Synthetic modification of the 2-oxypropionic acid moiety in 2-{4-[(7-chloro-2-quinoxalinyl)oxy]phenoxy}propionic acid (XK469), and consequent antitumor effects. Part 4

The criteria for the activity of 2-{4-[(7-chloro-2-quinoxalinyl)oxy]phenoxy}propionic acid (XK469) and 2-{4-[(7-bromo-2-quinolinyl)oxy]phenoxy}propionic acid (SH80) against transplanted tumors in mice established in previous studies, require a (7-halo-2-quinoxalinoxy)- or a (7-halo-2-quinolinoxyl)-residue, respectively, bridged via a 1,4-OC(6)H(4)O-linker to C(2) of propionic acid. The present work demonstrates that substitution of fluorine at the 3-position of the 1,4-OC(6)H(4)O-linker of XK469 leads to a 10-fold reduction in activity, whereas the corresponding 2-fluoro analog proved to be 100-fold less active than XK469. Moreover, the latter tolerated substitution of but a single, additional methyl group to the 2-position of the propionic acid moiety, that is, the isobutyric acid analog, without loss of significant in vivo activity. Indeed, an intact 2-oxypropionic acid moiety is a prerequisite for maximum antitumor activity of 1a.     

Synthesis and structure-activity relationships of 6-{4-[(3-fluorobenzyl)oxy]phenoxy}nicotinamide derivatives as a novel class of NCX inhibitors: a QSAR study

The sodium-calcium exchanger (NCX) transports Na+ and Ca2+ ions, and controls the Ca2+ concentration in myocytes. Calcium overload is induced via activation of reverse NCX, and is responsible for reperfusion injury in heart failure. Hence, NCX is an attractive target for prevention and treatment of reperfusion arrhythmias, myocardial contracture, and necrosis. We have synthesized a series of 6-{4-[(3-fluorobenzyl)oxy]phenoxy}nicotinamide derivatives, and evaluated their inhibitory activity against the reverse and forward modes of NCX. N-(3-Aminobenzyl)-6-{4-[(3-fluorobenzyl)oxy]phenoxy}nicotinamide (8) was shown to be a potent inhibitor of reverse NCX activity, with an IC50 value of 0.24 microM. A QSAR study showed that inhibition of reverse NCX activity by 6-{4-[(3-fluorobenzyl)oxy]phenoxy}nicotinamide derivatives is multiply dependent on the hydrophobicity (pi) and the shape (B(iv)) of the substituent at the 3-position of the phenyl ring.     

Synthesis and biological evaluation of conformationally constrained analogs of the antitumor agents XK469 and SH80. Part 5

Conformational restriction of bioactive molecules offers the possibility of generating structures of increased potency. To this end, a synthesis has been achieved of (R,S)-2-[(8-chlorobenzofurano[2,3-b]quinolinyl)oxy]propionic acid (12a), a highly rigidified, polycyclic analog of 2-[4-[(7-chloro-2-quinoxalinyl)oxy]phenoxy]propionic acid (2a, XK469). Efforts to effect the same synthesis of the corresponding 8-bromo-derivative led to a mixture of intermediate, 8-chloro (9a), and 8-bromo-2-hydroxybenzofurano[2,3-b]quinoline (9b), generated by halogen-exchange, via an aromatic S(RN)1(A(RN)1) reaction of precursor, 8b, with pyridine hydrochloride. The presumption that conformational restriction of 1b-12a might enhance the antitumor potency of the latter has not been sustained. In fact, 12a proved to be significantly less active than 1b. However, it is apparent that virtually all of the spatial and steric properties of 12a, necessary for improved activity, including the disposition of the 2-oxypropionic acid side chain remain to be identified.     

Effects of methy-2[(chloro-4'-benzoyl)-4-phenoxy]-2 propionic acid on the respiratory activity of isolated rat liver mitochondria]

The effects of methyl-2 [(chloro-4' benzoyl)-4 phenoxy]-2 propionic acid (LF 153) on mitochondrial respiration and oxidative phosphorylation are studied in vitro. Its activity is related to that of 3,5,3'-triiodo-L-thyronine (LT3), 3,5,3'-triiodothyroacetic acid (TA3), and to that of clofibrate, LF 153 acts as an inhibitory uncoupler of oxidative phosphorylation. Its uncoupling action is however very intense.     

