Synthesis and structure-activity relationship of ethacrynic acid analogues on glutathione-s-transferase P1-1 activity inhibition

Glutathione S-transferase: A versatile and dynamic enzyme

The dynamic and versatile group of enzymes referred to as glutathione S-transferases (GSTs) play diverse roles in cellular detoxification, safeguarding hosts from oxidative damage, and performing various other functions. This review explores different classes of GST, existence of polymorphisms in GST, functions of GST and utilizations of GST inhibitors in treatment of human diseases. The study indicates that the cytosolic GSTs, mitochondrial GSTs, microsomal GSTs, and bacterial proteins that provide resistance to Fosfomycin are the major classes. Given a GST, variation in its expression and function among individuals is due to the presence of polymorphic alleles that encode it. Genetic polymorphism might result in the modification of GST activity, thereby increasing individuals' vulnerability to harmful chemical compounds. GSTs have been demonstrated to play a regulatory function in cellular signalling pathways through kinases, S-Glutathionylation, and in detoxification processes. Various applications of bacterial GSTs and their potential roles in plants were examined. Targeting GSTs, especially GSTP1-1, is considered a potential therapeutic strategy for treating cancer and diseases linked to abnormal cell proliferation. Their role in cancer cell growth, differentiation, and resistance to anticancer agents makes them promising targets for drug development, offering prospects for the future.

Ethacrynic Acid: A Promising Candidate for Drug Repurposing as an Anticancer Agent

Ethacrynic acid (ECA) is a diuretic that inhibits Na-K-2Cl cotransporter (NKCC2) present in the thick ascending loop of Henle and muculo dens and is clinically used for the treatment of edema caused by excessive body fluid. However, its clinical use is limited due to its low bioavailability and side effects, such as liver damage and hearing loss at high doses. Despite this, ECA has recently emerged as a potential anticancer agent through the approach of drug repositioning, with a novel mechanism of action. ECA has been shown to regulate cancer hallmark processes such as proliferation, apoptosis, migration and invasion, angiogenesis, inflammation, energy metabolism, and the increase of inhibitory growth factors through various mechanisms. Additionally, ECA has been used as a scaffold for synthesizing a new material, and various derivatives have been synthesized. This review explores the potential of ECA and its derivatives as anticancer agents, both alone and in combination with adjuvants, by examining their effects on ten hallmarks of cancer and neuronal contribution to cancer. Furthermore, we investigated the trend of synthesis research of a series of ECA derivatives to improve the bioavailability of ECA. This review highlights the importance of ECA research and its potential to provide a cost-effective alternative to new drug discovery and development for cancer treatment.

Ethacrynic acid is an inhibitor of human factor XIIIa

Background

Ethacrynic acid (EA) is a loop diuretic that is approved orally and parenterally to manage edema-associated diseases. Nevertheless, it was earlier reported that it is also associated with bleeding upon its parenteral administration. In this report, we investigated the effects of EA on human factor XIIIa (FXIIIa) of the coagulation process using a variety of techniques.

Methods

A series of biochemical and computational methods have been used in this study. The potency and efficacy of human FXIIIa inhibition by EA was evaluated using a bisubstrate-based fluorescence trans-glutamination assay under near physiological conditions. To establish the physiological relevance of FXIIIa inhibition by EA, the effect on FXIIIa-mediated polymerization of fibrin(ogen) as well as the formation of fibrin(ogen) – α2-antiplasmin complex was evaluated using SDS-PAGE experiments. The selectivity profile of EA against other coagulation proteins was assessed by evaluating EA’s effect on human clotting times in the activated partial thromboplastin time (APTT) and the prothrombin time (PT) assays. We also used molecular modeling studies to put forward a putative binding mode for EA in the active site of FXIIIa. Results involving EA were the average of at least three experiments and the standard error ± 1 was provided. In determining the inhibition parameters, we used non-linear regression analysis.

