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Phosphodiesterase 5A1 (PDE5) is a key target for treating cardiovascular diseases and erectile dysfunction. Here, we report the crystal structure of PDE5 complexed with the sole second generation drug avanafil. Analysis of protein-drug interactions revealed the structural basis of avanafil's superior isoform selectivity. Moreover, a halogen bonding was observed between avanafil and a backbone carbonyl oxygen of an adjacent α-helix, whose contribution to inhibitory potency illustrates the feasibility of exploiting α-helix backbone in structure-based drug design.

We designed and synthesized quinazolin-2,4-dione-based hydroxamic acids to serve as selective competitive inhibitors of histone deacetylase-6 (HDAC6). The most potent and selective compound, 3d (IC50, 4 nM, HDAC6; IC50 > 10 μM, HDAC1), substantially increased acetylation of α-tubulin instead of histones in the lung cancer cell line, LL2. Paclitaxel in combination with 3d had a synergistic anticancer effect on reduction of programmed death-ligand 1 expression in LL/2 cells. When given orally, 3d was mainly found to locate in the liver and lungs, at a concentration 18- to 70-fold greater, respectively, than in plasma. As an orally active HDAC6 inhibitor, 3d (20 mg/kg) potentiated paclitaxel antitumor activity (percentage tumor growth inhibition, 67.5%) in a xenograft syngeneic non-small cell lung cancer mouse model.

[Image: see text] We demonstrate that the acrylamide group can be used to improve the drug-like properties of potential drug candidates. In the EGFR inhibitor development, both the solubility and membrane permeability properties of compounds 6a and 7, each containing an acrylamide group, were substantially better than those of gefitinib (1) and AZD3759 (2), respectively. We demonstrated that incorporation of an acrylamide moiety could serve as a good strategy for improving drug-like properties.

HDAC6 receives great attention because of its therapeutic potential for the treatment of various diseases. Selective fluorescence imaging for HDAC6 is important for its pathological and biological studies. However, specific detection of HDAC6 by using a fluorescent small molecule probe remains a great challenge. Herein, a series of fluorescent HDAC6-selective inhibitors incorporating a naphthalimide skeleton were designed and synthesized. A structure-activity relationship study identified that compound JW-1 had the greatest inhibitory activity and superior specificity against HDAC6. JW-1 could substantially increase α-tubulin acetylation and was active against a panel of six cancer cell lines. Photophysical characterization and cellular imaging of MDA-MB-231 cells demonstrated that JW-1 is a highly fluorescent, cell penetrable, small-molecule inhibitor of HDAC6 that can be used for the detection of HDAC6 in complex cellular environments.

Herein, we report the identification, design, and synthesis of a series of 4-substituted 2-amino-3,4-dihydroquinazolines with hairpin turn side chains as novel inhibitors of BACE-1. The dihydroquinazoline derivatives were rationally designed by modifying the amide group and relocating the α -hydrophobic substituent on the hairpin turn side chain of lead compound 2 to the C4-position on the 3,4-dihydroquinazoline scaffold to facilitate interactions with the S1, S2 and S1′ subsites of BACE-1. Among these derivatives, two compounds exhibited potent BACE-1 inhibitory activity: 4-methyl-substituted (22a, BACE-1 CFA IC50 = 0.38 μM; BACE-1 WCA IC50 = 0.14 μM) and 4-cyclohexylmethyl-substituted (22b, BACE-1 CFA IC50 = 0.49 μM; BACE-1 WCA IC50 = 0.14 μM) 2-amino-3,4-dihydroquinazoline, each bearing a side chain of N-cyclohexyl-N-((1-methyl-1H-pyrazol-4-yl)methyl amide. The results suggest that the structural modifications maintain the hairpin turn topology similar to that of compound 2 and provide an additional interaction with the S2 subsite.

MutT Homolog 1 (MTH1) has been proven to hydrolyze oxidized nucleotide triphosphates during DNA repair. It can prevent the incorporation of wrong nucleotides during DNA replication and mitigate cell apoptosis. In a cancer cell, abundant reactive oxygen species can lead to substantial DNA damage and DNA mutations by base-pairing mismatch. MTH1 could eliminate oxidized dNTP and prevent cancer cells from entering cell death. Therefore, inhibition of MTH1 activity is considered to be an anti-cancer therapeutic target. In this study, high-throughput screening techniques were combined with a fragment-based library containing 2,313 compounds, which were used to screen for lead compounds with MTH1 inhibitor activity. Four compounds with MTH1 inhibitor ability were selected, and compound MI0639 was found to have the highest effective inhibition. To discover the selectivity and specificity of this action, several derivatives based on the MTH1 and MI0639 complex structure were synthesized. We compared 14 complex structures of MTH1 and the various compounds in combination with enzymatic inhibition and thermodynamic analysis. Nanomolar-range IC50 inhibition abilities by enzyme kinetics and Kd values by thermodynamic analysis were obtained for two compounds, named MI1020 and MI1024. Based on structural information and compound optimization, we aim to provide a strategy for the development of MTH1 inhibitors with high selectivity and specificity.

