Additional Hydroxyl Research Articles

Antiproliferative activity of side-chain truncated vitamin D analogs (PRI-1203 and PRI-1204) against human malignant melanoma cell lines

Vitamin D compounds are versatile molecules widely considered as promising agents in cancer prevention and treatment, including melanoma. Previously we investigated series of double point modified vitamin D2 analogs as well as non-calcemic 20S-hydroxyvitamin D3 and 21-hydroxypregnacalciferol as to their anti-melanoma activity. Surprisingly, short side-chain vitamin D analogs were found to be biologically active compounds. Thus, here we tested novel derivatives of pregnacalciferol with an additional hydroxyl at the end of the truncated side chain, PRI-1203 and PRI-1204, as to their potency against human melanoma A375 and RPMI7951 cell lines. Tested compounds are geometric isomers, with 19-methylene positioned in PRI-1203 like in a calcitriol molecule, but reversed in the PRI-1204 analog to the (5E,7E) geometry (5,6-trans). We noticed a decrease in cells viability exerted by PRI-1203. The antiproliferative effect of PRI-1204 was very low, emphasizing the importance of the natural 19-methylene geometry in the PRI-1203. PRI-1203 was also effective in inhibition of A375 melanoma cells migration. PRI-1203, but not PRI-1204, increased the percentage of A375 and RPMI7951 melanoma cells in the G0/G1 phase of cell cycle, possibly in a p21 and p27 independent manner. Both, analogs have very low effect on the level of CYP24A1 mRNA, in comparison to active form of vitamin D – 1.25(OH)2D3. In addition, both tested compounds failed to elicit VDR translocation to the nucleus. Thus, it could be postulated that side chain shortening strongly affects binding of analogs to VDR and activation of genomic responses, however do not impair their antiproliferative activities.

Flotation separation of polystyrene and polyvinyl chloride based on heterogeneous catalytic Fenton and green synthesis of nanoscale zero valent iron (GnZVI)

It arises sharp concern that waste plastics entrain hazardous substances and accumulate in living organisms, endangering the environment and human health. To achieve clean plastic management and obtain qualified recycled products, separation deserves intensive research in preference to other technologies in plastic recycling. In this research, we proposed a novel flotation separation of binary plastic mixtures, polystyrene (PS) and polyvinyl chloride (PVC), based on heterogeneous advanced oxidation technology (AOT) and the green synthesis of nanoscale zero valent iron (GnZVI). The optimal conditions for separating PVC and PS (PS as a sinking plastic) are 1.5 mM H2O2, H2O2/Fe0 molar ratio 40:1, treatment time 300 s, room temperature, and pH 6. We revealed the oxidation mechanisms of PS after AOT treatment through extensive characterizations, such as scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and nuclear magnetic resonance spectroscopy (NMR). Surface-incorporated oxygenated functions, such as hydroxyl (C–OH) and carboxyl groups (OC–O), are introduced on PS through the scission of backbone chain and the addition of hydroxyl and hydroperoxy radicals, increasing the hydrophilicity of PS. Besides, we established a novel pretreatment kinetics based on flotation percentage and treatment time to research the flotation behavior of PS, providing a new research perspective for plastic flotation. With the characteristics of low reagents dosage, short treatment time, mild temperature, and slight pollution, the proposed flotation process is an applicable separation technology for plastic recycling.

Baikalomycins A-C, New Aquayamycin-Type Angucyclines Isolated from Lake Baikal Derived Streptomyces sp. IB201691-2A.