Design,physico-chemical properties and biological evaluation of some new N-[(phenoxy)alkyl]- and N-{2-[2-(phenoxy)ethoxy]ethyl}aminoalkanols as anticonvulsant agents

A series of thirty N-(phenoxy)alkyl or N-{2-[2-(phenoxy)ethoxy]ethyl}aminoalkanols has been designed, synthesized and evaluated for anticonvulsant activity in MES, 6 Hz test, and pilocarpine-induced status epilepticus. Among the title compounds, the most promising seems R-(−)-2N-{2-[2-(2,6-dimethylphenoxy)ethoxy]ethyl}aminopropan-1-ol hydrochloride (22a) with proved absolute configuration with X-ray analysis and enantiomeric purity. The compound is effective in MES test with ED₅₀ = 12.92 mg/kg b.w. and its rotarod TD₅₀ = 33.26 mg/kg b.w. The activity dose is also effective in a neurogenic pain model—the formalin test. Within high throughput profile assay, among eighty one targets, the strongest affinity of the compound is observed towards σ receptors and 5-HT transporter and the compound does not bind to hERG. It also does not exhibit mutagenic properties in the Vibrio harveyi test. Moreover, murine liver microsomal assay and pharmacokinetics profile (mice, iv, p.o., ip) indicate that the liver is the primary site of biotransformation of the compound, suggesting that both 22a and its metabolite(s) are active, compensating probably low bioavailability of the parent molecule.     

Synthesis and in vitro antitubercular activity of some 1-[(4-sub)phenyl]-3-(4-{1-[(pyridine-4-carbonyl)hydrazono]ethyl}phenyl)thiourea

Various isonicotinyl hydrazones were prepared by reacting isonicotinyl hydrazide [INH] with 1-(4-acetylphenyl)-3-[(4-sub)phenyl]thiourea and were tested for their antimycobacterial activity in vitro against Mycobacterium tuberculosis H37Rv and INH-resistant M. tuberculosis using the BACTEC 460 radiometric system. Among the synthesized compounds, 1-(4-fluorophenyl)-3-(4-{1-[(pyridine-4-carbonyl)-hydrazono]ethyl}phenyl)thiourea (4d) was found to be the most potent compound with a minimum inhibitory concentration of 0.49 microM against M. tuberculosis H37Rv and INH-resistant M. tuberculosis. When compared to INH, 4d was found to be 3 and 185 times more active against M. tuberculosis H37Rv and INH-resistant M. tuberculosis, respectively, with a selectivity index of >300.     

Effect of various 2-methyl-(4'-chlorobenzoyl)-4-phenoxy)-2 propionic acid (LF 153) analogs on the respiratory activity of rat liver mitochondria]

Seven analogs of methyl-2 [chloro-4' benzoyl)-4 phenoxy]-2 propionic acid, (LF 153) have been tested for their effects on respiration and phosphorylation of rat liver mitochondria suspensions. They differ from one another by the sort of binding between both aromatic cycle as well as by the nature and position of the halogenated substitutions and alpha methylation in the propionic chain. All the compounds which have been tested acted as inhibitors of the electron transport chain and uncouplers of phosphorylations.     

Discovery and pharmacological characterization of N-[2-({2-[(2S)-2-cyanopyrrolidin-1-yl]-2-oxoethyl}amino)-2-methylpropyl]-2-methylpyrazolo[1,5-a]pyrimidine-6-carboxamide hydrochloride (anagliptin hydrochloride salt) as a potent and selective DPP-IV inhibitor

In the course of our program for discovery of novel DPP-IV inhibitors, a series of pyrazolo[1,5-a]pyrimidines were found to be novel DPP-IV inhibitors. We identified N-[2-({2-[(2S)-2-cyanopyrrolidin-1-yl]-2-oxoethyl}amino)-2-methylpropyl]-2-methylpyrazolo[1,5-a]pyrimidine-6-carboxamide hydrochloride (4a) and described its pharmacological profiles.     

6-Acylamino-2-[(alkylsulfonyl)oxy]-1H-isoindole-1,3-dione mechanism-based inhibitors of human leukocyte elastase

A study of various 2-[(alkylsulfonyl)oxy]-6-substituted-1H-isoindole-1,3-diones' inhibition of chymotrypsin compared to inhibition of HLE reveals that acylamino substitution in the 6-position increases selectivity and potency of these inhibitors for HLE. The best HLE inhibitor in this series was 6-(methylglutaryl)amino-2-[(ethylsulfonyl)oxy]-1H-isoindole-1,3-di one with a kobs/[I] = 220,000 M(-1) s(-1).     

