Inhibition Of Glutathione S-transferase Research Articles

Exploratory Analysis on Herbicide Metabolism and Very-Long-Chain Fatty Acid Production in Metolachlor-Resistant Palmer Amaranth (Amaranthus palmeri S. Wats.).

A Palmer amaranth (Amaranthus palmeri S. Wats.) biotype resistant to S-metolachlor was confirmed from crop fields in Arkansas, USA. This study investigated the metabolic effects of malathion (cytochrome P450 inhibitor) and 4-chloro-7-nitrobenzofurazan [NBD-Cl; glutathione S-transferase inhibitor] on the S-metolachlor-resistant A. palmeri biotype. Root elongation of the resistant biotype was 20% more inhibited by treatment of NBD-Cl (50 nM) and S-metolachlor (2 μM) in mixture than by treatment of S-metolachlor alone. Metabolites of S-metolachlor were 1.4-12.1 times greater produced in the resistant biotype for 7 d than in the susceptible standard. Production of cerotic acid, one of the very-long-chain fatty acids containing 26 carbons, was more reduced in the susceptible standard (3.8-fold) than in the resistant biotype (1.8-fold) by S-metolachlor treatment. Conclusively, evolution of S-metolachlor resistance observed in this study was likely associated with improved activity of glutathione S-transferases. Further studies are needed to genetically evaluate plant endogenous enzymes involving cerotic acid production.

Metamifop resistance in Echinochloa glabrescens via glutathione S-transferases-involved enhanced metabolism.

Echinochloa glabrescens Munro ex Hook. f. is one of the main Echinochloa spp. seriously invading Chinese rice fields and has evolved resistance to commonly used herbicides. Previously, an E. glabrescens population (LJ-02) with suspected resistance to the acetyl-CoA carboxylase (ACCase)-inhibiting herbicide metamifop was collected. This study aimed to determine its resistance status to metamifop and investigate the internal molecular mechanisms of resistance. Single-dose testing confirmed that the LJ-02 population had evolved resistance to metamifop. Gene sequencing and a relative expression assay of ACCase ruled out target-site based resistance to metamifop in LJ-02. Whole-plant bioassays revealed that, compared with the susceptible population XZ-01, LJ-02 was highly resistant to metamifop and exhibited cross-resistance to fenoxaprop-P-ethyl. Pretreatment with the known glutathione S-transferase (GST) inhibitor, 4-chloro-7-nitrobenzoxadiazole (NBD-Cl), largely reversed the resistance to metamifop by approximately 81%. Liquid chromatography-tandem mass spectrometry analysis indicated that the metabolic rates of one of the major metabolites of metamifop, N-(2-fluorophenyl)-2-hydroxy-N-methylpropionamide (HPFMA), were up to 383-fold faster in LJ-02 plants than in XZ-01 plants. There were higher basal and metamifop-inducible GST activities toward 1-chloro-2,4-dinitrobenzene (CDNB) in LJ-02 than in XZ-01. Six GST genes were metamifop-induced and overexpressed in the resistant LJ-02 population. This study reports, for the first time, the occurrence of metabolic metamifop resistance in E. glabrescens worldwide. The high-level metamifop resistance in the LJ-02 population may mainly involve specific isoforms of GSTs that endow high catalytic activity and strong substrate specificity. © 2023 Society of Chemical Industry.

Computational perspectives on Chlorpyrifos and its degradants as human glutathione S-transferases inhibitors: DFT calculations, molecular docking study and MD simulations

Chlorpyrifos is the toxicant chemical from the class of organophosphorus insecticides. The insecticide undergoes environmental degradation to chlorpyrifos‐oxon (CPYO), des‐ethyl chlorpyrifos (DEC), 3,5,6‐trichloro‐2‐methoxypyridine (TMP) and 3,5,6‐trichloro‐2‐pyridinol (TCP). Herein, CPF along with its degradants were optimized employing density functional theory (DFT) and B3LYP/6-311G+(d,p) basis set to elucidate their thermal and frontier molecular orbital properties. The DFT outcome revealed that TCP showed the lowest HOMO-LUMO gap (4.38 eV), also highest dipole moment, electrophilicity index and basicity. Docking was done using AutoDock 4.2.6 against human glutathione S-transferases to search binding affinity and interactions of all pollutants with the protein. The docking results expressed that TCP required least binding energy (−5.51 kcal mol−1) which is relatable to the DFT studies and might act as the most powerful inhibitor. GROMACS 5.1.1 was utilized to perform simulation studies for each ligand–protein docked complexes. Results concluded that CPF, DEC, TMP, CPYO and TCP could possibly perform as toxic and inhibit enzymatic activity by interrupting the metabolic pathways in humans.

