Synthesis and biological evaluation of some acyclic alpha-(1H-pyrazolo-[3,4-d]pyrimidin-4-yl)thioalkylamide nucleosides

The chemical synthesis of some acyclic alpha-(1H-pyrazolo[3,4-d]pyrimidin-4-yl)thioalkylamide nucleosides (10-12)a-c is described. The treatment of IH-pyrazolo[3,4-d]pyrimidin-4-thione 1 with compounds 2a-c gave, regioselectively, ethyl alpha-(1H-pyrazolo[3,4-d]pyrimidin-4-yl)thioalkylates 3a-c, respectively. These heterocycles were alkylated, separately, with alkylating agents 4, 5 and 6 to give, regioselectively, the N1-acyclic nucleosides (7-9)a-c which were deprotected to afford the desired products (10-12)a-c. All synthetic compounds were characterized on the basis of their physical and spectroscopic properties. The products (10-12)a-c were evaluated for their inhibitory effects against the replication of HIV-1 (III(B)), HIV-2 (ROD), various DNA viruses, a variety of tumor-cell lines and M. tuberculosis. No marked biological activity was found.     

Synthesis of some acyclonucleosides alpha-(pyrazolo[3,4-d]pyrimidin-4-ylthio)alkylamides

The synthesis of some acyclic alpha-(pyrazolo[3,4-d]pyrimidin-4-ylthio)alkylamide nucleosides is described.     

Synthesis and biological evaluation of some acyclic 4,6-disubstituted 1H-pyrazolo[3,4-d]pyrimidine nucleosides

The chemical synthesis and biological evaluation of some acyclic alpha-[6-(1'-carbamoylalkylthio)-1H-pyrazolo[3,4-d]pyrimidin-4-yl]thioalkylamide nucleosides are described.     

Novel inhibitors of epidermal growth factor receptor: (4-(Arylamino)-7H-pyrrolo[2,3-d]pyrimidin-6-yl)(1H-indol-2-yl)methanones and (1H-indol-2-yl)(4-(phenylamino)thieno[2,3-d]pyrimidin-6-yl)methanones

Several members of the quinazoline class of known tyrosine kinase inhibitors are approved anticancer agents, often showing selectivity for receptors of the HER/ErbB-family. Combining structural elements of this class with the bisindolylmethanone-structure led to a series of novel compounds. These compounds inhibited EGFR in the nanomolar range. Moreover, inhibition of EGFR autophosphorylation in intact A431 cells was shown, with IC₅₀ values ranging form 0.3–1 μM for compound 42, and 0.1–0.3 μM for 45. In a panel of 42 human tumor cell lines the sensitivity profile of the novel compounds was shown to be similar to that of the quinazoline class of tyrosine kinase inhibitors lapatinib and erlotinib (Tarceva®).     

Novel 1,5-diphenyl-6-substituted 1H-pyrazolo[3,4-d]pyrimidin-4(5H)-ones induced apoptosis in RKO colon cancer cells

Novel 1,5-diphenyl-6-substituted-1H-pyrazolo[3,4-d]pyrimidin-4(5H)-ones were synthesized and characterized. All compounds were screened for their anti-proliferative activities in five different cancer cell lines. The results showed that compounds 7a and 7b comprising aminoguanidino or guanidino moiety at position 6 inhibited proliferation of RKO colon cancer cells with IC₅₀ of 8 and 4?μM, respectively. Compounds 7a and 7b induced apoptosis in RKO cells, which was confirmed by TUNEL and annexin V-FITC assays. Flow cytometric analysis indicated that compounds 7a and 7b arrested RKO cells in the G1 phase and the most active compound 7b increased levels of p53, p21, Bax, ERK1/2 and reduced levels of Bcl2 and Akt. Compound 7b also activates release of cytochrome c, which is consistent with activation of caspase-9. Additionally, compound 7b increased caspase-3 activity and cleaved PARP-1 in RKO cells. Collectively, these findings could establish a molecular basis for the development of new anti-cancer agents.     