Glioblastoma is the most fatal type of primary brain cancer, and current treatments for glioblastoma are insufficient. HDAC6 is overexpressed in glioblastoma, and siRNA-mediated knockdown of HDAC6 inhibits glioma cell proliferation. Herein, we report a high-selective HDAC6 inhibitor, J22352, which has PROTAC (proteolysis-targeting chimeras)-like property resulted in both p62 accumulation and proteasomal degradation, leading to proteolysis of aberrantly overexpressed HDAC6 in glioblastoma. The consequences of decreased HDAC6 expression in response to J22352 decreased cell migration, increased autophagic cancer cell death and significant tumor growth inhibition. Notably, J22352 reduced the immunosuppressive activity of PD-L1, leading to the restoration of host anti-tumor activity. These results demonstrate that J22352 promotes HDAC6 degradation and induces anticancer effects by inhibiting autophagy and eliciting the antitumor immune response in glioblastoma. Therefore, this highly selective HDAC6 inhibitor can be considered a potential therapeutic for the treatment of glioblastoma and other cancers.

Alzheimer's disease is a neurodegenerative disorder characterized by deposition of β-amyloid (Aβ) fibrils accompanied with progressive neurite loss. None of the clinically approved anti-Alzheimer's agents target both pathological processes. We hypothesized that conjugation of a metal chelator to destabilize Aβ fibrils (fAβs) and a long-chain fatty alcohol to induce neurite outgrowth may generate a novel molecular scaffold that targets both pathologies. The hydroxyalkylquinoline J2326 was designed and synthesized by joining an 11-carbon alcohol to 5-chloro-8-methoxyquinoline at the 2-position and its anti-neurodegenerative potentials in vitro and in vivo were characterized. It attenuated fAβ formation and disaggregated the existing fAβ zinc-dependently as well as zinc-independently. It also triggered extracellular signal-regulated kinase-dependent neurite outgrowth and increased synaptic activity in neuronal cells. In fAβ-driven neurodegeneration in vitro, J2326 reversed neurite collapse and neurotoxicity. These roles of J2326 were also demonstrated in vivo and were pivotal to the observed improvement in memory of mice with hippocampal fAβ lesions. These results show that the effectiveness of J2326 on fAβ-driven neurodegeneration is ascribed to its novel scaffold. This might give clues to evolving attractive therapy for future clinical trials.

The histone deacetylase inhibitor (HDACi) has been investigated for treating cancers and many other diseases as well as enhancing the reprogramming efficiency in cloned embryos for decades. In the present study, we investigated the effects of two novel HDAC inhibitors, i.e., HDACi-14 and -79, at the concentrations of 0, 1, 2, or 4 μM on the development of embryos cloned by the oocyte bisection cloning technique (OBCT). Blastocyst rates for the reconstructed embryos reached 60% in the 2 μM HDACi-14-treated groups, which was higher (P < 0.05) compared to the untreated group (36.9%). Similarly, HDACi-79 treatment at 2 and 4 μM also conferred higher (P < 0.05) blastocyst rates than that of the untreated group (79.4, 74.2, and 50.0%, respectively). Both HDACi-14 and -79 treatments had no beneficial effect on total cell numbers and apoptotic indices of cloned embryos (P > 0.05). Histone acetylation profile by both HDACi-14 (2 μM) and -79 (2 μM) treatments demonstrated a drastic increase (P < 0.05) mainly in two-cell stage embryos when compared to the control group. After seeding on the feeder cells, the aggregated cloned blastocysts produced by the HDACi-79 treatment showed a significant increase of primary outgrowths compared to the control group (60.0% vs. 42.9%; P < 0.05). Finally, the cloned embryo-derived ES cell lines from aggregated cloned embryos produced from the HDACi-79-treated, HDACi-14-treated and control groups were established (5, 3, and 2 lines, respectively). In conclusion, the novel histone deacetylation inhibitors improve blastocyst formation and potentially increase the derivation efficiency of ES cell lines from the cloned porcine embryos produced in vitro. Depending on the purposes, some fine-tuning may be required to maximize its beneficial effects of these newly synthesized chemicals.

The unique hydrogen binding capabilities of ureas make them an important functional group to make drug-target interactions and thus incorporated in small molecules displaying broad range of bioactivities. The related research and numerous excellent achievements of ureas applicability in drug design for the modulation of selectivity, stability, toxicity and pharmacokinetic profile of lead molecules have become active topic. This review aims to provide insights in to the significance of urea in drug design by summarizing successful studies of various urea derivatives as modulators biological targets (viz. kinases, NAMPT, soluble epoxide hydrolases, mTOR, proteases, gyrB/parE, and epigenetic enzymes (such as HDAC, PRMT or DOT1L etc.). The findings of this review confirm the importance of urea moiety in medicinal chemistry and stimulate its use as a structural motif with rational decision making approach.

An efficient microwave-assisted, palladium-catalyzed hydroxylation of aryl chlorides in the presence of a weak base carbonate was developed, which rapidly converts aryl and heteroaryl chlorides to phenols, and can be used when the aryl chloride is functionalized with a ketone, aldehyde, ester, nitrile, or amide.

The inbuilt 2-N-hydroxy-1-oxo-3-carboxylic acid of isoquinolone was designed as pyrophosphate mimic for hepatitis C NS5B polymerase. Various 2-hydroxy-1-oxo-1,2-dihydroisoquinoline-3-carboxylic acid derivatives 11a-p were synthesized and evaluated as HCV NS5B polymerase inhibitors. Compound 11c exhibited moderate inhibitory potency based on the inorganic pyrophosphate generation (IC50 = 9.5 μM) and based on NTP incorporation by NS5B enzyme (IC50 = 5.9 μM). Compound 11c demonstrated antiviral activity (EC50 = 15.7 μM) and good selectivity in HCV genotype 1b replicon Ava.5 cells. Compound 11c reduced the interaction of NTP to NS5B polymerase. Docking model showed that 11c situated in similar orientation to the bound uridine triphosphate in the active site of NS5B polymerase. As a result, 2-hydroxy-1-oxo-1,2-dihydroisoquinoline-3-carboxylic acid was disclosed as a novel inbuilt γ-keto-acid pharmacophore for HCV NS5B polymerase inhibitors.

