Synthesis and biological evaluation of compounds which contain pyrazole,thiazole and naphthalene ring as antitumor agents

A series of compounds which contain pyrazole, thiazole and naphthalene ring (1a–7a, 1b–7b, 1c–7c, 1d–7d) were firstly synthesized and their anti-proliferative activity, EGFR inhibitory activity, cytotoxicity and inhibition to Hela cell migration were evaluated. Compound 2-(3-(3,4-dimethylphenyl)-5-(naphthalen-2-yl)-4,5-dihydro-1H-pyrazol-1-yl)thiazol-4(5H)-one (7d) displayed the most potent inhibitory activity (IC₅₀ = 0.86 μM for Hela and IC₅₀ = 0.12 μM for EGFR). Structure–activity relationship (SAR) analysis showed that the anti-proliferative activity was affected by A-ring-substituent (–OCH₃ > –CH₃ > –H > –Br > –Cl > –F). Docking simulation of compound 7d into EGFR active site showed that naphthalene ring of 7d with LYS721 formed two p–π bonds, which enhanced antitumor activity. Therefore, compound 7d may be developed as a potential antitumor agent.     

Synthesis and cytotoxic activity of nitric oxide-releasing isosteviol derivatives

Fifteen novel hybrids containing diterpene skeleton and nitric oxide (NO) donor were prepared from isosteviol. All the compounds were tested on preliminary cytotoxicity, and the results showed that six target compounds (8c, 10b, 14a, 14c, 18c, and 18d) exhibited anti-proliferation activity on HepG2 cells, with 8c (IC₅₀ = 4.24 μM) and 18d (IC₅₀ = 2.75 μM) superior to the positive control CDDO-Me (2-cyano-3,12-dioxooleana-1,9(11)-dien-28-acid methyl ester, IC₅₀ = 4.99 μM); eleven target compounds (8a–c, 9a–c, 10a–b, 14a, 14c, 18d) exhibited anti-proliferation activities on B16F10 cells at different levels, among them, seven compounds were more potent than comptothecin (IC₅₀ = 2.78 μM) and CDDO-Me (IC₅₀ = 5.85 μM), particularly, 10b (IC₅₀ = 0.02 μM) presented the strongest effect, which was selected as a candidate for further study.     

A novel spirocyclic tropanyl-Δ2-isoxazoline derivative enhances citalopram and paroxetine binding to serotonin transporters as well as serotonin uptake

A group of spirocyclic tropanyl-Δ²-isoxazolines was synthesized exploiting the 1,3-dipolar cycloaddition of nitrile oxides to olefins. Their interaction with the dopamine and serotonin transporters (DAT and SERT, respectively) was evaluated through binding experiments. The majority of the compounds had no inhibitory effects (IC₅₀ >> 10 μM), while some had an IC₅₀ value in the range 5–10 μM (8a–c, 10b and 11c on DAT, 12b on SERT). Unexpectedly, one of the tertiary amines under investigation, that is 3′-methoxy-8-methyl-spiro{8-azabicyclo[3.2.1]octane-3,5′(4′H)-isoxazole 7a, was able to enhance at a concentration of 10 μM both [³H]citalopram and [³H]paroxetine binding to SERT in rat brain homogenate (up to 25%, due to an increase of B_max) and [³H]serotonin uptake (up to 30%) in cortical synaptosomes. This peculiar pharmacological profile of 7a suggests it binds to an allosteric site on SERT, and positions derivative 7a as a very useful tool to investigate SERT machinery.     