Radiosynthesis and preliminary evaluation of 4-[18F]fluoro-N-[4-[6-(isopropylamino)pyrimidin-4-yl]-1,3-thiazol-2-yl]-N-methylbenzamide as a new positron emission tomography ligand for metabotropic glutamate receptor subtype 1

The purpose of this study was to develop 4-[¹⁸F]fluoro-N-[4-[6-(isopropylamino)pyrimidin-4-yl]-1,3-thiazol-2-yl]-N-methylbenzamide ([¹⁸F]FITM, [¹⁸F]4) as a new PET ligand for imaging metabotropic glutamate receptor subtype 1 (mGluR1). [¹⁸F]4 was synthesized by [¹⁸F]fluorination of a novel nitro precursor 3 with [¹⁸F]KF in the presence of Kryptofix 222. At the end of synthesis, 429-936 MBq (n = 8) of [¹⁸F]4 was obtained with >99% radiochemical purity and 204-559 GBq/μmol specific activity starting from 6.7 to 13.0 GBq of [¹⁸F]F⁻. The brain distribution of [¹⁸F]4 was determined by the in vitro and ex vivo autoradiography using rat brain sections. The in vitro and in vivo specific binding of [¹⁸F]4 to mGluR1 was detected in the cerebellum, thalamus, hippocampus, and striatum. These results suggest that [¹⁸F]4 is a promising PET ligand for the in vivo evaluation of mGluR1.     

Synthesis and biological evaluation of 3,6-diamino-1H-pyrazolo[3,4-b]pyridine derivatives as protein kinase inhibitors

The synthesis and biological evaluation of a number of differently substituted 3,6-diamino-1H-pyrazolo[3,4-b]pyridine derivatives are reported. From the inhibition results on a selection of disease-relevant protein kinases [IC₅₀ (μM) DYRK1A = 11; CDK5 = 0.41; GSK-3 = 1.5] we have observed that 3,6-diamino-4-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile (4) constitutes a potential new and simple lead compound in the search of drugs for the treatment of Alzheimer’s disease.     

Synthesis of 3'-deoxy-3'-[4-(pyrimidin-1-yl)methyl-1,2,3-triazol-1-yl]thymidine via 1,3-dipolar cycloaddition

The synthesis of new 3'-deoxy-3'-[4-(pyrimidin-1-yl)methyl-1,2,3-triazol-1-yl]-thymidine 6a-f, from 3'-azido-3'-deoxy-5'-O-monomethoxytrityl-thymidine is described. The key step is the 1,3-dipolar cycloaddition between the azido group of the protected AZT 3 and N-1-propargylpyrimidine derivatives 2a-f. All new derivatives 6a-f were evaluated for their inhibitory effects against the replication of HIV-1 (IIIB), HIV-2 (ROD). No marked activity was found.     

Synthesis and biological evaluation of novel 1-substituted 3-(3-phenoxyprop-1-yn-1-yl)-1H-pyrazolo[3,4-d]pyrimidin-4-amines as potent Bruton's tyrosine kinase (BTK) inhibitors

A new series of 1-substituted pyrazolopyrimidine derivatives were synthesized as potent BTK inhibitors and they were evaluated by enzyme-based assay and anti-proliferation against multiple B-cell lymphoma cell lines in vitro. Among these compounds, 9h exhibited the highest potency against BTK enzyme, with IC₅₀ value of 4.2?nM. In particular, 8 and 9f performed better inhibition against the proliferation of B lymphoma cell lines DOHH2 and WSU-DLCL2 than the clinical drug ibrutinb. In addition, the test toward the normal PBMC cells showed that 8 possessed low cell cytotoxicity. All these explorations indicated that 8 could serve as a valuable anti-tumor agent for B-cell lymphoblastic leukemia treatment.     

Synthesis and 1H NMR studies of 3-(D-erythro-glycerol-1-yl)-1H-pyrazolo[3,4-b]quinoxaline and its 7-chloro and 7-methyl analogues

3-(D-erythro-Glycerol-1-yl)-1H-pyrazolo[3,4-b]quinoxaline and its 7-chloro and 7-methyl analogues (11 and 12) were prepared from the corresponding quinoxalines. The 7-substituted analogues 11 and 12 were obtained as the preponderant isomers, and the 6-substituted analogues as the minor isomers. The structure and position of the substituent were determined by 1H NMR studies. The effect of substitution on the chemical shift of other protons is discussed.     

