Cyclin-Dependent Kinase Inhibitors: Useful Targets in Cell Cycle Regulation

In-vitro Evaluation of Triazine Scaffold for Anticancer Drug Development: A Review

INTRODUCTION

The widespread importance of the synthesis and modification of anticancer agents has given rise to many numbers of medicinal chemistry programs. In this regard, triazine derivatives have attracted attention due to their remarkable activity against a wide range of cancer cells. This evaluation covers work reports to define the anticancer activity, the most active synthesized compound for the target, the SAR and, when described, the probable MOA besides similarly considered to deliver complete and target-pointed data for the development of types of anti-tumour medicines of triazine derivatives. Triazine scaffold for the development of anticancer analogues. Triazine can also relate to numerous beneficial targets, and their analogues have auspicious in-vitro and in-vivo anti-tumour activity. Fused molecules can improve efficacy, and drug resistance and diminish side effects, and numerous hybrid molecules are beneath diverse stages of clinical trials, so hybrid derivatives of triazine may offer valuable therapeutic involvement for the dealing of tumours.

OBJECTIVE

The objective of the recent review was to summarize the recent reports on triazine as well as its analogues with respect to its anticancer therapeutic potential.

CONCLUSION

The content of the review would be helpful to update the researchers working towards the synthesis and designing of new molecules for the treatment of various types of cancer disease with the recent molecules that have been produced from the triazine scaffold. Triazine scaffolds based on 1,3,5-triazine considerably boost molecular diversity levels and enable covering chemical space in key medicinal chemistry fields.

Insights into the selectivity of a brain-penetrant CDK4/6 vs CDK1/2 inhibitor for glioblastoma used in multiple replica molecular dynamics simulations

Cyclin dependent kinases (CDKs) play an important role in cell cycle regulation and their dysfunction is associated with many cancers. That is why CDKs have been attractive targets for the treatment of cancer. Glioblastoma is a cancer caused by the aberrant expression of CDK4/6, so exploring the mechanism of the selection of CDK4/6 toward inhibitors relative to the other family members CDK1/2 is essential. In this work, multiple replica molecular dynamics (MRMD) simulations, principal component analysis (PCA), free energy landscapes (FELs), molecular mechanics Poisson-Boltzmann/Generalized Born surface area (MM-PB/GBSA) and other methods were integrated to decipher the selectively binding mechanism of the inhibitor N1J to CDK4/6 and CDK1/2. Molecular electrostatic potential (MESP) analysis provides an explanation for the N1J selectivity. Residue-based free energy decomposition reveals that most of the hot residues are located at the same location of CDKs proteins, but the different types of residues in different proteins cause changes in binding energy, which is considered as a potential developmental direction to improve the selectivity of inhibitors to CDK4/6. These results provide insights into the source of inhibitor and CDK4/6 selectivity for the future development of more selective inhibitors.Communicated by Ramaswamy H. Sarma.

Development of a Crystallization-Induced Diastereomer Transformation of Oxime Isomers for the Asymmetric Synthesis of (1S,6R)-3,9-Diazabicyclo[4.2.1]nonane

Herein we report a practical crystallization-induced diastereomer transformation (CIDT) of oxime isomers for the scalable asymmetric synthesis of the bicyclic diamine (1S,6R)-3,9-diazabicyclo[4.2.1]nonane derivative that serves as a valuable building block in medicinal chemistry. The developed approach utilizes (S)-phenylethylamine as a chiral auxiliary handle for CIDT, and the starting nortropinone derivative is prepared in one step from commercially available materials. The resulting E-oxime is subjected to a stereospecific Beckmann rearrangement, followed by reduction of the resulting lactam with LiAlH4 to afford the monoprotected (1S,6R)-3,9-diazabicyclo[4.2.1]nonane derivative. The development of the CIDT and understanding of the mechanistic implications leading to the high selectivity are reported.

The ethanol extract of Cyperus exaltatus var. iwasakii exhibits cell cycle dysregulation, ERK1/2/p38 MAPK/AKT phosphorylation, and reduced MMP-9-mediated metastatic capacity in prostate cancer models in vitro and in vivo

BACKGROUND

Prostate cancer is the second most common cause of cancer death worldwide in men. The development of novel and highly efficient therapeutic strategies is strongly recommended to treat prostate cancer. Cyperaceae are an ecologically and economically important family of plants with several pharmacological effects. However, the biological efficacy of Cyperus exaltatus var. iwasakii (CE) is unknown.

PURPOSE

This study aimed to investigate the antitumor effect of the ethanol extract of CE against prostate cancer.

METHODS

In vitro antitumor efficacy of CE was explored by the MTT assay, cell counting assay, FACS analysis, immunoblot, wound-healing migration, invasion assay, zymographic assay, and EMSA in prostate cancer cells, DU145 and LNCaP. For in vivo experiments, xenograft mice were injected with LNCaP cells. Histology (H&E and Ki-67) and biochemical enzyme assay were then performed. The toxicity test was evaluated by an acute toxicity assay. The phytochemical constituents of CE were identified by spectrometric and chromatographic analyses.

RESULTS

CE exerted a significant antiproliferative effect against prostate cancer cells. CE-induced antiproliferative cells were associated with cell cycle arrest at G₀/G₁ (cyclin D1/CDK4, cyclin E/CDK2, p21^Waf1) in DU145 cells, but G₂/M (ATR, CHK1, Cdc2, Cdc25c, p21^Waf1, and p53) in LNCaP cells. CE stimulated the phosphorylation of ERK1/2, p38 MAPK, and AKT in DU145 cells, but only p38 MAPK phosphorylation was increased in LNCaP cells. CE treatment suppressed migration and invasion in the two types of prostate cancer cells by inhibiting MMP-9 activity through the regulation of transcription factors, such as AP-1 and NF-κB. In vivo experiments showed a reduction in tumor weight and size following oral CE administration. Histochemistry confirmed that CE inhibited tumor growth in the mouse LNCaP xenograft model. The administration of CE had no adverse effects on body weight, behavioral patterns, blood biochemistry, and histopathology findings of vital organs in mice. Finally, a total of 13 phytochemical constituents were identified and quantified in CE. The most abundant secondary metabolites in CE were astragalin, tricin, and p-coumaric acid.