Synthesis,biological evaluation and docking analysis of 3-methyl-1-phenylchromeno[4,3-c]pyrazol-4(1H)-ones as potential cyclooxygenase-2 (COX-2) inhibitors

As a part of our continued efforts to discover new COX inhibitors, a series of 3-methyl-1-phenylchromeno[4,3-c]pyrazol-4(1H)-ones were synthesized and evaluated for in vitro COX inhibitory potential. Within this series, seven compounds (3a–d, 3h, 3k and 3q) were identified as potential and selective COX-2 inhibitors (COX-2 IC₅₀’s in 1.79–4.35 μM range; COX-2 selectivity index (SI) = 6.8–16.7 range). Compound 3b emerged as most potent (COX-2 IC₅₀ = 1.79 μM; COX-1 IC₅₀ >30 μM) and selective COX-2 inhibitor (SI >16.7). Further, compound 3b displayed superior anti-inflammatory activity (59.86% inhibition of edema at 5 h) in comparison to celecoxib (51.44% inhibition of edema at 5 h) in carrageenan-induced rat paw edema assay. Structure–activity relationship studies suggested that N-phenyl ring substituted with p-CF₃ substituent (3b, 3k and 3q) leads to more selective inhibition of COX-2. To corroborate obtained experimental biological data, molecular docking study was carried out which revealed that compound 3b showed stronger binding interaction with COX-2 as compared to COX-1.     

Synthesis,anti-cancer and anti-inflammatory activity of novel 2-substituted isoflavenes

Fifteen novel 2-substituted isoflavenes were synthesised via nucleophilic addition to isoflavylium salts. Twelve of the newly synthesised isoflavenes, along with the unsubstituted parent isoflavene, were tested in cell viability assays against the SHEP neuroblastoma and MDA-MB-231 breast adenocarcinoma cell lines. While the 2-substituted isoflavenes displayed a range of anti-proliferative activities, in most cases they were less active that the unsubstituted isoflavene (IC₅₀ = 9.9 μM vs SHEP; IC₅₀ = 33 μM vs MDA-MB-231). However, compound 7f, derived from the reaction between isoflavylium salt 5 and para-methoxyacetophenone, showed improved anti-proliferative activity against breast cancer cells (IC₅₀ = 7.6 μM). Furthermore, compound 7f, as well as analogues 7a, 7c, 11d and 14, inhibited the production of interleukin-6 in LPS-activated RAW 264.7 cells.     

Synthesis and biological evaluation of N-mercaptoacylcysteine derivatives as leukotriene A4 hydrolase inhibitors

We studied synthetic modifications of N-mercaptoacylamino acid derivatives to develop a new class of leukotriene A₄ (LTA₄) hydrolase inhibitors. S-(4-Dimethylamino)benzyl-l-cysteine derivative 2a (SA6541) showed inhibitory activity against LTA₄ hydrolase (IC₅₀, 270 nM) and selectivity over other metallopeptidases except angiotensin-converting enzyme (ACE, IC₅₀, 520 nM). Modification at the para-substituent of the phenyl ring of compound 2a improved LTA₄ hydrolase inhibitory activity as well as selectivity over ACE. Finally, we obtained S-(4-cyclohexyl)benzy-l-cysteine derivatives 11l and 16i as potent and selective LTA₄ hydrolase inhibitors.     

Synthesis and antiproliferative evaluation of certain indolo[3,2-c]quinoline derivatives

The present report describes the synthesis and antiproliferative evaluation of certain indolo[3,2-c]quinoline derivatives. For the C₆ anilino-substituted derivatives, (11H-indolo[3,2-c]quinolin-6-yl)phenylamine (6a) was inactive. Structural optimization of 6a by the introduction of a hydroxyl group at the anilino-moiety resulted in the enhancement of antiproliferative activity in which the activity decreased in an order of para-OH, 7a > meta-OH, 8a > ortho-OH, 9a. For the C₆ alkylamino-substituted derivatives, 11a, 12a, 13a, 14a, and 15a exhibited comparable antiproliferative activities against all cancer cells tested and the skin Detroit 551 normal fibroblast cells. Three cancer cells, HeLa, A549, and SKHep, are very susceptible with IC₅₀ of less than 2.17 μM while PC-3 is relatively resistant to this group of indolo[3,2-c]quinolines. For the 2-phenylethylamino derivatives, compound 20a is active against the growth of HeLa with an IC₅₀ of 0.52 μM, but is less effective against the growth of Detroit 551 with an IC₅₀ of 19.32 μM. For the bis-indolo[3,2-c]quinolines, N,N-bis-[3-(11H-indolo[3,2-c]quinolin-6-yl)aminopropyl]amine hydrochloride (25) is more active than its N-methyl derivative 26 and the positive Doxorubicin. Mechanism studies indicated 25 can induce caspase-3 activation, γ-H2AX phosphorylation, cleavage of poly(ADP-ribose)polymerase and DNA fragmentation. These results provide evidence that DNA, topo I, and topo II are the primary targets of indolo[3,2-c]quinoline derivatives and that consequently inhibits proliferation and causes apoptosis in cancer cells.     