Synthesis and in-vitro anti-leishmanial activity of (4-arylpiperazin-1-yl)(1-(thiophen-2-yl)-9H-pyrido[3,4-b]indol-3-yl)methanone derivatives

In the present study, we have reported synthesis and biological evaluation of a series of fifteen 1-(thiophen-2-yl)-9H-pyrido[3,4-b]indole derivatives against both promastigotes and amastigotes of Leishmania parasites responsible for visceral (L. donovani) and cutaneous (L. amazonensis) leishmaniasis. Among these reported analogues, compounds 7b, 7c, 7f, 7g, 7i, 7j, 7m, 7o displayed potent activity (15.55, 7.70, 7.00, 3.80, 14.10, 9.25, 3.10, 4.85 μM, respectively) against L. donovani promastigotes than standard drugs miltefosine (15.70 μM) and pentamidine (32.70 μM) with good selectivity index. In further, in-vitro evaluation against amastigote forms, two compounds 7g (8.80 μM) and 7i (7.50 μM) showed significant inhibition of L. donovani amastigotes. Standard drug amphotericin B is also used as control to compare inhibition potency of compounds against both promastigote (0.24 μM) and amastigote (0.05 μM) forms.     

Synthesis and biological evaluation of novel 5-alkyl-2-arylthio-6-((3,4-dihydroquinolin-1(2H)-yl)methyl)pyrimidin-4(3H)-ones as potent non-nucleoside HIV-1 reverse transcriptase inhibitors

A series of novel S-DABO analogues of 5-alkyl-2-arylthio-6-((3,4-dihydroquinolin-1(2H)-yl)methyl)pyrimidin-4(3H)-ones were synthesized and evaluated as inhibitors of human immunodeficiency virus type-1 (HIV-1). Among them, the most potent HIV-1 inhibitors were compounds 6c1,6c6, and 6b1 (EC(50)=0.24 ± 0.05, 0.38 ± 0.13, 0.39 ± 0.05 μM, respectively), which possess improved or similar HIV-1 inhibitory activity compared with nevirapine (NVP) (EC(50)=0.21 μM) and delavirdine (DLV) (EC(50)=0.32 μM). None of these compounds were active against HIV-2 replication. Furthermore, enzyme inhibitory assays were performed with selected derivatives against HIV-1 wtRT, confirming that the main target of these compounds is the HIV-1 RT and these new S-DABOs are acting as NNRTIs. The preliminary structure-activity relationship (SAR) of these new congeners is discussed briefly and rationalized by docking studies.     

Design,synthesis and biological evaluation of 2-(3,4-dimethoxyphenyl)-6 (1,2,3,6-tetrahydropyridin-4-yl)imidazo[1,2-a]pyridine analogues as antiproliferative agents

Two series of forty five novel 2-(3,4-dimethoxyphenyl)-6-(1,2,3,6-tetrahydropyridin-4-yl) imidazo[1,2-a]pyridine analogues (IPA 1–22, IPS 1–22 and IP-NH) have been designed, synthesized and structures confirmed by ¹H NMR, ¹³C NMR, mass spectrometry. Furthermore, single crystal was developed for IPS-13. All the final derived conjugates were evaluated for their in vitro antiproliferative activity against a panel of diverse cancer cell lines viz., A549 (lung cancer), HeLa (cervical cancer), B16F10 (melanoma) and found to show potent anticancer activity on the tested cell lines. Many of them showed the IC₅₀ values in the range 2.0–20.0 µM. The most active compounds (IPA 5,6,8,9,12,16,17,19 and IPS 7,8,9,22) from IPA and IPS series were screened to determine their cytotoxicity on HEK-293 (human embryonic kidney) normal cell line and were found to be nontoxic to normal human cells. The molecular interactions of the derivatised conjugates were also supported by molecular docking simulations. These derivatives may serve as lead structures for development of novel potential anticancer drug candidates.     

Discovery of novel selective Janus kinase 2 (JAK2) inhibitors bearing a 1H-pyrazolo[3,4-d]pyrimidin-4-amino scaffold

Janus kinases (JAKs) regulate various cancers and immune responses and are targets for the treatment of cancers and immune diseases. A new series of 1H-pyrazolo[3,4-d]pyrimidin-4-amino derivatives were synthesized and optimized by introducing a functional 3,5-disubstituted-1H-pyrazole moiety into the C-3 moiety of pyrazole template, and then were biologically evaluated as potent Janus kinase 2 (JAK2) inhibitors. Among these molecules, inhibitors 11f, 11g, 11h and 11k displayed strong activity and selectivity against the JAK2 kinase, with IC₅₀ values of 7.2?nM, 6.5?nM, 8.0?nM and 9.7?nM, respectively. In particular, the cellular inhibitory assay and western blot analysis further support the JAK2 selectivity of compound 11g also in cells. Furthermore, compound 11g also exhibited potent inhibitory activity in lymphocytes proliferation assay and delayed hypersensitivity assay. Taken together, the novel JAK2 selective inhibitors discovered in this study may be potential lead compounds for new drug discovery via further development of more potent and selective JAK2 inhibitors.     