Natural products produced by bacteria found in unusual and poorly studied ecosystems, such as Lake Baikal, represent a promising source of new valuable drug leads. Here we report the isolation of a new Streptomyces sp. strain IB201691-2A from the Lake Baikal endemic mollusk Benedictia baicalensis. In the course of an activity guided screening three new angucyclines, named baikalomycins A–C, were isolated and characterized, highlighting the potential of poorly investigated ecological niches. Besides that, the strain was found to accumulate large quantities of rabelomycin and 5-hydroxy-rabelomycin, known shunt products in angucyclines biosynthesis. Baikalomycins A–C demonstrated varying degrees of anticancer activity. Rabelomycin and 5-hydroxy-rabelomycin further demonstrated antiproliferative activities. The structure elucidation showed that baikalomycin A is a modified aquayamycin with β-d-amicetose and two additional hydroxyl groups at unusual positions (6a and 12a) of aglycone. Baikalomycins B and C have alternating second sugars attached, α-l-amicetose and α-l-aculose, respectively. The gene cluster for baikalomycins biosynthesis was identified by genome mining, cloned using a transformation-associated recombination technique and successfully expressed in S. albus J1074. It contains a typical set of genes responsible for an angucycline core assembly, all necessary genes for the deoxy sugars biosynthesis, and three genes coding for the glycosyltransferase enzymes. Heterologous expression and deletion experiments allowed to assign the function of glycosyltransferases involved in the decoration of baikalomycins aglycone.

Residues of anilinopyrimidine fungicides and suspected metabolites in wine samples

The coexistence of the anilinopyrimidine fungicides pyrimethanil (PYR) and cyprodinil (CYP), and suspected metabolites in wine samples was investigated by liquid chromatography (LC) with tandem mass spectrometry (MS/MS), based on triple quadrupole (QqQ) and quadrupole time-of-flight (QTOF) MS instruments. For the first time, quantitative data obtained after solid-phase extraction (SPE) of wine samples have demonstrated the systematic presence of 4-hydroxyanilino derivatives of PYR and CYP in wines containing residues of parent fungicides, at concentrations from 0.2 to 58 ng mL−1. Higher concentration ratios (hydroxylated derivative/active fungicide) were measured in red than in white wines, particularly in case of PYR. On average, the concentrations of PYR-4OH were twice those measured for PYR in red wines. A targeted search of hydroxyl derivatives in wine extracts by LC-QTOF-MS showed the existence of additional hydroxylation positions in the pyrimidine ring and/or in the alkyl substituents bond to this cycle in the structure of both anti-botrytis fungicides. Moreover, free and glycosylated forms of the hydroxylated metabolites for both fungicides coexist in wine samples. In case of CYP, it is proved that hydroxylated and glycosylated metabolites are already present in grapes before vinification.

Highly efficient U(VI) removal by chemically modified hydrochar and pyrochar derived from animal manure

In recent decades, great attention has been given to developing methods for targeted modification of biochar with innovative properties to improve its remediation efficacy. This study investigated the sorption performance of animal manure-derived hydrochar and pyrochar modified with oxidizing agents (H2O2) and alkaline (NaOH) solutions for U(VI). Characterization results showed that H2O2 and NaOH modification provided more carboxyl and hydroxyl groups, respectively, on sample surface. NaOH treatment remarkably increased specific surface area by three to six times. H2O2 and NaOH impressively improved the maximum adsorption capacity (Qmax) of biochar for U(VI), and NaOH modification induced a higher enhancement. Among different biochar types, pyrochar produced at a medium-high temperature not only showed the highest Qmax but also the strongest improvement. After NaOH modification, its Qmax (221.4 mg/g) was roughly 5-fold higher than that of original sample, showing that with NaOH modification, the pyrochar produced from animal manure under a medium-high thermal temperature might be a promising candidate as a sorbent for U(VI) remediation. In addition, the obvious shift in the XPS spectrum and pore structure of sample after U(VI) loading, along with the semi-quantification of the contribution of surface complexation mechanism, demonstrated that additional carboxyl and hydroxyl groups and higher SSA jointly explained more efficient U(VI) adsorption. This study not only proposes a promising adsorbent for U(VI) in nuclear wastewater, but also provides a way for the efficient recycling of animal manure wastes.

Norepinephrine as new functional monomer for molecular imprinting: An applicative study for the optical sensing of cardiac biomarkers