Kojic acid derived hydroxypyridinone–chloroquine hybrids: Synthesis,crystal structure,antiplasmodial activity and β-haematin inhibition

Aminochloroquinoline–kojic acid hybrids were synthesized and evaluated for β-haematin inhibition and antiplasmodial activity against drug resistant (K1) and sensitive (3D7) strains of Plasmodium falciparum. Compound 7j was the most potent compound in both strains (IC₅₀^3D7 = 0.004 μM; IC₅₀^K1 = 0.03 μM) and had the best β-haematin inhibition activity (0.07 IC₅₀ equiv vs 1.91 IC₅₀ equiv for chloroquine). One compound 8c was found to be equipotent in both strains (IC₅₀ = 0.04 μM).     

Synthesis of novel pyrazole–thiadiazole hybrid as potential potent and selective cyclooxygenase-2 (COX-2) inhibitors

A series of 1,3,4-trisubstituted pyrazole derivatives (3a–f), (4a–f), and (5a–f) have been synthesized and evaluated for their cyclooxygenase (COX-1 and COX-2) inhibitory activity. The structures of newly synthesized compounds were characterized by IR, ¹H NMR, and mass spectral analysis. All of the compounds showed good inhibition of COX-2 with IC₅₀ of 1.33–17.5 μM. Among these derivatives, compound (5c) was the most potent and selective COX-2 inhibitor (IC₅₀ = 1.33 μM), with a significant selectivity index (SI >60). Molecular docking studies were carried out in order to predict the hypothetical binding mode of these compounds to the COX-2 isoenzyme. The result of present study suggests that pyrazole–thiadiazole hybrid could be an interesting approach for the design of new selective COX-2 inhibitory agents.     

Pyrazole-hydrazone derivatives as anti-inflammatory agents: Design,synthesis, biological evaluation,COX-1,2/5-LOX inhibition and docking study

A new series of pyrazole-hydrazone derivatives 4a-i were designed and synthesized, their chemical structures were confirmed by IR, ¹H NMR, ¹³C NMR, MS spectral data and elemental analysis. IC₅₀ values for all prepared compounds to inhibit COX-1, COX-2 and 5-LOX enzymes were determined in vitro. Compounds 4a (IC₅₀ = 0.67 μM) and 4b (IC₅₀ = 0.58 μM) showed better COX-2 inhibitory activity than celecoxib (IC₅₀ = 0.87 μM) with selectivity index (SI = 8.41, 10.55 in sequent) relative to celecoxib (SI = 8.85). Also, compound 4a and 4b exhibited superior inhibitory activity against 5-LOX (IC₅₀ = 1.92, 2.31 μM) higher than zileuton (IC₅₀ = 2.43 μM). All target pyrazoles were screened for their ability to reduce nitric oxide production in LPS stimulated peritoneal macrophages. Compounds 4a, 4b, 4f and 4i displayed concentration dependent reduction and were screened for in vivo anti-inflammatory activity using carrageenan-induced rat paw edema assay. Compound 4f showed the highest anti-inflammatory activity (% edema inhibition = 15–20%) at all doses when compared to reference drug celecoxib (% edema inhibition = 15.7–17.5%). Docking studies were carried out to investigate the interaction of target compounds with COX-2 enzyme active site.     

