Inhibition Of Glutathione S-transferase Research Articles

Synthesis and examination of 1,2,4-triazine-sulfonamide hybrids as potential inhibitory drugs: Inhibition effects on AChE and GST enzymes in silico and in vitro conditions.

The crucial functions of acetylcholinesterase (AChE) in neurotransmission and glutathione S-transferase (GST) in detoxification and cellular protection underscore their pivotal roles as key enzymes, essential for maintaining the integrity of neurological and cellular homeostasis. For this purpose, a series of 1,2,4-triazine-sulfonamide hybrids (3a-r) was successfully synthesized, and subsequently evaluated for their inhibitory effects on AChE and GST. The investigation was complemented by molecular docking studies and ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) predictions. The synthesized hybrids demonstrated significant promise in inhibiting both AChE and GST activities. Molecular docking analyses provided insights into the interactions between the compounds and the target enzymes, shedding light on potential binding modes and key amino acid residues involved. Furthermore, the study benefited from ADMET predictions, offering valuable information on the compounds' pharmacokinetic properties and potential toxicity. The promising results obtained from this comprehensive approach highlight the potential of these 1,2,4-triazine-sulfonamide hybrids as effective inhibitors of AChE and GST, paving the way for further development and optimization in the pursuit of novel therapeutic agents.

Polycyclic aromatic hydrocarbon (PAH) activation of AhR inhibits glutathione S-transferase (GST) activity in primary human small airway epithelial cells (hSAECs)

Background: PAH represents the organic phase of particulate matter (PM) in air pollution emitted via the incomplete combustion of various compounds (i.e. diesel fuel, wood, and plastics). It is widely regarded that PAH activation of aryl hydrocarbon receptor (AhR) plays an important role in pro-inflammatory signaling, however the mechanisms remain unknown. In contrast- endogenous AhR agonists, such as 6-Formylindolo[3,2-b]carbazole (FICZ), exert pleiotropic protective effects against inflammation, fibrosis, and oxidative stress. The objective of our research program is to delineate the differences between activation of AhR by PAH (with adverse effects) compared to its beneficial homeostatic activation by endogenous FICZ. PM may induce oxidative stress in part through inhibition of antioxidant defense mechanisms. GSTs are a superfamily of enzymes that plays an important role in protecting cells from oxidative damage (by conjugating reduced glutathione to substrates under pro-oxidizing conditions). We hypothesize that PAH activation of AhR contributes to oxidative stress via inhibition of GST activity in primary hSAECs. Methods: Primary hSAECs were subjected to varying dosages of PAH [0, 250, 500, 1000, 5000 ng/mL] to model airborne PM exposure levels, and to increasing doses of FICZ [0, 0.50, 10, 100, 1000 nM] to model normal and excessively high endogenous ligand activation of AhR. We determined the relative potencies of PAH and FICZ by measuring CYP1A1 and CYP1B1 gene expression. Oxidative stress was measured using DHE-labeling and GST activity was measured with enzymatic kits (Sigma Aldrich). AhR activity was pharmacologically inhibited using 10μM CH223191. Statistical analysis was conducted using SigmaPlot 14.0 (Systat Software). Results: PAH and FICZ maximally stimulate hSAEC CYP1A1 and CYP1B1 expression at 1000ng/mL and 100nM, respectively, and are therefore defined as equipotent concentrations used in our studies. In a representative experiment in hSAECs, PAH (1000ng/mL) significantly increased hSAEC oxidative stress vs FICZ (100nM) n=6, p<0.01), while significantly decreasing GST specific activity vs equipotent FICZ activation of AhR in primary hSAECs from a 66-year-old female without lung disease (26.6±0.874 vs 28.3±.611 nmol/mL/min); n=6 from 2 independent assays; p=0.032. Similar differential effects of PAH vs FICZ activation of AhR on GST were seen in additional experiments with male hSAECs and Calu-3 cells (male). Importantly, CH223191 inhibition of GST enzymatic activity suggests that AhR plays an important role in protecting cells from oxidative stress. Conclusions: Our studies indicate that airborne PAH exposure can have detrimental health effects on the lung via aberrant AhR signaling. Significance: Understanding activity of AhR signaling can leads to novel therapeutic options for redox disorders in the lung. Funding: VA 5I01BX001777-05 (RP) and R01HL137033 (MH). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Virtual screening, MMGBSA, and molecular dynamics approaches for identification of natural products from South African biodiversity as potential Onchocerca volvulus pi-class glutathione S-transferase inhibitors