Glutathione S-Transferases Mediate In Vitro and In Vivo Inactivation of Genipin: Implications for an Underlying Detoxification Mechanism.

Genipin (GP), the reactive metabolite of geniposide (GE), is responsible for GE-induced hepatotoxicity. As a potential detoxification pathway, the inactivation of GP by glutathione S-transferases (GSTs) has not yet been characterized. In this study, the thiol-GSH conjugates of GP, M532-1 and M532-2 were first identified and the catalytic activities of GSTs were investigated both in vitro and in vivo. GSTA1-1 and GSTA4-4 showed high activity in the formation of both thiol-GSH conjugates, whereas GSTA4-4 specifically catalyzed M532-2 formation in vitro. The active GST isoforms protect against alkylation of N-acetylcysteine (NAC), a classic model nucleophile. GST inhibition attenuated M532-1 formation in rat bile, confirming the in vivo catalytic role of GSTs. In conclusion, this study demonstrated the inactivation of GP by GSTs and implied that interindividual variability of GSTs may be a risk factor for susceptibility to GE-induced hepatotoxicity.

Ethanolic Extracts of Datura innoxia Have Promising Acaricidal Activity against Rhipicephalus microplus as It Blocks the Glutathione S-Transferase Activity of the Target Tick.

Rhipicephalus microplus is a major bovine ectoparasite that negatively impacts the cattle industry. The acaricidal activity of Datura innoxia ethanolic plant extract against R. microplus, compared with trichlorfon, was examined using the adult immersion test (AIT), and larval packet test (LPT). In vitro acaricidal activity of the selected plant extract against R. microplus engorged females was evaluated at different concentrations (2.5, 5, 10, 20, and 40 mg/mL), and was the same for AIT and LPT. It was further supported by in silico molecular docking of D. innoxia's 21 phytochemicals against the R. microplus Glutathione S-transferases (RmGST) protein's three-dimensional (3D) structure predicted by the trRosetta server. The modeled 3D structure was then evaluated and confirmed with PROCHECK, ERRAT, and Verify3D online servers. To predict the binding mechanisms of these compounds, molecular docking was performed using Auto dock Vina software, and molecular dynamic (MD) simulations were used to investigate the protein atom's dynamic motion. D. innoxia has a relatively higher inhibitory effect on oviposition (from 9.81% to 45.37%) and total larval mortality (42.33% at 24 h and 93.67% at 48 h) at 40 mg/mL. Moreover, the docking results showed that the chemicals norapoatropine and 7-Hydroxyhyoscyamine have strong interactions with active site residues of the target protein, with a docking score of -7.3 and -7.0 Kcal/mol, respectively. The current work also provided a computational basis for the inhibitors of Glutathione S-transferases that were studied in this research work, and this new knowledge should aid in creating new and effective acaricidal chemicals. Furthermore, this plant extract's acaricide activity and its effect on oviposition and larval mortality were established in this work for the first time, indicating the possible use of this extract in the management of ticks.

Metabolism of 2,4-D in resistant Amaranthus palmeri S. Wats. (Palmer amaranth)