Design,synthesis and biological evaluation of heterocyclic azoles derivatives containing pyrazine moiety as potential telomerase inhibitors

Three series of novel heterocyclic azoles derivatives containing pyrazine (5a–5k, 8a–8k and 11a–11k) have been designed, synthesized, structurally determined, and their biological activities were evaluated as potential telomerase inhibitors. Among the oxadiazole derivatives, compound 5c showed the most potent biological activity against SW1116 cancer cell line (IC₅₀ = 2.46 μM against SW1116 and IC₅₀ = 3.55 μM for telomerase). Compound 8h performed the best in the thiadiazole derivatives (IC₅₀ = 0.78 μM against HEPG2 and IC₅₀ = 1.24 μM for telomerase), which was comparable to the positive control. While compound 11f showed the most potent biological activity (IC₅₀ = 4.12 μM against SW1116 and IC₅₀ = 15.03 μM for telomerase) among the triazole derivatives. Docking simulation by positioning compounds 5c, 8h and 11f into the telomerase structure active site was performed to explore the possible binding model. The results of apoptosis demonstrated that compound 8h possessed good antitumor activity against HEPG2 cancer cell line. Therefore, compound 8h with potent inhibitory activity in tumor growth inhibition may be a potential antitumor agent against HEPG2 cancer cell. Therefore, the introduction of oxadiazole, thiadiazole and triazole structures reinforced the combination of our compounds and the receptor, resulting in progress of bioactivity.     

Calmodulin inhibitors from the fungus Emericella sp.

Two new xanthones identified as 15-chlorotajixanthone hydrate (1) and 14-methoxytajixanthone (2) were isolated from an Emericella sp. strain 25379 along with shamixanthone (3) and tajixanthone hydrate (4). The stereostructures of 1 and 2 were elucidated by spectroscopic and molecular modeling methods. The absolute configuration at the stereogenic centers of 1 was established according to CD measurements. In the case of 2, however, the absolute configuration at C-20 and C-25 was designated as S and R, respectively, by Mosher ester methodology. Thereafter, the configuration at C-14 and C-15 of 2 was established as S and S, respectively by comparing the optical rotation and ¹H–¹H coupling constant experimental values with those obtained through molecular modeling calculations at DFT B3LYP/DGDZVP level of theory for diasteroisomers 2a–2d. The activation of the calmodulin-sensitive cAMP phosphodiesterase (PDE1) was inhibited in the presence of 1–4 in a concentration-dependent manner. The effect of compounds 2 (IC₅₀ = 5.54 μM) and 4 (IC₅₀ = 5.62 μM) was comparable with that of chlorpromazine (CPZ; IC₅₀ = 7.26 μM), a well known CaM inhibitor used as a positive control. The inhibition mechanism of both compounds was competitive with respect to CaM according to a kinetic study. A docking analysis with 2 and 4 using the AutoDock 4.0 program revealed that they interacted with CaM in the same pocket as trifluoropiperazine (TFP).     

Oseltamivir hydroxamate and acyl sulfonamide derivatives as influenza neuraminidase inhibitors

Tamiflu_, the ethyl ester form of oseltamivir carboxylic acid (OC), is the first orally available anti-influenza drug for the front-line therapeutic option. In this study, the OC-hydroxamates, OC-sulfonamides and their guanidino congeners (GOC) were synthesized. Among them, an OC-hydroxamate 7d bearing an O-(2-indolyl)propyl substituent showed potent NA inhibition (IC₅₀ = 6.4 nM) and good anti-influenza activity (EC₅₀ = 60.1 nM) against the wild-type H1N1 virus. Two GOC-hydroxamates (9b and 9d) and one GOC-sulfonamide (12a) were active to the tamiflu-resistant H275Y virus (EC₅₀ = 2.3–6.9 μM).     