We investigated 1012 molecules from natural products previously isolated from the South African biodiversity (SANCDB, https://sancdb.rubi.ru.ac.za/), for putative inhibition of Onchocerca volvulus pi-class glutathione S-transferase (Ov-GST2) by virtual screening, MMGBSA, and molecular dynamics approaches. ADMET, docking, and MMGBSA shortlisted 12 selected homoisoflavanones-type hit molecules, among which two namely SANC00569, and SANC00689 displayed high binding affinities of −46.09 and −46.26 kcal mol−1, respectively towards π-class Ov-GST2, respectively. The molecular dynamics results of SANC00569 showed the presence of intermolecular H-bonding, hydrophobic interactions between the ligand and key amino acids of Ov-GST2, throughout the simulation period. This hit molecule had a stable binding pose and occupied the binding pockets throughout the 200 ns simulation. To the best of our knowledge, there is no report of any alleged anti–onchocerciasis activity referring to homoisoflavanones or flavonoids. Nevertheless, homoisoflavanones, which are a subclass of flavonoids, exhibit a plethora of biological activities. All these results led to the conclusion that SANC00569 is the most hypothetical Ov-GST2, which could lead the development of new drugs against Onchocerca volvulus pi-class glutathione S-transferase. Further validation of these findings through in vitro and in vivo studies is required.

Evaluation of the Aquatic Toxicity of Several Triazole Fungicides.

Fungicides play an important role in crop protection, but they have also been shown to adversely affect non-target organisms, including those living in the aquatic environment. The aim of the present study is to combine experimental and computational approaches to evaluate the effects of flutriafol, metconazole, myclobutanil, tebuconazole, tetraconazole and triticonazole on aquatic model organisms and to obtain information on the effects of these fungicides on Lemna minor, a freshwater plant, at the molecular level. The EC50 (the half-maximum effective concentration) values for the growth inhibition of Lemna minor in the presence of the investigated fungicides show that metconazole (EC50 = 0.132 mg/L) and tetraconazole (EC50 = 0.539 mg/L) are highly toxic, tebuconazole (EC50 = 1.552 mg/L), flutriafol (EC50 = 3.428 mg/L) and myclobutanil (EC50 = 9.134 mg/L) are moderately toxic, and triticonazole (EC50 = 11.631 mg/L) is slightly toxic to this plant. The results obtained with the computational tools TEST, ADMETLab2.0 and admetSAR2.0 also show that metconazole and tetraconazole are toxic to other aquatic organisms: Pimephales promelas, Daphnia magna and Tetrahymena pyriformis. A molecular docking study shows that triazole fungicides can affect photosynthesis in Lemna minor because they strongly bind to C43 (binding energies between -7.44 kcal/mol and -7.99 kcal/mol) and C47 proteins (binding energies between -7.44 kcal/mol and -8.28 kcal/mol) in the reaction center of photosystem II, inhibiting the binding of chlorophyll a to these enzymes. In addition, they can also inhibit glutathione S-transferase, an enzyme involved in the cellular detoxification of Lemna minor.

Mechanisms of lipopolysaccharide protection in tumor drug–induced macrophage damage

