Protocatechuic acid enhanced the selective degradation of sulfonamide antibiotics in Fe(III)/peracetic acid process under actually neutral pH conditions.

The practical application of the Fe-catalyzed peracetic acid (PAA) processes is seriously restricted due to the need for narrow pH working range and poor anti-interference capacity. This study demonstrates that protocatechuic acid (PCA), a natural and eco-environmental phenolic acid, significantly enhanced the removal of sulfonamide antibiotics in Fe(III)/PAA process under actually neutral pH conditions (6.0-8.0) by complexing Fe(III). With sulfamethoxazole (SMX) as the model contaminant, the pseudo-first-order rate constant of SMX elimination in PCA/Fe(III)/PAA process was 63.5 times higher than that in Fe(III)/PAA process at pH 7.0, surpassing most of the previously reported strategies-enhanced Fe-catalyzed PAA processes (i.e., picolinic acid and hydroxylamine etc.). Excluding the primary contribution of reactive species commonly found in Fe-catalyzed PAA processes (e.g., •OH, R-O•, Fe(IV)/Fe(V) and 1O2) to SMX removal, the Fe(III)-peroxy complex intermediate (CH3C(O)OO-Fe(III)-PCA) was proposed as the primary reactive species in PCA/Fe(III)/PAA process. DFT theoretical calculations indicate that CH3C(O)OO-Fe(III)-PCA exhibited stronger oxidation potential than CH3C(O)OO-Fe(III), thereby enhancing SMX removal. Four potential removal pathways of SMX were proposed and the toxicity of reaction solution decreased with the removal of SMX. Furthermore, PCA/Fe(III)/PAA process exhibited strong anti-interference capacity to common natural anions (HCO3-, Cl-and NO3-) and humic acid. More importantly, the PCA/Fe(III)/PAA process demonstrated high efficiency for SMX elimination in actual samples, even at a trace Fe(III) dosage (i.e., 5 µM). Overall, this study provided a highly-efficient and eco-environmental strategy to remove sulfonamide antibiotics in Fe(III)/PAA process under actually neutral pH conditions and to strengthen its anti-interference capacity, underscoring its potential application in water treatment.

Infiltrative Vessel Co-optive Growth Pattern Induced by IQGAP3 Overexpression Promotes Microvascular Invasion in Hepatocellular Carcinoma.

PURPOSE: Microvascular invasion (MVI) is a major unfavorable prognostic factor for intrahepatic metastasis and postoperative recurrence of hepatocellular carcinoma (HCC). However, the intervention and preoperative prediction for MVI remain clinical challenges due to the absent precise mechanism and molecular marker(s). Herein, we aimed to investigate the mechanisms underlying vascular invasion that can be applied to clinical intervention for MVI in HCC. EXPERIMENTAL DESIGN: The histopathologic characteristics of clinical MVI+/HCC specimens were analyzed using multiplex immunofluorescence staining. The liver orthotopic xenograft mouse model and mechanistic experiments on human patient-derived HCC cell lines, including coculture modeling, RNA-sequencing, and proteomic analysis, were used to investigate MVI-related genes and mechanisms. RESULTS: IQGAP3 overexpression was correlated significantly with MVI status and reduced survival in HCC. Upregulation of IQGAP3 promoted MVI+-HCC cells to adopt an infiltrative vessel co-optive growth pattern and accessed blood capillaries by inducing detachment of activated hepatic stellate cells (HSC) from the endothelium. Mechanically, IQGAP3 overexpression contributed to HCC vascular invasion via a dual mechanism, in which IQGAP3 induced HSC activation and disruption of the HSC-endothelial interaction via upregulation of multiple cytokines and enhanced the trans-endothelial migration of MVI+-HCC cells by remodeling the cytoskeleton by sustaining GTPase Rac1 activity. Importantly, systemic delivery of IQGAP3-targeting small-interfering RNA nanoparticles disrupted the infiltrative vessel co-optive growth pattern and reduced the MVI of HCC. CONCLUSIONS: Our results revealed a plausible mechanism underlying IQGAP3-mediated microvascular invasion in HCC, and provided a potential target to develop therapeutic strategies to treat HCC with MVI.

