Synthesis and biological evaluation of thieno[3,2-c]pyrazol-3-amine derivatives as potent glycogen synthase kinase 3ß inhibitors for Alzheimer's disease.

Glycogen synthase kinase 3ß (GSK-3ß) is a potential target for anti-Alzheimer's disease (AD) drug development. In this study, a series of novel thieno[3,2-c]pyrazol-3-amine derivatives was synthesized and evaluated as potential GSK-3ß inhibitors by structure-based drug design. The thieno[3,2-c]pyrazol-3-amine derivative 54 with a 4-methylpyrazole moiety which interacted with Arg141 by π-cation interaction was identified as a potent GSK-3ß inhibitor with an IC50 of 3.4 nM and an acceptable kinase selectivity profile. In the rat primary cortical neurons, compound 54 showed neuroprotective effects on Aß-induced neurotoxicity. Western blot analysis indicated that 54 inhibited GSK-3ß by up-regulating the expression of phosphorylated GSK-3ß at Ser9 and down-regulating the expression of phosphorylated GSK-3ß at Tyr216. Meanwhile, 54 decreased tau phosphorylation at Ser396 in a dose-dependent way. In astrocytes and microglia cells, 54 inhibited the expression of inducible nitric oxide synthase (iNOS), indicating that 54 showed an anti-neuroinflammatory effect. In the AlCl3-induced zebrafish AD model, 54 significantly ameliorated the AlCl3-induced dyskinesia, demonstrating its anti-AD activity in vivo.

Synthesis and biological evaluation of thieno[3,2-c]pyrazol-3-amine derivatives as potent glycogen synthase kinase 3ß inhibitors for Alzheimer's disease.

Glycogen synthase kinase 3ß (GSK-3ß) catalyses the hyperphosphorylation of tau protein in the Alzheimer's disease (AD) pathology. A series of novel thieno[3,2-c]pyrazol-3-amine derivatives were designed and synthesised and evaluated as potential GSK-3ß inhibitors by structure-guided drug rational design approach. The thieno[3,2-c]pyrazol-3-amine derivative 16b was identified as a potent GSK-3ß inhibitor with an IC50 of 3.1 nM in vitro and showed accepted kinase selectivity. In cell levels, 16b showed no toxicity on the viability of SH-SY5Y cells at the concentration up to 50 µM and targeted GSK-3ß with the increased phosphorylated GSK-3ß at Ser9. Western blot analysis indicated that 16b decreased the phosphorylated tau at Ser396 in a dose-dependent way. Moreover, 16b effectively increased expressions of ß-catenin as well as the GAP43, N-myc, and MAP-2, and promoted the differentiated neuronal neurite outgrowth. Therefore, the thieno[3,2-c]pyrazol-3-amine derivative 16b could serve as a promising GSK-3ß inhibitor for the treatment of AD.

SAR Investigation and Discovery of Water-Soluble 1-Methyl-1,4-dihydroindeno[1,2-c]pyrazoles as Potent Tubulin Polymerization Inhibitors.

Taking the previously discovered 1-methyl-1,4-dihydroindeno[1,2c]pyrazol derivative LL01 as a lead, systematic structural modifications were made at the phenolic 6- and 7-positions and the aniline at the 3-position of the indenopyrazole core to investigate the SARs and to improve water solubility. Among the designed indenopyrazoles ID01-ID33, a series of potent MTAs were identified. As the hydrochloride salt(s), ID09 and ID33 showed excellent aqueous solubility and favorable Log P value and displayed noteworthily low nanomolar potency against a variety of tumor cells, including those taxol-resistant ones. They inhibited tubulin polymerization, disrupted cellular microtubule networks by targeting the colchicine site, and promoted HepG2 cell cycle arrest and cell apoptosis. In the HepG2 xenograft mouse model, ID09 and ID33 effectively inhibited tumor growth at an oral dose of 25 mg/kg. At an intravenous (iv) injection dose of 10 mg/kg every other day, ID09 suppressed tumor growth by 68% without obvious toxicity.

Tubulin colchicine site binding agent LL01 displays potent antitumor efficiency both in vitro and in vivo with suitable drug-like properties.