The continuous research for alternatives to antibody-based detection drove, in the last decades, the development of numerous strategies. Molecularly imprinted polymers (MIPs) emerged thanks to the low-cost and long-term stability features, where the choice of natural functional monomer(s) represents the key step for efficient imprinting of biomolecules. The chemical structure of dopamine (DA), one of the most used natural functional monomers, provided the inspiration for this work. We wondered why norepinephrine (NE) that differs from dopamine only for an additional hydroxyl group was not investigated at all in biosensing applications. In fact, there is only one paper exploiting polynorepinephrine (PNE) in molecular recognition applications, taking advantage of molecular imprinting, but not for biosensing purposes. In contrast, hundreds of papers describe polydopamine-based sensors. Therefore, we firstly investigated how the additional hydroxyl group of NE could affect the properties of the resulting polymer, and how these properties could be exploited for biosensing applications. The results highlighted the reduced non-specific adsorption of proteins onto PNE with respect to dopamine polymer. Furthermore, as a case study, we successfully developed a PNE-based imprinted biosensor for the early detection of Troponin I, a crucial biomarker for heart failure, by coupling the MIP biosensor with surface plasmon resonance (SPR) detection. The results indicate the feasible use of imprinted PNE as synthetic receptor for biomolecules, opening new perspectives for this biopolymer, so far not considered, and encouraging further investigations on its potential application in biosensing.

Human metabolism and urinary excretion kinetics of the UV filter Uvinul A plus® after a single oral or dermal dosage.

Hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoate, better known under its trading name Uvinul A plus® is a UV filter mainly used in sunscreens, but also present in other cosmetic products with a maximum concentration of 10% (w/w) according to the EU directive. In this study we investigated the human metabolism after a single oral and a single dermal dose of Uvinul A plus®, respectively. Samples collected within 72h of administration were analyzed with a newly developed UHPLC-MS/MS method. Results of the study revealed three major urinary metabolites, namely 2-(4-amino-2-hydroxybenzoyl)benzoic acid (AHB), 2-(4-(ethylamino)-2-hydroxybenzoyl)benzoic acid (EHB) and 2-(4-(diethylamino)-2-hydroxybenzoyl)benzoic acid (DHB), representing 52% of the administered oral dose. The three major metabolites are further converted into four minor metabolites with an additional hydroxyl group in the aniline moiety. Toxicokinetic parameters (amount excreted, tmax, elimination constant and half-life t1/2) and conversion factors were determined for the three major metabolites. The conversion factors were used to estimate the mean daily exposure to Uvinul A plus® in spot urine samples from 58 volunteers not intentionally exposed to Uvinul A plus® derived from a pilot study. The three major metabolites were quantifiable in 26% of the samples. In 35% of the samples, at least one major metabolite could be quantified. The daily systemic exposure to Uvinul A plus® was estimated to approximately 8.1-9.3μg/d by applying the combined conversion factor for all three major metabolites. In conclusion, a very low systemic exposure to DHHB was observed with regard to the no observed adverse effect level (NOAEL) as an established threshold for chronic uptake.

Computational Investigation into the Oxidation of Guanine to Form Imidazolone (Iz) and Related Degradation Products.

Imidazolone (Iz) is one of the many products resulting from oxidative damage to DNA. Three pathways for the formation of Iz and related degradation products have been studied by density functional theory using the ωB97XD functional with the 6-31+G(d,p) basis set and SMD implicit water solvation plus a small number of explicit water molecules positioned to help stabilize charged species and facilitate reaction steps. The first pathway starts with guanine radical and the addition of superoxide at C5. Endoperoxide formation was calculated to have slightly lower barriers than diol formation. The next steps are pyrimidine ring opening and decarboxylation. Ring migration then proceeds via an acyclic intermediate rather than a bicyclic intermediate and is followed by formamide loss to yield Iz. The second pathway starts with 8oxoG and proceeds via C5 superoxide addition and diol formation to a relatively stable intermediate, oxidized guanidinohydantoin (Ghox). The barriers for hydroxide ion addition to Ghox are much lower than for water addition and should yield more Iz and parabanic acid at higher pH. The third pathway starts with 8-hydroxy guanine radical formed by hydroxyl radical addition to C8 of guanine or water addition to C8 of guanine radical. Superoxide addition at C5 is followed by diol formation, ring opening and decarboxylation similar to pathways 1 and 2, subsequently leading to Iz formation. The calculated pathways are in good agreement with experimental observations.

