity by the molecular simulation, inhibition kinetics, ultraviolet–visible spectra, circular dichroism spectrum, and fluorescence spectrum methods. Results showed that glycosylation and hydrogenation of QU were unfavorable for the XO inhibitory activity, while methylation and hydroxylation were beneficial. The types of hydrogen bonds between flavonoids and amino acid residues played an important role in the XO inhibitory activity. Meanwhile, the mixed inhibition type with XO was considered more effective than noncompetitive. Moreover, QU and its derivatives broke the secondary structure and hydrogen networks and quenched the intrinsic fluorescence of XO. The formation of XO-flavonoids complex was endothermic and spontaneous, and H-bonding and van der Waals forces might play a dominant role in this process. Absorption, distribution, metabolism, excretion, and toxicity (ADMET) prediction showed that QU and its derivatives possessed good pharmacokinetic properties. Furthermore, molecular dynamics simulation, inhibition types, ultraviolet–visible spectrum, fluorescence quenching, and thermodynamic parameters could quantitatively evaluate the XO inhibitory effect of flavonoids with different structures. However, there was a deviation in the quantitative evaluation of the XO inhibitory activity of flavonoids by molecular docking and circular dichroism spectrum. [Display omitted] • Glycosylation and hydrogenation were unfavorable for XO inhibitory activity. • Methylation and hydroxylation were beneficial to XO inhibitory activity. • Mixed inhibition type with XO was more effective than noncompetitive. • XO inhibitory activity was mainly attribute to the types of hydrogen bonds. • Physical evaluation methods showed a deviation with the actual inhibitory activity. [ABSTRACT FROM AUTHOR]

The biotransformations of capsaicin and dihydrocapsaicin were investigated using cultured plant cells of Phytolacca americana as biocatalysts. Four products, ie 15-hydroxycapsaicin, dihydrocapsaicin, 15-hydroxydihydrocapsaicin, and capsaicin 4-β-glucoside, were isolated from the suspension cultures of P. americana treated with capsaicin for 3 days, showing that capsaicin was regioselectively hydroxylated, reduced, and glucosylated by cultured P. americana cells. On the other hand, dihydrocapsaicin was regioselectively dehydrogenated, hydroxylated, reduced, and glucosylated to give four products, ie capsaicin, 15-hydroxycapsaicin, 15-hydroxydihydrocapsaicin, and capsaicin 4-β-glucoside, by cultured P. americana cells. In this paper, it is reported, for the first time, that dihydrocapsaicin is converted into 15-hydroxydihydrocapsaicin by plant cultured cells. [ABSTRACT FROM AUTHOR]

Kinetic Monte Carlo simulations of electrochemical oxidation and reduction are presented that match many features of the experimentally observed electrochemical and morphological response of Pt(111). Included in the simulation are all relevant microscopic transitions, including the formation of Pt-OH and Pt-O from Pt, surface diffusion of all three species, as well as an effective place exchange diffusion at high potential. A detailed description of this approach to modeling such a complex surface is also presented. Overall, it is found that many features of the Pt(111) CV, including hydroxylation, hysteresis, and surface roughening, can be correlated to events associated with n-coordinated surface species, such as the hydroxylation wave corresponding to a one-electron oxidation of 9-coordinated terrace sites. Oxidation to Pt-O species at potentials above 1.0 V are shown to correlate to the presence of growing surface roughness, and the simulations suggest the onset of Pt-O formation in steady-state cyclic voltammetry is dominated by the oxidation of 8-coordinated step edges rather than terrace sites. Implications for the stability of Pt(111) catalysts after thousands of voltammetric cycles are discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydroxyl and sulfate radicals-induced IMI degradation was theoretically probed. • Initial HA reactions occurring on alkylamine side chain of IMI are the most favorable. • Ring-opening reactions for benzene ring and seven-membered N -heterocycle occur hardly. • Stronger oxidizing ability was found for SO 4 •− compared with •OH in IMI degradation. • H 2 O and O 2 molecules exhibit significant influences over aqueous degradation of IMI. In the present work, hydroxyl (•OH) and sulfate radicals (SO 4 •−)-induced aqueous degradation of imipramine (IMI) was theoretically probed by carrying out density functional theory (DFT) calculation. Among the initial reactions of •OH (SO 4 •−) toward IMI, the hydrogen abstraction (HA) reactions occurring on saturated carbon atoms of the alkylamine side chain are the most favorable, followed by the addition (AD) reactions involving unsaturated carbon positions, and the HA reactions related to unsaturated carbon atoms are the most unfavorable. The most favorable subsequent reactions for the initial AD and HA intermediates can afford the hydroxylation, oxidation, dehydrogenation, C N or C C bond cleavage products of IMI, while the corresponding ring-opening reactions occur hard. The stronger oxidizing ability of SO 4 •− was predicted in comparison with •OH. The cationic form of IMI has lower reactivity than IMI.H 2 O and O 2 molecules may exert a significant influence over aqueous degradation of IMI. [ABSTRACT FROM AUTHOR]

The efficient capture of heavy metal ions from actual wastewater is a global challenge. To enhance Pb(II) and Cd(II) removal, novel biochar composites (MF@CBC, MF-S@CBC and MF-OH@CBC) were successfully fabricated by loading magnetic Mn-Fe binary oxides and functionalizing chitosan Schiff-base or hydroxyl on biochar in the study. The maximum adsorption capacities of MF-OH@CBC and MF-S@CBC toward Pb(II)/Cd(II) were 196.69/187.29 mg/g and 161.61/153.69 mg/g (pH = 5.0, adsorbent dosage = 0.5 g/L), which were 2.09/3.05 and 1.54/2.33 times higher than corn cob biochar (CBC), respectively. The adsorption processes were conformed to Langmuir isothermal model and pseudo second order model. The numerous functional groups presented on MF-OH@CBC resulting from loading Mn-Fe nanoparticle and hydroxylation might be the main reason for dominating adsorption of Pb(II)/Cd(II) by complex interaction (contribution rate (C R) = 45.66%/43.12%). And also, the negative charge on MF-OH@CBC might be another reason for enhancing adsorption of Pb(II)/Cd(II) by electrostatic interaction (C R = 23.11%/22.45%). Besides, ion exchange (C R = 17.95%/19.33%) and physical adsorption (C R = 13.28%/15.10%) could also contributed to Pb(II)/Cd(II) removal. In addition, MF-OH@CBC displayed favorable recycling ability and its adsorption capacity retained over 80% after five cycles. It also exhibited anti-interfering ability, the adsorption capacity for Pb(II)/Cd(II) in actual sewage was 85.27%/80.47%, respectively. The results indicated that MF-OH@CBC possessed good potential for eliminating Pb(II) and Cd(II) from the complex aqueous environment. [Display omitted] • Mn-Fe nanoparticles and -OH group was successfully introduced to biochar. • Adsorption capacity for Pb(II) and Cd(II) by MF-OH@CBC was 196.69 and 187.29 mg/g. • The Pb(II) and Cd(II) sorption was a spontaneous endothermic chemical reaction. • Complexation of -OH and Pb(II)/Cd(II) played a major role in the adsorption process. • MF-OH@CBC displayed favorable selectivity and reusability. [ABSTRACT FROM AUTHOR]

