Discovery of antichagasic inhibitors by high-throughput screening with Trypanosoma cruzi glucokinase

A high-throughput screening (HTS) campaign was carried out for Trypanosoma cruzi glucokinase (TcGlcK), a potential drug-target of the pathogenic protozoan parasite. Glycolysis and the pentose phosphate pathway (PPP) are important metabolic pathways for T. cruzi and the inhibition of the glucose kinases (i.e. glucokinase and hexokinase) may be a strategic approach for drug discovery. Glucose kinases phosphorylate d-glucose with co-substrate ATP to yield G6P, and moreover, the produced G6P enters both pathways for catabolism. The TcGlcK – HTS campaign revealed 25 novel enzyme inhibitors that were distributed in nine chemical classes and were discovered from a primary screen of 13,040 compounds. Thirteen of these compounds were found to have low micromolar IC₅₀ enzyme – inhibition values; strikingly, four of those compounds exhibited low toxicity towards NIH-3T3 murine host cells and notable in vitro trypanocidal activity. These compounds were of three chemical classes: (a) the 3-nitro-2-phenyl-2H-chromene scaffold, (b) the N-phenyl-benzenesulfonamide scaffold, and (c) the gossypol scaffold. Two compounds from the 3-nitro-2-phenyl-2H-chromene scaffold were determined to be hit-to-lead candidates that can proceed further down the early-stage drug discovery process.     

Optimisation of estrogen receptor subtype-selectivity of a 4-Aryl-4H-chromene scaffold previously identified by virtual screening

4-Aryl-4H-Chromene derivatives have been previously shown to exhibit anti-proliferative, apoptotic and anti-angiogenic activity in a variety of tumor models in vitro and in vivo generally via activation of caspases through inhibition of tubulin polymerisation. We have previously identified by Virtual Screening (VS) a 4-aryl-4H-chromene scaffold, of which two examples were shown to bind Estrogen Receptor α and β with low nanomolar affinity and <20-fold selectivity for α over β and low micromolar anti-proliferative activity in the MCF-7 cell line. Thus, using the 4-aryl-4H-chromene scaffold as a starting point, a series of compounds with a range of basic arylethers at C-4 and modifications at the C3-ester substituent of the benzopyran ring were synthesised, producing some potent ER antagonists in the MCF-7 cell line which were highly selective for ERα (compound 35; 350-fold selectivity) or ERβ (compound 42; 170-fold selectivity).     

Monoterpenoids from the aerial parts of Aruncus dioicus var. kamtschaticus and their antioxidant and cytotoxic activities

The aerial parts of Aruncus dioicus var. kamtschaticus afforded five new monoterpenoids (1-5): 4-(erythro-6,7-dihydroxy-9-methylpent-8-enyl)furan-2(5H)-one (1, aruncin A), 2-(8-ethoxy-8-methylpropylidene)-5-hydroxy-3,6-dihydro-2H-pyran-4-carboxylic acid (2, aruncin B), 4-(hydroxymethyl)-6-(8-methylprop-7-enyl)-5,6-dihydro-2H-pyran-2-one-11-O-β-d-glucopyranoside (3, aruncide A), (3S,4S,5R,10R)-3-(10-ethoxy-11-hydroxyethyl)-4-(5-hydroxy-7-methylbut-6-enyl)oxetan-2-one-11-O-β-d-glucopyranoside (4, aruncide B), and (3S,4S,5R,7R)-5-(9-methylprop-8-enyl)-1,6-dioxabicyclo[3,2,0]heptan-2-one-7-(hydroxymethyl)-12-O-β-d-glucopyranoside (5, aruncide C). Compound 2 showed potent cytotoxicity against Jurkat T cells with an IC₅₀ value of 17.15 μg/mL. In addition, compounds 7 and 10 exhibited moderate antioxidant activity with IC₅₀ values of 46.3 and 11.7 μM, respectively.     