Accelerated oxidation of iopamidol by ozone/peroxymonosulfate (O3/PMS) process: Kinetics, mechanism, and simultaneous reduction of iodinated disinfection by-product formation potential

Iopamidol (IPM) is a potential source of toxic iodinated byproducts (I-DBPs) during water disinfection. In this work, we determined the kinetics and mechanism of degradation of IPM by a combination of ozone (O3) and peroxymonosulfate (PMS, HSO5−), and assessed its effect on the formation of iodinated trihalomethanes (I-THMs) during chlorination treatment. The degradation of IPM was accelerated by the O3/PMS process, and the hydroxyl (HO•) and sulfate (SO4•−) radicals were major contributors to the degradation. Using identification of the second order reaction rate between SO4•− and IPM (kSO4•−, IPM = 1.6 × 109 M−1 s−1), the contribution of HO• to the degradation was determined to be 78.3%. The degradation of IPM was facilitated by pH > 7, and natural organic matter (NOM) and alkalinity had limited effects on the degradation of IPM in the O3/PMS process. The transformation products of IPM were determined and inferred by QTOF-MS/MS, and the degradation pathways were elucidated. These include amide hydrolysis, amino oxidation, hydrogen abstraction, deiodination, and hydroxyl radical addition. Interestingly, oxidation of IPM by O3/PMS also decreased its potential for formation of I-THMs. After oxidation of IPM, the I-THMs formed from 5-μΜ IPM decreased from 14.7 μg L−1 to 3.3 μg L−1 during chlorination. Although the presence of NOM provided the precursor of I-THMs during chlorination of IPM, the O3/PMS process decreased I-THMs formation by 71%, because oxidation of released iodide into iodate effectively inhibited I-THMs formation. This study provides a new approach for the accelerated degradation of IPM and control of the formation of I-DBPs.

DFT Study of the Hydroxyl Radical Addition to 2'-Deoxyguanosine and the Guanine Base in Four Double-Stranded B-Form Dimers.

Density functional theory (DFT) calculations of reactions between 2'-deoxyguanosine (dR-Gua) and hydroxyl radical (HO•) with water molecules (H2O)n, n = 0, 1, and 2, were carried out. The HO• addition to three carbon sites, C(4), C(5), and C(8), and the subsequent ring cleavage of the three HO adducts were investigated. The addition to C(5) is of the smallest activation energy according to the largest lobe of the dR-Gua highest occupied molecular orbital (HOMO) at C(5). However, its adduct has small stability, and the C(8) adduct has the largest one. The C(8) adduct and the ring-opened amide have similar stability, which would lead to the apparent small yield of the former. Calculations were also performed on HO• additions to the C(4) and C(8) sites of the guanine moiety of four dimer sequence models of B-form DNA with nucleotide moieties (a) 5'-GA-3', (b) 5'-GG-3', (c) 5'-GT-3', and (d) 5'-GC-3'. For instance, the (a) 5'-GA-3' model has a molecular formula C39H50N15Na2O21P2. The HO• attack to C(4) is ruled out owing to the reinforced deformation of the parallel stacking of base pairs. The clear selectivity that the (b) 5'-GG-3' sequence is most reactive was found with the inclusion of the water dimer.

Mechanism and kinetics of diuron oxidation by hydroxyl radical addition reaction

Diuron is a phenyl urea herbicide used to control weeds in agricultural lands. The degradation of diuron in the atmosphere takes place dominantly via reaction with OH radicals. In this work, the OH addition reaction of diuron has been studied by using density functional theory methods M06-2X, ωB97X-D and MPWB1K with 6-31G(d,p) basis set. The calculated thermochemical parameters show that OH addition reaction occurs favourably at C2 position of diuron. The rate constant is calculated for the favourable initial reaction pathway by using canonical variational transition state theory with small curvature tunnelling (SCT) correction over the temperature range of 200-1000K. The reaction of initially formed diuron-OH adduct intermediate with O2 leads to the formation of peroxy radical intermediate. The reaction of peroxy radical intermediate with HO2 and NOx (x = 1, 2) radicals is studied in detail. The results obtained from time-dependent density functional theory (TDDFT) calculations show that the intermediates and products formed from oxidation of diuron can be easily photolyzed in the sunlight. This study provides thermodynamical and kinetic data for the atmospheric oxidation of diuron by OH radical addition reaction and demonstrates the atmospheric chemistry of diuron and its derivatives.

