Molecular iodine promoted synthesis of new pyrazolo[3,4-d]pyrimidine derivatives as potential antibacterial agents

Design, synthesis, antineoplastic activity of new pyrazolo[3,4-d]pyrimidine derivatives as dual CDK2/GSK3β kinase inhibitors; molecular docking study, and ADME prediction

In the current study, novel pyrazolo[3,4-d]pyrimidine derivatives 5a-h were designed and synthesized as targeted anti-cancer agents through dual CDK2/GSK-3β inhibition. The designed compounds demonstrated moderate to potent activity on the evaluated cancer cell lines (MCF-7 and T-47D). Compounds 5c and 5 g showed the most promising cytotoxic activity against the tested cell lines surpassing that of the used reference standard; staurosporine. On the other hand, both compounds showed good safety and tolerability on normal fibroblast cell line (MCR5). The final compounds 5c and 5 g showed a promising dual CDK2/GSK-3β inhibitory activity with IC50 of 0.244 and 0.128 μM, respectively, against CDK2, and IC50 of 0.317 and 0.160 μM, respectively, against GSK-3β. Investigating the effect of compounds 5c and 5 g on CDK2 and GSK-3β downstream cascades showed that they reduced the relative cellular content of phosphorylated RB1 and β-catenin compared to that in the untreated MCF-7 cells. Moreover, compounds 5c and 5 g showed a reasonable selective inhibition against the target kinases CDK2/GSK-3β in comparison to a set of seven off-target kinases. Furthermore, the most potent compound 5 g caused cell cycle arrest at the S phase in MCF-7 cells preventing the cells' progression to G2/M phase inducing cell apoptosis. Molecular docking studies showed that the final pyrazolo[3,4-d]pyrimidine derivatives have analogous binding modes in the target kinases interacting with the hinge region key amino acids. Molecular dynamics simulations confirmed the predicted binding mode by molecular docking. Moreover, in silico predictions indicated their favorable physicochemical and pharmacokinetic properties in addition to their promising cytotoxic activity.

Crystal structure determination and analyses of Hirshfeld surface, crystal voids, inter-molecular inter-action energies and energy frameworks of 1-benzyl-4-(methyl-sulfan-yl)-3a,7a-di-hydro-1H-pyrazolo-[3,4-d]pyrimidine

The pyrazolo-pyrimidine moiety in the title mol-ecule, C13H12N4S, is planar with the methyl-sulfanyl substituent lying essentially in the same plane. The benzyl group is rotated well out of this plane by 73.64 (6)°, giving the mol-ecule an approximate L shape. In the crystal, C-H⋯π(ring) inter-actions and C-H⋯S hydrogen bonds form tubes extending along the a axis. Furthermore, there are π-π inter-actions between parallel phenyl rings with centroid-to-centroid distances of 3.8418 (12) Å. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯H (47.0%), H⋯N/N⋯H (17.6%) and H⋯C/C⋯H (17.0%) inter-actions. The volume of the crystal voids and the percentage of free space were calculated to be 76.45 Å3 and 6.39%, showing that there is no large cavity in the crystal packing. Evaluation of the electrostatic, dispersion and total energy frameworks indicate that the cohesion of the crystal structure is dominated by the dispersion energy contributions.

Synthesis, design, and antiproliferative evaluation of 6-(N-Substituted-methyl)pyrazolo[3,4-d]pyrimidines as the potent anti-leukemia agents