Overlooked Role of Coexistent Hydrogen Peroxide in Activated Peracetic Acid by Cu(II) for Enhanced Oxidation of Organic Contaminants.

Cu(II)-catalyzed peracetic acid (PAA) processes have shown significant potential to remove contaminants in water treatment. Nevertheless, the role of coexistent H2O2 in the transformation from Cu(II) to Cu(I) remained contentious. Herein, with the Cu(II)/PAA process as an example, the respective roles of PAA and H2O2 on the Cu(II)/Cu(I) cycling were comprehensively investigated over the pH range of 7.0-10.5. Contrary to previous studies, it was surprisingly found that the coexistent deprotonated H2O2 (HO2-), instead of PAA, was crucial for accelerating the transformation from Cu(II) to Cu(I) (kHO2-/Cu(II) = (0.17-1) × 106 M-1 s-1, kPAA/Cu(II) < 2.33 ± 0.3 M-1 s-1). Subsequently, the formed Cu(I) preferentially reacted with PAA (kPAA/Cu(I) = (5.84 ± 0.17) × 102 M-1 s-1), rather than H2O2 (kH2O2/Cu(I) = (5.00 ± 0.2) × 101 M-1 s-1), generating reactive species to oxidize organic contaminants. With naproxen as the target pollutant, the proposed synergistic role of H2O2 and PAA was found to be highly dependent on the solution pH with weakly alkaline conditions being more conducive to naproxen degradation. Overall, this study systematically investigated the overlooked but crucial role of coexistent H2O2 in the Cu(II)/PAA process, which might provide valuable insights for better understanding the underlying mechanism in Cu-catalyzed PAA processes.

Hydroxylamine enhanced the degradation of diclofenac in Cu(II)/peracetic acid system: Formation and contributions of CH3C(O)O•, CH3C(O)OO•, Cu(III) and •OH.

The slow reduction of Cu(II) into Cu(I) through peracetic acid (PAA) heavily limited the widespread application of Cu(II)/PAA system. Herein, hydroxylamine (HA) was proposed to boost the oxidative capacity of Cu(II)/PAA system by facilitating the redox cycle of Cu(I)/Cu(II). HA/Cu(II)/PAA system was quite rapid in the removal of diclofenac within a broad pH range of 4.5-9.5, with a 10-fold increase in the removal rate of diclofenac compared with the Cu(II)/PAA system at an optimal initial pH of 8.5. Results of UV-Vis spectra, electron paramagnetic resonance, and alcohol quenching experiments demonstrated that CH3C(O)O•, CH3C(O)OO•, Cu(III), and •OH were involved in HA/Cu(II)/PAA system, while CH3C(O)OO• was verified as the predominant reactive species of diclofenac elimination. Different from previously reported Cu-catalyzed PAA processes, CH3C(O)OO• mainly generated from the reaction of PAA with Cu(III) rather than CH3C(O)O• and •OH. Four possible elimination pathways for diclofenac were proposed, and the acute toxicity of treated diclofenac solution with HA/Cu(II)/PAA system significantly decreased. Moreover, HA/Cu(II)/PAA system possessed a strong anti-interference ability towards the commonly existent water matrix. This research proposed an effective strategy to boost the oxidative capacity of Cu(II)/PAA system and might promote its potential application, especially in copper-contained wastewater.

Combined transcriptome and proteome analysis revealed the molecular regulation mechanisms of zinc homeostasis and antioxidant machinery in tobacco in response to different zinc supplies.