Ag nanoparticles (AgNPs) catalyst material is bio-synthesized and fully examined using various spectroscopy and microscopy techniques. Further this synthesized material is used for hydroxylation reaction, for this purpose we developed a simple and versatile bio-based method from aryl boronic acids to phenol. The reaction was studied in the presence of low cost ligand in a hydrated reaction medium without any hazardous organic solvents, as a result a finite amount of yield was achieved in short time (<15 min). The hydroxylation reaction is further carried out in a series of different arenes substituted samples with good amount of yields. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Defects of MWCNTs are designed and hydroxylated by different treatment methods. • Defects on MWCNTs aren't used as active sites and show low activity of ODH in CO 2. • Hydroxylated disorder carbons of MWCNTs are not increased to enhance ODH activities. • Destructed disorder carbons of MWCNTs are hydroxylated to enhance ODH activities. • Defect skeleton carbons induce hydroxylation of MWCNTs to enhance ODH activities. Abstract The fabrication and hydroxylation of surface defects on multi-walled carbon nanotubes (MWCNTs) are performed through a single or combined method involving hydrothermal, ultrasonic and ball-milling treatments. These treatments cannot change the tubular morphology of the graphite structure in MWCNTs but they can alter the surface defect structure on MWCNTs. Surface defects on MWCNTs can promote the hydroxylation of the MWCNTs to produce hydroxyl groups. However, these defects are difficult to hydroxylate when occupied by other functional groups, such as carboxyl groups, even though the hydroxylation processes are the same. After hydroxylation, the MWCNTs with surface defects can be employed as metal-free catalysts for the oxidative dehydrogenation of ethylbenzene using CO 2 as soft oxidants. The inherent disorder or artificial skeleton defects on MWCNTs cannot directly act as catalytic active sites, but they can be hydroxylated to enhance the catalytic activity of the MWCNTs. For the same type of MWCNT defects formed after hydroxylation, the catalytic activity is closely related to the defect density. If the disorder or skeleton defects cause a higher defect density on the hydroxylated MWCNTs, the MWCNTs will exhibit a higher catalytic activity. Due to the different structures and positions of the MWCNT defect carbons, the artificial skeleton defects on MWCNTs more efficiently promote the hydroxylation of MWCNTs compared to the disorder defects, decreasing their defect density and enhancing their catalytic activity. Therefore, MWCNTs-BOH36 with skeleton defects has a catalytic activity that is twice as high as that of MWCNTs-CS-120 with disorder defects. [ABSTRACT FROM AUTHOR]

Abstract Polycyclic aromatic hydrocarbons (PAHs) are well-known carcinogenic and endocrine disrupting chemicals that have been concerned over the past few decades. We aimed to determine the hydroxylated PAH (OHPAH) metabolite concentrations in maternal urine collected from the e-waste-contaminated area of Guiyu and the reference area of Haojiang, China, and to evaluate their health effects on birth outcomes. The median ƩOHPAH concentration was 6.87 μg/g creatinine from Guiyu, and 3.90 μg/g creatinine from Haojiang. 2-OHNap and 1-OHPyr were the predominant metabolites. Residence in Guiyu and recycling in houses were associated with elevated 2-OHNap and 1-OHPyr. Standardized mean difference revealed that compared to low PAH metabolite levels in the first quartile, high PAH metabolite levels in the fourth quartile especially for 1-OHPyr, ƩOHPAHs and sometimes hydroxylphenanthrene compounds, presented a reduced size in birth outcomes (overall SMD: −0.09; 95% CI: −0.15, −0.03), including head circumference, BMI and Apgar 1 score, and increased size in height. After adjusting for confounders in regression models, an interquartile increase in ΣOHPAHs was associated with a decrease of 234.56 g in weight (95% CI: −452.00, −17.13), 1.72 cm in head circumference (95% CI: −2.96, −0.48), 1.06 kg/m2 in BMI (95% CI: −1.82, −0.31) and 0.42 in Apgar 1 score (95% CI: −0.66, −0.18), respectively. These findings suggest high exposure to PAHs during pregnancy in e-waste areas, posing a potential threat to neonatal development, which likely can be attributed to direct e-waste recycling activities. Ongoing studies should be continued to monitor human exposure and health, in particular for vulnerable individuals in e-waste-polluted areas. Graphical abstract Image 1 Highlights • Elevated PAH metabolites in maternal urine were found in the e-waste area. • 2-OHNap and 1-OHPyr were dominant compounds in the two study groups. • Residence in Guiyu and recycling in houses contributed to the main OHPAH exposure. • Size differences for birth outcomes were investigated by standardized mean difference. • High PAH metabolite levels were associated with reduced birth outcomes. [ABSTRACT FROM AUTHOR]

Abstract Class VIII self-sufficient CYP from Aspergillus fumigatus (CYP505X) and a variant with five mutations were heterologously expressed in Pichia pastoris. Ibuprofen – a widely used non-steroidal anti-inflammatory drug (NSAID) – was oxidized most efficiently in a whole cell mediated biotransformation. The two major metabolites were isolated by preparative HPLC and their structure elucidated by NMR. Specifically, ibuprofen was hydroxylated at the tertiary carbon atom and the benzylic position on the lipophilic side chain. Highlights • Microbial system established for the preparation of 1-hydroxyibuprofen and 2-hydroxyibuprofen. • Pichia pastoris expresses soluble CYP. • 13 APIs oxidized by microbial CYP in form of P. pastoris whole cell biocatalyst. • Activity of CYP505 quintuple mutant superior to the respective wild-type and selectivities different. [ABSTRACT FROM AUTHOR]

Abstract Systematically evaluation of the metabolism, distribution and effect of imidacloprid in Chinese lizards (Eremias argus) were carried out following oral exposure. Imidacloprid-olefin-guanidine was prone to accumulate in the brain and caused potential neurotoxicity. Percutaneous and excretory excretions were the primary ways for the elimination of imidacloprid and its metabolites. Liver was the main site for hydroxy reduction and nitro-reduction metabolism of imidacloprid. The metabolism of imidacloprid was a complex process in which many metabolic enzymes participated. Aldehyde oxidase and CYP2C9 were the key enzymes in nitro-reduction process. CYP3A4 dominated the process of hydroxylation and desaturation. The increase in Glutathione S-transferase expression may be related to the removal of imidacloprid, but also related to the oxidative stress reaction that imidacloprid may cause in tissues, especially in the kidney. The findings enrich and supplement the knowledge of the environmental fate of imidacloprid in reptiles. Graphical abstract fx1 Highlights • Molting and excretory exclusion are the main routes for the elimination of IMI. • AOX and CYP2C9 play a major role in the nitro-reduction process of IMI. • CYP3A4, 2C8 and 2D3 dominate the process of hydroxylation and desaturation. • IMI may pose a risk of damaging the oxidative stress system in kidney. [ABSTRACT FROM AUTHOR]