Synthesis and in vitro anti-tumor activity of N-{1-[(3-thioxo-5,6-dihydroimidazo[2,1-c][1,2,4]thiadiazol-7-ylthio)thiocarbonyl]-2-imidazolidene}arylsulfonamides

A series of N-{1-[(3-thioxo-5,6-dihydroimidazo[2,1-c][1,2,4]thiadiazol-7-ylthio)thiocarbonyl]-2-imidazolidene}arylsulfonamides (2a-z) was obtained by reacting 6,7-dihydro-1H-imidazo[2,1-c][1,2,4]thiadiazol-3-thione (1) with arylsulfonyl chlorides. The relationships between structure and anti-tumor activity revealed that compound 2o with p-Cl substituent at the phenyl ring was most active (-log GI50>8.00, -log TGI=7.66) and was found to exhibit high selectivity toward the leukemia CCRF-CEM cell line (Deltaf=3.08 and 3.31, respectively).     

Synthesis and structure-activity relationships of N-{1-[(6-fluoro-2-naphthyl)methyl]piperidin-4-yl}benzamide derivatives as novel CCR3 antagonists

A novel class of potent CCR3 receptor antagonists were designed and synthesized starting from N-{1-[(6-fluoro-2-naphthyl)methyl]piperidin-4-yl}benzamide (1),which was found by subjecting our chemical library to high throughput screening (HTS). The CCR3 inhibitory activity of the synthesized compounds against eotaxin-induced Ca(2+) influx was evaluated using CCR3-expressing preB cells. Systematic chemical modifications of 1 revealed that the 6-fluoro-2-naphthylmethyl moiety was essential for CCR3 inhibitory activity in this new series of CCR3 antagonists. Further structural modifications of the benzamide and piperidine moieties of 1 led to the identification of exo-N-{8-[(6-fluoro-2-naphthyl)methyl]-8-azabicyclo[3.2.1]oct-3- yl}biphenyl-2-carboxamide [corrected] (31) as a potent CCR3 antagonist with an IC(50) value of 0.020 microM.     

Design,synthesis, and in vitro antiprotozoal,antimycobacterial activities of N-{2-[(7-chloroquinolin-4-yl)amino]ethyl}ureas

We have synthesized a new series of quinoline tripartite hybrids from chloroquine, ethambutol, and isoxyl drugs, using a short synthetic route. Compounds 1–8 were tested in vitro against five protozoa (Giardia intestinalis, Trichomonas vaginalis, Entamoeba histolytica, Leishmania mexicana and Trypanosoma cruzi) and Mycobacterium tuberculosis. N-(4-Butoxyphenyl)-N′-{2-[(7-chloroquinolin-4-yl)amino]ethyl}urea (6) was the most active compound against all parasites tested. Compound 6 was 670 times more active than metronidazole, against G. intestinalis. It was as active as pentamidine against L. mexicana, and it was twofold more potent than ethambutol and isoxyl versus M. tuberculosis. This compound could be considered as a new broad spectrum antimicrobial agent.     

Synthesis, cytotoxicity, and anti-inflammatory evaluation of 2-(furan-2-yl)-4-(phenoxy)quinoline derivatives. Part 4