Pyrazolopyrimidine derivatives, including pyrazolopyrimidines, 6-aminopyrazolopyrimidines, 6-[(formyloxy)methyl]pyrazolopyrimidines, 6-(hydroxymethyl)pyrazolopyrimidine, and 6-(aminomethyl)pyrazolopyrimidines have been successfully prepared and tested against NCI-H226, NPC-TW01, and Jurkat cancer cell lines. Among the tested pyrazolopyrimidine compounds, we found 6-aminopyrazolopyrimidines and 6-(aminomethyl)pyrazolopyrimidines with essential o-ClPh or p-ClPh substituted moieties on N-1 pyrazole ring exhibited the best IC50 inhibition activity for Jurkat cells. Furthermore, optimization of the SAR study on the C-6 position of pyrazolopyrimidine ring demonstrated that 6-(N-substituted-methyl)pyrazolopyrimidines 17b, 17d, and 19d possessed the significant IC50 inhibitory activity for the different leukemia cell lines, especially for Jurkat, K-562, and HL-60. On the other hand, further SAR inhibition and docking model studies revealed that compound 19d, which has a 3-(1H-imidazol-1-yl)propan-1-amino side-chain on the C-6 position, was able to form four hydrogen bonds with residues Ala226, Leu152, and Glu194 and specifically extended into the P1 pocket subsite with Aurora A, resulting in improved inhibitory activity almost similar to SNS-314. To explore the anti-cancer mechanism, compound 19d was measured by Western blot analysis in Jurkat T-cells, however, it showed non-responsibility to Aurora B. For the further structural modifications on the lateral chain of compound 19d, compounds 24 with longer lateral chain were designed and synthesized for testing leukemia cell lines. However, compounds 24 was significantly decrease inhibition potency against leukemia cell lines. Based on the in-vitro results, compounds 17b and 19d could be considered to be the best potential lead drug in our study for the development of new and effective therapies for leukemia treatment. On the other hand, the DHFR inhibition results indicated compound 19d possessed good inhibitory activity and better than the reported naphthalene derivative. Through further comparisons of the model superposition of three-dimensional (3D) conformations in DHFR, compound 19d presented a similar structural alignment to Methotrexate and the reported naphthalene derivative and led to similar drug-like functional relationships. As a results, compound 19d would be a potential DHFR inhibitor for anti-leukemia drug candidate.

Multi-target rational design and synthesis of novel diphenyl-tethered pyrazolopyrimidines targeting EGFR and topoisomerase II with potential DNA intercalation and apoptosis induction

Herein, we envisioned the design and synthesis of novel pyrazolopyrimidines (confirmed by elemental analysis, 1H and 13C NMR, and mass spectra) as multitarget-directed drug candidates acting as EGFR/TOPO II inhibitors, DNA intercalators, and apoptosis inducers. The target diphenyl-tethered pyrazolopyrimidines were synthesized starting from the reaction of phenyl hydrazine and ethoxymethylenemalononitrile to give aminopyrazole-carbonitrile 2. The latter hydrolysis with NaOH and subsequent reaction with 4-chlorobenzaldhyde afforded the corresponding pyrazolo[3,4-d]pyrimidin-4-ol 4. Chlorination of 4 with POCl3 and sequential reaction with different amines afforded the target compounds in good yields (up to 73 %). The growth inhibition % of the new derivatives (6a-m) was investigated against different cancer and normal cells and the IC50 values of the most promising candidates were estimated for HNO97, MDA-MB-468, FaDu, and HeLa cancer cells. The frontier derivatives (6a, 6i, 6k, 6l, and 6m) were pursued for their EGFR inhibitory activity. Compound 6l decreased EGFR protein concentration by a 6.10-fold change, compared to imatinib as a reference standard. On the other side, compounds (6a, 6i, 6k, 6l, and 6m) underwent topoisomerase II (TOPO II) inhibitory assay. In particular, compounds 6a and 6l exhibited IC50s of 17.89 and 19.39 μM, respectively, surpassing etoposide with IC50 of 20.82 μM. Besides, the DNA fragmentation images described the great potential of both candidates 6a and 6l in inducing DNA degradation at lower concentrations compared to etoposide and doxorubicin. Moreover, compound 6l, with the most promising EGFR/TOPO II inhibition and DNA intercalation, was selected for further investigation for its apoptosis induction ability by measuring caspases 3, 7, 8, and 9, Bax, p53, MMP2, MMP9, and BCL-2 proteins. Additionally, molecular docking was used to explain the SAR results based on the differences in the molecular features of the investigated congeners and the target receptors' topology.