Modulation of Platelet Activation and Thrombus Formation Using a Pan-PI3K Inhibitor S14161

The phosphatidylinositol 3–kinase (PI3K) signaling pathway is critical in modulating platelet functions. In the present study, we evaluated the effect of {"type":"entrez-protein","attrs":{"text":"S14161","term_id":"98844","term_text":"pir||S14161"}}S14161, a recently identified pan-class I PI3K inhibitor, on platelet activation and thrombus formation. Results showed that {"type":"entrez-protein","attrs":{"text":"S14161","term_id":"98844","term_text":"pir||S14161"}}S14161 inhibited human platelet aggregation induced by collagen, thrombin, U46619, and ADP in a dose-dependent manner. Flow cytometric studies showed that {"type":"entrez-protein","attrs":{"text":"S14161","term_id":"98844","term_text":"pir||S14161"}}S14161 inhibited convulxin- or thrombin-induced P-selectin expression and fibrinogen binding of single platelet. {"type":"entrez-protein","attrs":{"text":"S14161","term_id":"98844","term_text":"pir||S14161"}}S14161 also inhibited platelet spreading on fibrinogen and clot retraction, processes mediated by outside-in signaling. Using a microfluidic chamber we demonstrated that {"type":"entrez-protein","attrs":{"text":"S14161","term_id":"98844","term_text":"pir||S14161"}}S14161 decreased platelet adhesion on collagen-coated surface by about 80%. Western blot showed that {"type":"entrez-protein","attrs":{"text":"S14161","term_id":"98844","term_text":"pir||S14161"}}S14161 inhibited phosphorylation of Akt at both Ser473 and Thr308 sites, and GSK3β at Ser9 in response to collagen, thrombin, or U46619. Comparable studies showed that {"type":"entrez-protein","attrs":{"text":"S14161","term_id":"98844","term_text":"pir||S14161"}}S14161 has a higher potential bioavailability than {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002, a prototypical inhibitor of pan-class I PI3K. Finally, the effects of {"type":"entrez-protein","attrs":{"text":"S14161","term_id":"98844","term_text":"pir||S14161"}}S14161 on thrombus formation in vivo were measured using a ferric chloride-induced carotid artery injury model in mice. The intraperitoneal injection of {"type":"entrez-protein","attrs":{"text":"S14161","term_id":"98844","term_text":"pir||S14161"}}S14161 (2 mg/kg) to male C57BL/6 mice significantly extended the first occlusion time (5.05±0.99 min, n = 9) compared to the vehicle controls (3.72±0.95 min, n = 8) (P<0.05), but did not prolong the bleeding time (P>0.05). Taken together, our data showed that {"type":"entrez-protein","attrs":{"text":"S14161","term_id":"98844","term_text":"pir||S14161"}}S14161 inhibits platelet activation and thrombus formation without significant bleeding tendency and toxicity, and considering its potential higher bioavailability, it may be developed as a novel therapeutic agent for the prevention of thrombotic disorders.     

Rational design and synthesis of 2-(1H-indazol-6-yl)-1H-benzo[d]imidazole derivatives as inhibitors targeting FMS-like tyrosine kinase 3 (FLT3) and its mutants

Fms-like tyrosine kinase 3 (FLT3) has been verified as a therapeutic target for acute myeloid leukaemia (AML). In this study, we report a series of 2-(1H-indazol-6-yl)-1H-benzo[d]imidazol-5-yl benzamide and phenyl urea derivatives as potent FLT3 inhibitors based on the structural optimisation of previous FLT3 inhibitors. Derivatives were synthesised as benzamide 8a–k, 8n–z, and phenyl urea 8l–m, with various substituents. The most potent inhibitor, 8r, demonstrated strong inhibitory activity against FLT3 and FLT3 mutants with a nanomolar IC₅₀ and high selectivity profiles over 42 protein kinases. In addition, these type II FLT3 inhibitors were more potent against FLT3 mutants correlated with drug resistance. Overall, we provide a theoretical basis for the structural optimisation of novel benzimidazole analogues to develop strong inhibitors against FLT3 mutants for AML therapeutics.     

Structure-activity relationships of 2-aryl-1H-indole inhibitors of the NorA efflux pump in Staphylococcus aureus

The synthesis of 22 2-aryl-1H-indoles, including 12 new compounds, has been achieved via Pd- or Rh-mediated methodologies, or selective electrophilic substitution. All three methods were based on elaborations from simple indole precursors. SAR studies on these indoles and 2-phenyl-1H-indole in Staphylococcus aureus as NorA efflux pump inhibitors indicated 5-nitro-2-(3-methoxycarbonyl)phenyl-1H-indole was a slightly more potent inhibitor than the lead INF55. A promising new antibacterial lead compound against S. aureus (2-phenyl-1H-indol-5-yl)-methanol, was also found.     