A number of 2-(furan-2-yl)-4-phenoxyquinoline derivatives have been synthesized and evaluated for anti-inflammatory evaluation. 4-[(2-Furan-2-yl)quinolin-4-yloxy]benzaldehyde (8), with an IC(50) value of 5.0 microM against beta-glucuronidase release, was more potent than its tricyclic furo[2,3-b]quinoline isomer 3a (>30 microM), its 4'-COMe counterpart 7 (7.5 microM), and its oxime derivative 13a (11.4 microM) and methyloxime derivative 13b (>30 microM). For the inhibition of lysozyme release, however, oxime derivative 12a (8.9 microM) and methyloxime derivative 12b (10.4 microM) are more potent than their ketone precursor 7 and their respective tricyclic furo[2,3-b]quinoline counterparts 4a and 4b. Among them, 4-[4-[(2-furan-2-yl)-quinolin-4-yloxy]phenyl]but-3-en-2-one (10) is the most active against lysozyme release with an IC(50) value of 4.6 microM, while 8 is the most active against beta-glucuronidase release with an IC(50) value of 5.0 microM. (E)-1-[3-[(2-Furan-2-yl)quinolin-4-yloxy]phenyl] ethanone oxime (11a) is capable of inhibiting both lysozyme and beta-glucuronidase release with IC(50) values of 7.1 and 9.5 microM, respectively. For the inhibition of TNF-alpha formation, 1-[3-[(2-furan-2-yl)quinolin-4-yloxy]phenyl]ethanone (6) is the most potent with an IC(50) value of 2.3 microM which is more potent than genistein (9.1 microM). For the inhibitory activity of fMLP-induced superoxide anion generation, 11a (2.7 microM), 11b (2.8 microM), and 13b (2.2 microM) are three of the most active. None of above compounds exhibited significant cytotoxicity.     

Discovery of N-[5-({2-[(cyclopropylcarbonyl)amino]imidazo[1,2-b]pyridazin-6-yl}oxy)-2-methylphenyl]-1,3-dimethyl-1H-pyrazole-5-carboxamide (TAK-593), a highly potent VEGFR2 kinase inhibitor

Vascular endothelial growth factor (VEGF) plays important roles in tumor angiogenesis, and the inhibition of its signaling pathway is considered an effective therapeutic option for the treatment of cancer. In this study, we describe the design, synthesis, and biological evaluation of 2-acylamino-6-phenoxy-imidazo[1,2-b]pyridazine derivatives. Hybridization of two distinct imidazo[1,2-b]pyridazines 1 and 2, followed by optimization led to the discovery of N-[5-({2-[(cyclopropylcarbonyl)amino]imidazo[1,2-b]pyridazin-6-yl}oxy)-2-methylphenyl]-1,3-dimethyl-1H-pyrazole-5-carboxamide (23a, TAK-593) as a highly potent VEGF receptor 2 kinase inhibitor with an IC₅₀ value of 0.95 nM. The compound 23a strongly suppressed proliferation of VEGF-stimulated human umbilical vein endothelial cells with an IC₅₀ of 0.30 nM. Kinase selectivity profiling revealed that 23a inhibited platelet-derived growth factor receptor kinases as well as VEGF receptor kinases. Oral administration of 23a at 1 mg/kg bid potently inhibited tumor growth in a mouse xenograft model using human lung adenocarcinoma A549 cells (T/C = 8%).     

5-{2-[4-(2-methyl-5-quinolinyl)-1-piperazinyl]ethyl}-2(1H)-quinolinones and 3,4-dihydro-2(1H)-quinolinones: dual-acting 5-HT1 receptor antagonists and serotonin reuptake inhibitors. Part 3

5-{2-[4-(2-Methyl-5-quinolinyl)-1-piperazinyl]ethyl}-2(1H)-quinolinones and 3,4-dihydro-2(1H)-quinolinones have been identified with different combinations of 5-HT(1) autoreceptor antagonist and hSerT potencies and excellent rat PK profiles. The availability of tool compounds with a range of profiles at targets known to play a key role in the control of synaptic 5-HT levels will allow exploration of different pharmacological profiles in a range of animal behavioral and disease models.     

Inhibition of estrone sulfatase (ES) by derivatives of 4-[(aminosulfonyl)oxy] benzoic acid

In our search for potent inhibitors of the enzyme estrone sulfatase (ES), we have undertaken the synthesis and biochemical evaluation of a range of straight chain alkyl esters of 4-[(aminosulfonyl)oxy] benzoic acid. The results of the study show that the synthesised compounds possess greater inhibitory activity when compared to COUMATE, although they were all found to possess lower inhibitory activity with respect to EMATE. Furthermore, the data suggest a strong correlation between logP and IC(50) and therefore adds further support to our previous report where we suggested a link between inhibitory activity and hydrophobicity.     

Inhibition of estrone sulfatase (ES) by alkyl and cycloalkyl ester derivatives of 4-[(aminosulfonyl)oxy] benzoic acid

In our search for potent inhibitors of the enzyme estrone sulfatase (ES), we have undertaken the synthesis and biochemical evaluation of a range of esters of 4-[(aminosulfonyl)oxy] benzoic acid. The results of the study show that the synthesised compounds possess potent inhibitory activity, indeed the cyclooctyl derivative was found to be more potent than 667-COUMATE, which is currently undergoing clinical trials.     