Through rational drug design, we previously identified an indenoprazole derivative, 2-(6-ethoxy-3-(3-ethoxyphenylamino)-1-methyl-1,4-dihydroindeno[1,2-c]pyrazol-7-yloxy)acetamide (LL01), as a potent tubulin polymerization inhibitor targeting the tubulin colchicine binding site. In this study, we further demonstrated that LL01 was not a P-gp substrate. It potently inhibited the growth of a variety of tumor cells, including those with multidrug resistance, with GI50 values in the low nanomole ranges. In vitro liver microsome stability assay, LL01 was modest stable in the liver microsomes of human, mouse and rat, but was fast metabolized in dog. After single oral administration of LL01 at a dose of 10 mg/kg in SD male rats, LL01 showed acceptable PK properties with a mean bioavailability of 41%. In human HepG2 hepatoma xenograft, at the oral doses of 25 mg/kg/day and 12.5 mg/kg/day, LL01 inhibited the tumor growth by 61.27%, and 43.74%, respectively, which is much better than the positive drug sorafenib (29.45%; 30 mg/kg/day). Therefore, LL01 might be a potential drug candidate for further investigation for hepatocellular carcinoma therapy.

The discovery of novel indazole derivatives as tubulin colchicine site binding agents that displayed potent antitumor activity both in vitro and in vivo.

Tubulin inhibitors that bind to the colchicine site are widely studied anticancer agents. In continuous our researches, we designed a series of novel indazole derivatives as microtubule-targeting agents (MTAs). The structure-activity relationships (SARs) investigations indicated that a 3,4,5-trimethoxyphenyl moiety and a methyl or methoxy substitution were preferred for the better antiproliferative activity. The indazole derivatives 3c and 3f showed noteworthy low nanomolar potency against HepG2, HCT116, SW620, HT29 and A549 tumor cells. In mechanism studies, 3c and 3f were proved to target the colchicine site, inhibited tubulin polymerization and disrupted cellular microtubule networks, arrested HCT116 cell in G2/M phase and induced cell apoptosis. In the HCT116 xenografts mouse model, 3c and 3f suppressed tumor growth by 45.3% and 58.9% at an orally dose of 25 mg/kg without causing obvious weight loss. The indazole 3f may serve as a good lead or drug candidate for colorectal cancer therapy.

Synthesis and Evaluation of Novel 2H-Benzo[e]-[1,2,4]thiadiazine 1,1-Dioxide Derivatives as PI3Kδ Inhibitors.

In previous work, we applied the rotation-limiting strategy and introduced a substituent at the 3-position of the pyrazolo [3,4-d]pyrimidin-4-amine as the affinity element to interact with the deeper hydrophobic pocket, discovered a series of novel quinazolinones as potent PI3Kδ inhibitors. Among them, the indole derivative 3 is one of the most selective PI3Kδ inhibitors and the 3,4-dimethoxyphenyl derivative 4 is a potent and selective dual PI3Kδ/γ inhibitor. In this study, we replaced the carbonyl group in the quinazolinone core with a sulfonyl group, designed a series of novel 2H-benzo[e][1,2,4]thiadiazine 1,1-dioxide derivatives as PI3Kδ inhibitors. After the reduction of nitro group in N-(2,6-dimethylphenyl)-2-nitrobenzenesulfonamide 5 and N-(2,6-dimethylphenyl)-2-nitro-5-fluorobenzenesulfonamide 6, the resulting 2-aminobenzenesulfonamides were reacted with trimethyl orthoacetate to give the 3-methyl-2H-benzo[e][1,2,4]thiadiazine 1,1-dioxide derivatives. After bromination of the 3-methyl group, the nucleophilic substitution with the 3-iodo-1H-pyrazolo[3,4-d]pyrimidin-4-amine provided the respective iodide derivatives, which were further reacted with a series of arylboronic acids via Suzuki coupling to furnish the 2H-benzo[e][1,2,4]thiadiazine 1,1-dioxide derivatives 15a-J and 16a-d. In agreement with the quinazolinone derivatives, the introduction of a 5-indolyl or 3,4-dimethoxyphenyl at the affinity pocket generated the most potent analogues 15a and 15b with the IC50 values of 217 to 266 nM, respectively. In comparison with the quinazolinone lead compounds 3 and 4, these 2H-benzo[e][1,2,4]thiadiazine 1,1-dioxide derivatives exhibited much decreased PI3Kδ inhibitory potency, but maintained the high selectivity over other PI3K isoforms. Unlike the quinazolinone lead compound 4 that was a dual PI3Kδ/γ inhibitor, the benzthiadiazine 1,1-dioxide 15b with the same 3,4-dimethoxyphenyl moiety was more than 21-fold selective over PI3Kγ. Moreover, the introducing of a fluorine atom at the 7-position of the 2H-benzo[e][1,2,4]thiadiazine 1,1-dioxide core, in general, was not favored for the PI3Kδ inhibitory activity. In agreement with their high PI3Kδ selectivity, 15a and 15b significantly inhibited the SU-DHL-6 cell proliferation.