Synthesis and antiproliferative activity of new 2-glyco-3-nitro-2H-chromenes

3-nitro-2H-chromenes and derivatives are compounds with diverse biological activity, among them, new 2-glyco-3-nitro-2H-chromenes have been prepared by one-pot oxa-Michael-Henry-dehydration reactions between carbohydrate-derived nitroalkenes and several salicylaldehydes, using a minimal amount of solvent and DBU as catalyst. The antiproliferative activity of these new compounds has been evaluated against a panel of six human solid tumor cell lines, and compared to pharmacological reference compounds, finding that their activities are in the low micromolar range and that some of them are more effective than the standards.     

New 4H-chromen-4-one and 2H-chromene derivatives as anti-picornavirus capsid-binders

Substituted (E)-3-styryl-4H-chromen-4-ones 1a–d, 3-[(1E,3E)-4-phenylbuta-1,3-dienyl]-4H-chromen-4-ones 2a–d, (E)-3-styryl-2H-chromenes 3a–d and 3-[(1E,3E)-4-phenylbuta-1,3-dienyl]-2H-chromenes 4a–d were designed and synthesized to improve the anti-picornavirus activity of previously tested analogues. The new compounds were evaluated in vitro against human rhinovirus (HRV) serotypes 1B and 14 and enterovirus (EV) 71. All the compounds interfered with the replication of picornaviruses, although considerable differences were observed in the sensitivity of viruses to each compound. Generally, both HRVs were more susceptible than EV71 and their sensitivity was dependent upon the linker chain length as well as upon the oxidation state of the heterocyclic ring. (E)-3-Styryl-2H-chromene (3a) emerged as the most effective inhibitor of both HRVs showing IC₅₀ values of 0.20 μM and 1.38 μM towards serotype 1B and 14, respectively. The potent activity was also coupled with low cytotoxicity resulting in high therapeutic indexes (250 and 36, respectively). Mechanism of action studies indicated that 3a, like structurally related compounds, behaves as a capsid binder interfering with the early stages of rhinovirus infection, probably at the adsorption and/or uncoating level.     

Triterpenes and lignans from the leaves of Styrax tonkinensis

Two triterpenes (1 and 2) and eight lignans (3–10) were isolated from the ethyl acetate-soluble fraction of the leaves of Styrax tonkinensis (Pierre) Craib ex Hartw (Styracaceae). Their structures were established as ursolic acid (1), pomolic acid (2), 3,3′-bis(3,4-dihydro-6-methoxy-2H-1-benzopyran) (3), rac-(8α,8′β)-4,4′-dihydroxy-3,3′-dimethoxylignan-9,9′-diyldiacetate (4), (-)-secoisolariciresinol (5), (+)-pinoresinol (6), 4,4′-dihydroxy-3,3′-dimethoxy-9-ethoxy-9,9′-epoxylignan (7), (2S,3R, 4R)-4-[1-ethoxy-1-(4-hydroxy-3-methoxy)phenyl]methyl-2-(4-hydroxy-3-methoxy)phenyl-3-hydroxymethyl-tetrahydrofuran (8), (-)-neo-olivil-(9-O-9″)-seco-isolariciresinol (9) and isolariciresinol (10) based on MS, ¹H-and ¹³C-NMR spectral data. All these compounds (1–10) were firstly isolated from this plant, and compounds 2–5 and 7–9 were reported from the Styrax genus for the first time. Furthermore, the chemotaxonomic significance of the isolated compounds was discussed.     

Design,synthesis and biological evaluation of novel hydrogen sulfide releasing capsaicin derivatives

Capsaicin (CAP), the prototypical TRPV1 agonist, is the major active component in chili peppers with health-promoting benefits. However, its use is limited by the low bioavailability and irritating quality. In this study, for improving the activity of CAP and alleviating its irritating effects, a series of H₂S-releasing CAPs were designed and synthesized by combining capsaicin and dihydro capsaicin with various hydrogen sulfide donors. The resulting compounds were evaluated their TRPV1 agonist activity, analgesic activity, anticancer activities, H₂S-releasing ability, and gastric mucosa irritation. Biological evaluation indicated that the most active compound B₉, containing 5-(4-hydroxyphenyl)-3H-1,2-dithiole-3-thione moiety as H₂S donor, had better analgesic activity and displayed more potent cytotoxic effects on the test cell lines than the lead compound CAP. Furthermore, the preferred compound, B₉ reduced rat gastric mucosa irritation caused by CAP. Notably, the improved properties of this derivative are associated with its H₂S-releasing capability.     