Malignant tumors contribute significantly to human mortality. Chemotherapy is a commonly used treatment for tumors. However, due to the low selectivity of chemotherapeutic drugs, immune cells can be damaged during antitumor treatment, resulting in toxicity. Lipopolysaccharide (LPS) can stimulate immune cells to respond to foreign substances. Here, we found that 10 ng/mL LPS could induce tolerance to antitumor drugs in macrophages without altering the effect of the drugs on tumor cells. Differentially expressed genes (DEGs) were identified between cells before and after LPS administration using transcriptome sequencing and found to be mainly associated with ATP-binding cassette (ABC)-resistant transporters and glutathione S-transferase (GST). LPS was shown by qRT-PCR and western blotting to promote the expression of ABCC1, GSTT1, and GSTP1 by 38.3 %, 194.8 %, and 27.0 %. Furthermore, three inhibitors (inhibitors of GST, glutathione synthesis, and ABCC1) were used for further investigation, showing that these inhibitors reduced macrophage survival rates by 44.0 %, 52.3 %, and 43.3 %, while the intracellular adriamycin content increased by 28.9 %, 42.9 %, and 51.3 %, respectively. These findings suggest that the protective mechanism of LPS on macrophages is associated with increased GST activity, the consumption of glutathione, and increased expression of ABCC1 protein. Therefore, LPS has a potential role in enhancing immunity.

In-silico exploration and structure-based design of Praziquantel derivatives as potential inhibitors of schistosoma mansoni Glutathione S-transferase (SmGST)

Schistosomiasis is a chronic parasitic disease with significant public health challenges due to the limited number of treatment options and increasing levels of drug resistance against the only available drug, Praziquantel (PZQ). Consequently, there has been ongoing research in discovering new and more effective drugs for treating schistosomiasis. In this regards, structure-based drug design was employed to generate novel derivatives of PZQ with enhanced binding affinities. Molecular-docking simulations of twenty-four derivatives was performed, with the goal of identifying a prominent lead for further design. Among the screened derivatives, compound 23 showed the most favorable binding energies (Moldock score of -101.846 kcal mol−1) making it the preferred lead candidate. Five novel `compounds were designed, each demonstrating enhanced binding energies (ranging from -108.645 to -112.237 kcal mol−1) compared to the standard drug with a Moldock score of -90.663 kcal mol−1. Notably, 23d demonstrated the highest binding energies among the designed entities (-112.237 kcal mol−1). The identified compounds displayed potent inhibition of Schistosoma mansoni Glutathione S-transferase (SmGST) and met the drug-likeness criteria of the Lipinski, Ghose, Verber, and Egan. Additionally, a blood-brain barrier (BBB) value > -1 and a central nervous system (CNS) value > -3, signifying their capability to efficiently traverse the BBB and access the CNS. Furthermore, they were found to be non-AMES toxic, ensuring their safety in this regard. Molecular dynamic simulations and density function theory confirmed the ligands' chemical reactivity and ligand-complex stability under biological conditions. This makes them promising candidates for the development of drugs for treating Schistosomiasis.

Inhibition of Aflatoxin Production in Aspergillus flavus by a Klebsiella sp. and Its Metabolite Cyclo(l-Ala-Gly).

During an experiment where we were cultivating aflatoxigenic Aspergillus flavus on peanuts, we accidentally discovered that a bacterium adhering to the peanut strongly inhibited aflatoxin (AF) production by A. flavus. The bacterium, isolated and identified as Klebsiella aerogenes, was found to produce an AF production inhibitor. Cyclo(l-Ala-Gly), isolated from the bacterial culture supernatant, was the main active component. The aflatoxin production-inhibitory activity of cyclo(l-Ala-Gly) has not been reported. Cyclo(l-Ala-Gly) inhibited AF production in A. flavus without affecting its fungal growth in a liquid medium with stronger potency than cyclo(l-Ala-l-Pro). Cyclo(l-Ala-Gly) has the strongest AF production-inhibitory activity among known AF production-inhibitory diketopiperazines. Related compounds in which the methyl moiety in cyclo(l-Ala-Gly) is replaced by ethyl, propyl, or isopropyl have shown much stronger activity than cyclo(l-Ala-Gly). Cyclo(l-Ala-Gly) did not inhibit recombinant glutathione-S-transferase (GST) in A. flavus, unlike (l-Ala-l-Pro), which showed that the inhibition of GST was not responsible for the AF production-inhibition of cyclo(l-Ala-Gly). When A. flavus was cultured on peanuts dipped for a short period of time in a dilution series bacterial culture broth, AF production in the peanuts was strongly inhibited, even at a 1 × 104-fold dilution. This strong inhibitory activity suggests that the bacterium is a candidate for an effective biocontrol agent for AF control.