Synthesis of Novel Pyrazole Derivatives and Their Tumor Cell Growth Inhibitory Activity.

To find novel antitumor agents, a series of 1H-benzofuro[3,2-c]pyrazole derivatives 4a-e were designed and synthesized. The treatment of 6-methoxybenzofuran-3(2H)-one 3 with LiHMDS in anhydrous tetrahydrofuran (THF) followed by reaction with 3-substitued phenyl isothiocyanate gave the thioamide intermediates, which underwent condensation with hydrazine monohydrate in dioxane/EtOH (1:1) to provide the benzofuropyrazole derivatives 4a⁻e as well as the unexpected pyrazole derivatives 5a⁻e. In tumor cell growth inhibitory assay, all the benzofuropyrazole derivatives were not active against the breast tumor MCF-7 cell, only 4a was highly active and more potent than ABT-751 against the leukemia K562 (GI50 = 0.26 µM) and lung tumor A549 cells (GI50 = 0.19 µM), while other benzofuropyrazoles showed very weak inhibitory activity. In contrast, the pyrazoles 5a-e were in general more potent than the benzofuropyrazoles 4a⁻e. Compound 5a exhibited a similar tendency to that of 4a with high potency against K562 and A549 cells but weak effects on MCF-7 cell. Both pyrazoles 5b and 5e exhibited high inhibitory activities against K562, MCF-7 and A549 cells. The most active compound 5b was much more potent than ABT-751 against K562 and A549 cells with GI50 values of 0.021 and 0.69 M, respectively. Moreover, 5b was identified as a novel tubulin polymerization inhibitor with an IC50 of 7.30 M.

Discovery of novel quinazolinone derivatives as high potent and selective PI3Kδ and PI3Kδ/γ inhibitors.

PI3Kδ and PI3Kγ regulate immune cell signaling. Selective PI3Kδ or PI3Kγ inhibitors and dual PI3Kδ/γ inhibitors have the potential for the treatment of immune cell-mediated diseases and hematological malignancies. Based on the quinazolinone pharmacophore, we used a pyrazolo[3,4-d]pyrimidin-4-amine portion as the hinge region binding moiety, an aromatic or a heteroaromatic substituent at the 3-position of the pyrazolo[3,4-d]pyrimidine core as the affinity element, and designed novel 2-tolyl and 2,6-dimethylphenyl quinazolinone derivatives as potential PI3Kδ inhibitors. Most of these compounds displayed high inhibitory rates (89-97%) against PI3Kδ at the concentration of 1 µM, with the IC50 values of 8.4 nM-106 nM. Among the 3-(2,6-dimethylphenyl)quinazolinone series, the introduction of an indol-5-yl substituent at the pyrazolo[3,4-d]pyrimidine 3-position led to a potent and selective PI3Kδ (IC50 = 8.6 nM) inhibitor 10d, that was more than 3630-fold, 390-fold and 40-fold selective for PI3Kδ over PI3Kα, ß and γ, while the substitution with a 3,4-dimethoxyphenyl resulted in a potent and selective dual PI3Kδ/γ inhibitor 10e with IC50 values of 8.4 nM and 62 nM against PI3Kδ and PI3Kγ, respectively. Compound 10e was also more than 1400-fold, 820-fold selective for PI3Kδ over PI3Kα and PI3Kß. In agreement with their remarkable PI3Kδ inhibitory activity, compounds 10d and 10e showed high antiproliferative activity against human B-cell SU-DHL-6 cells. Moreover, the dual PI3Kδ/γ inhibitor 10e had reasonable pharmacokinetic profiles with a good plasma exposure, low clearance, low volume distribution, and an acceptable oral bioavailability of 34.9%.

Design, Synthesis, and Biological Evaluation of 1-Methyl-1,4-dihydroindeno[1,2-c]pyrazole Analogues as Potential Anticancer Agents Targeting Tubulin Colchicine Binding Site.