Abstract This paper evaluates the UV photodegradation of 17β-estradiol (E2) on silica gel and in natural soil with different soil components. Silica gel was chosen as a stable and pure support to simulate the photochemical behavior of E2 on the surface of natural soil. Ultraviolet light, rather than visible light, was confirmed to play a decisive role in the photodegradation of E2 on silica gel. The effect of three soil components, including humic acid (HA), inorganic salts, and relative humidity (RH), on the photochemical behavior of E2 on silica gel or soil under UV irradiation was then evaluated. Two HA concentrations (10 and 20 mg g−1) and three salts (ferric sulfate, copper sulfate and sodium carbonate) were observed to obviously inhibit the degradation of E2 on silica gel. Interestingly, nitrate was found to obviously improve the removal efficiency of E2. Both too-dry and too-wet conditions obviously reduced the removal rate of E2, and the optimum relative humidity (RH) value was found to be approximately about 35% (30 °C). Furthermore, twenty intermediate products and two major pathways were proposed to describe the transformation processes of E2 treated by UV irradiation, among which oligomers were found to be the major intermediate products before complete mineralization. The efficient UV removal of E2 on silica gel and natural soil suggested a feasible strategy to remediate E2 contaminated soil. Graphical abstract Image 1 Highlights • UV irradiation rapidly removed E2 on the silica gel and natural soil. • Effect of soil organic matter, mineral salts and relative humidity were studied. • Oligomers were identified as intermediates during UV treatment of E2. • Hydroxylation, oligomerization, ring opening, bond cleavage were observed. • Wiberg bond order was employed to rationalize the reaction mechanism of E2. Silica gel and soil components were mixed together to simulate natural soil and efficient removal of E2 in natural soil by UV treatment was demonstrated. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Bacterial collagen-like proteins differ from vertebrate collagens in that they do not contain hydroxyproline, which is seen as a characteristic of the vertebrate collagens, and which provides a significant contribution to the stability of the collagen triple-helix at body temperature. Despite this difference, the bacterial collagens are stable at around body temperature through inclusion of other stabilising sequence elements. Another difference is the lack of aggregation, and certain vertebrate collagen binding domains that can be introduced into the bacterial sequence lack full function when hydroxyproline is absent. In the present study we have demonstrated that a simple method utilising co-translational incorporation during fermentation can be used to incorporate hydroxyproline into the recombinant bacterial collagen. The presence and amount of hydroxyproline incorporation was shown by amino acid analysis and by mass spectrometry. A small increase in thermal stability was observed using circular dichroism spectroscopy. Statement of Significance Recombinant bacterial collagens provide a new opportunity for biomedical materials as they are readily produced in large quantity in E. coli. Unlike animal collagens, they are stable without the need for inclusion of a secondary modification system for hydroxyproline incorporation. In animal collagens, however, introduction of hydroxyproline is essential for stability and is also important for functional molecular interactions within the mammalian extracellular matrix. The present study has shown that hydroxyproline can be readily introduced into recombinant S. pyogenes bacterial collagen through direct co-translational incorporation of this modified imino acid during expression using the codons for proline in the introduced gene construct. This hydroxylation further improves the stability of the collagen and is available to enhance any introduced molecular functions. [ABSTRACT FROM AUTHOR]

Highlights • Fe-MFI catalyzed wet peroxide oxidation of ibuprofen through free radical mechanism. • Very low catalyst leaching evidenced main contribution of surface iron species. • Reaction rate was improved by higher temperature, catalyst & oxidant concentrations. • Hydroxylated ibuprofen adducts were found as main oxidation intermediates. • Preliminary acidification maintained catalyst activity in WWTP effluent matrix. Abstract Heterogeneous Fenton oxidation using Fe-zeolite catalyst (of ZSM5 type) was investigated for the removal of ibuprofen (20 mg/L) in water. In particular, the effects of catalyst concentration, oxidant dosage, temperature, solution pH, and water matrix on pollutant conversion and mineralization were evaluated. The activity of leached iron species in solution was also measured to determine the contribution of the homogeneous reaction. Oxidation rate of ibuprofen obeyed a pseudo-first-order kinetics with respect to the pollutant concentration, and the apparent rate constant increased with catalyst and hydrogen peroxide concentrations in the investigated ranges (1-5 g/L of Fe-zeolite and 0.5-7 times the stoichiometric amount of oxidant). Energy activation of 53 kJ/mol was obtained from Arrhenius plot. However, the mineralization yield was not significantly improved by a too large excess of H 2 O 2 or increase of temperature. In the selected conditions (25 °C, 4.8 g/L of catalyst, 2 times the stoichiometric amount of H 2 O 2), 88% of ibuprofen and 27% of TOC were removed after 3 hours of reaction under "natural" pH conditions. Very low leaching (up to 0.2 mg/L) and negligible activity of leached iron in solution indicated that Fenton reaction was mainly induced by iron species on the catalyst surface. Degradation rate of ibuprofen was slower in wastewater effluent as compared to distilled water, mainly due to alkaline buffering and radical scavenging effects of organic and inorganic compounds present in the matrix. Mono- and multi-hydroxylated ibuprofen adducts were found as main oxidation intermediates -in line with free-radical mechanism- as well as 4-isobutylacetophenone from decarboxylation route. [ABSTRACT FROM AUTHOR]

Pyriclobenzuron 1 1 PBU – pyriclobenzuron. (PBU) is a novel molluscicide developed to control Pomacea canaliculate , and little information on its environmental fate has been published. In this study, the photolysis of PBU in an aqueous environment was simulated using a xenon lamp. Results showed that the photolysis of PBU in water followed first-order kinetics, exhibiting a t 0.5 of 95.1 h and 83.6 h in Milli-Q water and river water, respectively. Two main photolysis products 2 2 PPs – photolysis products. (PPs) were detected by HPLC-UV and identified by UPLC-Q/TOF MS, which were formed via the hydroxylation and photocatalytic hydro-dehalogenation of PBU, respectively. The initial relative abundance of photolysis product 1 3 3 PP-1 – photolysis product 1. (PP-1) in Milli-Q water was 1.55 times higher than that in river water. PP-1 was detected at 26.5 % and 76.8 % of the maximum relative abundance in the river water and Milli-Q water after 720 h, respectively. Photolysis product 2 4 4 PP-2 – photolysis product 2. (PP-2) was stable in water because of its weak hydrophilicity. The PP-2 detected after 720 h in Milli-Q water and river water was 93.7 % and 93.5 % of the maximum relative abundance, respectively. Finally, ECOSAR software was used to evaluate the acute aquatic toxicity of PBU and its PPs, revealing that the PPs had lower toxicity levels to non-target aquatic organisms. [Display omitted] • Photolysis t 0.5 values of PBU in two aqueous environments were 95.1 h and 83.6 h. • The photolysis pathways of PBU were hydroxylation and hydro-dehalogenation. • PP-2 was more stable than PP-1 in aqueous environments. • ECOSAR predicted that aquatic toxicity of PPs was lower than that of PBU. [ABSTRACT FROM AUTHOR]

[Display omitted] • Doping and surface hydroxylation leads to modification in properties of MgO nanotubes. • Adsorption of chemical warfare agent simulants (DMMP, CEES, paraoxon) on the MgO nanotubes causes changes in structural and electronic characteristics of the simulants. • Dissociative chemisorption of CEES occurs on MgO nanotube. • Partially hydroxylated MgO nanotube provides best adsorption surface for all the simulants. The present study investigates the adsorption of three chemical warfare agent simulants (DMMP, CEES and paraoxon) on MgO and Ti-doped MgO nanotubes. Simulated annealing has been used to identify all low energy modes of adsorption. The study reveals that both DMMP and paraoxon interact with the metal oxide surface via their phosphoryl oxygens, but in the case of CEES, the adsorption via Cl is highly exothermic on the Ti-doped surface and results in the dissociation of the C Cl bond. The effect of hydroxylation on the properties of the nanotube surface has also been investigated. The results reveal that as the number of water molecules attached to the nanotube is increased, the properties are also modified. Moreover, it is found that partial hydroxylation of the MgO surface favors maximal adsorption. This may be because complete hydration leads to blocking of all sites, hence the hydration should be partial, as the presence of a few hydroxyl groups assists the decomposition of the molecule. [ABSTRACT FROM AUTHOR]