Insight into the herbicide resistance patterns in Lolium rigidum populations in Tunisian and Moroccan wheat regions.

Rigid ryegrass (Lolium rigidum Gaud.) is one of the most troublesome weeds in Moroccan and Tunisian cereal crop fields. In total, 19 rigid ryegrass field populations were randomly selected in northern wheat crop areas of Morocco and Tunisia to examine the patterns of herbicide resistance to acetolactate synthase (ALS)- and acetyl-CoA carboxylase (ACCase)-inhibiting herbicides. Greenhouse experiments confirmed reduced sensitivity to ALS- and/or ACCase-inhibiting herbicides in all L. rigidum populations. The occurrence of target-site resistance (TSR) was tested using high-throughput genotyping. The advent of next-generation sequencing (NGS) has enabled easy identification of causal mutations and confirmed the presence of ALS and ACCase mutations at specific codons conferring TSR. Thirteen populations showed resistance to ALS-inhibiting herbicides associated with point mutations in positions Pro-197-Thr, Pro-197-Ser, Pro-197-Leu, Pro-197-Gln and Trp-574-Leu, while resistance to ACCase-inhibiting herbicides was detected in 18 populations in positions Asp-2078-Val, Trp-2027-Cys, Ile-1781-Leu, Gly-2096-Ala, and Ile-2041-Asn of the enzymes conferring TSR. Additionally, dose-response experiments with pyroxsulam applied after the inhibition of cytochrome P450 monooxygenase by malathion showed an increase in sensitivity in two out of seven highly resistant (HR) rigid ryegrass populations. This demonstrates the presence of non-target-site resistance (NTSR) in some ryegrass populations. Further evidence of NTSR was investigated in dose-response experiments with pyroxsulam, following pretreatment with the glutathione S-transferase (GST) inhibitor 4-chloro-7-nitrobenzoxadiazole (NBD-Cl), which partially reversed resistance in only a few individuals of two L. rigidum populations. Hence, our study confirms the existence of multiple and cross-resistance to ALS- and ACCase-inhibiting herbicides in L. rigidum from Morocco and Tunisia with both TSR and NTSR mechanisms. These results emphasize local resistance management as an important tool to detect and mitigate gene flow from rigid ryegrass populations where resistance has evolved.

The roles of the biochemical and molecular changes in resistance of Tetranychus urticae populations selected with spiromesifen+abamectin mixture </p >

The physiological changes in Tetranychus urticae selected with spiromesifen+abamectin (S+A) mixture formulation were demonstrated by biochemical and molecular methods. The susceptible (GSS) population of T. urticae, was selected with S+A and made resistant with increasing doses of the mixture formulation. The resistant population was divided into two, and selection pressure was terminated in one population which is named IR (Interrupt resistant). In the other population, the selection with S+A was continued and the population named IR2. Activities of some detoxification enzymes (esterase, glutathione-S-transferase (GST) and cytochrome P450) were investigated in the GSS and IR populations. The activity of esterase, GST and P450 enzymes were increased by 1.77, 2.57 and 2.58-fold, respectively, in the IR population compared to the GSS population. Also, investigation of synergistic effects with esterase inhibitor (TTP), GST inhibitor (DEM) and P450 inhibitor (PBO) in this population revealed that all three synergists showed significant synergistic effects in IR population. In molecular studies, when the population was screened for the presence of two previously identified glutamate channel mutations (G314D and G326E) by qPCR with TaqMan probes no mutations could be detected in glutamate channels. and the CTD domain of acetyl coenzyme-A carboxylase (ACCase). Furthermore, possible genetic mutations in the biotin carboxylase domain (BCD) and carboxyl transferase domain (CTD) of the ACCase target sites were determined by sequencing. Although a single amino acid mutation G37D in the BCD of the ACCase gene of the IR and IR2 populations was detected, its association with spiromesifen resistance was not confirmed. The results indicated that increased detoxification and possible target site mutation may be responsible for the S+A resistance in the IR and IR2 populations.