By targeting a new binding region at the interface between αß-tubulin heterodimers at the colchicine binding site, we designed a series of 7-substituted 1-methyl-1,4-dihydroindeno[1,2-c]pyrazoles as potential tubulin polymerization inhibitors. Among the compounds synthesized, 2-(6-ethoxy-3-(3-ethoxyphenylamino)-1-methyl-1,4-dihydroindeno[1,2-c]pyrazol-7-yloxy)acetamide 6a and 2-(6-ethoxy-3-(3-ethoxyphenylamino)-1-methyl-1,4-dihydroindeno[1,2-c]pyrazol-7-yloxy)-N-hydroxyacetamide 6n showed noteworthy low nanomolar potency against HepG2, Hela, PC3, and MCF-7 cancer cell lines. In mechanism studies, 6a inhibited tubulin polymerization and disorganized microtubule in A549 cells by binding to tubulin colchicine binding site. 6a arrested A549 cells in G2/M phase that was related to the alterations in the expression of cyclin B1 and p-cdc2. 6a induced A549 cells apoptosis through the activation of caspase-3 and PARP. In addition, 6a inhibited capillary tube formation in a concentration-dependent manner. In nonsmall cell lung cancer xenografts mouse model, 6a suppressed tumor growth by 59.1% at a dose of 50 mg/kg (ip) without obvious toxicity, indicating its in vivo potential as anticancer agent.

Preparation of S14161 and its analogues and the discovery of 6-bromo-8-ethoxy-3-nitro-2H-chromene as a more potent antitumor agent in vitro.

The small chemical compound 8-ethoxy-2-(4-fluorophenyl)-3-nitro-2H-chromene (S14161) was recently identified as an inhibitor of the phosphoinositide 3-kinase (PI3K). In the present study, we designed a novel synthesis of S14161 and prepared a series of its analogues via the oxa-Michael-Henry reaction in the presence of catalytic amounts of l-proline and triethylamine. Further structural simplification led to the identification of 6-bromo-8-ethoxy-3-nitro-2H-chromene (BENC-511) that exhibited potent antiproliferative activities against a panel of 12 tumor cell lines. Compared with S14161, BENC-511 was more potent in blocking the AKT phosphorylation and inducing cancer cell apoptosis. BENC-511 also displayed more potent effects on human umbilical vein epithelial cells (HUVEC) migration, suggesting its anti-angiogenesis activity.

Recoverable Pd/C catalyst mediated dehydrogenation of sterols and an improved synthesis of 1α-hydroxydehydroepiandrosterone.

A novel recyclable Pd/C catalyst mediated dehydrogenation of sterols is developed. The conversion of sterols to 1,4,6-trien-3-ones is best achieved with Pd/C as a catalyst (10%) in the presence of six equivalents of allyl diethyl phosphate (ADP) and excess amount of sodium carbonate in DMF under vigorous reflux conditions. This transformation gives 17,17-ethylenedioxyandrost-1,4,6-trien-3-one in better yield than that of DDQ oxidation and thus provides an improved synthesis of 1α-hydroxydehydroepiandrosterone from DHEA.

Design and synthesis of potent HIV-1 protease inhibitors incorporating hydroxyprolinamides as novel P2 ligands.

A series of new HIV-1 protease inhibitors with the hydroxyethylamine core and different hydroxyprolinamide P2 ligands were designed and synthesized. Variation of substitutions at the P2 significantly affected the enzyme inhibitory potency of the inhibitors. Compounds 2a and 2d showed excellent enzyme inhibitory activity with IC(50) values in the nanomolar range. An active site binding model for inhibitors 2a and 2d was suggested based upon the computational-docking results of the ligand with HIV-1 protease. This model offers molecular insights regarding ligand-binding site interactions of the hydroxyprolinamide-derived novel P2-ligand.

Synthesis and evaluation of trehalose-based compounds as anti-invasive agents.

Brartemicin is a trehalose-based inhibitor of tumor cell invasion produced by the actinomycete of the genus Nonomuraea. In order to explore the preliminary structure-activity relationship and obtain more potent inhibitors, a series of brartemicin analogs were synthesized through the Mitsunobu coupling of the secondary hydroxyls benzyl protected α,α-D-trehalose with benzoic acid derivatives, followed by modification of functional groups and deprotection. These compounds were evaluated for their inhibitory activity against invasion of murine colon 26-L5 carcinoma cells in vitro. Among the synthetic analogs tested, 6,6'-bis(2,3-dimethoxybenzoyl)-α,α-D-trehalose (5e) was found to be the most potent anti-invasive agent, exhibited a 2.6-fold improvement with regard to the parent natural product brartemicin, and it is considered to be a promising lead molecule for the anti-metastasis.