Zinc (Zn) is an essential micronutrient for plants. Adequate regulation of Zn uptake, transport and distribution, and adaptation to Zn-deficiency stress or Zn-excess toxicity are crucial for plant growth and development. However, little has been done to understand the molecular responses of plants toward different Zn supply levels. In the present study, we investigated the growth and physiological responses of tobacco seedlings grown under Zn-completely deficient, Zn-limiting, Zn-normal, and Zn-4-fold sufficient conditions, respectively, and demonstrated that Zn deficiency/limitation caused oxidative stress and impaired growth of tobacco plants. Combined transcriptome and proteome analysis revealed up-regulation of genes/proteins associated with Zn uptake and distribution, including ZIPs, NAS3s, and HMA1s, and up-regulation of genes/proteins involved in regulation of oxidative stress, including SODs, APX1s, GPX6, and GSTs in tobacco seedlings in response to Zn deficiency/limitation, suggesting that tobacco possessed mechanisms to regulate Zn homeostasis primarily through up-regulation of the ZIPs-NAS3s module, and to alleviate Zn deficiency/limitation-induced oxidative stress through activation of the antioxidant machinery. Our results provide novel insights into the adaptive mechanisms of tobacco in response to different Zn supplies, and would lay a theoretical foundation for development of varieties of tobacco or its relatives with high tolerance to Zn-deficiency.

ABTS as Both Activator and Electron Shuttle to Activate Persulfate for Diclofenac Degradation: Formation and Contributions of ABTS•+, SO4•-, and •OH.

The activation of peroxydisulfate (PDS) by organic compounds has attracted increasing attention. However, some inherent drawbacks including quick activator decomposition and poor anti-interference capacity limited the application of organic compound-activated PDS. It was interestingly found that 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) could act as both activator and electron shuttle for PDS activation to enhance diclofenac (DCF) degradation over a pH range of 2.0-11.0. Multiple reactive species of ABTS•+, •OH, and SO4•- were generated in the PDS/ABTS system, while only ABTS•+ and •OH directly contributed to DCF degradation. ABTS•+, generated via the reactions of ABTS with PDS, SO4•-, and •OH, was the dominant reactive species of DCF degradation. No significant decomposition of ABTS was observed in the PDS/ABTS system, and ABTS acted as both activator and electron shuttle. Four possible degradation pathways of DCF were proposed, and the toxicity of DCF decreased after treatment with the PDS/ABTS system. The PDS/ABTS system had good anti-interference capacity to common natural water constituents. Additionally, ABTS was encapsulated into cellulose to obtain ABTS@Ce beads, and the PDS/ABTS@Ce system possessed excellent performance on DCF degradation. This study proposes a new perspective to reconsider the mechanism of activating PDS with organic compounds and highlights the considerable contribution of organic radicals on contaminant removal.

Sodium tetraborate simultaneously enhances the degradation of acetaminophen and reduces the formation potential of chlorinated by-products with heat-activated peroxymonosulfate oxidation.

In this study, sodium tetraborate (Na2B4O7) was introduced to enhance the degradation of acetaminophen (ACT) in heat-activated peroxymonosulfate (PMS) process. The elimination of ACT in Na2B4O7/heat/PMS process followed the pseudo-first order kinetics. The corresponding kobs value with 10 mM Na2B4O7 was 33.1 times higher than that in heat/PMS process. 1O2 and HO· were identified as primary reactive species via quenching experiments and electron paramagnetic resonance technology. B(OH)4-, the hydrolysis product of Na2B4O7, reacted with PMS to generate HOOB(OH)3-. 1O2 was generated by the self-decomposition of PMS using B(OH)4- as catalyst, while HO· was produced via the breakage of peroxide bond of PMS and HOOB(OH)3-under high temperature. ACT was degraded by reactive species via the pathways of -NH- bond breakage, -OH replacement, -NH2 oxidation and benzene ring cleavage. Nine transformation intermediates were detected by LC/Q-TOF/MS, and the toxicity of reaction solution decreased significantly with the elimination of ACT. Increasing Na2B4O7 dosage, PMS concentration, initial pH and reaction temperature were conducive to ACT elimination. Humic acid, Cl- and CO32- inhibited the degradation of ACT heavily, while SO42- and NO3- had the negligible effects. Moreover, B(OH)4- could react with free chlorine to the inert B(OH)3OCl- and further significantly suppress the formation of chlorinated by-products for the treatment of Cl--containing water in Na2B4O7/heat/PMS process. This study provided an effective way to enhance the oxidation capacity of heat/PMS process and suppress the formation of chlorinated by-products in chloride-containing water, and the findings had important implications for using borate buffer in the studies of PMS-based advanced oxidation processes.