3-Substituted-4-hydroxycoumarin as a new scaffold with potent CDK inhibition and promising anticancer effect: Synthesis,molecular modeling and QSAR studies

A new series of 3-substituted-4-hydroxycoumarin derivatives was designed, synthesized, and evaluated for CDK inhibiting and anticancer activities. All the synthesized target compounds showed remarkably high affinity and selectivity towards CDK1B, compared to flavopiridol, with Ki values in the low nanomolar range (Ki = 0.35–0.88 nM). Most of them elicited considerable inhibiting effect against CDK9T1 (Ki = 3.26–23.45 nM). Moreover, all the target compounds were tested in vitro against eighteen types of human tumor cell lines. The hydrazone 3a, N-phenylpyrazoline derivative 6b and 2-aminopyridyl-3-carbonitrile derivative 8c were the most potent anticancer agents against MCF-7 breast cancer cell line (IC₅₀ = 0.21, 0.21 and 0.23 nM, respectively). The target compounds 3a, 6b and 8c were further evaluated in MCF-7 breast cancer mouse xenograft model and showed in vivo efficacy at 10 mg/kg dose. The docking study confirmed a unique binding mode in the active site of CDK1B with better score than flavopiridol. Quantitative structure activity relationship study was done and revealed a highly predictive power R² of 0.81.     

Synthesis of dammarane-type triterpene derivatives and their ability to inhibit HIV and HCV proteases

We synthesized dammarane-type triterpene derivatives and evaluated their ability to inhibit HIV-1 and HCV proteases to understand their structure–activity relationships. All of the mono- and di-succinyl derivatives (5a–5f) were powerful inhibitors of HIV-1 protease (IC₅₀ < 10 μM). However, only di-succinyl (5e) and 2,3-seco-2,3-dioic acid (3b) derivatives similarly inhibited HCV protease (IC₅₀ < 10 μM). A-nor dammarane-type triterpenes (4a and 4b, IC₅₀ 10.0 and 29.9 μM, respectively) inhibited HIV-1 protease moderately or strongly, but were inactive against HCV protease. All compounds that powerfully inhibited HIV-1 or HCV protease did not appreciably inhibit the general human proteases, renin and trypsin (IC₅₀ > 1000 μM). These findings indicated that the mono-succinyl dammarane type derivatives (5a–5d) selectively inhibited HIV-1 protease and that the di-succinyl (5e, 5f) as well as 2,3-seco-2,3-dioic acid (3b) derivatives preferably inhibited both viral proteases.     

Triazino indole–quinoline hybrid: A novel approach to antileishmanial agents

A novel series of 1,2,4-triazino-[5,6b]indole-3-thione covalently linked to 7-chloro-4-aminoquinoline have been synthesized and evaluated for their in vitro activity against extracellular promastigote and intracellular amastigote form of Leishmania donovani. Among all tested compounds, compounds 7a and 7b were found to be the most active with IC₅₀ values 1.11, 0.36 μM and selectivity index (SI) values 67, >1111, respectively, against amastigote form of L. donovani which is several folds more potent than the standard drugs, miltefosine (IC₅₀ = 8.10 μM, SI = 7) and sodium stibo-gluconate (IC₅₀ = 54.60 μM, SI ⩾ 7).     

Synthesis,biological evaluation of novel 4,5-dihydro-2H-pyrazole 2-hydroxyphenyl derivatives as BRAF inhibitors

A series of novel 4,5-dihydropyrazole derivatives (3a–3t) containing hydroxyphenyl moiety as potential V600E mutant BRAF kinase (BRAF^V600E) inhibitors were designed and synthesized. Docking simulation was performed to insert compounds 3d (1-(5-(5-chloro-2-hydroxyphenyl)-3-(p-tolyl)-4,5-dihydro-1H-pyrazol-1-yl)ethanone) and 3m (1-(3-(4-chlorophenyl)-5-(3,5-dibromo-2-hydroxyphenyl)-4,5-dihydro-1H-pyrazol-1-yl)ethanone) into the crystal structure of BRAF^V600E to determine the probable binding model, respectively. Based on the preliminary results, compound 3d and 3m with potent inhibitory activity in tumor growth may be a potential anticancer agent. Results of the bioassays against BRAF^V600E, MCF-7 human breast cancer cell line and WM266.4 human melanoma cell line all showed several compounds had potent activities IC₅₀ value in low micromolar range, among them, compound 3d and compound 3m showed strong potent anticancer activity, which were proved by that 3d: IC₅₀ = 1.31 μM for MCF-7 and IC₅₀ = 0.45 μM for WM266.5, IC₅₀ = 0.22 μM for BRAF^V600E, 3m: IC₅₀ = 0.97 μM for MCF-7 and IC₅₀ = 0.72 μM for WM266.5, IC₅₀ = 0.46 μM for BRAF^V600E, which were comparable with the positive control Erlotinib.     