3-(4-Bromophenyl)-6-nitrobenzo[1.3.2]dithiazolium ylide 1,1-dioxide (5) was discovered as a new prototype for dual inhibitors of cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX). Thus, the structure–activity relationships of benzo[1.3.2]dithiazolium ylide 1,1-dioxide skeleton were carried out. The 6-NO2 group played an essential role in the inhibitory activity. In addition, moderate-sized lipophilic substituents at the para-position of the 3-aryl moiety were required for dual COX-2/5-LOX inhibitory activity. Among the identified potent dual inhibitors, 3-(4-tbutylphenyl) derivative 30c (IC50 values of 0.27 μM and 0.30 μM against COX-2 and 5-LOX, respectively) and 3-(4-biphenyl) derivative 30f (IC50 values of 0.50 μM and 0.15 μM against COX-2 and 5-LOX, respectively) were the most potent dual COX-2/5-LOX inhibitors. Intraperitoneal administration of 30c at 100 mg/kg demonstrated potent acute anti-inflammatory activity. As a result, benzo[1.3.2]dithiazolium ylide 1,1-dioxide represented a novel scaffold for the exploitation in developing dual COX-2/5-LOX inhibitors.

The construction of diaryl sulfides through the cross-coupling of aryl iodides and thiols in microwave heating is described. By using this method, a variety of diaryl sulfides can be prepared in a mild condition and in high yields. Deactivated 4-nitrothiophenol was effective to afford the product in 94% yield. Sterically hindered ortho-substituted aryl iodides or thiophenols provided diaryl sulfides effectively by this microwave-assisted coupling reaction.

Comprehensive studies support the notion that selective inhibitors of cyclooxygenase-2 (COX-2) display anticancer activities in numerous types of cancer cells, including prostate cancers. Our previous study showed that the benzodithiazolium-based compound CX9051 selectively inhibited COX-2 activity. We now show that CX9051 inhibits cell proliferation and induces apoptosis in numerous human cancer cell types. Biochemical analyses, including flow cytometry, showed that CX9051 induced apoptosis in the absence of cell cycle checkpoint arrest and down-regulated the expression of Bcl-2, Bcl-x(L), and Mcl-1, but up-regulated tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) expression, leading to proteolytic activation of caspase-8, -9, -7, and -3. These data suggest that CX9051 functions in both mitochondria-mediated intrinsic and death receptor-induced extrinsic apoptosis pathways. Moreover, confocal microscopy demonstrated that CX9051 induced nuclear translocation of nuclear factor-kappa B (NF-kappaB) at initial stage and then caused a marked decrease of total cellular NF-kappaB at later stage in both PC-3 and DU145 cells. Taken together, our data suggest that CX9051 induces TRAIL up-regulation and activation of extrinsic apoptotic signaling, which in turn activates mitochondria-mediated intrinsic apoptotic signaling, leading to cancer cell apoptosis.

To evaluate the effects and elucidate the mechanisms of a series of indoloquinazolines as novel anticancer agents. Condensation of the substituted isatoic anhydride with the substituted isatin was performed to prepare compounds 1–4, followed by adding malononitrile to prepare compounds 5–7. Cytotoxicity was measured by MTT assays. Apoptosis induction was evaluated using DNA fragmentation, cell cycle assay, caspase 3/7 activity and Western blot. Compounds 3, 4, and 5 display cytotoxicity against MCF-7, HeLa, SKOV3, and A498 cancer cells. DNA ladders appear in cells treated with compounds 3, 4, and 5. Within those, compound 4 exhibits the greatest activity in regards to sub-G1 accumulations in the cell cycle and the activation of caspase-3/7. Furthermore, Fas and Fas ligand levels are elevated by compound 4, implying that the apoptosis is in part mediated through the signals. On the other hand, compounds 1 and 7 display chemosensitizing activity since cytotoxicity of doxorubicine and etoposide is enhanced in combination with compound 1 and 7, respectively, in MCF-7/adr (doxorubicin-resistant) and MCF-7/vp (etoposide-resistant). The cytotoxicity of indoloquinazolines is structure-dependent rather than cell type-dependent due to the similar degree of cytotoxicity induced by the individual compounds in all four cell lines. Further modification of the tryptanthrin skeleton is important to develop novel anticancer agents bearing either cytotoxicity against MCF-7 cells or drug resistance reversal in MCF-7/adr and MCF-7/vp.

In the present study we have discovered compound 1 , a benzo[1.3.2]dithiazolium ylide-based compound, as a new prototype dual inhibitor of cyclooxygenase (COX) and 5-lipoxygenase (5-LOX). Compound 1 was initially discovered as a COX-2 inhibitor, resulting indirectly from the COX-2 structure-based virtual screening that identified compound 2 as a virtual hit. Compounds 1 and 2 inhibited COX-1 and COX-2 in mouse macrophages with IC 50 in the range of 1.5–18.1 μM. Both compounds 1 and 2 were also found to be potent inhibitors of human 5-LOX (IC 50 = 1.22 and 0.47 μM, respectively). Interestingly, compound 1 also had an inhibitory effect on tumor necrosis factor-α (TNF-α) production (IC 50 = 0.44 μM), which was not observed with compound 2 . Docking studies suggested the ( S )-enantiomer of 1 as the biologically active isomer that binds to COX-2. Being a cytokine-suppressive dual COX/5-LOX inhibitor, compound 1 may represent a useful lead structure for the development of advantageous new anti-inflammatory agents.