Brown adipose tissue (BAT) plays a crucial role in regulating non-shivering thermogenesis under cold exposure. Proline hydroxylases (PHDs) were found to be involved in adipocyte differentiation and lipid deposition. However, the effects of PHDs on regulatory mechanisms of BAT thermogenesis are not fully understood. We detected the expression of PHDs in different adipose tissues by using immunoblotting and real-time PCR. Further, immunoblotting, real-time PCR, and immunostaining were performed to determine the correlation between proline hydroxylase 2 (PHD2) and UCP1 expression. Inhibitor of PHDs and PHD2-sgRNA viruses were used to construct the PHD2-deficiency model in vivo and in vitro to investigate the impacts of PHD2 on BAT thermogenesis. Afterward, the interaction between UCP1 and PHD2 and the hydroxylation modification level of UCP1 were verified by Co-IP assays and immunoblotting. Finally, the effect of specific proline hydroxylation on the expression/activity of UCP1 was further confirmed by site-directed mutation of UCP1 and mass spectrometry analysis. PHD2, but not PHD1 and PHD3, was highly enriched in BAT, colocalized, and positively correlated with UCP1. Inhibition or knockdown of PHD2 significantly suppressed BAT thermogenesis under cold exposure and aggravated obesity of mice fed HFD. Mechanistically, mitochondrial PHD2 bound to UCP1 and regulated the hydroxylation level of UCP1, which was enhanced by thermogenic activation and attenuated by PHD2 knockdown. Furthermore, PHD2-dependent hydroxylation of UCP1 promoted the expression and stability of UCP1 protein. Mutation of the specific prolines (Pro-33, 133, and 232) in UCP1 significantly mitigated the PHD2-elevated UCP1 hydroxylation level and reversed the PHD2-increased UCP1 stability. This study suggested an important role for PHD2 in BAT thermogenesis regulation by enhancing the hydroxylation of UCP1. • PHD2 is highly expressed in brown adipose tissue and participates in the regulation of brown adipose activation. • PHD2 is expressed in mitochondrial protein and binds to UCP1 protein. • PHD2 regulates UCP1 protein activity and stability by hydroxylating Pro residues. [ABSTRACT FROM AUTHOR]

Diclofenac (DCF) is a widely used non-steroidal anti-inflammatory pharmaceutical which is detected in the environment at concentrations which can pose a threat to living organisms. In this study, biodegradation of DCF was assessed using the bacterial strain Labrys portucalensis F11. Biotransformation of 70% of DCF (1.7–34 μM), supplied as the sole carbon source, was achieved in 30 days. Complete degradation was reached via co-metabolism with acetate, over a period of 6 days for 1.7 µM and 25 days for 34 μM of DCF. The detection and identification of biodegradation intermediates was performed by UPLC-QTOF/MS/MS. The chemical structure of 12 metabolites is proposed. DCF degradation by strain F11 proceeds mainly by hydroxylation reactions; the formation of benzoquinone imine species seems to be a central step in the degradation pathway. Moreover, this is the first report that identified conjugated metabolites, resulting from sulfation reactions of DCF by bacteria. Stoichiometric liberation of chlorine and no detection of metabolites at the end of the experiments are strong indications of complete degradation of DCF by strain F11. To the best of our knowledge this is the first report that points to complete degradation of DCF by a single bacterial strain isolated from the environment. [ABSTRACT FROM AUTHOR]

Carbonates formed from hyperalkaline aqueous solutions at the Earth́s surface are known to bear the most extreme disequilibrium isotope signatures reported so far in nature. We present here the results for stable carbon (C), oxygen (O), and barium (Ba) isotope fractionation during the precipitation of witherite (BaCO 3 ) induced by the chemical absorption of atmospheric carbon dioxide (CO 2 ) into an aqueous hyper-alkaline solution (at 4° and 21 °C; 1 atm total pressure). Independent from temperature, the barium carbonate formation was associated with a substantial enrichment of the lighter C and O isotopes in the solid compared to the atmosphere (C, O), close to previous results found in experiments and nature. A new approach is introduced to explain oxygen isotope fractionation upon hydroxylation of CO 2 . With Ba isotope enrichment factors between −0.45 and −0.53‰ ( 138/134 ε) or −0.34 and −0.40‰ ( 137/134 ε), respectively, the synthesized BaCO 3 displays the highest kinetic enrichment of the light Ba isotope in the carbonate solid reported so far. [ABSTRACT FROM AUTHOR]

Polybrominated diphenyl ethers (PBDEs) and their hydroxylated (OH) and methoxylated (MeO) structural analogues have been found widely distributed in aquatic ecosystems, and may exhibit potential adverse effects to humans due to their bioaccumulative behavior through food chain. Fishmeal is an important animal feed applied around the world and is generally of marine origin. However, the levels and sources of PBDEs in fishmeal have not been thoroughly evaluated and their structural analogues have not been reported to date. The present study collected ninety-two fishmeal samples from world main fishmeal producing area to determine 27 PBDEs, 10 MeO-PBDEs and 11 OH-PBDEs. The concentrations of Σ 27 PBDEs, Σ 10 MeO-PBDEs and Σ 11 OH-PBDEs were in the ranges of 0.1–1498 (mean: 75.8), 1.14–881 (37.4) and 1.00–47.5 (8.17) ng/g lipid, respectively. PBDEs were found primarily correlated with the historically commercial production, meaning higher production of certain commercial product in a country, higher corresponding PBDE congeners in local fishmeal. A market shift from penta- and octa-formulations toward deca-formulation was observed. BDE209 was identified as a major congener in fishmeal. Both the MeO-PBDEs and the OH-PBDEs were influenced by fishmeal producing areas (p < 0.001). High MeO-PBDEs were identified in the Southeast Asian fishmeal, which might be due to the suitable environmental conditions for the generation of bromoperoxidase-contained algae in local area. The ratio of two major MeO-PBDE congeners, 6-MeO-BDE47/2′-MeO-BDE68, were generally >1 in the northern hemisphere and <1 in the southern hemisphere in the present study, which was consistent with the results obtained from previous published papers. Both MeO-PBDEs and OH-PBDEs were in accordance with the specialties of naturally produced halogenated compounds. [ABSTRACT FROM AUTHOR]

Vitamin D is produced in the skin upon sun-exposure or obtained through the diet. Vitamin D is hydroxylated to 25-hydroxyvitamin D (25(OH)D) in the liver and to the active form 1,25-dihydroxyvitamin D (1,25(OH)2D) in the kidneys. To exert its effect 1,25(OH)2D has to bind to the nuclear vitamin D receptor VDR. Lack of vitamin D leads to rickets in children and to osteomalacia in adults. 25(OH)D is used as a marker of a subject's vitamin D status. Low serum 25(OH)D levels are associated with a number of diseases, risk factors for disease and increased mortality. However, intervention studies with vitamin D have generally been disappointing. Many, if not most cells have the hydroxylases necessary for intra-cellular activation of vitamin D. It is likely that more vitamin D diffuses or are transported into the cells than 25(OH)D and 1,25(OH)2D, and accordingly, most of the 1,25(OH)2D that bind to the VDR are derived from intra-cellular hydroxylation of vitamin D. Therefore, our hypothesis is that serum vitamin D is a better marker of a subject's vitamin D status than 25(OH)D. Since the half-life in serum for vitamin D is approximately one day, giving vitamin D weekly or monthly will result in short-lived serum vitamin D peaks with periods of vitamin D deficiency in between. On the other hand, serum 25(OH)D, which has a half-life of weeks, will show high and stable serum levels throughout. Important vitamin D effects may have been missed in studies with intermittent dosing, and vitamin D in intervention trials should be given daily. Likewise, in epidemiological studies and clinical practice 25(OH)D has uniformly been used as marker. This may lead to gross misclassification of individuals that do not have a stable influx of vitamin D from sun-exposure or diet. In epidemiological studies serum vitamin D should be measured as well as 25(OH)D, and in clinical practice a 25(OH)D measurement should be interpreted in view of recent sun-exposure and diet history. [ABSTRACT FROM AUTHOR]