SAR development of a series of 8-azabicyclo[3.2.1]octan-3-yloxy-benzamides as kappa opioid receptor antagonists. Part 2

Further structure activity relationship studies on a previously reported 8-azabicyclo[3.2.1]octan-3-yloxy-benzamide series of potent and selective kappa opioid receptor antagonists is discussed. Modification of the pendant N-substitution to include a cyclohexylurea moiety produced analogs with greater in vitro opioid and hERG selectivity such as 12 (κ IC₅₀ = 172 nM, μ:κ ratio = 93, δ:κ ratio = >174, hERG IC₅₀ = >33 μM). Changes to the linker conformation and identity as well as to the benzamide ring moiety were also investigated.     

Molecular design,synthesis and biological evaluation of cyclic imides bearing benzenesulfonamide fragment as potential COX-2 inhibitors. Part 2

A group of cyclic imides (1–10) was designed for evaluation as a selective COX-2 inhibitors and investigated in vivo for their anti-inflammatory activity. Compounds 6a, 6b, 8a, 8b, 9a, 9b, 10a and 10b were proved to be potent COX-2 inhibitors with IC₅₀ range of 0.1–4.0 μM. In vitro COX-1/COX-2 inhibition structure–activity studies identified compound 8a as a highly potent (IC₅₀ = 0.1 μM), and an extremely selective [COX-2 (SI) > 1000] comparable to celecoxib [COX-2 (SI) > 384], COX-2 inhibitor that showed superior anti-inflammatory activity (ED₅₀ = 72.4 mg/kg) relative to diclofenac (ED₅₀ = 114 mg/kg). Molecular modeling was carried out through docking the designed compounds into the COX-2 binding site to predict if these compounds have analogous binding mode to the COX-2 inhibitors. The study showed that the homosulfonamide fragment of 8a inserted deep inside the 2°-pocket of the COX-2 active site, where the SO₂NH₂ group underwent H-bonding interaction with Gln¹⁹²(2.95 Å), Phe⁵¹⁸(2.82 Å) and Arg⁵¹³(2.63 and 2.73 Å). Docking study of the synthesized compound 8a into the active site of COX-2 revealed a similar binding mode to SC-558, a selective COX-2 inhibitor.     

Urea and carbamate derivatives of primaquine: Synthesis,cytostatic and antioxidant activities

The novel urea primaquine derivatives 3 were prepared by aminolysis of primaquine benzotriazolide 2 with several hydroxyamines and ethylendiamine, while carbamates 4 were synthesized from the same precursor 2 and alcohols. All compounds are fully chemically characterized and evaluated for their cytostatic and antioxidant activities. The most prominent antiproliferative activity was obtained by compounds 3c, 3d, 3g, and 5b (IC₅₀ = 9–40 μM). 1-(5-Hydroxypentyl)-3-[4-(6-methoxy-quinolin-8-ylamino)-pentyl]urea (3c) showed extreme selectivity toward SW 620 colon cancer cells (IC₅₀ = 0.2 μM) and a bit less toward lung cancer cells H 460. Hydroxyurea 3h showed the highest interaction with DPPH. Primaquine twin drug 3g showed very significant inhibition on LOX soybean (IC₅₀ = 62 μM). Almost all the tested derivatives highly inhibited lipid peroxidation, significantly stronger than primaquine phosphate.