A novel series of topoisomerase I (Top I) inhibitors were designed on the basis of camptothecin using scaffold modification strategy. Thirty-one new compounds were synthesized and evaluated for anticell proliferation activity. The most potent compound 26 presented a significant inhibitory effect on Top I, leading to Top I-mediated cleavage and influences on Top I expression at the cellular level. Moreover, 26 was proved to induce cell death via apoptosis and accelerated DNA strand breaks without significant alteration in cell cycle populations. All of the experimental results herein indicated that 26 could interact with DNA-Top I complex and induce cancer cell apoptosis to produce antitumor effects. The in vivo evaluation of 26 on the growth of HT-29 tumor xenografts in nude mice suggested its therapeutic potential for further development.

Overexpression of GSTpi and underexpression of Topo II expression are associated with multidrug resistance (MDR) phenotype through nontransporter pathway. Tryptanthrin, a quinazoline derivative, was reported to sensitize resistant cells to doxorubicin by downregulation of MDR1 expression. This study aims to extendedly investigate the effect of tryptanthrin on the role of nontransporter-based genes in determining the MDR response in doxorubicin-resistant MCF-7 cells (MCF-7/adr). Results show that tryptanthrin downregulates GSTpi expression and reduces glutathione S-transferase (GST) activity, but has no effect on Topo II expression. Less production of GSTpi decomposes the protein-protein interactions of GSTpi and c-jun NH2-terminal kinase (JNK). The resulting free-form JNK undergoes phosphorylation upon elevated intracellular doxorubicin accumulation and subsequently activates JNK-mediated apoptosis. In conclusion, in addition to transporter pathway, tryptanthrin reverses MDR partly by modulating GSTpi-related pathway, a nontransporter pathway, in MCF-7/adr cells. It indicates that tryptanthrin may act as a potential chemoadjuvant agent through multiple targets.

In this study, a series of tetrahydroisoquinolines have been synthesized and identified as novel kinesine spindle protein (KSP) inhibitors based on the pharmacophore we have mapped and the crystal structure of monastrol bound to the target protein. The KSP inhibitory activities of all the designed compounds were tested using cloned Human KSP protein. All thirteen compounds were more potent than the control, monastrol, in Human KSP protein adenosine triphosphatase (ATPase) assays. Three compounds (1b, 1g, 1h) exhibited over 100 times higher potency than monastrol. Cytotoxic results in vitro by MTT method indicated that nine of these compounds (1a, 1b, 1c, 1d, 1e, 1g, 1h, 1j, 1k) were more active than monastrol. In particular, compounds 1b and 1g, each of which contains a hydrophilic group on the side chain at the 2-position, exhibited excellent cell-killing activities against HepG2 cells.

—Because both c-Src and iNOS are key regulatory enzymes in tumorigenesis, a new series of 4-heteroarylamino-3-quino-linecarbonitriles as potent dual inhibitors of both enzymes were designed, prepared, and evaluated for blocking multiple signalingpathways in cancer therapy. All compounds were evaluated by two related enzyme inhibition assays and an anti-proliferation assayin vitro. The results showed that most compounds could inhibit both enzymes, and several of them showed potent inhibition activityagainst different cancer cell lines. The best compound 20 (CPU-Y020) showed the IC 50 values of 6.58 and 7.61 lM toward coloncancer HT-29 and liver cancer HepG2 cell lines. 2008 Elsevier Ltd. All rights reserved. 1. IntroductionThe Src family of protein tyrosine kinases (SFKs) playskey roles in regulating signal transduction, including cellgrowth, differentiation, cell shape, migration, and sur-vival, and specialized cell signals. 1 However, c-Src wasalso identified as a proto-oncogene based on decadesof research on an avian RNA tumor (sarcoma) virus.In some abnormal cases, such as mutation of the c-Srcor over-expression, these enzymes can become hyper-activated, resulting in uncontrolled cell proliferation.

A beta-glucuronidase-activated prodrug approach was applied to 10-hydroxycamptothecin, a Camptotheca alkaloid with promising antitumor activity but poor water solubility. We synthesized a glucuronide prodrug of 10-hydroxycamptothecin ( 7) in which glucuronic acid is connected via a self-immolative 3-nitrobenzyl ether linker to the 10-OH group of 10-hydroxycamptothecin. Compound 7 was 80 times more soluble than 10-hydroxycamptothecin in aqueous solution at pH 4.0 and was stable in human plasma. Prodrug 7 was 10- to 15-fold less toxic than the parent drug to four human tumor cell lines. In the presence of beta-glucuronidase, prodrug 7 could be activated to elicit similar cytotoxicity to the parent drug in tumor cells. Enzyme kinetic studies showed that Escherichia coli beta-glucuronidase had a quite low K m of 0.18 microM for compound 7 and exhibited 520 times higher catalytic efficiency for 7 than for 6 (a glucuronide prodrug of 9-aminocamptothecin). Molecular modeling studies predicted that compound 7 would have a higher binding affinity to human beta-glucuronidase than compound 6. Prodrug 7 may be useful for selective cancer chemotherapy by a prodrug monotherapy (PMT) or antibody-directed enzyme prodrug therapy (ADEPT) strategy.