Rapid discovery of a novel “green” and natural GST inhibitor for sensitizing hepatocellular carcinoma to Cisplatin by visual screening strategy

Over-expression of glutathione S-transferase (GST) can promote Cisplatin resistance in hepatocellular carcinoma (HCC) treatment. Hence, inhibiting GST is an attractive strategy to improve Cisplatin sensitivity in HCC therapy. Although several synthesized GST inhibitors have been developed, the side effects and narrow spectrum for anticancer seriously limit their clinical application. Considering the abundance of natural compounds with anticancer activity, this study developed a rapid fluorescence technique to screen “green” natural GST inhibitors with high specificity. The fluorescence assay demonstrated that schisanlactone B (hereafter abbreviated as C1) isolated from Xue tong significantly down-regulated GST levels in Cisplatin-resistant HCC cells in vitro and in vivo. Importantly, C1 can selectively kill HCC cells from normal liver cells, effectively improving the therapeutic effect of Cisplatin on HCC mice by down-regulating GST expression. Considering the high GST levels in HCC patients, this compound demonstrated the high potential for sensitizing HCC therapy in clinical practice by down-regulating GST levels.

Some anticancer agents as effective glutathione S-transferase (GST) inhibitors

Abstract The objective of this research was to investigate the impact of anthraquinone (AQ) compounds on the activity of the enzyme glutathione S-transferase (GST). The interaction between GST and some AQs (alizarin, purpurin, quinizarin, and dantron) was investigated, and IC50 and K i levels were determined for each compound. The results obtained reveal that these compounds are potent GST inhibitors. K i values of these compounds against GST were found ranging from 9.133 ± 0.895 to 36.992 ± 6.194 μM. In the in vitro study, purpurin was identified as the most potent AQ against GST. Thereafter, binding mode exploration of purpurin to the enzyme was undertaken to elucidate its mechanism of action. To this end, molecular docking was conducted. According to the docking results, purpurin can bind to the enzyme and form a stable complex. Together with this, binding potential of purpurin was less than the standard ligand. Examination of both the inhibitory activity in vitro and molecular docking interactions of these anticancer agents with GST, an enzyme important for detoxification metabolism, led to the identification of important relationships between these compounds and GST. The findings may offer structural direction for developing superior anticancer drugs or powerful GST inhibitors.

A common mechanism of detoxification for lambda-cyhalothrin and abamectin in Cydia pomonella

BackgroundThe primary method utilized by orchard owners to combat Cydia pomonella is the application of various chemical insecticides. However, this has resulted in the development of resistance. The resistance mechanisms to insecticides from different chemical classes are diverse but interconnected. Therefore, it is crucial to comprehend the commonalities in these mechanisms to effectively develop strategies for managing resistance.Materials and methodsTo determine whether target-site insensitivity to LCT and AM plays a role in resistance, the sequences of voltage-gated sodium channel (VGSC) and glutamate-gated chloride channel (GluCl) containing the mutation domains were detected. To validate whether similar mechanisms were involved in the detoxification process of lambda-cyhalothrin (LCT) and abamectin (AM) at sublethal doses (specifically LD10 and LD30), cytochrome P450 monooxygenases (P450), glutathione S-transferases (GST), and carboxylesterases (CarE) activities were evaluated after insecticides exposure; synergistic experiments were conducted using piperonyl butoxide (PBO), diethyl maleate (DEM), and triphenyl phosphate (TPP) as inhibitors of P450, GST, and CarE respectively. RNA-sequencing (RNA-Seq) was performed to compare the expression levels of detoxification-related genes between susceptible (SS) and resistant strains.ResultsThe best known target-site mutations caused by LCT and AM, including L1014F in VGSC and V263I, A309V, I321T, and G326E in GluCl were not occurred. We observed that PBO had a strong synergistic effect on LCT and AM, while DEM on LCT. The activities of detoxification enzymes increased after insecticide exposures, indicating that the detoxification of LCT was primarily carried out by P450 and CarE enzymes, while P450 and GST enzymes played a major role in the detoxification of AM. A total of 72 P450 genes and 75 CarE genes were identified in the C. pomonella transcriptome, with 43 of these genes (including 11 P450, 3 GST, 10 CarE, 11 ABC transporters, and 8 UDP-glycosyl transferases) being over-expressed in response to both insecticides Interestingly, ABC transporters were predominantly induced by AM treatment, while GST showed higher induction levels with LCT treatment. Furthermore, LCT-resistant strains of C. pomonella exhibited higher levels of induction of detoxification-related genes compared to susceptible strains.ConclusionThe up-regulation of these detoxification genes is a common metabolic mechanism employed by C. pomonella to counteract the effects of insecticides, although the extent of gene expression change varies depending on the specific insecticide.