Results

FXIIIa is a transglutaminase that works at the end of the coagulation process to form an insoluble, rigid, and cross-linked fibrin rich blood clot. In fact, inhibition of FXIIIa-mediated biological processes has been reported to result in a bleeding diathesis. Inhibition of FXIIIa by EA was investigated given the nucleophilic nature of the thiol-containing active site of the enzyme and the Michael acceptor-based electrophilicity of EA. In a bisubstrate-based fluorescence trans-glutamination assay, EA inhibited FXIIIa with a moderate potency (IC50 ~ 105 µM) and efficacy (∆Y ~ 66%). In SDS-PAGE experiments, EA appears to significantly inhibit the FXIIIa-mediated polymerization of fibrin(ogen) as well as the formation of fibrin(ogen) – α2-antiplasmin complex which indicates that EA affects the physiological functions of FXIIIa. Interestingly, EA did not affect the clotting times of human plasma in the APTT and the PT assays at the highest concentration tested of 2.5 mM suggesting the lack of effects on the coagulation serine proteases and potentially the functional selectivity of EA with respect to the clotting process. Molecular modeling studies demonstrated that the Michael acceptor of EA forms a covalent bond with catalytic residue of Cys314 in the active site of FXIIIa.

Conclusions

Overall, our studies indicate that EA inhibits the physiological function of human FXIIIa in vitro which may potentially contribute to the bleeding complications that were reported with the association of the parenteral administration of EA.

Phosphorus Dendrimers as Nanotools against Cancers

This review concerns the use of dendrimers, especially of phosphorhydrazone dendrimers, against cancers. After the introduction, the review is organized in three main topics, depending on the role played by the phosphorus dendrimers against cancers: (i) as drugs by themselves; (ii) as carriers of drugs; and (iii) as indirect inducer of cancerous cell death. In the first part, two main types of phosphorus dendrimers are considered: those functionalized on the surface by diverse organic derivatives, including known drugs, and those functionalized by diverse metal complexes. The second part will display the role of dendrimers as carriers of anticancer “drugs”, which can be either small molecules or anticancer siRNAs, or the combination of both. In the third part are gathered a few examples of phosphorhydrazone dendrimers that are not cytotoxic by themselves, but which under certain circumstances induce a cytotoxic effect on cancerous cells. These examples include a positive influence on the human immune system and the combination of bioimaging with photodynamic therapy properties.

F. A review on the development of urease inhibitors as antimicrobial agents against pathogenic bacteria

Ureases are enzymes that hydrolyze urea into ammonium and carbon dioxide. They have received considerable attention due to their impacts on living organism health, since the urease activity in microorganisms, particularly in bacteria, are potential causes and/or factors contributing to the persistence of some pathogen infections. This review compiles examples of the most potent antiurease organic substances. Emphasis was given to systematic screening studies on the inhibitory activity of rationally designed series of compounds with the corresponding SAR considerations. Ureases of Canavalia ensiformis, the usual model in antiureolytic studies, are emphasized. Although the active site of this class of hydrolases is conserved among bacteria and vegetal ureases, the same is not observerd for allosteric site. Therefore, inhibitors acting by participating in interactions with the allosteric site are more susceptible to a potential lack of association among their inhibitory profile for different ureases. The information about the inhibitory activity of different classes of compounds can be usefull to guide the development of new urease inhibitors that may be used in future in small molecular therapy against pathogenic bacteria.

Assembly of ligands interaction models for glutathione-S-transferases from Plasmodium falciparum, human and mouse using enzyme kinetics and molecular docking

BACKGROUND

Glutathione-s-transferases (GSTs) are enzymes that principally catalyze the conjugation of electrophilic compounds to the endogenous nucleophilic glutathione substrate, besides, they have other non-catalytic functions. The Plasmodium falciparum genome encodes a single isoform of GST (PfGST) which is involved in buffering the toxic heme, thus considered a potential anti-malarial target. In mammals several classes of GSTs are available, each of various isoforms. The human (human GST Pi-1 or hGSTP1) and mouse (murine GST Mu-1 or mGSTM1) GST isoforms control cellular apoptosis by interaction with signaling proteins, thus considered as potential anti-cancer targets. In the course of GSTs inhibitors development, the models of ligands interactions with GSTs are used to guide rational molecular modification. In the absence of X-ray crystallographic data, enzyme kinetics and molecular docking experiments can aid in addressing ligands binding modes to the enzymes.