Derivatives of 5,7-dichloro-2-styrylquinoline (1), modified at position 8 of quinoline moiety with a methyl ether (4, DCSQM) or acetate (5, DCSQA), were synthesized and investigated. Both compounds exhibited high thermal stability (Td > 320 °C). The UV-vis absorption of DCSQM and DCSQA varied only slightly in different solvents, whereas the emission spectra showed pronounced red shifts with increasing solvent polarity, suggesting the intramolecular charge transfer character of the emission state. Compounds 4 and 5 can emit lights from blue to green color in different solvents. The solvent polarity dependent electronic transitions are attributed to efficient intramolecular charge transfer (ICT) processes, in which the HOMOs and LUMOs are localized on the styrene-based ring and the quinoline-based moiety, respectively. The quinoline-based LUMO provides compelling evidence that the first reduction site occurs on the electron-deficient quinoline moiety.

Derivatives of indolo[2,1-b]quinazolinone containing aminoalkylamino side chains were synthesized as specific DNA triplex stabilizing agents. The aminoalkylamino side chains are essential for triplex stabilization. The position-8 fluorine atom or a methyl group to the nitrogen adjacent to the planar core can enhance triplex stability by 6 degrees C and the effect is additive. Conformational analysis reveals that the orientation of the side chain underlies the ability of this compound to stabilize a DNA triplex.

SummaryMana-Hox, an analog of β-carbolines with anticancer activity, induces aberrant mitosis and delays mitotic exit. However, the cellular target is not known. In this study, we visualized the intracellular localization of Mana-Hox. Mana-Hox rapidly penetrated into cells (within 1 min) and concentrated on disorganized metaphase chromosomes after 13 hr of exposure. We demonstrated that Mana-Hox is a noncovalent DNA binder that can interact with DNA through intercalation and/or through minor groove binding. Furthermore, Mana-Hox also inhibits topoisomerase II relaxation activity in vitro, suggesting that Mana-Hox could perturb mitotic chromosome decatenation. Overall, Mana-Hox binding to DNA plays a critical role in the induction of aberrant mitosis and contributes to its anticancer activity.

4-Sulfonamide substituted benzamidobenzimidazolones were designed and docked into the active site model of CDK2, using an oxindole inhibitor as the template. Compounds 6a-6i were then prepared from the reaction of the sulfonyl chloride 1 with different amines to give the corresponding acids (2a-2i), which were converted to their corresponding acyl chlorides (3a-3i). Reaction of 3a-3i with o-nitrophenylhydrazine afforded the respective nitro derivatives (4a-4i). The nitro groups were then reduced to give the corresponding amines (5a-5i), which, upon reaction with ethyl chloroformate, the target compounds (6a-6i) were produced. Target benzimidazolone derivatives (9a-9e) were also prepared from the reaction of isopropenyl benzimidazolone (8) with different sulfonyl or acyl chlorides. The target compounds were then tested by a modified 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay against the cancer cell lines, Hep G2, HT-29, CL1-5 and AGS. Despite similar binding properties of the flexible benzamidobenzimidazolones and rigid cytotoxic oxindole inhibitors at the active site of CDK2, biological screening results indicated that benzamidobenzimidazolones did not exhibit significant cell growth inhibition in vitro. Their analogue, 3-acyl benzimidazolone (12), however, revealed cytotoxicity similar to that of the reference oxindole inhibitor.

Isoguanosine (3) underwent a coupling reaction with diaryl disulfides in the presence of tri-n-butylphosphine when its 6-amino group was protected by N,N-dimethylaminomethylidene. The synthesis of 5-deoxyN 3 ,5-cycloisoguanosine (6) and its 2,3-O-isopropylidene derivative (11) were accomplished in excellent yields from isoguanosines (3 & 10) in the presence of triphenylphospine and carbon tetrachloride in pyridine. Chlorination at the 5-position of isoguanosine (3) with thionyl chloride followed by the aqueous basepromoted cyclization afforded the same product 6. The structures were elucidated by spectroscopic analysis including IR, UV, 1-D and 2-D NMR.

It has been suggested that terazosin has an inhibitory effect on prostate tumor growth. We determined if terazosin action contributes to direct suppression of the angiogenic effect.PC-3 cells and primary cultures of human benign prostatic cells were used in this study. The cytotoxic effect was examined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and lactate dehydrogenase release reaction. The in vivo angiogenic effect was determined in nude mice models, followed by histological examination and quantification by the hemoglobin detection assay. In vitro determination of cell migration, proliferation and tube formation was performed in cultured human umbilical vein endothelial cells. RESULTS Terazosin induced cytotoxicity in PC-3 and human benign prostatic cells with an IC50 of more than 100 microM. The positive terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling and lactate dehydrogenase release reaction was associated with terazosin induced cytotoxicity, indicating apoptotic and necrotic cell death. Furthermore, cytotoxicity due to terazosin action was not a common characteristic of a quinazoline based structure. Terazosin significantly inhibited vascular endothelial growth factor induced angiogenesis in nude mice with an IC50 of 7.9 microM., showing that it had a more potent anti-angiogenic than cytotoxic effect. Terazosin also effectively inhibited vascular endothelial growth factor induced proliferation and tube formation in cultured human umbilical vein endothelial cells (IC50 9.9 and 6.8 microM., respectively).Together our data suggest that terazosin shows direct anti-angiogenic activity through the inhibition of proliferation and tube formation in endothelial cells. This action may partly explain the in vivo antitumor potential of terazosin.