ALS gene overexpression and enhanced metabolism conferring Digitaria sanguinalis resistance to nicosulfuron in China.

Crabgrass (Digitaria sanguinalis) is a common malignant weed in corn fields in China. Recently, the acetolactate synthase (ALS) inhibitor, nicosulfuron, has shown decreasing efficacy against crabgrass. In order to elucidate the molecular basis of resistance to nicosulfuron in crabgrass, we conducted bioassays, combined with gene sequence analysis, relative expression and relative copy number analysis, to characterize resistance in crabgrass populations collected from Beijing, Heilongjiang, Jilin and Anhui provinces. Whole-plant dose-response results indicated that only population collected in Heilongjiang province (HLJ) had developed low level of resistance to nicosulfuron compared with the sensitive population (SD22). No known resistant mutation of ALS gene was found in HLJ population. The real-time fluorescence quantitative PCR results showed that the ALS gene copy number did not differ significantly between the HLJ and SD22 populations. However, the ALS gene expression in the HLJ was 2.07-fold higher than that of the SD22 population at 24 h after treatment with nicosulfuron. Pretreatment with the cytochrome P450 (CYP450) inhibitor malathion, piperonyl butoxide (PBO), and the glutathione S-transferase (GST) inhibitor 4-Chloro-7-nitro-1,2,3-benzoxadiazole (NBD-Cl) all partially reversed HLJ resistance. Among them, the synergistic effect of PBO and nicosulfuron is the most significant. This is the first report of resistance to nicosulfuron in crabgrass through ALS gene overexpression and possible metabolic resistance.

A glutathione S-transferase and a cytochrome P450 may confer cyhalofop-butyl resistance in Leptochloa chinensis (L.) Nees

BackgroundLeptochloa chinensis (L.) Nees is a troublesome weed across China in rice fields, and a suspected L. chinensis resistant population (R) that has survived the recommended field dose of cyhalofop-butyl was collected in a rice field of Hunan Province, China. In this study, we aimed to determine the acetyl-CoA carboxylase-inhibiting herbicide resistance profile of this R population and to investigate its mechanisms of resistance to cyhalofop-butyl. ResultsCompared with the susceptible population (S), the R population was confirmed to be 18.9-, 3.2-, 4.1-, 3.6- and 5.8- fold resistant to the APP herbicides cyhalofop-butyl, haloxyfop-P-methyl, clodinafop-propargyl, metamifop and fenoxaprop-P-ethyl, respectively. ACCase gene sequencing analysis revealed no known resistance mutations for TSR in the R population. Pretreatment with the glutathione S-transferase (GST) inhibitor 4-chloro-7-nitrobenzoxadiazole (NBD-Cl) and cytochrome P450 (CYP450) inhibitor malathion reversed resistance to cyhalofop-butyl. The GST gene GSTU1 and CYP450 gene CYP707A5 were constitutively upregulated in the R population according to RNA-seq analysis and RT-qPCR verification. The molecular docking results indicated a good affinity of the active site for five APP herbicides with GSTU1 and CYP707A5. ConclusionThis study shows that the GSTU1 and CYP707A5 genes expressed highly in the R population may be responsible for cyhalofop-butyl resistance in L. chinensis.

Overexpression of Glutathione S-Transferases in Human Diseases: Drug Targets and Therapeutic Implications.