The Bio-Fenton reaction was applied to degrade bisphenol A (BPA, 0.1 mM), a commonly used plastic additive, via in-situ produced hydrogen peroxide (H 2 O 2) from glucose oxidase (GOx, 10 U), glucose (32 mM), and Fe(III)-citrate (0.5 mM) at pH 5.3. The reaction produced 0.15–1.1 × 10−16 M of •OH at a steady-state ([•OH] ss), which contributed significantly to BPA degradation. The second-order rate constant (k) for BPA degradation was 1.39–2.38 × 109 M−1 s−1, with 80% degradation of 0.1 mM BPA in 10 days of incubation and the production of hydroxylated intermediates, 4-hydroxyacetophenone, and hydroquinone, which were further filtered into small carboxylic acids via •OH-mediated reactions: hydroxylation, oxidation, scission of the C-C bond between the two BPA aromatic rings, and ring cleavage. Based on the successful application of the Bio-Fenton reaction to the radical scavenger and plastic additive BPA, microorganisms capable of producing H 2 O 2 through diverse oxidase enzymatic systems can be applied to degrade diverse pollutants in environments where ubiquitous Fe(III) with organic iron chelators is present. [Display omitted] • Bio-Fenton reaction was applied to degrade bisphenol A (BPA), a plastic additive. • In-situ produced H 2 O 2 and Fe(III)-citrate enabled the Bio-Fenton reaction at pH 5.3. • Degradation kinetics ([•OH] ss , k •OH,BPA) of the Bio-Fenton was firstly examined. • Hydroxyl radicals (•OH) were steadily produced and contributed to BPA degradation. • BPA was degraded to small carboxylic acids via •OH mediated oxidative reactions. [ABSTRACT FROM AUTHOR]

Diclofenac (DCF) is the frequently detected non-steroidal pharmaceuticals in the aquatic environment. In this study, the degradation of DCF was evaluated by UV-254 nm activated persulfate (UV/PS). The degradation of DCF followed the pseudo first-order kinetics pattern. The degradation rate constant (k obs ) was accelerated by UV/PS compared to UV alone and PS alone. Increasing the initial PS dosage or solution pH significantly enhanced the degradation efficiency. Presence of various natural water constituents had different effects on DCF degradation, with an enhancement or inhibition in the presence of inorganic anions (HCO 3 − or Cl − ) and a significant inhibition in the presence of NOM. In addition, preliminary degradation mechanisms and major products were elucidated using LC-MS/MS. Hydroxylation, decarbonylation, ring-opening and cyclation reaction involving the attack of SO 4 • − or other substances, were the main degradation mechanism. TOC analyzer and Microtox bioassay were employed to evaluate the mineralization and cytotoxicity of solutions treated by UV/PS at different times, respectively. Limited elimination of TOC (32%) was observed during the mineralization of DCF. More toxic degradation products and their related intermediate species were formed, and the UV/PS process was suitable for removing the toxicity. Of note, longer degradation time may be considered for the final toxicity removal. [ABSTRACT FROM AUTHOR]

A Gram-positive bacteriumLentzeasp. 7887 hydroxylates a cyclosporine derivative FR901459 into AS1837812 (9-hydroxide), which is an important intermediate of candidate drugs that target the hepatitis C virus. We screened a UV-induced mutant, named M-1, which showed about 1.2-fold higher conversion yields, 2-fold higher substrate concentrations (3.69 mM), and 2.5-fold higher yield per unit volume than the wild-type strain. [ABSTRACT FROM PUBLISHER]

Wogonin and astringin were synthesized from inexpensive chrysin and piceid in short steps. The key feature of these syntheses is site-selective transformation. The target molecules were obtained in 27 and 62% yields from the starting materials, respectively. wogonin and astringin were synthesized from chrysin and piceid in short steps, based on site-selective transformations of acetyl protective groups. [ABSTRACT FROM PUBLISHER]

Cytochrome P450 monooxygenases are a unique family of enzymes that are able to catalyze regio- and stereospecific oxidations for a broad substrate range. However, their highly-effective industrial application is often limited by the regeneration of cofactor NADPH. In this study, G6PDH from Rhizopus oryzae was expressed to enhance the regeneration of NADPH in the industrial strain, R. nigricans . The results showed the fermentation time of the engineered strain was shortened to 52 h when the hydroxylation yields reached the maximum, which was 4 h ahead compared to that of the original strain. 95.4%-higher-level NADPH could be generated and the hydroxylation yield increased by 15.6% in an engineered strain after 52-h fermentation compared to those in the original strain after 56-h fermentation. The results indicated that the strategy of enhancing NADPH regeneration by expressing G6PDH was simple and effective on improving the P450-monooxygenase-dependent hydroxylation ability in filamentous fungi. [ABSTRACT FROM AUTHOR]

The search of new substrates with pharmaceutical and industrial potential for biocatalysts including cytochrome P450 enzymes is always challenging. Cytochrome P450 BM3 mutant 139-3 , a versatile biocatalyst, exhibited hydroxylation activities towards fatty acids and alkanes. However, there were limited reports about its hydroxylation activity towards steroids. Herein, an Escherichia coli –based whole-cell extract containing the recombinant 139-3 protein was used as the biocatalyst to screen 13 steroids. Results revealed that 139-3 was able to specifically hydroxylate androstenedione ( 1 ) at 1 α -position, generating a hydroxylated steroid 1 α -OH-androstenedione ( 1a ). To investigate whether C-1 α hydroxylation catalyzed by BM3 mutant 139-3 could be industrially used, an optimization of catalyzing conditions was performed. Accordingly, the BM3 mutant 139-3 enzyme was observed to display maximum activity at 37 °C, under pH 7.0 for 4 h, with 37% transformation rate. Moreover, four 139-3 variants were generated by random mutagenesis with the aim of improving its activity and expanding substrate scope. Surprisingly, these mutants, sharing a common mutated site R379S, lost their activities towards androstenedione ( 1 ). These data clearly indicated that arginine residue located at site 379 played key role in the hydroxylation activities of 139-3. Overall, these new findings broadened the substrate scope of 139-3 enzyme, thereby expanding its potential applications as a biocatalyst on steroids hydroxylation in pharmaceutical industry. [ABSTRACT FROM AUTHOR]

In this work, we study the interaction of DNA/RNA nucleobases with hydroxyl- and carboxyl-functionalized armchair carbon nanotubes (CNTs) using density functional theory (DFT) methods. Our results show that the interaction strengths of the nucleobases with hydroxylated (CNT-OH) and carboxylated (CNT-COOH) follow the sequence of C > G > T > A > U and C > G > A > T > U, respectively, which are different from the G > A > T > C > U sequence observed with pristine CNTs. Both CNT-OH and CNT-COOH show different binding energies with the bases, thereby indicting their potential applications in drug delivery and in DNA sequencing. Furthermore, hydrogen-bonding interactions form the main forces stabilizing the bases on CNT-OH and CNT-COOH surfaces. [ABSTRACT FROM AUTHOR]

In this paper, hydroxylated α-Fe 2 O 3 nanofiber was synthesized by the combination of electrospinning method and in-situ polymerization and its potential for the adsorption of cationic dyes was investigated. The vinyl acetate monomer was polymerized onto the surface of α-Fe 2 O 3 nanofiber and subsequently it was hydrolyzed in an alkaline solution to convert the acetate group to hydroxyl group. The optimized condition of polymerization was reported. The characteristics of nanofiber were investigated by Fourier transform infrared spectroscopy (FTIR), Field Emission Scanning Electron Microscope (FE-SEM), energy-dispersive X-ray (EDX) and Brunauer–Emmett–Teller (BET). The FTIR result confirmed successful polymerization of vinyl acetate and generation of hydroxyl group on the surface. Microscopic analyses revealed that the modified nanofiber has a long continuous structure because of attaching the adjacent silanol group of nanofibers. Also, decreasing in the total surface area of nanofiber was detected by BET analysis. Furthermore, the influence of parameters affecting on dye removal such as adsorbent dosage, initial dye concentration and pH was investigated. The mechanism and rate of adsorption were evaluated by different adsorption isotherm and kinetic models. Non-linear regression was used to determine the best fit model for each system. To do this, three error functions were applied to predict the optimum model. It was found that the adsorption of dyes onto hydroxylated nanofiber is based on Langmuir isotherm and pseudo-second-order kinetic model. [ABSTRACT FROM AUTHOR]