METHODS

Kinetic studies were used to investigate the interactions between the three GSTs and each of glutathione, 1-chloro-2,4-dinitrobenzene, cibacron blue, ethacrynic acid, S-hexyl glutathione, hemin and protoporphyrin IX. Since hemin displacement is intended for PfGST inhibitors, the interactions between hemin and other ligands at PfGST binding sites were studied kinetically. Computationally determined binding modes and energies were interlinked with the kinetic results to resolve enzymes-ligands interaction models at atomic level.

RESULTS

The results showed that hemin and cibacron blue have different binding modes in the three GSTs. Hemin has two binding sites (A and B) with two binding modes at site-A depending on presence of GSH. None of the ligands were able to compete hemin binding to PfGST except ethacrynic acid. Besides bind differently in GSTs, the isolated anthraquinone moiety of cibacron blue is not maintaining sufficient interactions with GSTs to be used as a lead. Similarly, the ethacrynic acid uses water bridges to mediate interactions with GSTs and at least the conjugated form of EA is the true hemin inhibitor, thus EA may not be a suitable lead.

CONCLUSIONS

Glutathione analogues with bulky substitution at thiol of cysteine moiety or at γ-amino group of γ-glutamine moiety may be the most suitable to provide GST inhibitors with hemin competition.

Potent anti-proliferative actions of a non-diuretic glucosamine derivative of ethacrynic acid

Ethacrynic acid (EA), a known inhibitor of the neoplastic marker glutathione S-transferase P1 and other GSTs, exerts a weak antiproliferative activity against human cancer cells. The clinical use of EA (Edecrin) as an anticancer drug is limited by its potent loop diuretic activity. In this study, we developed a non-diuretic 2-amino-2-deoxy-d-glucose conjugated EA (EAG) to target tumors cells via the highly expressed glucose transporter 1 (GLUT1). Cell survival assays revealed that EAG had little effect on normal cells, but was cytotoxic 3 to 4.5-fold greater than EA. Mechanistically, the EAG induced selective cell death in cancer cells by inhibiting GSTP1 and generating abundant reactive oxygen species. Furthermore, EAG induced p21(cip1) expression and a G2/M cell cycle block irrespective of the p53 gene status in tumor cells. These data encourage the development of new EA analogs.

Influence of glutathione-S-transferase (GST) inhibition on lung epithelial cell injury: role of oxidative stress and metabolism

Oxidant-mediated tissue injury is key to the pathogenesis of acute lung injury. Glutathione- S-transferases (GSTs) are important detoxifying enzymes that catalyze the conjugation of glutathione with toxic oxidant compounds and are associated with acute and chronic inflammatory lung diseases. We hypothesized that attenuation of cellular GST enzymes would augment intracellular oxidative and metabolic stress and induce lung cell injury. Treatment of murine lung epithelial cells with GST inhibitors, ethacrynic acid (EA), and caffeic acid compromised lung epithelial cell viability in a concentration-dependent manner. These inhibitors also potentiated cell injury induced by hydrogen peroxide (H2O2), tert-butyl-hydroperoxide, and hypoxia and reoxygenation (HR). SiRNA-mediated attenuation of GST-π but not GST-μ expression reduced cell viability and significantly enhanced stress (H2O2/HR)-induced injury. GST inhibitors also induced intracellular oxidative stress (measured by dihydrorhodamine 123 and dichlorofluorescein fluorescence), caused alterations in overall intracellular redox status (as evidenced by NAD+/NADH ratios), and increased protein carbonyl formation. Furthermore, the antioxidant N-acetylcysteine completely prevented EA-induced oxidative stress and cytotoxicity. Whereas EA had no effect on mitochondrial energetics, it significantly altered cellular metabolic profile. To explore the physiological impact of these cellular events, we used an ex vivo mouse-isolated perfused lung model. Supplementation of perfusate with EA markedly affected lung mechanics and significantly increased lung permeability. The results of our combined genetic, pharmacological, and metabolic studies on multiple platforms suggest the importance of GST enzymes, specifically GST-π, in the cellular and whole lung response to acute oxidative and metabolic stress. These may have important clinical implications.