Multi-wavelength spectrophotometric determination of peracetic acid and the coexistent hydrogen peroxide via oxidative coloration of ABTS with the assistance of Fe2+ and KI.

In this study, a multi-wavelength spectrophotometric method for simultaneous determination of peracetic acid (PAA) and coexistent hydrogen peroxide (H2O2) was presented. This method was based on the oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) with the assistance of Fe2+/KI to produce a stable green radical (ABTS●+), which could be determined at four characteristic peaks (i.e., 415 nm, 650 nm, 732 nm, and 820 nm). The absorbances of ABTS●+ at four peaks were well linear (R2 > 0.999) with concentrations of both total peroxides (PAA + H2O2) and PAA in the range of 0-40 µM under optimized conditions. The sensitivities for determining total peroxides at 415 nm, 650 nm, 732 nm and 820 nm were determined to be 4.248 × 104 M-1 cm-1, 1.682 × 104 M-1 cm-1, 2.132 × 104 M-1 cm-1, and 1.928 × 104 M-1 cm-1, respectively. For determining PAA, the corresponding sensitivities were 4.622 × 104 M-1 cm-1, 1.895 × 104 M-1 cm-1, 2.394 × 104 M-1 cm-1 and 2.153 × 104 M-1 cm-1, respectively. The concentration of coexistent H2O2 was gained by deducting PAA concentration from total peroxides concentration. The ABTS method was accurate enough to determine PAA concentration in natural water samples. Moreover, the ABTS method was successfully used to determine the changes of PAA and coexistent H2O2 and to distinguish their role on naproxen degradation in heat-activated PAA process. Overall, the ABTS method could be used as an alternative method for the convenient, rapid and sensitive determination of PAA and the coexistent H2O2 in water samples.

Hydroxylamine enhanced Fe(II)-activated peracetic acid process for diclofenac degradation: Efficiency, mechanism and effects of various parameters.

In this study, a commonly used reducing agent, hydroxylamine (HA), was introduced into Fe(II)/PAA process to improve its oxidation capacity. The HA/Fe(II)/PAA process possessed high oxidation performance for diclofenac degradation even with trace Fe(II) dosage (i.e., 1 µM) at pH of 3.0 to 6.0. Based on electron paramagnetic resonance technology, methyl phenyl sulfoxide (PMSO)-based probe experiments and alcohol quenching experiments, FeIVO2+ and carbon-centered radicals (R-O•) were considered as the primary reactive species responsible for diclofenac elimination. HA accelerated the redox cycle of Fe(III)/Fe(II) and itself was gradually decomposed to N2, N2O, NO2- and NO3-, and the environmentally friendly gas of N2 was considered as the major decomposition product of HA. Four possible degradation pathways of diclofenac were proposed based on seven detected intermediate products. Both elevated dosages of Fe(II) and PAA promoted diclofenac removal. Cl-, HCO3- and SO42- had negligible impacts on diclofenac degradation, while humic acid exhibited an inhibitory effect. The oxidation capacity of HA/Fe(II)/PAA process in natural water matrices and its application to degrade various micropollutants were also investigated. This study proposed a promising strategy for improving the Fe(II)/PAA process and highlighted its potential application in water treatment.

Iodometric spectrophotometric determination of peroxydisulfate in hydroxylamine-involved AOPs: 15 min or 15 s for oxidative coloration?