BODIPY-fused uracil: synthesis, photophysical properties, and applications

Fluorescent nucleobase and nucleic acid analogs are important tools in chemical and molecular biology as fluorescent labelling of nucleobases has applications in cellular imaging and anti-tumor activity. Boron-dipyrromethene (BODIPY) dyes exhibiting high brightness and good photostability are extensively used as fluorescent labelling agents and as type II photosensitizers for photodynamic therapy. Thus, the combination of nucleobases and BODIPY to obtain new compounds with both anti-tumor activity and fluorescent imaging functions is the focus of our research. We synthesized two new nucleobase analogs 1 and 2 by fusing the BODIPY core directly with uracil which resulted in favorable photophysical properties and high emission quantum efficiencies particularly in organic solvents. Further, we explored the newly synthesized derivatives, which possessed good singlet oxygen generation efficiencies and bio-compatibility, as potential PDT agents and our results show that they exhibit in vitro anti-tumor activities.

New pyrazolo[3,4-d]pyrimidine derivatives as EGFR-TK inhibitors: design, green synthesis, potential anti-proliferative activity and P-glycoprotein inhibition

In this study, four series of new pyrazolo[3,4-d]pyrimidine derivatives were designed and synthesized with both green and conventional methods. All the synthesized candidates were chemically confirmed using spectroscopic methods, and the DFT of the reaction mechanism was illustrated. The anti-proliferative activity of the synthesized compounds was evaluated against NCI 60 cancer cell lines. Two compounds (15 & 16) exhibited excellent broad-spectrum cytotoxic activity in NCI 5-log dose assays against the full 60-cell panel with GI50 values ranging from 0.018 to 9.98 μM. Moreover, the enzymatic assessment of the most active derivatives 4, 15, and 16 against EGFR tyrosine kinase showed significant inhibitory activities with IC50 of 0.054, 0.135, and 0.034 μM, respectively. The quantitative real-time PCR for the P-glycoprotein effect of compounds 15 and 16 was examined and illustrated the ability to inhibit the P-glycoprotein by 0.301 and 0.449 fold in comparison to the control. Mechanistic study using reversal activity in MDA-MB-468 cell line revealed the effect of both compounds 15 and 16 cytotoxicity against DOX/MDA-MB-468 with IC50 = 0.267 and 0.844 μM, respectively. Additionally, compound 16 was found to induce cell cycle arrest at the S phase with a subsequent increase in pre-G cell population in MDA-MB-468 cell line. It also increased the percentage of apoptotic cells in a time-dependent manner. Moreover, a molecular docking study was carried out to explain the target compounds' potent inhibitory activity within the EGFR binding site.

Novel pyrimidin-4-one derivatives as potential T3SS inhibitors against Xanthomonas campestris pv. campestris

BACKGROUND

Cruciferous black rot is caused by Xanthomonas campestris pv. campestris (Xcc) infection and is a widespread disease worldwide. Excessive and repeated use of bactericide is an important cause of the development of bacterial resistance. It is imperative to take new approaches to screening compounds that target virulence factors rather than kill bacterial pathogens. The type III secretion system (T3SS) invades a variety of cells by transporting virulence effector factors into the cytoplasm and is an attractive antitoxic target. Toward the search of new T3SS inhibitors, an alternative series of novel pyrimidin-4-one derivatives were designed and synthesized and assessed for their effect in blocking the virulence.

RESULTS

All of the target compounds were characterized by proton (1 H) nuclear magnetic resonance (NMR), carbon-13 (13 C) NMR, fluorine-19 (19 F) NMR and high-resolution mass spectrometry (HRMS). All compounds were evaluated using high-throughput screening systems against Xcc. The results of the biological activity test revealed that the compound SPF-9 could highly inhibit the activity of xopN gene promoter and the hypersensitivity (HR) of tobacco without affecting bacterial growth. Moreover, messenger RNA (mRNA) level measurements showed that compound SPF-9 inhibited the expression of some representative genes (hrp/hrc genes). Compound SPF-9 weakened the pathogenicity of Xcc to Raphanus sativus L.