The purpose of this study was to synthesize compounds in which the 1,2,4-oxadiazole moiety replaced the amide bond of ONO3805 and to evaluate its 5α-reductase inhibitory activity as a potential benign prostatic hyperplasia therapeutic target. Four 1,2,4-oxadiazole derivatives, 1, 2, 8, and 20, were evaluated in vitro against 5α-reductase of rat liver microsome. The prepared 1 and 2 possessed similar binding affinity (Ki) to that of ONO3805. Therefore, the use of 1,2,4-oxadiazole ring as surrogate of the amide bond in ONO3805 has a successful result in this study. It leads not only to enhance chemical stability but also to maintain meaningful inhibitory activity. The butyric acid moiety of these inhibitors is considered to play an important role in mimicing the phosphoric acid portion of coenzyme-NADPH in interacting with the active site of 5α-reductase.

A series of 6-acylureido derivatives containing a 3-(pyrrol-2-ylmethylidene)indolin-2-one scaffold were synthesized as potential dual Aurora B/FLT3 inhibitors by replacing the 6-arylureido moiety in 6-arylureidoindolin-2-one-based multi-kinase inhibitors. (Z)-N-(2-(pyrrolidin-1-yl)ethyl)-5-((6-(3-(2-fluoro-4-methoxybenzoyl)ureido)-2-oxoindolin-3-ylidene)methyl)-2,4-dimethyl-1H-pyrrole-3-carboxamide (54) was identified as a dual Aurora B/FLT3 inhibitor (IC50 = 0.4 nM and 0.5 nM, respectively). Compound 54 also exhibited potent cytotoxicity with single-digit nanomolar IC50 values against the FLT3 mutant-associated human acute myeloid leukemia (AML) cell lines MV4-11 (FLT3-ITD) and MOLM-13 (FLT3-ITD). Compound 54 also specifically induced extrinsic apoptosis by inhibiting the phosphorylation of the Aurora B and FLT3 pathways in MOLM-13 cells. Compound 54 had a moderate pharmacokinetic profile. The mesylate salt of 54 efficiently inhibited tumor growth and reduced the mortality of BALB/c nude mice (subcutaneous xenograft model) that had been implanted with AML MOLM-13 cells. Compound 54 is more potent than sunitinib not only against FLT3-WT AML cells but also active against sunitinib-resistant FLT3-ITD AML cells. This study demonstrates the significance of dual Aurora B/FLT3 inhibitors for the development of potential agents to treat AML.

Bioisosteric replacement of acylureido moiety in 6-acylureido-3-pyrrolylmethylidene-2-oxoindoline derivatives resulted in a series of malonamido derivatives with indolin-2-one scaffold (11-14). Further conformational restrictions of the malonamido moiety led to 2-oxo-1,2-dihydropyridine (21-25) or a 4-oxo-1,4-dihydropyridine derivatives (31-36). 4-Oxo-1,4-dihydropyridine derivatives were more potent Aurora B inhibitors than their 2-oxo-1,2-dihydropyridine counterparts and demonstrated cytotoxicities against A549 and HepG2 cells in the submicromolar range. In A549 cells, 31h decreased phosphorylation of histone H3, triggered polyploidy, induced expression of pro-apoptotic Fas and FasL with subsequent activation of caspase 8, resulting into apoptosis. In a Huh7-xenograft mouse model, 31h demonstrated potent in vivo efficacy with a daily dose of 5 mg/kg.

Because the transcription factor, nuclear factor (NF)-kappaB, plays a key role in cellular inflammatory and immune responses, components of the NF-kappaB-activating signaling pathways are frequently used as targets for anti-inflammatory agents. This study shows that 2-(3',4'-dihydroxyphenyl)-5-hydroxybenzo[b]furan (GF-015) and 2,3-di(3',4'-dihydroxy-transstyryl) pyridine (GF-90), two conjugated polyhydroxybenzene derivatives, inhibited a common step in NF-kappaB activation in human NCI-H292 epithelial cells by preventing tumor necrosis factor (TNF)-alpha- and 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced IkappaB kinase (IKK) complex activation. Both agents inhibited the TNF-alpha- or TPA-induced expression of cyclooxygenase (COX)-2 mRNA and protein, COX-2 promoter activity, and prostaglandin E2 (PGE2) production. Overexpression of wild-type NF-kappaB-inducing kinase, IKKalpha, and IKKbeta led, respectively, to 3.5-, 2.6-, and 2.6-fold increases in COX-2 promoter activity, and these effects were inhibited by both compounds. GF-015 and GF-90 also prevented the TNF-alpha- and TPA-induced activation of IKK and NF-kappaB-specific DNA-protein binding activity. These results suggest that the inhibitory effect of GF-015 and GF-90 on TNF-alpha-induced COX-2 protein expression was caused by suppression of IKK activity and NF-kappaB activation in the COX-2 promoter, resulting in attenuation of COX-2 gene expression and PGE2 production.

A hypothetical pharmacophore of 5 alpha-reductase inhibitors was generated and served as a template in virtual screening. When the pharmacophore was used, eight isoflavone derivatives were characterized as novel potential nonsteroidal inhibitors of rat 5 alpha-reductase. This investigation has demonstrated a practical approach toward the development of lead compounds through a hypothetic pharmacophore via three-dimensional database searching.

A novel approach towards the synthesis of substituted naphthalene derivatives is achieved by a treatment of the 4-aryl-4-hydroxy-3-p-toluenesulfonylbutanal ethylene acetals (6a–e) with a catalytic amount of p-toluene sulfonic acid.