In this study, iodometric spectrophotometry, the most-used method for detecting peroxydisulfate (PDS), was modified by increasing the concentration of potassium iodide (KI) for realizing the immediate PDS determination and avoiding the interference of hydroxylamine. Kinetic studies showed that the reaction between PDS and I- to generate the yellow-colored I3- followed the kinetic equation as [Formula: see text] . Detection time of the iodometric spectrophotometry was shortened from 15 min to 15 s when KI concentration was increased from 0.6 M to 4.8 M. Different with the previous iodometric spectrophotometry, the modified method using 4.8 M KI as the indicator was well tolerable to the interference of hydroxylamine at acidic pH conditions. The calibration curve of the modified method showed a well linear relationship (R2 = 0.999) between the absorbance of I3- at 352 nm and PDS concentration in the range of 0-80 µM. The modified method was highly sensitive with the absorptivity of 2.5 × 104 M-1 cm-1 and the limit of detection of 0.11 µM. Moreover, the modified method was successfully applied for monitoring the change of PDS concentration during the degradation of diclofenac with four different PDS-based AOPs, the calculated reaction stoichiometric efficiency (RSE(%)=DiclofenacdegradedPDSconsumed×100%) followed the order as heat/PDS system > hydroxylamine/Fe2+/PDS system > hydroxylamine/Cu2+/PDS system > Fe2+/PDS system.

ABTS as an electron shuttle to accelerate the degradation of diclofenac with horseradish peroxidase-catalyzed hydrogen peroxide oxidation.

Horseradish peroxidase (HRP)-catalyzed hydrogen peroxide (H2O2) oxidation could degrade a variety of organic pollutants, but the intrinsic drawback of slow degradation rate limited its widespread application. In this study, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) was introduced into HRP/H2O2 system as an electron shuttle to enhance diclofenac degradation under neutral pH conditions. The green-colored ABTS radical (ABTS•+), generated by the oxidation of ABTS with HRP-catalyzed H2O2 oxidation, was proved to be the main reactive species for the rapid degradation of diclofenac in HRP/H2O2/ABTS system. There was no destruction of ABTS/ABTS•+ in HRP/H2O2/ABTS system, and ABTS was verified as an ideal electron shuttle. The reaction conditions including solution pH (4.5-10.5), HRP concentration (0-8 units mL-1) and H2O2 concentration (0-500 µM) would impact the formation of ABTS•+, and affect the degradation of diclofenac in HRP/H2O2/ABTS system. Moreover, compared with Fenton and hydroxylamine/Fenton systems, HRP/H2O2/ABTS system had better diclofenac degradation efficiency, higher H2O2 utilization efficiency and stronger anti-interference capacity in actual waters. Overall, the present study provided a meaningful and promising way to enhance the degradation of organic pollutants in water with HRP-catalyzed H2O2 oxidation.

Oleoylethanolamide inhibits α-melanocyte stimulating hormone-stimulated melanogenesis via ERK, Akt and CREB signaling pathways in B16 melanoma cells.

The present study aimed to examine the potential inhibitory activity of oleoylethanolamide (OEA) on α-melanocyte stimulating hormone (α-MSH)-stimulated melanogenesis and the molecular mechanism(s) involved in the process in B16 mouse melanoma cells. Our data demonstrated that OEA markedly inhibited melanin synthesis and tyrosinase activity in α-MSH-stimulated B16 cells. In addition, the expression of melanogenesis-related proteins, such as melanocortin-1 receptor (MC1R), microphthalmia-associated transcription factor (MITF), tyrosinase-related protein-1 (TRP-1) and tyrosinase, was suppressed in a concentration-dependent manner by OEA. In addition, OEA may suppress melanogenesis through a peroxisome proliferator-activated receptor α (PPARα)-independent pathway. Moreover, OEA activated ERK, Akt, p38 pathways and inhibits CREB pathway in α-MSH-stimulated B16 cells. The specific ERK inhibitor PD98059 partly blocked OEA-inhibited melanin synthesis and tyrosinase activity and partly abrogated the OEA-suppressed expression of melanogenic proteins. Furthermore, OEA presented remarkable inhibition on the body pigmentation in the zebrafish model system. Our findings demonstrated that OEA is an effective inhibitor of hyperpigmentation through activation of ERK, Akt and p38 pathways, inhibition of the CREB pathway, and subsequent down-regulation of MITF, TRP-1 and tyrosinase production.