Amaranthus palmeri S. Wats. is one of troublesome weed species in field crops in the mid-southern USA. In our recent results of screening for herbicide resistance of various weeds collected from agricultural areas of the mid-southern USA, three A. palmeri accessions resistant to 2,4-D (R1, R2, and R3) were verified. In this study, all three resistant (R) accessions, along with two 2,4-D-susceptible (S1 and S2) standards, were subjected to dose-response experiments to characterize their sensitivity to 2,4-D. Based on the dose-response results, resistance/susceptibility ratios of the tested A. palmeri accessions were greater in the order of R2 (7.1) ≥ R1 (5.7) = R3 (5.7) > S2 (1.9) ≥ S1 (1.0). Treatment of malathion (cytochrome P450 inhibitor) or 4-chloro-7-nitrobenzofurazan [glutathione S-transferase (GST) inhibitor] followed by 2,4-D choline increased the mortality of R1 and R2 accessions, which means that enhanced metabolism of 2,4-D contributed to evolution of the herbicide resistance in such R accessions. In contrast, the mortality of R3 accession was not affected by either of the metabolic inhibitors. Absorption and translocation of 2,4-D were similar between S1 and R accessions for 48 h after the herbicide treatment. However, the 48-h metabolism of 2,4-D in R1 (48%) and R2 (68%) accessions were 2- to 3-fold greater than those in S1 (21%) and R3 (19%) accessions. Thus, enhanced metabolism by activities of cytochrome P450s and GSTs can be one of multiple mechanisms conferring 2,4-D resistance to A. palmeri. Further genetic studies are needed to verify the presence of target-site resistance mechanisms in all three R accessions.

Synthesis, characterization and biological evaluation of two cyclometalated iridium(III) complexes containing a glutathione S-transferase inhibitor

The cyclometalated iridium(III) compounds have been intensively studied for health-related applications due to their outstanding luminescent properties and multiple anticancer modes of action. Herein, two iridium(III) compounds Ir-1 and Ir-3 containing glutathione S-transferase inhibitor (GSTi) were developed and studied together with two unfunctionalized compounds Ir-2 and Ir-4 as a comparison. Biological study indicated that GSTi-bearing complexes Ir-1 and Ir-3 exert a synergistic effect on the inhibition of cancer cells. The photophysical properties of Ir-1 ∼ Ir-4 were investigated by UV/vis absorption and fluorescence spectroscopy and rationalized with TD-DFT calculations. As expected, GSTi-bearing complexes Ir-1 and Ir-3 exhibited considerable cytotoxicity against both A549 and cisplatin-resistant A549/cis cancer cells, much higher than the unfunctionalized iridium compounds Ir-2 and Ir-4. Further study indicated that Ir-1 and Ir-3 mainly localize in the mitochondria of tumor cells, and exert their cytotoxicity via generating ROS and inhibiting GST activity. The flow cytometry investigations demonstrated that Ir-1 and Ir-3 can arrest the cell cycle in S phase and induce the cell death through apoptosis process. Overall, the complexation of GST inhibitors with cyclometalated iridium(III) agents provides an effective way for potentiating the cytotoxicity of iridium(III) anticancer agents and resensitizing the efficacy against cisplatin resistant cancer cells.

Role of ZmGST Gene Family Involved in Nicosulfuron Stress Tolerance Revealed by Genomic and Transcriptomic Analyses

Glutathione S-transferases (GST) are a large family of polymorphous proteins that play important roles in herbicide detoxification and stress response. Nicosulfuron is the most broadly used herbicide in maize fields, and it can cause different injuries to maize varieties, but little is studied about the systemic and comprehensive GST gene family responding to nicosulfuron stress in maize. In this research, pre-treatment with glutathione S-transferase inhibitor 4-chloro-7-nitrobenzoxadiazole (NBD-Cl) increased nicosulfuron phytotoxicity to both sensitive and tolerant maize genotypes. A total of 55 ZmGST genes belonging to six major sub-classes were identified in the maize genome and named according to the nomenclature system. Based on phylogenetic analyses, highly conserved gene structure and motif distribution were detected in the same class. Chromosome mapping results showed that ZmGST genes were distributed over the 10 chromosomes unevenly. There were thirteen and eight gene pairs identified as tandem and segmental duplication events, respectively, which played important roles in the expansion of the GST gene family in maize. RNA-seq and qRT-PCR analyses showed that there were great dissimilarities in ZmGST gene expression patterns between the tolerant and sensitive maize plants. More highly expressed ZmGST genes were found in the tolerant than in the sensitive without nicosulfuron stress. However, under 60 g a.i. ha−1 nicosulfuron stress, more ZmGST genes were significantly upregulated in HB41 than in HB09. This study provided experimental evidence showing that glutathione S-transferases were involved in nicosulfuron stress in maize. It will contribute to the further functional analysis of the GST gene family in maize.