Understanding the effect of depth refining on upgrading of dissolving pulp during cellulase treatment

Reactivity is a critical parameter of dissolving pulp, which determines toxic chemical (i.e. carbon disulfide) consumption in rayon production. In this study, the depth refining was carried out to upgrade pre-hydrolysis kraft (PHK) pulp prior to cellulase treatment. The hypothesis is that the mechanical refining can not only increase reactivity by liberating additional hydroxyl groups, but also enhance cellulase efficiency by improving enzymatic accessibility. Results showed that the Fock reactivity of refined pulp (beating degree of 50°SR) was increased to 78.0 % from 54.8 % of the original (19°SR), which was mainly caused by inter- molecular hydrogen bond changes, supported by FTIR analysis. In addition, the cellulase adsorption ratio of refined pulp (30–50 °SR) was increased in a range of 39.7–71.2 %, which verified the improvement of enzymatic accessibility. As a result, the integrated process consisting of mechanical refining and cellulase treatment (at cellulase dosage of 0.5 mg/g pulp) yielded a much better result than the control (at cellulase dosage of 1 mg/g pulp) in terms of reactivity increase and viscosity decrease. Other pulp properties, such as fiber length and fines content, water retention value (WRV), specific surface area (SSA), crystallinity, and morphology, were all supported the positive effect of depth refining on activation of dissolving pulp during cellulase treatment.

Chemical pathways for the formation of benzofuran and dibenzofuran in combustion

Understanding and predicting the formation of polycyclic aromatic compounds (PACs) and their role in the formation of high molecular mass compounds is still an unresolved topic in combustion. PACs characteristics, such as chemical composition, size, and presence of side chains, play an important role not only in terms of environmental and health impact, but also when developing models that describe the formation of nanoparticles and soot. In this paper, we report on a detailed analysis of the reaction pathways describing the chemistry of furan-embedded PACs using ab initio G3-type electronic structure calculations leading to the formation of benzofuran and dibenzofuran from benzene and biphenyl. The 82 elementary reactions, identified in this work, contain unexplored pathways involving triplet oxygen atom and hydroxyl radical addition reactions. A protocol for improving the calculations of reaction energetics from ab initio compound methods is proposed, which consists of the thorough usage of IRCmax scheme to identify the transition state structure and an energy correction ( ~ 0.2 kcal/mol) to the empirical term in G3 formula for systems with open-shell singlet type of electronic configurations. Based on these ab initio calculations, temperature dependent reaction rate constants are calculated according to statistical theories, together with thermodynamics data. Branching ratio analysis based on steady-state approximation is carried out to illustrate the relative importance of the new pathways in an ethylene premixed flame. Results show that the newly discovered benzofuran formation pathways can play a relative important role when in presence of phenol or phenoxyl radicals at various locations in the flame.

Eriodictyol and naringenin inhibit the formation of AGEs: An in vitro and molecular interaction study.

Maillard reaction occurs between the carbonyl group of reducing sugars and the free amino groups of protein, which eventually results in the formation and accumulation of advanced glycation end products (AGEs) irreversibly. Excessive production of AGEs is associated with many diseases, such as Alzheimer disease, neuropathy, retinopathy, and nephropathy. In this study, the effects of eriodictyol and naringenin on the inhibition of AGEs were studied with bovine serum albumin (BSA)-methylglyoxal (MGO) model by spectroscopic techniques and molecular docking methods. The fluorescence spectroscopy results suggested that eriodictyol and naringenin could inhibit the formation of AGEs. Circular dichroism (CD) studies indicated that eriodictyol and naringenin could stabilize the structure of BSA and inhibit the formation of AGEs. The molecular docking results demonstrated that eriodictyol formed two hydrogen bonds with Lys 350 and Leu 480 and the main forces were hydrogen bonding and hydrophobic interactions. However, naringenin interacted with Arg 484 of BSA, and the main force was hydrophobic interaction. It can be concluded that eriodictyol and naringenin can inhibit the formation of AGEs and eriodictyol has stronger inhibitory activity of AGEs than that of naringenin, which is probably due to the additional hydroxyl group in the position C-3' of B ring of eriodictyol.