Investigations on dendrimer space reveal solid and liquid tumor growth-inhibition by original phosphorus-based dendrimers and the corresponding monomers and dendrons with ethacrynic acid motifs

The well-known reactive diuretic ethacrynic acid (EA, Edecrin), with low antiproliferative activities, was chemically modified and grafted onto phosphorus dendrimers and the corresponding simple branched phosphorus dendron-like derivatives affording novel nanodevices showing moderate to strong antiproliferative activities against liquid and solid tumor cell lines, respectively.

Coniferyl Ferulate, a Strong Inhibitor of Glutathione S-Transferase Isolated from Radix Angelicae sinensis, Reverses Multidrug Resistance and Downregulates P-Glycoprotein

Glutathione S-transferase (GST) is the key enzyme in multidrug resistance (MDR) of tumour. Inhibition of the expression or activity of GST has emerged as a promising therapeutic strategy for the reversal of MDR. Coniferyl ferulate (CF), isolated from the root of Angelica sinensis (Oliv.) Diels (Radix Angelicae sinensis, RAS), showed strong inhibition of human placental GST. Its 50% inhibition concentration (IC₅₀) was 0.3 μM, which was greater than a known GSTP1-1 inhibitor, ethacrynic acid (EA), using the established high-throughput screening model. Kinetic analysis and computational docking were used to examine the mechanism of GST inhibition by CF. Computational docking found that CF could be fully docked into the gorge of GSTP1-1. The further exploration of the mechanisms showed that CF was a reversible noncompetitive inhibitor with respect to GSH and CDNB, and it has much less cytotoxicity. Apoptosis and the expression of P-gp mRNA were evaluated in the MDR positive B-MD-C1 (ADR+/+) cell line to investigate the MDR reversal effect of CF. Moreover, CF showed strong apoptogenic activity and could markedly decrease the overexpressed P-gp. The results demonstrated that CF could inhibit GST activity in a concentration-dependent manner and showed a potential MDR reversal effect for antitumour adjuvant therapy.

The pleiotropic effects of ethacrynic acid

Ethacrynic acid (EC), an effective loop diuretic especially in patients allergic to sulfa-containing drugs, possesses a number of potentially useful actions in addition to the inhibition of the Na⁺-K⁺-2Cl⁻ kidney symport. Inhibition of the enzyme glutathione S-transferase plays an important role in reducing chemotherapy drug resistance. Chemical modifications of EC increase inhibition of glutathione S-transferase and reduce toxicity due to diuretic action (hypotension and hypovolemia). This work may lead to effective therapies in reducing chemotherapy resistance in cancer chemotherapeutics. In addition, EC or conjurers may be a radiation enhancer, an anti-inflammatory agent, or a treatment for glaucoma.

The clinical pharmacology of ethacrynic acid

Ethacrynic acid (Edecrin) is a loop diuretic that produces a prompt and profound diuresis. The primary action of ethacrynic acid is the inhibition of the activity of the Na⁺-K⁺-2Cl⁻ symporter in the thick ascending limb of the loop of Henle. The onset of action is usually within 30 minutes after an oral dose and within 5 minutes after an intravenous injection. After oral administration, peak diuretic effect occurs in about 2 hours and the effect lasts about 6-8 hours. After intravenous administration, peak diuretic effect occurs within 30 minutes and the diuretic effect is virtually completed in 2-4 hours. The bioavailability of ethacrynic acid approximates 100%, with maximal blood level between 40 and 92 minutes. The elimination half-life has been reported to be less than 1 hour, but highly variable (average 30 minutes with a range of 12-160 minutes). Intravenous ethacrynic acid has a prompt venous dilatory effect and immediately relieves symptoms of pulmonary congestion, before a diuresis can occur. Ethacrynic acid is effective in all types of edema whether there is clinical acidosis, alkalosis, or electrolyte imbalance. Most side effects of ethacrynic acid can be attributed to its effectiveness (volume depletion); however, it may cause metabolic alkalosis that is preventable by KCl replacement. Ethacrynic acid has ototoxic effect that occasionally results in temporally or permanent deafness. Despite limitations, ethacrynic acid has been employed in the treatment of congestive heart failure and other edematous states, especially in patients allergic to sulfa-containing drugs because all the other loop diuretics have a sulfa moiety.