Inhibition of glutathione S-transferases by photoactive calix[4]arene α-ketophosphonic acids

Calix[4]arenes bearing photoactive α-ketophosphonic acid groups at the upper rim of the macrocycle were synthesized and evaluated as inhibitors of glutathione S-transferases. Irradiation at 365 nm increased the inhibition effects of some macrocyclic compounds on GSTP1-1 by more than two orders of magnitude. Calix[4]arene bis-α-ketophosphonic acids substituted at the lower rim by n-propyl or n-butyl groups showed IC50 values in the low micromolar range. Kinetics of the irreversible inhibition was described by pseudo-first-order rate constants dependent on inhibitor concentration. The values of second-order rate constants were higher for glutathione S-transferase from human placenta than for the enzyme from equine liver. Molecular docking suggested that photoactive macrocyclic compounds cover the active site of glutathione S-transferase, providing the possibility to modify the catalytically important amino acid residues during irradiation.

Glutathione-S-Transferases as Potential Targets for Modulation of Nitric Oxide-Mediated Vasodilation.

Glutathione-S-transferases (GSTs) are highly promiscuous in terms of their interactions with multiple proteins, leading to various functions. In addition to their classical detoxification roles with multi-drug resistance-related protein-1 (MRP1), more recent studies have indicated the role of GSTs in cellular nitric oxide (NO) metabolism. Vasodilation is classically induced by NO through its interaction with soluble guanylate cyclase. The ability of GSTs to biotransform organic nitrates such as nitroglycerin for NO generation can markedly modulate vasodilation, with this effect being prevented by specific GST inhibitors. Recently, other structurally distinct pro-drugs that generate NO via GST-mediated catalysis have been developed as anti-cancer agents and also indicate the potential of GSTs as suitable targets for pharmaceutical development. Further studies investigating GST biochemistry could enhance our understanding of NO metabolism and lead to the generation of novel and innovative vasodilators for clinical use.

Analysis of glutathione-S-transferases from larvae of Galleria mellonella (Lepidoptera, Pyralidae) with potential alkaloid detoxification function.

The greater wax moth, Galleria mellonella, is a global pest for beehives, doing damage in the larval stage. Although a significant number of studies have reported on larvae and adults, to date no effective pest control has been implemented. In this study, we tested larval resistance to alkaloids from Berberis microphylla, and the objective was to identify enzymes that participate in alkaloid detoxification through enzymatic assays, bioinformatics analysis and qRT-PCR. Findings suggest glutathione-S-transferases (GSTs), from an increased metabolic mechanism, are responsible for alkaloid detoxification rather than cytochrome P450 (CYP), carboxylesterases (CarE). A bioinformatics analysis from transcriptome data revealed 22 GSTs present in both G. mellonella larvae and adults. The qRT-PCR experiments corroborated the presence of the 22 GSTs in larvae, where GST8 and GST20 stood out with the highest expression after berberine treatment. Structural information around GST8 and GST20 suggests that GST8 could bind berberine stronger than GST20. These findings represent an important advance in the study of detoxification enzymes in G. mellonella, expanding the role of delta-class GSTs towards alkaloids. Likewise, GST inhibition by alkaloid analogs is proposed in the framework of integrated pest management strategies.

Ursolic acid alleviates tetrandrine-induced hepatotoxicity by competitively binding to the substrate-binding site of glutathione S-transferases

BackgroundTetrandrine (TET), a bisbenzylisoquinoline alkaloid isolated from Stephania tetrandra S. Moore, is the only approved medicine in China for silicosis. However, TET-induced hepatotoxicity has raised safety concerns. The underlying toxic targets and mechanism induced by TET remain unclear; there are no targeted detoxification strategies developed for TET-induced hepatotoxicity. Ursolic acid (UA), a pentacyclic triterpene with liver protective effects, may have detoxification effects on TET-induced hepatotoxicity. PurposeThis study aims to explore toxic targets and mechanism of TET and present UA as a potential targeted therapy for alleviating TET-induced hepatotoxicity. MethodsA TET-induced liver-injury model was established to evaluate TET toxicity and the potential UA detoxification effect. Alkenyl-modified TET and UA probes were designed to identify potential liver targets. Pharmacological and molecular biology methods were used to explore the underlying toxicity/detoxification mechanism. ResultsTET induced liver injury by covalently binding to the substrate-binding pocket (H-site) of glutathione S-transferases (GSTs) and inhibiting GST activity. The covalent binding led to toxic metabolite accumulation and caused redox imbalance and liver injury. UA protected the liver from TET-induced damage by competitively binding to the GST H-site. ConclusionThe mechanism of TET-induced hepatotoxicity is related to irreversible binding with the GST H-site and GST-activity inhibition. UA, a natural antidote, competed with TET on H-site binding and reversed the redox imbalance. This study revealed the hepatotoxic mechanism of TET and provided a targeted detoxifying agent, UA, to alleviate hepatotoxicity caused by GST inhibition.