Fiber shedding from artificial textiles is among the primary sources of pervasive microplastics in various aquatic habitats. To avoid molten drop burning, triphenyl phosphate (TPhP), a typical flame retardant additive, is commonly incorporated into textile fibers. However, the role of microplastic fibers (MFs) as a vehicle for TPhP remains largely unknown. In this study, we investigated the effects of MFs on the bioaccumulation and metabolism of TPhP in zebrafish. We applied the compound spinning technique for a non-disruptive in situ measurement of fluorescent MFs in fish, and the desorption electrospray ionization mass spectrometry (DESI-MS) to display the tissue distribution of TPhP and its metabolites vividly. Laboratory results showed that ingested MFs did not change the TPhP distribution in fish; however, they statistically increased the metabolite p -OH-TPhP concentration in the fish hindgut, which was probably because the high accumulation of MFs there enhanced the TPhP hydroxylation. Field investigation further supported the lab-based analyses. Higher concentrations of MFs did cause a higher ratio of [ p -OH-TPhP]/[TPhP] in the wild fish gut, particularly in the hindgut. Collectively, our results demonstrated that MFs can change the distribution and bioavailability of TPhP metabolites, which was confirmed by both laboratory and fieldwork. Therefore, the ingestion of MFs can indirectly but substantially influence the bioaccumulation and biotransformation of co-existing pollutants. [Display omitted] • Microplastic fibers (MFs) in the fish gut enhanced the hydroxylation of TPhP. • The MFs ingestion did not change the accumulation of parent TPhP in fish. • Desorption electrospray ionization mass spectrometry (DESI-MS) is a powerful MS imaging method. • Various amounts of MFs were detected in wild fish collected from different rivers. • Field work confirmed MFs' effects on the accumulation and metabolism of TPhP. [ABSTRACT FROM AUTHOR]

The regio- and stereo-selective hydroxylations of two ingenane diterpenoids, 20-deoxyingenol (1) and 13-oxyingenol dodecanoat (2), by the filamentous fungi Mortierella ramanniana and Gibberella fujikuroi were investigated in the present study. Four undescribed metabolites (3–6) of substrate 1 and two undescribed metabolites (7 and 8) of substrate 2 were isolated. All the metabolites were identified as hydroxylated ingenane derivatives by extensive NMR and HR-ESI-MS data analyses. All the biotransformed compounds and the substrates were evaluated for their cytotoxicities against three human cancer cell lines, including human colon cancer Caco-2, breast cancer MCF-7, and adriamycin (ADM)-resistant MCF-7/ADM cell lines. All ingenane alcohols (1, and 3–6) displayed no significant cytotoxic activities. The substrate 13-oxyingenol dodecanoat (2) showed moderate cytotoxicity with IC 50 values being 35.59 ± 5.37 μmol·L −1 (Caco-2), 24.04 ± 4.70 μmol·L −1 (MCF-7), and 22.24 ± 5.19 μmol·L −1 (MCF-7/ADM). However, metabolites 7 and 8 displayed no significant cytotoxicity. These results indicated that the hydroxylation at the C-13 aliphatic acid ester of substrate 2 can significantly reduce the cytotoxic activity. [ABSTRACT FROM AUTHOR]

Background Propofol biotransformation occurs in the liver via hydroxylation by CYP450 enzymatic complex and by glucuronidation, however extra-hepatic metabolism has also been described. Objectives To better understand the metabolic pathways involved in propofol biotransformation, the expression of CYP1A1, CYP1A2, the enzymatic and non-enzymatic antioxidant activity and the amount of propofol and its non-conjugated metabolites were investigated. Methods Twenty-one NewZealand rabbits were allocated into three groups continuously treated for 20 h. Each group received: NaCl 0.9%, vehicle (SMOFlipid) and propofol 2% (Lipuro). At the end, liver and kidney samples were collected for histopathology and immunohistochemistry and plasma for quantification of propofol and its metabolites. Results CYP1A1 and CYP1A2 were observed in zone 1 and zone 3 regions of the liver acinus. The propofol and saline groups showed a higher expression of CYP1A1 when compared to vehicle group. Propofol significantly increased CYP1A2 expression, compared to saline. CYP1A1 and CYP1A2 immunoexpression were observed in the kidney but no differences were registered between groups. Conclusions This suggests that propofol may act as selective inhibitor of CYP1A1 and an inducer of CYP1A2 expression in different regions of the liver. Propofol seems to have an antioxidative protective effect on liver parenchyma, comparatively to the emulsion alone. In the rabbit, extra-hepatic propofol biotransformation may also occur in the kidney. [ABSTRACT FROM AUTHOR]

• A new benzene hydroxylation process was stablished by density functional theory. • The NIH shift in hydroxylation process was explicitly demonstrated. • Two intermediate products in the hydroxylation process were meticulously investigated. • One vital intermediate product in the benzene hydroxylation was confirmed. Phenol is one of the most important chemicals in industry, generally produced from benzene in cumene processes. Alternatively, the direct hydroxylation of benzene catalysed by Fenton reagent has been a potentially sustainable process for the production of phenol. Computational calculation method combined with experiments were both employed to investigate the Fenton reagent catalysed hydroxylation of benzene. Computational calculation turned out that the H migration National Institutes of Health (NIH) shift in the benzene hydroxylation reaction including intramolecular immigration and an intermolecular process. The activation energy (ΔG) for the H migration between IM2 molecules was 17.5 kcal mol−1, while the ΔG for the intramolecular H transfer was 49.4 kcal mol−1. The crucial intermediates in the direct hydroxylation reaction were characterised by a variety of analysis methods. There were three types of C-C bonds in IM1 with Mayer bond order (MBO) equivalent to 1.272, 1.581, and 1.041 respectively, and the C-C bonds in IM2 were not equal based on the localised orbitals and orbital composition analysis and a series of electronic structure information. Moreover, the global electron delocalisation analysis visually demonstrated an uneven distribution of π electron, revealing the aromaticity of these two intermediates. These two intermediates exhibited both aromaticity and antiaromaticity features under external magnetic conditions. Notably, the nuclear magnetic resonance results showed the existence of one of the prominent intermediates. [Display omitted] [ABSTRACT FROM AUTHOR]

Self-assembled monolayers (SAMs) are extensively used in microelectronic copper metallization primarily as seed-trapping layers, diffusion barriers, or pore-sealants for porous dielectric materials. However, direct electroless copper plating of nitride barrier layers assisted by a seed-trapping SAM is rarely examined. Therefore, this work uses TaN, a standard barrier material for Cu metallization, as a model substrate to develop a new seeding (catalyst formation) process for electroless copper plating, involving substrate pretreatments from piranha etching (hydroxylation), octadecyltrichlorosilane SAM (OTS-SAM) deposition and subsequent functionalization. Catalytic particles upon adsorption onto piranha-treated (reference) TaN layers via Ta-OH linkages tend to agglomerate to give a limited density of 8 × 1013 m-2. In contrast, those adsorbed on piranha-treated TaN layers with a plasmafunctionalized OTS-SAM over-coating are free from agglomeration and remain an average size of only 3 nm, along with an elevated density of 1 × 1015 m-2. X-ray photoelectron spectroscopy, together with transmission electron microscopy, clearly identifies the thin-film materials deposited and functional groups induced by each of the pretreatments, allowing the mechanism of seeding enhancement to be clarified. Finally, the enhancement of seeding to benefit electroless copper plating will be demonstrated. [ABSTRACT FROM AUTHOR]