Highly efficient visible-light-driven photo-Fenton catalytic performance over FeOOH/Bi2WO6 composite for organic pollutant degradation

Amorphous FeOOH quantum dots (QDs)-decorated Bi2WO6 nanosheet heterostructures (FeOOH/Bi2WO6) were successfully fabricated through a combined hydrothermal and impregnation approach, characterized by many modern techniques, and employed as an efficient visible-light-driven photo-Fenton catalyst for the degradation of organic pollutants including methylene blue, rhodamine B and tetracycline hydrochloride. The results showed that the photo-Fenton catalytic performance of FeOOH/Bi2WO6 composite is much higher than those of single FeOOH QDs, Bi2WO6 and their physical mixture. Especially, 0.9% FeOOH/Bi2WO6 composite indicated a highest photo-Fenton catalytic activity. This can be attributed to that the synergistic effects of FeOOH and Bi2WO6 can promote the rapid transfer of photo-generated electrons from Bi2WO6 to FeOOH QDs and accelerate the reduction of Fe (III) to Fe (II) by photo-generated electrons and the conversion of dissolved oxygen in water into the strong oxidant superoxide negative radicals (·O2−). The presence of hydrogen peroxide (H2O2) enables the oxidation of Fe (II) to Fe (III) and the formation of a great number of additional hydroxyl radicals (·OH). These active radicals ·OH and ·O2− confirmed by electron spinning resonance spectra greatly improved the degradation of organic pollutants. In addition, the dosage effect (catalyst, H2O2) and acidity-basicity effect were investigated and a reasonable mechanism of pollutant degradation was proposed. Finally, the superior stability and reusability of catalyst were confirmed by five-recycled use for a promising candidate for water remediation in industrial application.

Inactivation of antibiotic resistance gene by ternary nanocomposites of carbon nitride, reduced graphene oxide and iron oxide under visible light

Antibiotic resistance gene (ARG) should be eliminated during wastewater treatment to prohibit the rapid growth and colonization of antibiotic resistant bacteria (ARB) in different waterbodies. With an aim to do so, we have synthesized ternary nanocomposites of graphitic carbon nitride, reduced graphene oxide and iron oxide as visible light photocatalysts. The materials structures have been confirmed by XPS, FTIR, PL spectroscopy, and electron microscopy. The photocatalytic measurements confirmed that the composites can be activated by visible light. Two types of commercially available plasmid DNAs containing ARGs, pUC 18 (2686 bp) and pBR 322 (4361 bp) were successfully inactivated and consequently fragmented by the nanocomposite in presence of hydrogen peroxide and under visible light. The performance of nanocomposite was proven to be better than that of pure carbon nitride. Agarose gel electrophoresis confirmed that supercoiled plasmid DNAs were first converted to single stranded relaxed circular forms followed by their complete fragmentation. The photocatalytic inactivation of plasmids may be attributed to the photocatalytic activity of carbon nitride alone, relaxation of photogenerated charge carriers by reduced graphene oxide, quenching of electron-hole pairs and generation of additional hydroxyl radicals by hydrogen peroxide, photo-Fenton activity by iron oxide in presence of hydrogen peroxide and additional photocatalytic activity of iron oxide alone.

A study of synergistic oxidation between ozone and chlorine on benzalkonium chloride degradation: Reactive species and degradation pathway

Ozonation and chlorination are widely used for disinfection or micropollutant elimination in water treatment or reclamation fields. It was found in this study that the presence of free chlorine increased the production of reactive species significantly during ozonation of dodecylbenzyldimethylammonium chloride (DDBAC, quaternary ammonium compound). DDBAC hardly underwent degradation by the chlorination process. However, the removal of DDBAC by ozonation after 10 min increased from 22% to 92%, when the dosage of free chlorine increased from 0 to 112 mg/L. pH affected the synergistic effect of ozone/chlorine oxidation of DDBAC. The promotion effect of free chlorine was greater at acidic conditions than that at basic conditions. The radical quenching experiments suggested that various reactive species formed during ozone/chlorine oxidation of DDBAC. The contributions of ozone, reactive species that could or could not be quenched by tBuOH were 8%, 78% and 13%, respectively. In the mixed system of DDBAC and pCBA, the degradation percentage of DDBAC and pCBA after 15 min increased from 31.0% and 13.1% to 53.8% and 28.3% with the presence of chlorine, respectively. Based on the steady-state concentration assumption, the steady-state concentration of OH during ozone/chlorine oxidation of DDBAC was 2.3 times higher than that during the sole ozonation process, being 7.5 × 10−14 M and 3.3 × 10−14 M, respectively. Ten oxidation products were identified by HPLC-MS/MS during ozone/chlorine oxidation of DDBAC. Three degradation mechanisms were observed: the hydrogen abstraction of the alkyl chain by hydroxyl radical; the cleavage of the benzyl-nitrogen bond of DDBAC; and the addition of hydroxyl radical on the aromatic ring or the alkyl chain.