CONCLUSION

Compound SPF-9 has good potential for further development as a novel T3SS inhibitor against Xcc. © 2023 Society of Chemical Industry.

Crystal structure determination, Hirshfeld surface, crystal void, intermolecular interaction energy analyses, as well as DFT and energy framework calculations of 2-(4-oxo-4,5-dihydro-1H-pyrazolo[3,4-d]pyrimidin-1-yl)acetic acid

In the title molecule, C7H6N4O3, the bicyclic ring system is planar with the carboxymethyl group inclined by 81.05 (5)° to this plane. In the crystal, corrugated layers parallel to (010) are generated by N—H...O, O—H...N and C—H...O hydrogen-bonding interactions. The layers are associated through C—H...π(ring) interactions. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H...O/O...H (34.8%), H...N/N...H (19.3%) and H...H (18.1%) interactions. The volume of the crystal voids and the percentage of free space were calculated to be 176.30 Å3 and 10.94%, showing that there is no large cavity in the crystal packing. Computational methods revealed O—H...N, N—H...O and C—H...O hydrogen-bonding energies of 76.3, 55.2, 32.8 and 19.1 kJ mol−1, respectively. Evaluations of the electrostatic, dispersion and total energy frameworks indicate that the stabilization is dominated via dispersion energy contributions. Moreover, the optimized molecular structure, using density functional theory (DFT) at the B3LYP/6–311G(d,p) level, was compared with the experimentally determined one. The HOMO–LUMO energy gap was determined and the molecular electrostatic potential (MEP) surface was calculated at the B3LYP/6–31G level to predict sites for electrophilic and nucleophilic attacks.

Development of fluorinated nicotinonitriles and fused candidates as antimicrobial, antibiofilm, and enzyme inhibitors

The antimicrobial assessments of two new series of nicotinonitriles and pyrido[2,3-d]pyrimidines were performed using amoxicillin and nystatin as reference standards. Outstanding antifungal activities were achieved by some target compounds; for instance, compounds 7 and 9 displayed a minimal inhibitory concentration (MIC) value of 1.95 µg/ml toward Candida albicans, compound 11 showed a potent anti-Rhizopus effect (MIC 1.95 µg/ml) and compound 14 elicited remarkable antifungal effects against both Aspergillis niger and C. albicans (MIC 1.95 µg/ml). However, pyrido[2,3-d]pyrimidines 12, 14, and 16 showed moderate antibacterial activities against some gram-negative bacteria. The antibiofilm results of these compounds against resistant strains of Proteus mirabilis were better than those of Pseudomonas aeruginosa. Docking studies of these hits at the DNA gyrase active site revealed affinity and docking scores comparable to that of the reference standards. Gyrase-inhibitory activities revealed that 14 (IC₅₀  = 0.31 µM) is the most potent hit as DNA gyrase A inhibitor; it exhibited 1.66-fold the activity of ciprofloxacin (IC₅₀  = 0.50 µM) and it was a 44.3 times more potent gyrase B inhibitor (IC₅₀  = 0.04 µM) than novobiocin (IC₅₀  = 1.77 µM). Regarding its antifungal activity, it displayed 0.78% of the fluconazole activity as a 14α-demethylase inhibitor. The cytotoxicity of 12, 14, and 16 on human diploid lung fibroblasts (WI38 cells) ensured their safety. Moreover, they are orally bioavailable with no permeation of the blood-brain barrier.

Recent green approaches for the synthesis of pyrazolo[3,4-d]pyrimidines: A mini review

Pyrazolo[3,4-d]pyrimidine as a bioisostere of purine has drawn considerable attention as a privileged scaffold for the design and discovery of novel drugs. Green synthesis is an emerging area in the field of chemistry that provides economic and environmental benefits as an alternative to traditional methods. The present mini review reflects recent advances in the green synthesis of pyrazolo[3,4-d]pyrimidines, published in the time frame from 2006 to 2019.