Many anticancer drugs have an impaired bioavailability and poor brain penetration because they are substrates to drug efflux pumps such as P-glycoprotein and Breast Cancer Resistance Protein. Elacridar is a strong inhibitor of these two drug efflux pumps and therefore has great potential to improve oral absorption and brain penetration of many anticancer drugs. Currently, a clinical formulation of elacridar is unavailable and therefore the pharmaceutical development of a drug product is highly warranted. This also necessitates the availability of an analytical method for its quality control. A reverse-phase high-performance liquid chromatographic method with ultraviolet detection was developed for the pharmaceutical quality control of products containing elacridar as the active pharmaceutical ingredient. The analytical method was validated for linearity, accuracy, precision, selectivity, carry-over, stability of stock and reference solutions, stability of the final extract, stability-indicating capability and impurity testing. We found that elacridar is unstable in aqueous solutions that are exposed to light because a hydroxylation product of elacridar is formed. Therefore, sample solutions with elacridar must be protected from light. [ABSTRACT FROM AUTHOR]

This paper presents the first results related to PBDE concentrations in sediments of the Nador Lagoon (N-E Morocco), an area endangered by different pollutant sources. Analyses were performed by HRGC-LRMS and confirmed by HRGC-HRMS on selected samples. Total surficial concentrations were 0.059–8.2 ng g − 1 . The maxima were found close to Nador City. Along the sedimentary records, the highest total concentrations (11 and 2.2 ng g − 1 ) were found at depths corresponding to times (1930s–1950s) when these chemicals were not yet produced. Dehydroxylation or demethoxylation of naturally occurring structural analogues of PBDEs under reducing conditions was suggested. BDE-47 dominated the congener compositions, while BDE-209, when present, could be detected only by HRGC-HRMS, proving that analytical degradation modified the original assemblage. Microbial anaerobic degradation could have changed congener compositions in sediments deposited from the 1970s to the 2000s. Current values are not harmful, but increasing trends call for constant monitoring. [ABSTRACT FROM AUTHOR]

Polybrominated diphenyl ethers (PBDEs) are persistent and toxic organic pollutants, causing hazardous to ecosystems and human health but are difficult to remove from contaminated environments. The mechanism and kinetics of a Chlorella isolate to remove BDE-47 were investigated. This species isolated from the influent of wastewater treatment plants in Hong Kong was PBDE tolerant. More than 80% of BDE-47 was removed in short- and long-term experiments lasting 1 h and 7 days, respectively. The dominant removal process was adsorption on cell surfaces, with 73% of the spiked BDE-47 removed within five minutes of exposure. As the exposure prolonged, the adsorption became saturated. BDE-47 on cell surfaces was then gradually taken up into cells. At the end of the 7-day exposure, 17% of the spiked BDE-47 was within cells, while 27% was metabolized. Four metabolites, including BDE-28, 6-OH- and 5-OH-BDE-47, and 6-MeO-BDE-47, were produced from the debromination, hydroxylation and methoxylation of BDE-47. The removal kinetics of BDE-47 by freshwater microalgae could be explained by the multi-compartmental adsorption-uptake-metabolism model developed in this study. [ABSTRACT FROM AUTHOR]

Due to their bioaccumulative properties, hydroxylated and methoxylated polybrominated diphenyl ethers (HO-/MeO-PBDEs) may pose ecological risks to wild life, including birds. However, their toxicity potencies in avian species are largely unknown. In the present study, an avian AHR1 luciferase reporter gene (LRG) assay with luciferase probes from chicken, pheasant and quail was used to test activations of avian aryl hydrocarbon receptor (AHR)-mediated pathways by 19 HO- or MeO-PBDEs in different avian species. Species-specific relative potencies (RePs) of HO-/MeO-PBDEs to tetrachlorodibenzo-p-dioxin (TCDD) and relative sensitivities of various species to each chemical were estimated. The results indicated that the ReP of the most potent HO-/MeO-PBDEs, 5-Cl-6-HO-BDE-47, was 7.8×10 −4 for chicken, 1.1×10 −2 for pheasant, and 1.7×10 −1 for quail comparing to TCDD. In addition, it was found that avian species with the greatest sensitivity to TCDD did not always have the greatest sensitivity to HO-/MeO-PBDEs and vice versa. This study contributed to filling in the knowledge gap regarding the dioxin-like activity of HO-/MeO-PBDEs in birds, and provided beneficial information for the prioritization of HO-/MeO-PBDEs for further research. Capsule abstract HO-/MeO-PBDEs activate avian AHR-mediated pathways in a congener- and species- specific manner. 5-Cl-6-HO-BDE-47 was the most potent among the nineteen HO-/MeO-PBDEs tested. [ABSTRACT FROM AUTHOR]

The biotransformation of soy isoflavones into ortho -hydroxyisoflavones by CYP105D7 from Streptomyces avermitilis MA4680 is investigated through chimeric expression in Pichia pastoris . Using N-terminal fusion with the transmembrane domain of CYP57B3 from Aspergillus oryzae and C-terminal fusion with a P450 reductase from Saccharomyces cerevisiae , CYP105D7 was expressed in the form of reductase fusion and membrane anchoring in P. pastoris . Recombinant P. pastoris expressing the chimera catalyzed the biotransformation of both daidzein and genistein. This is the first study to show the catalyzing activity of CYP105D7 towards genistein. The major product from daidzein was identified as 6-hydroxydaidzein by comparing the results of the ultra-performance liquid chromatography analysis with the authentic standard. The major product from genistein was purified using preparative high-performance liquid chromatography and identified as 3ʹ-hydroxygenistein based on nuclear magnetic resonance and mass data. The recombinant P. pastoris produced 6-hydroxydaidzein and 3ʹ-hydroxygenistein in a 5-l fermenter, with maximal yields of 7.5 and 15.0 mg/l, respectively. The production of 3ʹ-hydroxygenistein was higher than any previously reported in the literature. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants generated primarily during the incomplete combustion of organic materials (e.g. coal, oil, petrol, and wood). Emissions from anthropogenic activities predominate; nevertheless, some PAHs in the environment originate from natural sources such as open burning, natural losses or seepage of petroleum or coal deposits, and volcanic activities. Major anthropogenic sources of PAHs include residential heating, coal gasification and liquefying plants, carbon black, coal-tar pitch and asphalt production, coke and aluminum production, catalytic cracking towers and related activities in petroleum refineries as well as and motor vehicle exhaust. PAHs are found in the ambient air in gas-phase and as sorbet to aerosols. Atmospheric partitioning of PAH compounds between the particulate and the gaseous phases strongly influences their fate and transport in the atmosphere and the way they enter into the human body. The removal of PAHs from the atmosphere by dry and wet deposition processes are strongly influenced by their gas/particle partitioning. Atmospheric deposition is a major source for PAHs in soil. Many PAHs have toxic, mutagenic and/or carcinogenic properties. PAHs are highly lipid soluble and thus readily absorbed from the gastrointestinal tract of mammals. They are rapidly distributed in a wide variety of tissues with a marked tendency for localization in body fat. Metabolism of PAHs occurs via the cytochrome P450-mediated mixed function oxidase system with oxidation or hydroxylation as the first step. Several different remediation technologies have been tested in efforts to remove these environmental contaminants. Among them, bioremediation is showing particular promise as a safe and cost-effective option. In spite of their xenobiotic properties, a variety of genera of gram-positive and -negative bacteria, fungi and algae have been isolated and characterized for their ability to utilize PAHs. The aim of this review is to discuss PAHs impact on the environmental and the magnitude of the human health risks posed by such substances. They also contain important information on concentrations, burdens and fate of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere. The main anthropogenic sources of PAHs and their effect on the concentrations of these compounds in air are discussed. The fate of PAHs in the air, their persistence and the main mechanisms of their losses are presented. Health hazards associated with PAH air pollution are stressed. [ABSTRACT FROM AUTHOR]