Structural Insight into the In Vitro Anti-Intravasative Properties of Flavonoids

We investigated the effect of 21 flavonoids in a three-dimensional in vitro system for their ability to inhibit gap formation by MCF-7 breast cancer spheroids in monolayers of lymphendothelial cells. Different representatives of the classes of flavones, flavonols, and flavanones were tested in the circular chemorepellent-induced defects (CCID)-assay. Bay11-7082, a known inhibitor of CCID formation served as the positive control. This study provides the first comparison of the potential of flavonoids to suppress features influencing the intravasation of MCF-7 breast cancer cells aggregates through the lymph endothelial barrier. The most significant effects were seen after incubation with the flavones luteolin, chrysin, and apigenin. Additional hydroxylation or methoxylation in positions 6 or 8, as expected, resulted in decreased activity. The tested flavanones remained without or low efficacy.

The oxidative degradation of diclofenac using the activation of peroxymonosulfate by BiFeO3 microspheres—Kinetics, role of visible light and decay pathways

BiFeO3 (BFO) microspheres were synthesized by a microwave-assisted hydrothermal method for the first time. The as-prepared BFO was comprehensively characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Mössbauer spectroscopy. The synthesized BFO was used to activate peroxymonosulfate (PMS) for the decomposition of diclofenac (DCF) in aqueous solution. DCF degradation was found to follow double-exponential decay kinetics in the BFO/PMS system. The effects of several operating parameters such as pH value, BFO dosage and PMS concentration on DCF degradation by BFO/PMS process were investigated in detail. Visible (Vis) light irradiation was observed to promote the DCF degradation by BFO/PMS process by producing additional sulfate and hydroxyl radicals and accelerating the FeIII-FeII-FeIII redox cycle. Both sulfate radicals (SO4−) and hydroxyl radicals (OH) were detected in the BFO/PMS system by electron spin resonance (ESR). The reusability of as-prepared BFO microspheres was evaluated in both the BFO/PMS and the Vis/BFO/PMS systems. Nine intermediates were identified during DCF degradation in the BFO/PMS system and DCF decay pathways were proposed accordingly.

Highly Selective Detection of Hypochlorous Acid by a Bis-heteroleptic Ru(II) Complex of Pyridyl-1,2,3-triazole Ligand via C(sp2)-H Hydroxylation.

A Ru(II) complex (Ru-1) of a substituted pyridyl-1,2,3-triazole ligand (BtPT) for highly selective "light-up" detection of hypochlorous acid is presented. An unusual anti-Markovnikov HOCl addition to the C═C bond of 1,2,3-triazole and a highly specific C(sp2)-H hydroxylation over epoxidation made Ru-1 a highly selective luminescent HOCl probe. The abnormal regio- and stereoselective HOCl addition and subsequent hydroxylation mechanism in detail is supported by the combination of ESI-MS, 1H/13C NMR spectroscopy, and 1H NMR titration. The hydroxylation at the C5 center in 1,2,3-triazole increases the electron density and makes BtPT a better σ-donor as well as π-donor, which in turn increases the 3MC-3MLCT energy gap and inhibits the nonradiative decay from the excited state of Ru-1 and is the key reason for luminescence light-up. Most importantly, the exogenous and endogenous HOCl imaging in the living HEK293T cells is also demonstrated. The probe showed low cytotoxicity and efficiently permeated the cell membrane. The cell-imaging experiments revealed rapid staining of the extranuclear region of HEK293T cells which clearly indicates the presence of cytoplasmic HOCl. The endogenous HOCl generation and imaging, stimulated by lipopolysaccharides (LPS) and paraquat in the HEK293T cells, is also demonstrated.