Glutathione S-transferases (GSTs) are a major class of phase II metabolic enzymes. Besides their essential role in detoxification, GSTs also exert diverse biological activities in the occurrence and development of various diseases. In the past few decades, much research interest has been paid to exploring the mechanisms of GST overexpression in tumor drug resistance. Correspondingly, many GST inhibitors have been developed and applied, solely or in combination with chemotherapeutic drugs, for the treatment of multi-drug resistant tumors. Moreover, novel roles of GSTs in other diseases, such as pulmonary fibrosis and neurodegenerative diseases, have been recognized in recent years, although the exact regulatory mechanisms remain to be elucidated. This review, firstly summarizes the roles of GSTs and their overexpression in the above-mentioned diseases with emphasis on the modulation of cell signaling pathways and protein functions. Secondly, specific GST inhibitors currently in pre-clinical development and in clinical stages are inventoried. Lastly, applications of GST inhibitors in targeting cell signaling pathways and intracellular biological processes are discussed, and the potential for disease treatment is prospected. Taken together, this review is expected to provide new insights into the interconnection between GST overexpression and human diseases, which may assist future drug discovery targeting GSTs.

Feedback enhanced tumor targeting delivery of albumin-based nanomedicine to amplify photodynamic therapy by regulating AMPK signaling and inhibiting GSTs

Oxidative therapies receive a limited antitumor efficiency due to the insufficient reactive oxygen species (ROS) levels at focal sites and the evolvement of antioxidant defense systems. Herein, we develop an albumin-based nanomedicine to co-deliver chlorin e6 (Ce6) and COH-SR4 (CS), which can simultaneously enhance the yield and lethality of intracellular ROS for amplified photodynamic therapy (PDT). In which, CS acts as both an activator of AMP-activated protein kinase (AMPK) and an inhibitor of glutathione S-transferases (GSTs). Benefiting from it, the prepared HSA-Ce6@COH-SR4 (HCCS) enables positive feedback uptake by promoting AMPK phosphorylation, leading to rapid and extensive tumor accumulation of drugs. As a result, HCCS obviously increases the ROS production to elevate intracellular oxidative stress. Furthermore, HCCS can inhibit GSTs to disturb the antioxidant defense system of tumor cells, intensifying the oxidative damage of ROS. Ultimately, the PDT of HCCS is significantly strengthened by improving the ROS yield and lethality, which greatly declines the proliferation of breast cancer in vivo. This study may open a window in the development of drug co-delivery system for enhanced oxidative therapy of tumors.

A dual-acting aldose reductase inhibitor impedes oxidative and carbonyl stress in tissues of fructose- and streptozotocin-induced rats: comparison with antioxidant stobadine

Inhibiting aldose reductase (ALR2, AR) as well as maintaining a concomitant antioxidant (AO) activity via dual-acting agents may be a rational approach to prevent cellular glucotoxicity and at least delay the progression of diabetes mellitus (DM). This study was aimed at evaluating the dual-acting AR inhibitor (ARI) cemtirestat (CMTI) on tissue oxidative stress (OS) and carbonyl stress (CS) biomarkers in rats exposed to fructose alone (F) or fructose plus streptozotocin (D; type-2 diabetic). D and F rats were either untreated or treated daily with low- or high-dose CMTI, ARI drug epalrestat (EPA) or antioxidant stobadine (STB) for 14 weeks. Malondialdehyde (MDA), glutathione S-transferase (GST), nitric oxide synthase (NOS), and catalase (CAT) were increased in the sciatic nerve of F and D. These increases were attenuated by low doses of CMTI and STB in D, but exacerbated by low-dose EPA and high-dose CMTI in F. STB and CMTI and to a lesser extent EPA improved MDA, protein-carbonyl, GST and CAT in the hearts and lungs of F and D. CMTI and STB were more effective than EPA in improving the increased MDA and protein-carbonyl levels in the kidneys of F and especially D. CMTI ameliorated renal GST inhibition in D. In the lungs, hearts, and kidneys of F and D, the GSH to GSSG ratio decreased and caspase-3 activity increased, but partially resolved with treatments. In conclusion, CMTI with ARI/AO activity may be advantageous in overcoming OS, CS, and their undesirable consequences, with low dose efficacy and limited toxicity, compared to ARI or antioxidant alone.

Eleusine indica Cytochrome P450 and Glutathione S-Transferase Are Linked to High-Level Resistance to Glufosinate.