Sulphonated graphene oxide catalyzed continuous flow synthesis of pyrazolo pyrimidinones, sildenafil and other PDE-5 inhibitors

Sulphonated graphene oxide was used for cascade condensation and cyclization reactions towards accessing substituted pyrazolo pyrimidinones. Further, sulphonation and amination reactions were integrated through continuous flow chemistry to access PDE-5 inhibitors. Herein, we report a simple continuous synthetic platform that reduce tedious manual operations and accelerate the synthesis of several potent inhibitors of phosphodiesterase type-5. The developed platform enabled us to perform one-flow multi-step, multi-operational process to synthesize the PDE-5 inhibitors such as sildenafil and its analogues in 32.3 min of the reaction time, with minimal human intervention and single solvent.

Pyrazolopyrimidines as anticancer agents: A review on structural and target-based approaches

Pyrazolopyrimidine scaffold is one of the privileged heterocycles in drug discovery. This scaffold produced numerous biological activities in which anticancer is important one. Previous studies showed its importance in interactions with various receptors such as growth factor receptor, TGFBR2 gene, CDK2/cyclin E and Abl kinase, adenosine receptor, calcium-dependent Protein Kinase, Pim-1 kinase, Potent Janus kinase 2, BTK kinase, P21-activated kinase 1, extracellular signal-regulated kinase 2, histone lysine demethylase and Human Kinesin-5. However, there is a need of numerous studies for the discovery of target based potential compounds. The structure activity relationship studies may help to explore the generation of potential compounds in short time period. Therefore, in the present review we tried to explore the structural aspects of Pyrazolopyrimidine with their structure activity relationship against various targets for the development of potential compounds. The current review is the compilation of significant advances made on Pyrazolopyrimidines reported between 2015 and 2020.

Novel Pyrazolo[3,4-d]pyrimidin-4-one Derivatives as Potential Antifungal Agents: Design, Synthesis, and Biological Evaluation

Plant pathogenic fungi seriously threaten agricultural production. There is an urgent need to develop novel fungicides with low toxicity and high efficiency. In this study, we designed and synthesized 44 pyrazolo[3,4-d]pyrimidin-4-one derivatives and evaluated them for their fungicidal activities. The bioassay data revealed that most of the target compounds possessed moderate to high in vitro antifungal activities. Especially compound g22 exhibited remarkable antifungal activity against Sclerotinia sclerotiorum with an EC₅₀ value of 1.25 mg/L, close to that of commercial fungicide boscalid (EC₅₀ = 0.96 mg/L) and fluopyram (EC₅₀ = 1.91 mg/L). Moreover, compound g22 possessed prominent protective activity against S. sclerotiorum in vivo for 24 h (95.23%) and 48 h (93.78%), comparable to positive control boscalid (24 h (96.63%); 48 h (93.23%)). Subsequent studies indicated that compound g22 may impede the growth and reproduction of S. sclerotiorum by affecting the morphology of mycelium, destroying cell membrane integrity, and increasing cell membrane permeability. In addition, the application of compound g22 did not injure the growth or reproduction of Italian bees. This study revealed that compound g22 is expected to be developed for efficient and safe agricultural fungicides.

High activity, high selectivity and high biocompatibility BODIPY-pyrimidine derivatives for fluorescence target recognition and evaluation of inhibitory activity