Synthesis and Herbicidal Activity of Phenoxypropionic Acid Derivatives with Imidazo[1,2-α]pyridine Moiety

Phenoxypropionic acid derivatives (Ia-s) with an imidazo[1,2-a]pyridine moiety were synthesized and their herbicidal activities were examined. The activities were affected dramatically by the substituents on the imidazo[1,2-a]pyridine ring, and good substituents to enhance the herbicidal activity were a cyano group at the 3-position and a chlorine atom at the 6-position. Among the compounds, n-propyl 2-[4-(6-chloro-3-cyano-2-imidazo[1,2-a]pyridinyloxy)phenoxy]propionate(Iq) was most active against gramineous weeds and the activity was comparable to that of the commercial herbicide fluazifop-butyl.     

Molecular pharmacology of the AMPA agonist, (S)-2-amino-3-(3-hydroxy-5-phenyl-4-isoxazolyl)propionic acid [(S)-APPA] and the AMPA antagonist, (R)-APPA

The heterocyclic analogue of (S)-glutamic acid, (S)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid [(S)-AMPA] is a potent and selective AMPA receptor agonist, whereas the enantiomeric compound, (R)-AMPA, is virtually inactive. We have previously characterized (RS)-2-amino-3-(3-hydroxy-5-phenyl-4-isoxazolyl)propionic acid [(RS)-APPA] as a partial AMPA receptor agonist showing about 60% of the efficacy of (RS)-AMPA. This partial agonism produced by (RS)-APPA is, however, only apparent, since resolution of (RS)-APPA has now been shown to provide the full AMPA receptor agonist, (S)-APPA, whereas (R)-APPA is a acid (non-NMDA) receptor antagonist showing preferential AMPA blocking effects. In agreement with classical theories for competitive interaction between agonists and antagonists, the efficacy of depolarizations produced by (S)-APPA in the rat cortical wedge preparation was shown to be progressively reduced with increasing molar ratios of (R)-APPA/(S)-APPA. These compounds and the competitive antagonists (RS)-2-amino-3-(3-carboxymethoxy-5-methyl-4-isoxazolyl)propionic acid [(RS)-AMOA], 6-cyano-7-nitroquinoxalin-2,3-dione (CNQX) and 6-nitro-7-sulfamoylbenzo(f)quinoxalin-2,3-dione (NBQX) were also tested in [³H]AMPA and [³H]CNQX binding systems, the latter ligand being used in the absence or presence of thiocyanate ions. On the basis of these studies it is suggested that (RS)-AMPA and the AMPA agonist (S)-APPA interact with a high-affinity receptor conformation, whereas the competitive antagonists (RS)-AMOA and (R)-APPA, derived from these agonists, preferentially bind to a low-affinity AMPA receptor conformation. The competitive antagonists, CNQX and NBQX which are structurally unrelated to (RS)-AMPA or (RS)-APPA, do not seem to discriminate between these two AMPA receptor conformations. The modified [³H]CNQX binding assay containing thiocyanate ions was shown to provide receptor affinity data for AMPA receptor agonists as well as antagonists, which correlate with the potencies of these compounds in the cortical wedge preparation. Using autoradiographic techniques, (S)- and (R)-APPA were shown to exhibit significantly different absolute potencies as inhibitors of [³H]AMPA binding in a number of regions of the rat brain.     

Synthesis of (2E)-3-{2-[(substituted benzyl)oxy]phenyl}acrylaldehydes as novel anti-inflammatory agents

As part of our continuing effort for development of novel anti-inflammatory agents, the highly potential agent CCY1a, which we reported recently, was selected as lead compound to synthesize a series of its derivatives for evaluation. Most of the newly synthesized compounds exhibited superior inhibitory activity than both the lead compound and the positive control (trifluoperazine) toward fMLP-stimulated neutrophil superoxide formation. (2E)-3-[2-(Benzyloxy)-5-methoxyphenyl]-acrylaldehyde (31) was among the most potent with action mechanism different from CCY1a in that it does not act as cAMP-elevating agent but inhibits the increase in cellular Ca(2+) with greater potency.