Synthesis and evaluation of (S)-2-ethoxy-3-phenylpropanoic acid derivatives as insulin-sensitizing agents

A series of (S)-2-ethoxy-3-phenylpropanoic acid derivatives were synthesized and their insulin-sensitizing activities were evaluated in 3T3-L1 cells. Compounds 1b and 1d exhibited more potent insulin-sensitizing activity than rosiglitazone.     

Synthesis and pharmacological evaluation of coumarin derivatives as cannabinoid receptor antagonists and inverse agonists

In the present study we synthesized 36 coumarin and 2H-chromene derivatives applying a recently developed umpoled domino reaction using substituted salicylaldehyde and α,β-unsaturated aldehyde derivatives as starting compounds. In radioligand binding studies 5-substituted 3-benzylcoumarin derivatives showed affinity to cannabinoid CB₁ and CB₂ receptors and were identified as new lead structures. In further GTPγS binding studies selected compounds were shown to be antagonists or inverse agonists.     

The bacterial mutagenicity of nitropolychlorinated dibenzo-p-dioxins

The bacterial mutagenicity of 2-nitrodibenzo-p-dioxin, a mixture of 2-nitro-7-chloro- and 2-nitro-8-chlorodibenzo-p-dioxin, 7-nitro-2,3-dichloro-, 8-nitro-2,3,7-trichloro-, 2-nitro-1,3,7,8-tetrachloro- and 3-nitro-1,2,4,7,8-pentachlorodibenzo-p-dioxin was determined using Salmonella typhimurium tester strains TA98 and TA100 with and without rat hepatic S9 for metabolic activation. All the nitro-PCDDs exhibited some direct-acting mutagenicity with both tester strains, however, the activity was significantly lowered in the presence of exogenous S9 and the compounds were more mutagenic to tester strain TA98. The mutagenicity of the nitro-PCDDs was also dependent on structure because there was a marked decrease in activity with increasing chlorine content. Because nitro-PCDDs have recently been identified as incomplete combustion products of municipal waste, this study confirms that this new class of compounds contains some bacterial mutagens.     

Synthesis and SAR of substituted pyrazolo[1,5-a]quinazolines as dual mGlu2/mGlu3 NAMs

Herein we report the design and synthesis of a series of substituted pyrazolo[1,5-a]quinazolin-5(4H)-ones as negative allosteric modulators of metabotropic glutamate receptors 2 and 3 (mGlu₂ and mGlu₃, respectively). Development of this series was initiated by reports that pyrazolo[1,5-a]quinazoline-derived scaffolds can yield compounds with activity at group II mGlu receptors which are prone to molecular switching following small structural changes. Several potent analogues, including 4-methyl-2-phenyl-8-(pyrimidin-5-yl)pyrazolo[1,5-a]quinazolin-5(4H)-one (10b), were discovered with potent in vitro activity as dual mGlu₂/mGlu₃ NAMs, with excellent selectivity versus the other mGluRs.     

Mutagenic activity of carcinogenic and noncarcinogenic nitrofurans and of urine of rats fed these compounds

The nitrofurans, 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF-2), N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT), nitrofurantoin, 5-nitro-2-furoic acid, 5-nitro-2-furamidoxime, 5-nitrofurfurylidene diacetate and the urine of rats fed these compounds, were assayed for mutagenic activity in Salmonella typhimurium strains TA100 and TA100FR1. All the nitrofurans were mutagenic in the order: AF-2 and FANFT > nitrofurantoin > 5-nitro-2-furamidoxime > 5-nitrofurfurylidene diacetate > 5-nitro-2-furoic acid. Strain TA100 was more sensitive than TA100FR1 to the mutagenic influence of these nitrofurans. Only the urine of rats fed AF-2, FANFT and nitrofurantoin had mutagenic activity. Again, TA100 was more sensitive than TA100FR1. The mutagenicity of the urine was not increased by treatment with β-glucuronidase. AF-2, 2-amino-4-(5-nitro-2-furyl)thiazole (deformylated product of FANFT) and nitrofurantoin were excreted in the urine of rats fed these compounds; whereas the other nitrofurans were not excreted.     