Eleusine indica has become a global nuisance weed and has evolved resistance to glufosinate. The involvement of target-site resistance (TSR) in glufosinate resistance in E. indica has been elucidated, while the role of nontarget-site resistance (NTSR) remains unclear. Here, we identified a glufosinate-resistant (R) population that is highly resistant to glufosinate, with a resistance index of 13.5-fold. Molecular analysis indicated that the resistance mechanism of this R population does not involve TSR. In addition, pretreatment with two known metabolic enzyme inhibitors, the cytochrome P450 (CYP450) inhibitor malathion and the glutathione S-transferase (GST) inhibitor 4-chloro-7-nitrobenzoxadiazole (NBD-Cl), increased the sensitivity of the R population to glufosinate. The results of subsequent RNA sequencing (RNA-seq) and quantitative real-time PCR (RT-qPCR) suggested that the constitutive overexpression of a GST gene (GSTU3) and three CYP450 genes (CYP94s and CYP71) may play an important role in glufosinate resistance. This study provides new insights into the resistance mechanism of E. indica.

Arylcoumarin and novel biscoumarin derivatives as potent inhibitors of human glutathione S-transferase

A series of arylcoumarin derivatives and two novel biscoumarin derivatives were investigated for their human recombinant glutathione S-transferase P1-1 (GSTP1-1) enzyme inhibitory activities for the first time. 4-(3,4-Dihydroxyphenyl)-6,7-dihydroxycoumarin (compound 24) was observed to be the most active coumarin derivative (IC50: 0.14 µM). The inhibition was found to be time-dependent and irreversible. Hypothetical binding modes of the ten most active compounds were calculated by molecular docking. Ligand efficiency indices (LEI) were estimated to better understand the binding performance of the coumarin derivatives. Extensive structure-activity relationship studies showed that hydroxy substitution on both the coumarin and the aryl ring enhanced the biological activity and the position of hydroxy group on the coumarin ring is critical for the binding pose and the activity. Top three ligands were subjected to molecular dynamics simulations and MM/PBSA for further investigation. Binding mode of compound 24 suggested that its high inhibitory activity might be attributed to its position between Tyr7 and the cofactor, glutathione (GS-DNB). Exhibiting favorable druglikeness profiles and pharmacokinetics based on ADME studies, compound 5 and 24 can be considered as potential drug leads in future studies for further development. Communicated by Ramaswamy H. Sarma

Busulfan induces steatosis in HepaRG cells but not in primary human hepatocytes: Possible explanations and implication for the prediction of drug-induced liver injury.

The antineoplastic drug busulfan can induce different hepatic lesions including cholestasis and sinusoidal obstruction syndrome. However, hepatic steatosis has never been reported in patients. This study aimed to determine whether busulfan could induce steatosis in primary human hepatocytes (PHH) and differentiated HepaRG cells. Neutral lipids were determined in PHH and HepaRG cells. Mechanistic investigations were performed in HepaRG cells by measuring metabolic fluxes linked to lipid homeostasis, reduced glutathione (GSH) levels, and expression of genes involved in lipid metabolism and endoplasmic reticulum (ER) stress. Analysis of two previous transcriptomic datasets was carried out. Busulfan induced lipid accumulation in HepaRG cells but not in six different batches of PHH. In HepaRG cells, busulfan impaired VLDL secretion, increased fatty acid uptake, and induced ER stress. Transcriptomic data analysis and decreased GSH levels suggested that busulfan-induced steatosis might be linked to the high expression of glutathione S-transferase (GST) isoenzyme A1, which is responsible for the formation of the hepatotoxic sulfonium cation conjugate. In keeping with this, the GST inhibitor ethacrynic acid and the chemical chaperone tauroursodeoxycholic acid alleviated busulfan-induced lipid accumulation in HepaRG cells supporting the role of the sulfonium cation conjugate and ER stress in steatosis. While the HepaRG cell line is an invaluable tool for pharmacotoxicological studies, it might not be always an appropriate model to predict and mechanistically investigate drug-induced liver injury. Hence, we recommend carrying out toxicological investigations in both HepaRG cells and PHH to avoid drawing wrong conclusions on the potential hepatotoxicity of drugs and other xenobiotics.