BODIPY-Pyrimidine (BP) is a highly selective, highly active, and highly biocompatible fluorescent drug, which is characterized by its own activity combined with a fluorophore. The combination of pyrimidines with good biological activity and fluorophores to obtain new compounds with both anti-tumor activity and fluorescent targeting probe functions is the focus of this research. In terms of biological activity, in vitro cytotoxicity of the compounds on four human cancer cells (HepG2, HeLa, A-459, and HCT-116) and the human normal cell line L-02 was studied. BP-4 has good antiproliferative activity, and its IC₅₀ values are 19.12 ± 2.29, 13.47 ± 3.80, 18.59 ± 7.42, 14.57 ± 2.44 and 92.48 ± 6.03 μM, respectively. Good biocompatibility with tumor cells can be observed in cell imaging. The anti-tumor mechanism of the compound was further studied by flow cytometry. After BP-2, BP-3 and BP-4 treated HeLa cells, the percentage of apoptotic cells was 19.07%, 22.09% and 27.3%, respectively. The cell cycle study found that, compared with the positive control 5-FU (48.05%), the compounds BP-2, BP-3 and BP-4 all increased the proportion of HeLa cells in the G1 phase, reaching 57.65%, 55.46% and 53.58%, respectively. In vivo bioimaging results show that all three compounds can be targeted and accurately expressed in tumor tissues. In addition, molecular docking analyzes the possible interaction between the compound and the active site of thymidylate synthase.

Floro-pyrazolo[3,4-d]pyrimidine derivative as a novel plant activator induces two-pathway immune system

Plants are known to develop a multi-faceted innate immune system for pathogenic defense. Systemic acquired resistance (SAR) and induced systemic resistance (ISR) are the two main pathways. Many chemical inducers known as plant activators that activate innate immunity to defend against pathogens have been discovered. Currently, the exploitation of new plant activators is mainly done to develop analogs of salicylic acid as SAR-signaling molecules; however, the ISR pathway is hardly investigated for new plant activators. Based on recent studies on 1-methyl pyrazolo [3,4-d]pyrimidine bioactivity and ATP-induced resistance to biotrophic and necrotrophic pathogens, a new lead compound, 1-methyl-4-amino-pyrazolo [3,4-d]pyrimidine, was obtained as a new scaffold of plant activators for possible inducing ISR immunity system. Additionally, fluorine atom plays an important role in the design and development of new pesticides due to the unique physical chemistry effect, a series of pyrazolo [3,4-d]pyrimidine derivatives were designed and synthesized. Several compounds showed good broad-spectrum induced resistance in vivo, but there was no direct antibacterial activity in vitro. Notably, the introduction of fluorine atom at the para-position of the benzene ring greatly enhanced the induction activity of P1d both involved in SAR and ISR pathways, which implied the inducing resistance both in defending pathogens and insects.

Dimroth rearrangement-based synthesis of novel derivatives of [1,3]selenazolo[5,4-e][1,2,4]triazolo[1,5-c]pyrimidine as a new class of selenium-containing heterocyclic architecture

As a part of our ongoing endeavor towards developing novel heterocyclic architectures, a number of novel Se-containing tricyclic heterocycles of the type [1,3]selenazolo[5,4-e][1,2,4]triazolo[1,5-c]pyrimidine have been synthesized through heteroannulation of a newly produced hydrazino derivative of selenazolo[4,5-d]pyrimidine with either orthoesters or carbon disulfide in pyridine followed by S-alkylation. Moreover, the multistep protocol employed in this investigation provides a new insight into the Dimroth rearrangement in both acidic and basic media as a means for the cyclocondensation of triazole on the selenazolopyrimidine framework leading to selenazolotriazolopyrimidines. The synthesis of new derivatives of novel selenazolotriazolopyrimidines via Dimroth rearrangement in both acidic and basic media is presented.

Synthesis and Antibacterial Evaluation of New Pyrazolo[3,4-d]pyrimidines Kinase Inhibitors

Pyrazolo[3,4-d]pyrimidines represent an important class of heterocyclic compounds well-known for their anticancer activity exerted by the inhibition of eukaryotic protein kinases. Recently, pyrazolo[3,4-d]pyrimidines have become increasingly attractive for their potential antimicrobial properties. Here, we explored the activity of a library of in-house pyrazolo[3,4-d]pyrimidines, targeting human protein kinases, against Staphylococcus aureus and Escherichia coli and their interaction with ampicillin and kanamycin, representing important classes of clinically used antibiotics. Our results represent a first step towards the potential application of dual active pyrazolo[3,4-d]pyrimidine kinase inhibitors in the prevention and treatment of bacterial infections in cancer patients.