Synthesis and antimicrobial studies of hydrazone derivatives of 4-[3-(2,4-difluorophenyl)-4-formyl-1H-pyrazol-1-yl]benzoic acid and 4-[3-(3,4-difluorophenyl)-4-formyl-1H-pyrazol-1-yl]benzoic acid

Microbial resistance to antibiotics is an unresolved global concern, which needs urgent and coordinated action. One of the guidelines of the Centers for Disease Control and Preventions (CDC) to combat antibiotic resistance is the development of new antibiotics to treat drug-resistant bacteria. In our effort to find new antibiotics, we report the synthesis and antimicrobial studies of 30 new pyrazole derivatives. These novel molecules have been synthesized by using readily available starting materials and benign reaction conditions. Some of these molecules have shown activity with MIC values as low as 0.78?µg/mL against four bacterial strains; Staphylococcus aureus, methicillin-resistant S. aureus, Bacillus subtilis, and Acinetobacter baumannii. Furthermore, active molecules are non-toxic to mammalian cell line.

     

Synthesis and biological activity of some unsaturated 6-azauracil acyclonucleosides

A useful route is described for obtaining Z and E unsaturated alkylating agents 3 and 4. Coupling 6-azauracils 5 and 6 with unsaturated alkylating agent followed by the deprotection with H+ resin gave acyclonucleosides 11-14 in good overall yields. Unsaturated acyclonucleosides phosphonates 19 and 20 were prepared using potassium carbonate as base and 4-bromobut-2-enyl diethyl phosphonate 16 as the alkylating agent. The introduction of a propargyl group at the N-3 position of acyclonucleosides 7, 8 17, 18, 19, and 20 was achieved using potassium carbonate in DMF.     

Synthesis and anti-tumor activities of N'-benzylidene-2-(4-oxothieno[2,3-d]pyrimidin-3(4H)-yl)acetohydrazone derivatives

A compound with a cyclic thienopyrimidine moiety and an aceto-hydrazone moiety in its chemical structure was discovered in a cell-based screening to have noticeable cytotoxicity on several tumor cell lines. A total of 38 derivatives of this compound were synthesized at five steps with high yields. These compounds were tested in standard MTT assays, and several compounds exhibited improved cytotoxic activities. The most potent compounds have IC(50) values of 10-20 μM on A549, HeLa, and MBA-MD-231 tumor cells. Flow cytometry analysis of several active compounds and subsequent examination of caspase activation indicate that they induce caspase-dependent apoptosis in tumor cells. In addition, these compounds do not have obvious effect on a normal cell line HEK-293T, demonstrating the desired selectivity against tumor cells. Results from a fluorescence polarization-based in vitro binding assay indicate that this class of compounds does not significantly interrupt the interactions between Mcl-1 and Bid. Their cytotoxicity is achieved presumably through other mechanisms.     

Synthesis and preliminary biological evaluation of [11C]methyl (2-amino-5-(benzylthio)thiazolo[4,5-d]pyrimidin-7-yl)-d-leucinate for the fractalkine receptor (CX3CR1)

The reference standard methyl (2-amino-5-(benzylthio)thiazolo[4,5-d]pyrimidin-7-yl)-d-leucinate (5) and its precursor 2-amino-5-(benzylthio)thiazolo[4,5-d]pyrimidin-7-yl)-d-leucine (6) were synthesized from 6-amino-2-mercaptopyrimidin-4-ol and BnBr with overall chemical yield 7% in five steps and 4% in six steps, respectively. The target tracer [¹¹C]methyl (2-amino-5-(benzylthio)thiazolo[4,5-d]pyrimidin-7-yl)-d-leucinate ([¹¹C]5) was prepared from the acid precursor with [¹¹C]CH₃OTf through O-[¹¹C]methylation and isolated by HPLC combined with SPE in 40–50% radiochemical yield, based on [¹¹C]CO₂ and decay corrected to end of bombardment (EOB). The radiochemical purity was >99%, and the specific activity (SA) at EOB was 370–1110 GBq/μmol with a total synthesis time of ～40-min from EOB. The radioligand depletion experiment of [¹¹C]5 did not display specific binding to CX₃CR1, and the competitive binding assay of ligand 5 found much lower CX₃CR1 binding affinity.