Ethacrynic acid and a derivative enhance apoptosis in arsenic trioxide-treated myeloid leukemia and lymphoma cells: the role of glutathione S-transferase p1-1

PURPOSE

Arsenic trioxide (ATO) as a single agent is used for treatment of acute promyelocytic leukemia (APL) with minimal toxicity, but therapeutic effect of ATO in other types of malignancies has not been achieved. We tested whether a combination with ethacrynic acid (EA), a glutathione S-transferase P1-1 (GSTP1-1) inhibitor, and a reactive oxygen species (ROS) inducer will extend the therapeutic effect of ATO beyond APL.

EXPERIMENTAL DESIGN

The combined apoptotic effects of ATO plus ethacrynic acid were tested in non-APL leukemia and lymphoma cell lines. The role of ROS, GSTP1-1, glutathione (GSH), and Mcl-1 in apoptosis was determined. The selective response to this combination of cells with and without GSTP1-1 expression was compared.

RESULTS

ATO/EA combination synergistically induced apoptosis in myeloid leukemia and lymphoma cells. This treatment produced high ROS levels, activated c-jun-NH(2)-kinase (JNK), and reduced Mcl-1 protein. This led to the decrease of mitochondrial transmembrane potential, release of cytochrome c, and subsequently, to activation of caspase-3 and -9. Induction of apoptosis in leukemia and lymphoma cells expressing GSTP1-1 required high ethacrynic acid concentrations to be combined with ATO. Silencing of GSTP1 in leukemia cells sensitized them to ATO/EA-induced apoptosis. In a subgroup of B-cell lymphoma, which does not express GSTP1-1, lower concentrations of ethacrynic acid and its more potent derivative, ethacrynic acid butyl-ester (EABE), decreased intracellular GSH levels and synergistically induced apoptosis when combined with ATO.

CONCLUSION

B-cell lymphoma cells lacking GSTP1-1 are more sensitive than myeloid leukemia cells to ATO/EA-induced apoptosis.

The synthesis of ethacrynic acid thiazole derivatives as glutathione S-transferase pi inhibitors

Glutathione S-transferase pi (GSTpi) is a phase II enzyme which protects cells from death and detoxifies chemotherapeutic agents in cancer cells. Ethacrynic acid (EA) is a weak GSTpi inhibitor. Structure modifications were done to improve the ability of EA to inhibit GSTpi activity. Eighteen EA thiazole derivatives were designed and synthesized. Compounds 9a, 9b and 9c with a replacement of carboxyl group of EA by a heterocyclic thiazole exhibited improvement over EA to inhibit GSTpi activity.

Selective methoxy ether cleavage of 2,6-dimethoxyphenol followed by a selective acylation

A Friedel-Crafts reaction of 2,6-dimethoxyphenol in the presence of aluminum chloride and propanoyl or butanoyl chlorid, respectively, lead, at elevated temperatures, to a selective cleavage of one of the methoxy groups followed by a selective acylation of the meta position with respect to the phenolic hydroxyl group. Under the same reaction conditions 2-methoxyphenol doesn't get demethylated; a mechanism to account for these findings is proposed. This reaction gives access to a variety of ortho-acylated catechols. Substituted catechols are widely used in supramolecular chemistry and are precursors of pesticides, flavors and fragrances. Additionally, catechol moieties are found in various natural products.