HpaBC monooxygenase was previously reported to hydroxylate resveratrol to piceatannol. In this article, we report a novel catalytic activity of HpaBC for the synthesis of a pentahydroxylated stilbene. WhenEscherichia colicells expressing HpaBC were incubated with resveratrol, the resulting piceatannol was further converted to a new product. This product was identified by mass spectrometry and NMR spectroscopy as a 5-hydroxylated piceatannol, 3,4,5,3′,5′-pentahydroxy-trans-stilbene (PHS), which is a reportedly valuable biologically active stilbene derivative. We attempted to produce PHS from piceatannol on a flask scale. After examining the effects of detergents and buffers on PHS production,E. colicells expressing HpaBC efficiently hydroxylated piceatannol to PHS in a reaction mixture containing 1.5% (v/v) Tween 80 and 100 mM 3-morpholinopropanesulfonic acid-NaOH buffer at pH 7.5. Under the optimized conditions, the whole cells regioselectively hydroxylated piceatannol, and the production of PHS reached 6.9 mM (1.8 g L−1) in 48 h. HpaBC regioselectively hydroxylates piceatannol to 3,4,5,3′,5′-pentahydroxy-trans-stilbene, a valuable biologically active stilbene derivative. [ABSTRACT FROM PUBLISHER]

The fungal species Fusarium can cause devastating disease in agricultural crops. Phenamacril is an extremely specific cyanoacrylate fungicide and a strobilurine analog that has excellent efficacy against Fusarium. To date, information on the mechanisms involved in the uptake, accumulation, and metabolism of phenamacril in plants is scarce. In this study, lettuce and radish were chosen as model plants for a comparative analysis of the absorption, accumulation, and metabolic characteristics of phenamacril from a polluted environment. We determined the total amount of phenamacril in the plant-water system by measuring the concentrations in the solution and plant tissues at frequent intervals over the exposure period. Phenamacril was readily taken up by the plant roots with average root concentration factor ranges of 60.8–172.7 and 16.4–26.9 mL/g for lettuce and radish, respectively. However, it showed limited root-to-shoot translocation. The lettuce roots had a 2.8–12.4-fold higher phenamacril content than the shoots; whereas the radish plants demonstrated the opposite, with the shoots having 1.5 to 10.0 times more phenamacril than the roots. By the end of the exposure period, the mass losses from the plant-water systems reached 72.0% and 66.3% for phenamacril in lettuce and radish, respectively, suggesting evidence of phenamacril biotransformation. Further analysis confirmed that phenamacril was metabolized via hydroxylation, hydrolysis of esters, demethylation, and desaturation reactions, and formed multiple transformation products. This study furthers our understanding of the fate of phenamacril when it passes from the environment to plants and provides an important reference for its scientific use and risk assessment. [Display omitted] • Lettuce and radish were capable of absorbing phenamacril by roots. • Phenamacril showed limited root-to-shoot translocation in lettuce plants. • Phenamacril had a 1.5–10.0-fold higher content in radish shoots than the roots. • Phenamacril was metabolized to multiple transformation products within plants. [ABSTRACT FROM AUTHOR]

Low pg levels of PBDD/Fs in 0.8–38.9 pg g −1 (fat) range (mean 14.2 pg g −1 ) observed in the tested cod liver samples were significantly lower than levels of their chlorinated analogues (25.1–95.9 range, 37.7 mean pg g −1 fat). Brominated furans dominated the congener profile. Elevated levels of OH-/MeO-BDE were however observed with mean concentrations at 2769 ± 1319 and 5441 ± 2918 pg g −1 (fat) respectively. The observed congener profiles with the predominance of 6-OH-BDE 47 and the relatively high proportion between the native and hydroxylated compounds indicate on natural origin of those compounds or at least presence of various exposure sources. A large fraction of studied samples did not comply with the currently standing EU regulations concerning PCBs and chlorinated dioxins (11%), especially as regards non-dioxin like PCBs (88%). [ABSTRACT FROM AUTHOR]

Nanocomposites consisting of multi wall carbon wall carbon nano tubes MWCNT/polyurethane (PU) had been successfully prepared based on hydroxy terminated polybutadiene HTPB and the prepared MWCNT. The effect of concentration of prepared MWCNT and surface modified CNT on the morphology, mechanical reinforcement, and thermal properties of PU-based composites had been evaluated by FESEM, tensile testing, thermo gravimetric analysis TGA and differential scanning calorimeter DSC. Polyurethane (PU) networks based on hydroxyl terminated polybutadiene (HTPB) and isophorone diisocyanate (IPDI) compound were prepared by a batch process. Two methods had been used to fabricate PU matrix/carbon nanotube nanocomposites: direct incorporation of unfunctional CNT (UCNT) into polymer matrices (noncovalent attachment) and in situ polymerization at their surface (covalent attachment). TGA showed a much better improvement of thermal stability of the composites than pure PU. Glass temperature (Tg) increased due to high interaction of CNT with PU. Also Young’s modulus increased. FESEM gave that the covalent attachment was better than noncovalent attachment for preparing PU/CNT composites. [ABSTRACT FROM AUTHOR]

Sphingobium sp. PNB, like other sphingomonads, has multiple ring-hydroxylating oxygenase (RHO) genes. Three different fosmid clones have been sequenced to identify the putative genes responsible for the degradation of various aromatics in this bacterial strain. Comparison of the map of the catabolic genes with that of different sphingomonads revealed a similar arrangement of gene clusters that harbors seven sets of RHO terminal components and a sole set of electron transport (ET) proteins. The presence of distinctly conserved amino acid residues in ferredoxin and in silico molecular docking analyses of ferredoxin with the well characterized terminal oxygenase components indicated the structural uniqueness of the ET component in sphingomonads. The predicted substrate specificities, derived from the phylogenetic relationship of each of the RHOs, were examined based on transformation of putative substrates and their structural homologs by the recombinant strains expressing each of the oxygenases and the sole set of available ET proteins. The RHO AhdA1bA2b was functionally characterized for the first time and was found to be capable of transforming ethylbenzene, propylbenzene, cumene, p -cymene and biphenyl, in addition to a number of polycyclic aromatic hydrocarbons. Overexpression of aromatic catabolic genes in strain PNB, revealed by real-time PCR analyses, is a way forward to understand the complex regulation of degradative genes in sphingomonads. [ABSTRACT FROM AUTHOR]

Zirconium dispersed in aluminum-pillared montmorillonite was prepared as a catalyst for phenol hydroxylation. The effects of varying the Zr content on the catalyst’s physicochemical character and activity were studied with XRD, BET surface area analysis, surface acidity measurements and scanning electron microscopy before investigating the performance for phenol conversion. The zirconia dispersion significantly affects the specific surface area, the total surface acidity and surface acidity distribution related to the formation of porous zirconia particles on the surface. The prepared samples exhibited excellent catalytic activity during phenol hydroxylation. [ABSTRACT FROM AUTHOR]