RHI-βG-PEG, formed by linking poly(ethylene glycol)-modified β-glucuronidase to Mab RH1, was employed to examine bystander killing of antigen-negative N1S1 rat hepatoma cells by activation of a glucuronide prodrug (BHAMG) of p-hydroxyaniline mustard (pHAM) at antigen-positive AS-30D rat hepatoma cells. Sequential treatment of cells with 10 μg ml−1 RH1-βG-PEG and 20 μM BHAMG was not toxic to N1S1 cells but killed 99% of AS-30D cells. Over 98% of N1S1 cells, however, were killed in mixed populations containing as few as 2% AS-30D cells after identical treatment, demonstrating an in vitro bystander effect. Subcutaneous injection of AS-30D and N1S1 cells in BALB/c nu/nu mice produced solid tumours containing both cells. Uptake of radiolabelled RH1-βG-PEG in solid AS-30D and mixed AS-30D/N1S1 tumours was 11.6 and 9.3 times greater than a control antibody conjugate 120 h after i.v. injection. Intravenous treatment with RH1-βG-PEG and BHAMG cured seven of seven nude mice bearing solid s.c. AS-30D tumours and significantly delayed, compared with control conjugate and prodrug treatment, the growth of mixed N1S1/AS-30D tumours with one cure, showing that targeted activation of BHAMG kills bystander tumour cells in vivo. © 1999 Cancer Research Campaign

Treatment of 1-phthaloylamino-3-[4-(2-methoxyphenyl)piperazin-1-yl]-propanol (7) with DAST induced 1,2-migration via a proposed spiro-aziridinium intermediate to give N-[2-fluoro-3-[4-(2-methoxyphenyl)piperazin-1-yl]propyl]-phthalimide (11a) in 13 % yield and N-[2-fluoromethyl-2-[4-(2-methoxyphenyl)-piperazin-1-yl]ethyl]phthalimide (11b) in 73% yield.

A series of 2-substituted methyl 2,3-dihydroimidazo[1,2-c]quinazolin-5(6H)-ones (4), 3-substituted methyl 2,3-dihydroimidazo[1,2-c]quinazolin-5(6H)-ones (5), 3-substituted methyl 2,3-dihydro-5H-thi...

Condensation of anthranilamide and its derivatives with various 1,3-cyclohexanediones 5a, b or 2,4-pentanediones under acidic conditions produced a variety of heterocycles, leading to the synthesis of tetrahydropyrido[2,1-b]-quinazolin-11-one derivatives. Condensation of anthranilamide with 5a or 5b in the presence of p-toluenesulfonic acid at the reflux temperature of tetrahydrofuran (THF) afforded compound 6a (40%) and compound 7a (22%) or compound 6b (47%) and compound 7b (39%), respectively. However, reflux of anthranilamide with 5a or 5b in 6% ethanolic hydrogen chloride provided compounds 6a and 6b in 77% and 73% yields, respectively. Heating 7a with 5a in 6% ethanolic hydrogen chloride furnished 6a in 82.4% yield. Reaction of anthranilamide with 5c under the same conditions resulted in the formation of 11 (57%). Treatment of compounds 6a and 6b with NaBH 4 furnished 8a,b (89, 87% yields), which were subsequently subjected to the Mitsunobu reaction to produce 6,7,8,9-tetrahydro-9-methyl-11H-pyrido[2,1-b]quinazolin-11-on (9a) and 6,7,8,9-tetrahydro-7,7,9-trimethyl-11H -pyrido[2,1-b]quinazolin-11-one (9b) in 56 and 72% yields, respectively. However, heating 14 with 15a in CH 3 CN in the presence of p-toluenesulfonic acid furnished 19 in 31% yield. Under similar conditions, treatment of 21 with 15a provided 23a (42.4% yield), a key intermediate for the synthesis of rutaecarpine. Analogous reaction of 21 with 15b, 15c and 5a provided 22b-d in 63-99.3% yield, respectively.

A series of sulfonyl-N-hydroxyguanidine derivatives was designed and synthesized for cytotoxic evaluation as potential anticancer agents on the basis of the lead compound LY-181984. Replacement of the ureido moiety of the lead compound with hydroxyguanidine provided a stable cytotoxic agent. The conformation of sulfonyl-N-hydroxyguanidine derivatives, such as N-(4-chlorophenyl)-N'-[(benzo[2,1,3]thiadiazol-4-yl)sulfonyl]-N"- hydroxyguanidine (4g), investigated utilizing HMBC NMR, theoretical calculations, and X-ray crystallography, indicated stacking of the two aromatic rings. The derivatives were evaluated for in vitro cytoxicity against five human tumor cell lines, including HepG2, TSGH 8302, COLO 205, KB, and MOLT-4. The cytotoxic activities of the derived compounds against the human tumor cell lines were equal to or greater than that of the lead compound. N-(4-Chlorophenyl)-N'-[[3,5-dichloro-4-(4-nitrophenoxy)phenyl]sulfonyl]- N"- hydroxyguanidine (4n) and N-(4-chlorophenyl)-N'-[[3,5-dichloro-4-(2-chloro-4-nitrophenoxy)phenyl] sulfonyl]-N"-hydroxyguanidine (4o) exhibited the greatest growth inhibition of solid tumor cell lines. Compound 4o was found to possess antitumor activity against murine K1735/M2 melanoma xenografts.