Inhibitory effects of ethacrynic acid analogues lacking the α,β-unsaturated carbonyl unit and para-acylated phenols on human cancer cells

A series of ethacrynic acid analogues, lacking the α,β-unsaturated carbonyl unit, was synthesized and subsequently evaluated for their ability to inhibit the migration of human breast cancer cells, Hs578Ts(i)8 as well as of human prostate cancer cells, C4-2B. These cell lines provide a good model system to study migration and invasion, since they represent metastatic cancer. Our studies show that ethacrynic acid analogues with methyl substituents at the aromatic ring demonstrate no inhibitory effect on the migration of both cancer cell lines, whereas a precursor in the synthesis of these ethacrynic acid analogues (II-1, a para-acylated m-cresol) is an excellent inhibitor of the migration of both cancer cell lines.

The tunable functionality of alpha,beta-unsaturated carbonyl compounds enables their differential application in biological systems

alpha,beta-Unsaturated carbonyl compounds as potential drug candidates is a controversial topic since their potential Michael acceptor activity can lead to cell damage and cytotoxicity. Nevertheless, the alpha,beta-unsaturated carbonyl functionality can be employed as a tool to fine tune biological activity by directly manipulating this entity. Depending on their electronic properties, alpha,beta-unsaturated carbonyl functionalities display different reactivities, namely Michael addition, radical scavenging, oxidation or double bond isomerization. Modifying the alpha-position of the alpha,beta-unsaturated carbonyl system, a concept that has not been widely explored, could produce new, very interesting derivatives. Currently in drug development, irreversible binding in active sites has proven to be one answer to drug resistance in cancer treatment. Overall, natural products containing the alpha,beta-unsaturated carbonyl unit possess multiple biological activities that could be transferred into novel pharmaceutical agents.

Ethacrynic acid analogues lacking the alpha,beta-unsaturated carbonyl unit--potential anti-metastatic drugs

A series of ethacrynic acid analogues, lacking the alpha,beta-unsaturated carbonyl unit, was synthesized and subsequently evaluated for their ability to inhibit the migration of human breast cancer cells, MCF-7/AZ. Several of the analogues were already active in the low micromolar range, whereas ethacrynic acid itself shows no potential to inhibit the migration of these cancer cells. Preliminary studies show that the presence of one or more methoxy groups at the phenyl ring of ethacrynic acid is important in order for the ethacrynic acid analogues to demonstrate an inhibitory effect on the migration.

Chalcone derivatives inhibit glutathione S-transferase P1-1 activity: insights into the interaction mode of alpha, beta-unsaturated carbonyl compounds

Resistance to chemotherapeutic drugs has long been a considerable barrier to successful treatment of many cancers and over-expression of glutathione S-transferase P1-1 is correlated to carcinogenesis and resistance of cancer cells against chemotherapeutic agents. This study throws light on the role of chalcone derivatives, a new class of glutathione S-transferase P1-1 inhibitors potentially to overcome glutathione S-transferase P1-1-mediated chemotherapy resistance. Nineteen alpha-substituted chalcone derivatives were synthesized and their in vitro inhibitory effects on glutathione S-transferase P1-1 were determined. We interestingly found that most of these compounds showed inhibitory effect on glutathione S-transferase P1-1 activity. In addition, molecular field-based similarity analysis provides the necessary three-dimensional molecular field properties of alpha, beta-unsaturated carbonyl derivatives to inhibit glutathione S-transferase P1-1 activity. Thus, these compounds have great potential to be developed into novel chemotherapeutic sensitizers.

Organometallic ruthenium inhibitors of glutathione-S-transferase P1-1 as anticancer drugs

Ruthenium-arene complexes conjugated to ethacrynic acid were prepared as part of a strategy to develop novel glutathione-S-transferase (GST) inhibitors with alternate modes of activity through the organometallic fragment, ultimately to provide targeted ruthenium-based anticancer drugs. Enzyme kinetics and electrospray mass spectrometry experiments using GST P1-1 and its cysteine-modified mutant forms revealed that the complexes are effective enzyme inhibitors, but they also rapidly inactivate the enzyme by covalent binding at Cys 47 and, to a lesser extent, Cys 101. They are highly effective against the GST Pi-positive A2780 and A2780cisR ovarian carcinoma cell lines, are among the most effective ruthenium complexes reported so far, and target ubiquitous GST Pi overexpressed in many cancers.