Inhibition of glutathione S-transferases by calix[4]arene-based phosphinic acids

Calix[4]arene-, thiacalix[4]arene- and sulfonylcalix[4]arene-based derivatives with upper rim phosphinic acid groups were studied as inhibitors of glutathione S-transferases. It was found that the macrocyclic compounds can exhibit good to potent activity against GST from equine liver and human recombinant GSTA1-1, while being selective over the enzyme from human placenta and GSTP1-1. The thiacalix[4]arene phosphinic acid was the most active inhibitor of equine liver GST and GSTA1-1 with IC50 values of 85 nM and 50 nM, respectively. Kinetic studies revealed that the inhibition was of non-competitive type concerning both enzyme substrates, glutathione, and 1-chloro-2,4-dinitrobenzene. Molecular docking was carried out to predict possible binding sites for thiacalix[4]arene-based phosphinic acid on the surface of homodimeric GSTA1-1

Synthesis of two novel mercaptobenzimidazole derivative Schiff bases and their in vitro antioxidant and enzyme inhibitory effects

In this study, 5-(2-hydroxy-4-methoxybenzylidenamino)-2-mercaptobenzimidazole and 5-(4-hydroxy-3-methoxybenzylidenamino)-2-mercaptobenzimidazole Schiff base compounds were synthesized and their structure were characterized with spectroscopic techniques, namely, 1H NMR, IR, and 13C NMR. In vitro ABTS, DPPH, CUPRAC, and FRAP tests were applied to calculate the antioxidant activities of the newly designed compounds. Beside, the enzyme inhibitory abilities of the mercaptobenzimidazole derivative Schiff base were assessed against the glutathione S-transferase (GST) enzyme. The Ki values were calculated as 20.06 ± 3.11 and 36.86 ± 6.17 μM, as well as the IC50 values were calculated as 6.30 μM and 5.33 μM respectively. Besides, molecular docking interactions of the compounds with the GST target enzyme (PDB ID:5JCU) were estimated via Chimera and AutoDock Vina software. −8.7 kcal/mol, and −8.5 kcal/mol were calculated as best binding scores of compounds against the GST enzyme. Since the novel Schiff base, 5-(4-hydroxy-3-methoxybenzylidenamino)-2-mercaptobenzimidazole has a good potential in the GST inhibition, it should be subjected to the further pharmacological studies.

Early loss of glutathione -s- transferase (GST) activity during diverse forms of acute renal tubular injury.

Glutathione‐S‐transferases (GSTs) are a diverse group of phase II detoxification enzymes which primarily evoke tissue protection via glutathione conjugation to xenobiotics and reactive oxygen species. Given their cytoprotective properties, potential changes in GST expression during AKI has pathophysiologic relevance. Hence, we evaluated total GST activity, and the mRNA responses of nine cytosolic GST isotypes (GST alpha1, kappa1, mu1/5, omega1, pi1 sigma1, theta1, zeta1 mRNAs), in five diverse mouse models of AKI (glycerol, ischemia/reperfusion; maleate, cisplatin, endotoxemia). Excepting endotoxemia, each AKI model significantly reduced GST activity (~35%) during both the AKI “initiation” (0‐4 h) and “maintenance” phases (18 or 72 h). During the AKI maintenance phase, increases in multiple GST mRNAs were observed. However, no improvement in GST activity resulted. Increased urinary GST excretion followed AKI induction. However, this could not explain the reduced renal GST activity given that it also fell in response to ex vivo renal ischemia (i.e., absent urinary excretion). GST alpha, a dominant proximal tubule GST isotype, manifested 5–10‐fold protein increases following AKI, arguing against GST proteolysis as the reason for the GST activity declines. Free fatty acids (FFAs) and lysophospholipids, which markedly accumulate during AKI, are known to bind to, and suppress, GST activity. Supporting this concept, arachidonic acid addition to renal cortical protein extracts caused rapid GST activity reductions. Based on these results, we conclude that diverse forms of AKI significantly reduce GST activity. This occurs despite increased GST transcription/translation and independent of urinary GST excretion. Injury‐induced generation of endogenous GST inhibitors, such as FFAs, appears to be a dominant cause.