Novel quinazolin-4-one derivatives containing a hydroxamic acid moiety were designed and synthesized. All compounds were subjected to histone deacetylase (HDAC) enzymatic assays to identify selective HDAC6 inhibitors with nanomolar IC50 values. (E)-3-(2-Ethyl-7-fluoro-4-oxo-3-phenethyl-3,4-dihydroquinazolin-6-yl)-N-hydroxyacrylamide, 4b, is the most potent HDAC6 inhibitor (IC50, 8 nM). In vitro, these compounds induced neurite outgrowth accompanied by growth-associated protein 43 expression, and they enhanced the synaptic activities of PC12 and SH-SY5Y neuronal cells without producing toxic or mitogenic effects. Several of the compounds dramatically increased nonhistone protein acetylation, specifically of α-tubulin. Some of the more potent HDAC6 inhibitors decreased zinc-mediated β-amyloid aggregation in vitro. N-Hydroxy-3-(2-methyl-4-oxo-3-phenethyl-3,4-dihydro-quinazolin-7-yl)-acrylamide, 3f, the most promising drug candidate, selectively inhibits HDAC6 (IC50, 29 nM), practically does not affect human ether-a-go-go-related membrane channel activity (IC50 >10 μM) or cytochrome P450 activity (IC50 >6.5 μM) in vitro, and significantly improves learning-based performances of mice with β-amyloid-induced hippocampal lesions.

2′, 3′-Didehydro-2′, 3′-dideoxyisoguanosine (2) and 2′, 3′- dideoxyisoguanosine (3) have been synthesized by utilizing the Corey-Winter approach starting from isoguanosine. The 6-amino and 5′-hydroxy biprotected isoguanosine derivative was converted to the corresponding 2′, 3′- thionocarbonate, which was heated with triethyl phosphite to afford the 2′,3′- olefinic product. Either a tert-butyldimethylsilyl or a 4, 4′-dimethoxytrityl group was used in the protection of 5′-hydroxy function. Compounds 2 and 3 were found inactive against human immunodeficiency virus (HIV), human cytomegalovirus (HCMV), and herpes simplex virus type 1 (HSV-1). 1. Previous paper in this series: Chien, T.-C.; Chen, C.-S.; Yeh, J.-Y.; Wang, K.C.; Chern, J.-W. Tetrahedron Lett. 1995, 36, 7881.

The hypotensive effect of DC-015, a newly synthesized quinazoline derivative, was investigated and compared with prazosin in spontaneously hypertensive rats (SHR). Intravenous administration of DC-015 and prazosin (both at 0.01, 0.05 and 0.1 mg/kg) induced a dose-dependent reduction of mean arterial pressure (MAP) which reached a maximal effect at 5 min after injection and persisted over 2 h in SHR. Furthermore, at higher doses DC-015 (0.1 mg/kg i.v. and 2.0 mg/kg orally, respectively) did not cause any significant changes in heart rate (HR); whereas the same doses of prazosin (0.1 mg/kg i.v. and 2.0 mg/kg orally, respectively) produced a decrease in HR which seems to parallel the time course of the hypotensive response in SHR. DC-015 and prazosin attenuated pressor responses to phenylephrine (10mgr;g/kg) but failed to inhibit the pressor effects of angiotensin II (0.5mgr;g/kg) even at the maximal hypotensive dose (0.1 mg/kg). This observation indicates that DC-015 appears to exert its hypotensive effect through alpha(1)-adrenoceptor blockade. On the other hand, in SHR fed a high-fat-high-cholesterol (HF-HC) diet, oral administration of DC-015 and prazosin (both at 1.0 mg/kg, twice a day) for 4 weeks caused significant reductions in total plasma cholesterol (CE), low-density lipoprotein (LDL)-cholesterol and total plasma triglyceride (TG). DC-015 therapy also increased high-density lipoprotein (HLD)-cholesterol levels, thus the ratio of total plasma cholesterol to HDL-CE was improved. In contrast, prazosin did not significantly increase the HDL-CE level in this study. It is concluded that DC-015 decreased MAP, plasma CE, LDL-CE, plasma TG and increased HDL-CE levels. DC-015 may have therapeutic potential as a potent antihypertensive drug via the alpha(1)-adrenoceptor antagonist. Concurrently, DC-015 may thus hold some advantage for the reduction of two of the major risk factors, hypertension and hyperlipidemia, for cardiovascular diseases. Copyright 1996 S. Karger AG, Basel

The new quinazolinone derivative,2-{4-[1-(2-chlorophenyl)piperazinyl]} methyl-2,3-dihydroimidazo[1,2-c]quinazolin-5(6H)-one(CK53), inhibited platelet aggregation and ATP release induced by arachidonic acid, collagen, PAF and U46619 in washed rabbit platelets. In human platelet-rich plasma CK53 also significantly suppressed the platelet aggregation and ATP release challenged by epinephrine and ADP. The thromboxane B 2 formation of rabbit washed platelets caused by collagen and thrombin was reduced by CK53 but that induced by arachidonic acid. CK53 inhibited the intracellular calcium increase stimulated by collagen and thrombin in quin-2/AM-loaded rabbit platelets. Phosphoinositides breakdown caused by collagen, U46619, PAF and thrombin was inhibited by CK53. CK53 also suppressed the aggregation of elastase-treated human platelets induced by fibrinogen but no alteration in platelet cyclic-AMP level. In conclusion, these data indicate that antiplatelet effect of CK53 may be mainly due to the direct inhibition of phosphoinositides breakdown.