Relationship between GST Yp Induction and Hepatocyte Proliferation in Rats Treated with Phase II Drug Metabolizing Enzyme Inducers

Butylated hydroxyanisole (BHA) and 1,2-bis(2-pyridyl)ethylene (2PY-e) are phase II drug metabolizing enzyme inducers which cause hepatomegaly without hepatocyte hypertrophy and induce glutathione S-transferase Yp (GST Yp, pi-class GST), which is known as a tumor marker. To evaluate the relationship between GST Yp induction and hepatocyte proliferation, male F344/DuCrj rats were treated with BHA, 2PY-e, or phenobarbital (PB) for three or seven days. All three chemicals caused increases in liver weight after three and seven days. Immunohistochemical examinations revealed that BHA and 2PY-e induced GST Yp in the hepatocytes of the periportal and centrilobular areas at three and seven days, respectively, whereas PB did not. Significant increases in the BrdU labeling indices were found in the livers of rats in each of the three-day treatment groups, but the labeling index of rat livers treated with BHA was decreased to the control level at seven days, although the high labeling indices of 2PY-e and PB persisted at seven days. Double immunostaining confirmed that BrdU-positive nuclei corresponded to GST Yp-positive hepatocytes in both BHA and 2PY-e treated rats. These results suggest that the GST Yp induction caused by BHA or 2PY-e has some kind of relationship with hepatocyte proliferation.

New bioactive natural products from Coprinus micaceus

Chemical studies on the crude methanolic extract of Coprinus micaceus, collected from the Canadian Prairie region, have resulted in the isolation of two new natural products, micaceol (1), a sterol and (Z,Z)-4-oxo-2,5-hetpadienedioic acid (2). Compound 2 was isolated for the first time as a natural product. Structures of these new compounds were established with the aid of extensive NMR spectroscopic studies. Compound 1 has shown anti-bacterial activity against Corynebacterium xerosis and Staphylococcus aureus, whereas compound 2 exhibited glutathione S-transferase inhibition.

The synthesis of α,β-unsaturated carbonyl derivatives with the ability to inhibit both glutathione S-transferase P1-1 activity and the proliferation of leukemia cells

Ethacrynic acid (EA), an alpha,beta-unsaturated carbonyl compound, is a glutathione S-transferase P1-1 (GSTP1-1) inhibitor. Twenty-one novel EA derivatives have been synthesized. The effects of these compounds on GSTP1-1 activity and on the proliferation of human leukemia HL-60 cells have been determined. Compounds with a halogen substitution at the 3'-position of the aromatic ring have greater inhibitory effects on GSTP1-1 activity than those of compounds with a methyl substitution there. Compounds with substitutions at both the 2'- and 3'-positions of the aromatic ring have more antiproliferative ability than those with one substitution at 3'-position. Esterification of the carboxyl group appears to increase the antiproliferative ability.

Enantiomeric impurities in chiral synthons, catalysts, and auxiliaries. Part 3

The enantiomeric excess of chiral reagents used in asymmetric syntheses directly affects the reaction selectivity and product purity. In this work, 84 of the more recently available chiral compounds were evaluated to determine their actual enantiomeric composition. These compounds are widely used in asymmetric syntheses as chiral synthons, catalysts, and auxiliaries. These include chiral alcohols, amines, amino alcohols, amides, carboxylic acids, epoxides, esters, ketones, and oxolanes among other classes of compounds. All enantiomeric test results were categorized within five purity levels (i.e. <0.01%, 0.01% to 0.1%, 0.1% to 1%, 1% to 10%, and >10%). The majority of the reagents tested were determined to have enantiomeric impurities over 0.01%, and two of them were found to contain enantiomeric impurities exceeding the 10% level. The most effective enantioselective analysis method was a GC approach using a Chiraldex GTA chiral stationary phase (CSP). This method worked exceedingly well with chiral amines and alcohols.