Anticholinesterase activity and Antioxidant Effect of Vitamin E in Aluminum Chloride Induced Toxicity in Drosophila Melanogaster

BackgroundAluminum chloride (AlCl3) has been used to model neurotoxicity and Alzheimer’s disease (AD) like neurodegeneration in various animal models (Bondy, 2010). AlCl3 toxicity has been reported to be associated with impaired locomotor performance, learning, memory, oxidative stress and cholinergic impairment which are features seen in AD patients (Ribes et al., 2008). AlCl3acts as a cholinotoxin (Gulya et al., 1990) and cause alterations on the cholinergic activity, a key event in the neurochemistry of AD (Rakonczay et al., 2005). Reduced cholinergic function in the brain has been shown to result in memory impairment in AD (Mukherjee et al., 2007). The use of compounds to inhibit acetylcholinesterase (AChE) activity (to reduce the hydrolysis of acetylcholine) has been a therapeutic approach in managing AD (Taylor and Radić 1994). Vitamin E has been proposed as a potential clinical intervention for AD given its antioxidant and anti‐inflammatory characteristics. However, there are very few studies on its anticholinesterase activity and there also controversies as to whether vitamin E is beneficial in AD. We therefore evaluated the anticholinesterase and antioxidant activity of vitamin E in aluminium chloride induced toxicity in Drosophila melanogaster.MethodsD. melanogaster (Harwich strain, 3‐5 days) were utilized for this study. In order to determine the appropriate dose of vitamin E to be utilized for this study, a 15 days survival study (where mortality rate was recorded daily) was carried out with varying dose of Vitamin E (2.5mg and 5mg). Subsequently, 2.5mg of vitamin E produced the least mortality of flies and was utilized for this study. The choice of concentration for AlCl3was based on previous studies on aluminum toxicity in D. melanogaster [Wu et al., 2012; Ogunsuyi, 2020]. Flies (both genders) were divided into 4 groups with 50 flies per vial. Group I served as control and were reared on their cornmeal diet while group II were treated with 40mM aluminum chloride (AlCl3) via their diet. Group III flies were fed with normal diet containing 2.5mg of vitamin E while Group IV were co‐administered with 40 mM AlCl3and 2.5mg of vitamin E via their diet. The flies were maintained on these treatments at room temperature for seven (7) days. All experiments were carried out in five replicates (n=5). Negative geotaxis was carried out to assess for locomotion deficit. At the end of the experimental period, the flies were homogenized and the supernatant were used to assay for AchE activity, malonaldehyde (MDA) concentration, superoxide dismutase (SOD), catalase (CAT) and glutathione S‐transferase (GST) activities.ResultsAlCl3induced toxicity reduced the survival rate, decreased the climbing activity, elevated MDA concentration and AChE activities of flies. SOD, CAT and GST activities were also reduced in AlCl3treated flies. Vitamin E was able to improve the survival rate, restored AlCl3induced reduction in climbing activity, ameliorated AlCl3 increase in AChE activity and MDA concentration in flies. In addition, Vitamin E attenuated AlCl3induced inhibition of SOD, CAT and GST activities.ConclusionThis study has shown that Vitamin E has both antioxidant and anticholinesterase activities and can be regarded as a therapeutic agent against AlCl3 induced toxicity and associated diseases.