New optically active 1,3-oxathiolanes

cis- and trans-5-Ethoxy-1,3-oxathiolane-2-carboxylic acids were obtained in pure form. The cis isomer was resolved into its enantiomers through diastereoisomeric salt formation with enantiomerically pure α-methylbenzylamine. Reduction of the salt followed by benzoylation led to 2-benzoyloxymethyl-5-ethoxy-2(R)-5(S)-1,3-oxathiolane and 2-benzoyloxymethyl-5-ethoxy-2(S)-5(R)-1,3-oxathiolane, useful intermediates in nucleoside chemistry. © 1993 Wiley-Liss, Inc.     

An extracellular H2O2-requiring enzyme preparation involved in lignin biodegradation by the white rot basidiomycete Phanerochaete chrysosporium

An H₂O₂-requiring enzyme system was found in the extracellular medium of ligninolytic cultures of Phanerochaete chrysosporium. The enzyme system generated ethylene from 2-keto-4-thiomethyl butyric acid (KTBA), and oxidized a variety of lignin model compounds including the diarylpropane 1-(4′-ethoxy-3′-methoxyphenyl) 1,3-dihydroxy-2-(4″-methoxyphenyl)propane (I), a β-ether dimer 1-(4′-ethoxy-3′-methoxyphenyl)glycerol-β-guaiacyl ether (IV) and an olefin 1-(4′-ethoxy-3′-methoxy-phenyl)1,2-propene (VI). The products found were equivalent to the metabolic products previously isolated from intact ligninolytic cultures. In addition, the enzyme system partially degraded ¹⁴C-ring labeled lignin. The enzyme was not found in high nitrogen (N) cultures, nor in cultures of a ligninolytic mutant strain which is incapable of metabolizing lignin.     

Design, synthesis and in vitro evaluation of novel chroman-4-one, chroman, and 2H-chromene derivatives as human rhinovirus capsid-binding inhibitors

As part of an effort to generate broad-spectrum inhibitors of rhinovirus replication, novel series of (E)-3-[(E)-3-phenylallylidene]chroman-4-ones 1a–e, (E)-3-(3-phenylprop-2-yn-1-ylidene)chroman-4-ones 2a and 2b, (Z)-3-[(E)-3-phenylallylidene]chromans 3a–e, and (E)-3-(3-phenylprop-1-en-1-yl)-2H-chromenes 4a–d were designed and synthesized. All the compounds were tested in vitro for their efficacy against infection by human rhinovirus (HRV) 1B and 14, two representative serotypes for rhinovirus group B and A, respectively. Most of the analogues were found to be potent and selective inhibitors of both HRVs, although HRV 1B was generally more susceptible than HRV 14. Mechanism of action studies of (E)-6-chloro-3-(3-phenylprop-1-en-1-yl)-2H-chromene 4b, the most potent compound on HRV 1B infection, suggested that 4b behaves as a capsid-binder probably acting at the uncoating level.     

Antiproliferative activity of novel benzo[b][1,6]naphthyridines in human solid tumor cell lines

A series of 2-substituted 1,2-dihydro-3-phenyl-1-(trichloromethyl)benzo[b][1,6]naphthyridines were synthesized and their in vitro antiproliferative activities were examined against human solid tumor cell lines and relevant strains of bacteria and Candida. The compounds induced considerably growth inhibition in all cancer cell lines, whilst showed inactive against microbial strains. Furthermore, we found analog 2-ethoxy-1H-pyrano[4,3-b]quinoline as selective inhibitor of microbial strains.     

2-Phenyl-9H-purine-6-carbonitrile derivatives as selective cathepsin S inhibitors

Starting from previously disclosed equally potent cathepsin K and S inhibitor 4-propyl-6-(3-trifluoromethylphenyl)pyrimidine-2-carbonitrile 1, a novel 2-phenyl-9H-purine-6-carbonitrile scaffold was identified to provide potent and selective cathepsin S inhibitors.