Advances in the chemical and biological diversity of heterocyclic systems incorporating pyrimido[1,6-a]pyrimidine and pyrimido[1,6-c]pyrimidine scaffolds

Heterocycles incorporating a pyrimidopyrimidine scaffold have aroused great interest from researchers in the field of medical chemistry because of their privileged biological activities; they are used as anti-bacterial, antiviral, anti-tumor, anti-allergic, antihypertensive, anticancer, and hepatoprotective agents. Therefore, the present study aims to investigate the chemistry of heterocycles incorporating pyrimido[1,6-a]pyrimidine and pyrimido[1,6-c]pyrimidine skeletons and their biological characteristics. The main sections discuss (1) the synthetic routes to obtain substituted pyrimidopyrimidines, pyrimido[1,6-a]pyrimidin-diones, pyrimidoquinazolines, tricyclic, tetracyclic, and binary systems; (2) the reactivity of the substituents attached to the pyrimidopyrimidine skeleton, including thione and amide groups, nucleophilic substitutions, condensations, ring transformations, and coordination chemistry; (3) compounds of this class of heterocycles containing a significant characteristic scaffold and possessing a wide range of biological characteristics.

Design and Synthesis of New Substituted Pyrazolopyridines with Potent Antiproliferative Activity

Background:

Purine isosteres are often endowed with interesting pharmacological properties, due to their involvement in cellular processes replacing the natural purines. Among these compounds, pyrazolopyridines are under active investigation for potential anticancer properties.

Objective:

Based on previously discovered substituted pyrazolopyridines with promising antiproliferative activity, we designed and synthesized new, suitably substituted analogues aiming to investigate their potential activity and contribute to SAR studies of this class of bioactive compounds.

Methods:

The new compounds were synthesized using suitably substituted 2-amino-4-picolines, which upon ring-closure provided substituted pyrazolo[3,4-c] pyridine-5-carbonitriles that served as key intermediates for the preparation of the target 3,5,7 trisubstituted derivatives. The antiproliferative activity of 31 new target derivatives was evaluated against three cancer cell lines (MIA PaCa-2, PC-3 and SCOV3), whereas cell-cycle perturbations of exponentially growing PC-3 cells, using three selected derivatives were also performed.

Results:

Eight compounds displayed IC50 values in the low μM range, allowing the extraction of interesting SAR’s. Two of the most potent compounds against all cell lines share a common pattern, by accumulating cells at the G0/G1 phase. From this project, a new carboxamidine-substituted hit has emerged.

Conclusion:

Among the new compounds, those possessing the 3-phenylpyrazolo[3,4-c]pyridine scaffold, proved to be worth investigating and the majority of them showed strong cytotoxic activity against all cell lines, with IC50 values ranging from 0.87-4.3 µM. A carboxamidine analogue that resulted from the synthetic procedure, proved to be highly active against the cancer cells and could be considered as a useful lead for further optimization.

Starch/Poly(glycerol-adipate) Nanocomposites: A Novel Oral Drug Delivery Device

Biocompatible and bio-based materials are an appealing resource for the pharmaceutical industry. Poly(glycerol-adipate) (PGA) is a biocompatible and biodegradable polymer that can be used to produce self-assembled nanoparticles (NPs) able to encapsulate active ingredients, with encouraging perspectives for drug delivery purposes. Starch is a versatile, inexpensive, and abundant polysaccharide that can be effectively applied as a bio-scaffold for other molecules in order to enrich it with new appealing properties. In this work, the combination of PGA NPs and starch films proved to be a suitable biopolymeric matrix carrier for the controlled release preparation of hydrophobic drugs. Dynamic Light Scattering (DLS) was used to determine the size of drug-loaded PGA NPs, while the improvement of the apparent drug water solubility was assessed by UV-vis spectroscopy. In vitro biological assays were performed against cancer cell lines and bacteria strains to confirm that drug-loaded PGA NPs maintained the effective activity of the therapeutic agents. Dye-conjugated PGA was then exploited to track the NP release profile during the starch/PGA nanocomposite film digestion, which was assessed using digestion models mimicking physiological conditions. The collected data provide a clear indication of the suitability of our biodegradable carrier system for oral drug delivery.