Pinoxaden resistance in Lolium perenne L. is due to both target-site and non-target-site mechanisms

Application of herbicides inhibiting acetyl CoA carboxylase (ACCase) has been one of the main strategies for selectively controlling grass weed species such as perennial ryegrass (Lolium perenne L.) in wheat and barley crops in New Zealand. In this study, we have confirmed and characterized resistance to pinoxaden, an ACCase-inhibiting herbicide, in a population of L. perenne. Dose-response experiments were conducted to assess the level of pinoxaden resistance, and based on the LD50 values, the studied population was 41.4-times more resistant to pinoxaden than a susceptible population. Application of malathion, an inhibitor of the cytochrome P450s, preceding pinoxaden treatment reduced the level of resistance to 9.7-fold. However, pre-treatment with the glutathione S-transferase (GST) inhibitor 4-chloro7- nitrobenzoxadiazole prior to pinoxaden treatment did not affect pinoxaden resistance. Partial sequencing of the ACCase gene revealed that the resistant population had an isoleucine to valine replacement at position 2041. These results suggest that both cytochrome P450-based and target-site mechanisms are jointly associated with this instance of pinoxaden resistance in L. perenne. The pinoxaden-resistant L. perenne individuals were also resistant to quizalofop-p-ethyl (108.6-fold), but they were susceptible to clethodim, which can, therefore, be used to manage this pinoxaden-resistant L. perenne. This is the first report of a L. perenne population in which a rare target-site mutation works in concert with enhanced cytochrome P-450 activity to confer pinoxaden resistance. Evolution of resistance to ACCase-inhibiting herbicides in this L. perenne population indicates that integrated weed management practices are required to prevent widespread resistance developing in New Zealand cereal crop systems.

MiR-513a-3p promotes radiation-induced apoptosis of human lung cells by inhibiting glutathione S-transferase P1.

Radiotherapy is a common treatment for lung cancer. However, radiation pneumonitis caused by radiotherapy can affect the quality of life and prognosis of lung cancer patients. miR-513a-3p has been found to sensitize human lung adenocarcinoma cells to chemotherapy by targeting glutathione S-transferase P1 (GSTP1). Here, we found that x-ray induced the apoptosis of BEAS-2B and miR-513a-3p expression in a dose- and time-dependent manner, and miR-513a-3p-mimic significantly increased x-ray induced apoptosis, while miR-513a-3p-inhibitor significantly decreased x-ray induced apoptosis. Dual luciferase gene reporter system showed that miR-513a-3p targeted to inhibit the expression of GSTP1 in BEAS-2B cells. Moreover, knockdown of GSTP1 significantly increased, while overexpression of GSTP1 decreased the apoptosis of BEAS-2B induced by x-ray. Importantly, overexpression of GSTP1 significantly reduced miR-513a-3p-mimic elevated x-ray -induced apoptosis in BEAS-2B cells. In conclusion, x-ray caused increased expression of miR-513a-3p, and miR-513a-3p promoted x-ray-induced apoptosis of human lung cells by inhibiting GSTP1.

Mefenacet resistance in multiple herbicide-resistant Echinochloa crus-galli L. populations

Echinochloa crus-galli L., a notorious weed in rice paddy fields, is usually kept under control by mefenacet application at the pre-emergence or early post-emergence stage. Due to continuous and repeated usage, E. crus-galli is developing resistance to mefenacet in China. Two putative resistant and one susceptible E. crus-galli populations were collected from paddy fields in Jiangsu Province to characterize their herbicide resistance. Compared with the susceptible population, the two mefenacet-resistant populations had 2.8- and 4.1-times greater pre-emergence resistance, and 10- and 6.8-times greater early post-emergence resistance to mefenacet. These mefenacet-resistant E. crus-galli populations also exhibited cross- or multiple-resistance to acetochlor, pyraclonil, imazamox, and quinclorac. However, when the glutathione S-transferase (GST) inhibitor 4-chloro-7-nitrobenzoxadiazole (NBD-Cl) was applied prior to post-emergence treatment, mefenacet resistance levels were reduced in both populations. Additionally, GST activity in vivo in one resistant population was much higher than the susceptible population after mefenacet application. The very long chain fatty acid elongases (VLCFAEs) from both mefenacet-resistant populations required much higher mefenacet concentration to inhibit their activity. The reduced sensitivity of VLCFAEs to mefenacet indicates the presence of a target-site resistance mechanism and induction of high GST activity may provide additional contribution to E. crus-galli mefenacet resistance through a non-target-site mechanism.

Carrier-free nanomedicine for enhanced photodynamic tumor therapy through glutathione S-transferase inhibition

A chlorine e6 and coniferyl ferulate-based self-delivery nanomedicine is developed to inhibit intracellular glutathione S-transferase (GST) and enhance the photodynamic therapy (PDT)-mediated oxidative damage on tumor cells.