One-Pot Acid-Promoted Synthesis of 6-Aminopyrazolopyrimidines from 1H-Pyrazol-5-yl-N,N-dimethylformamidines or 5-Amino-1H-pyrazole-4-carbaldehydes with Cyanamide

A convenient and efficient one-pot acid-promoted synthesis of 6-aminopyrazolo[3,4-d]pyrimidine has been developed by treatment of 1H-pyrazol-5-yl-N,N-dimethylformamidines or 5-amino-1H-pyrazole-4-carbaldehydes with cyanamide (NH₂C≡N) in an acid-mediated solution. This synthetic route involves four steps of deprotection, imination, the key acid-promoted heterocyclization, and aromatization. On the basis of optimized studies, methanesulfonylchloride is considered to be the best solvent. Furthermore, the microwave-assisted synthetic technique was also carried out to improve the major product 6-aminopyrazolo[3,4-d]pyrimidines in this method. Moreover, our proposed mechanism was confirmed in this study, which demonstrates that N-[(5-amino-1,3-diaryl-1H-pyrazol-4-yl)methylene]cyanamide is the intermediate.

Synthesis and anticancer evaluation of some novel pyrimido[5,4-e][1,2,4]triazines and pyrazolo[3,4-d]pyrimidine using DMF-DMA as methylating and cyclizing agent

Background

Described a series of main target compounds pyrimido[5,4-e][1,2,4]triazines is obtained via condensation of 6-hydrazinyluracil with different aromatic aldehydes to give the hydrazones followed by nitrosation with HNO₂ then intramolecular cyclization. On the other hand, pyrazolopyrimidines can be obtained by the reaction of hydrazones with dimethylformamide-dimethylacetal (DMF-DMA), DMF-DMA in the presence of DMF or by refluxing the hydrazinyluracil with DMF-DMA in the presence of DMF directly. The newly synthesized compounds are evaluated in vitro for their anticancer activity against human lung carcinoma (A549).

Results

A newly substituted compounds of benzaldehyde-pyrimidin-4-yl)hydrazones (5a–f), pyrimido[5,4-e][1,2,4]triazines 6a–e, arylethylidenehydrazinylpyrimidine 7a,b and pyrazolopyrimidines 9,11 are screened for cytotoxic activity against human lung carcinoma (A549) cell line. They exhibited a good yield. Compound 6b shows the highest effect with IC₅₀ value 3.6 μM, followed by compounds 9, 5a, 8, 5e, 6e, 5b, 5f, 7a, 5c, 6c, 7b, 6a, 11, 5d and 6d.

Conclusion

A simple and efficient route is used for the synthesis of pyrimido[5,4-e][1,2,4]triazines and pyrazolopyrimidines. The synthesized compounds are screened for antitumor activity.

Continuous-flow retro-Diels-Alder reaction: an efficient method for the preparation of pyrimidinone derivatives

The syntheses of various pyrimidinones as potentially bioactive products by means of the highly controlled continuous-flow retro-Diels-Alder reaction of condensed pyrimidinone derivatives are presented. Noteworthy, the use of this approach allowed us to rapidly screen a selection of conditions and quickly confirm the viability of preparing the desired pyrimidinones in short reaction times. Yields typically higher than those published earlier using conventional batch or microwave processes were achieved.

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

The condensation of 5-aminopyrazole with various bielectrophilic moieties results in the formation of pyrazoloazines, an interesting array of fused heterocyclic systems. The development of new synthetic routes towards pyrazoloazines for their biological and medicinal exploration is an attractive area for researchers throughout the world. The present review focuses on various synthetic methods developed in the last decade for the synthesis of differently substituted pyrazoloazines by a broad range of organic reactions by means of 5-aminopyrazole as a precursor.