CONCLUSION

Our results demonstrated the antitumor efficacy of CE against prostate cancer. These findings suggest that CE might be a potential candidate for prostate cancer prevention or treatment.

An Effective Synthesis of Previously Unknown 7-Aryl Substituted Paullones

A straightforward three-step procedure affording a wide range of novel 7-aryl substituted paullone derivatives was developed. This scaffold is structurally similar to 2-(1H-indol-3-yl)acetamides-promising antitumor agents-hence, could be useful for the development of a new class of anticancer drugs.

Palbociclib and Michael-acceptor hybrid compounds as CDK4/6 covalent inhibitors: improved potency, broad anticancer spectrum and overcoming drug resistance

To search for potent CDK4/6 covalent inhibitors, total 14 compounds have been designed and synthesized by connecting different Michael-acceptor to the piperazine moiety of palbociclib. All the compounds displayed good antiproliferative activity against human hepatoma cell (HepG2), non-small cell lung cancer (A549), and breast cancer (MDA-MB-231 and MCF-7) cell lines. In particular, compound A4 showed the highest inhibitory activity to MDA-MB-231 and MCF-7 cells with IC₅₀ values of 0.51 μM and 0.48 μM, respectively. More importantly, A4 also showed strong inhibition against MDA-MB-231/palbociclib cells, indicating that A4 could effectively avoid the resistance of palbociclib. In the enzyme test, A4 showed selective inhibitory activity against CDK4/6, with the IC₅₀ value of 18 nM and 13 nM, respectively. It was also found that A4 could efficiently induce apoptosis and arrest the cell cycle at G0/G1 phase. Moreover, A4 could significantly decrease the phosphorylation level of CDK4 and CDK6. HPLC and molecular modeling studies suggested that A4 could form a covalent bond with the target protein.

Effects of activation with a Ca ionophore and roscovitine on the development of human oocytes that failed to fertilize after ICSI

OBJECTIVE

The effects of oocyte activation with a Ca ionophore and roscovitine (Ca+R), a selective inhibitor of M-phase promoting factor, on unfertilized oocytes after intracytoplasmic sperm injection (ICSI) or testicular sperm extraction (TESE)-ICSI were evaluated.

METHOD

Oocytes without pronuclei at 18 hours after ICSI were judged to be unfertilized and were exposed to the Ca ionophore A23187 (5 ?M) with or without roscovitine (50 ?M). The activation rate was measured 3, 7, and 18 hours later. Oocytes with two polar bodies and two pronuclei with a sperm tail were judged to have been activated.

RESULTS

At 18 hours, the activation rates in the control, Ca ionophore, and Ca+R groups were 3.5% (4/112), 26.9% (7/26), and 32.1% (17/53), respectively. The activation rate of the Ca+R group was significantly higher than that of the control and similar to that of the Ca ionophore group. Among the oocytes that remained unfertilized after TESE-ICSI, the activation rates of the Ca ionophore and Ca+R groups were 22.2% (2/9) and 43.8% (7/16), respectively.

CONCLUSIONS

Sequential treatment with an Ca ionophore and roscovitine activates oocytes that remain unfertilized after ICSI. In TESE-ICSI, the activation rate tended to be increased by the co-administration of roscovitine with a Ca ionophore. J. Med. Invest. 70 : 321-324, August, 2023.

1,3-diarylpyrazolones as potential anticancer agents for non-small cell lung cancer: Synthesis and antiproliferative activity evaluation

A series of pyrazolone compounds with different substitution patterns have been synthesized using microwave-assisted methods and evaluated their in vitro antiproliferative activity against human lung adenocarcinoma cell lines (A549 and NCI-H522). Among the tested compounds, the pyrazolone P7 exhibited high antiproliferative activity against both A549 and NCIH522 cancer cell lines while being 10 times less cytotoxic to non-cancerous cells. Moreover, our compounds P7 and P11 exhibited higher antiproliferative activity and selectivity against A549 and NCIH522 cells compared with the clinically approved drugs Afatinib and Gefitinib. The cell cycle analysis showed that the compound P7 and P11 arrests the cell cycle at G0/G1 phase, whereas the compounds P13 and P14 involved in G2/M phase arrest. The results from antiproliferative activity screening, cell cycle analysis, and kinase profiling indicate that the suitably substituted 1,3-diarylpyrazolones exhibit high antiproliferative activity against non-small cell lung cancer cells.

A revised synthesis of 6-alkoxy-2-aminopurines with late-stage convergence allowing for increased molecular complexity

This streamlined synthesis allows the alcohol at the 6-position of 6-alkoxy-2-arylaminopurines to be used only in moderate excess, rather than as solvent, opening up the possibility of accessing more complicated molecules.

Pharmacological relevance of CDK inhibitors in Alzheimer's disease

Evidence suggests that cell cycle activation plays a role in the pathophysiology of neurodegenerative diseases. Alzheimer's disease is a progressive, terminal neurodegenerative disease that affects memory and other important mental functions. Intracellular deposition of Tau protein, a hyperphosphorylated form of a microtubule-associated protein, and extracellular aggregation of Amyloid β protein, which manifests as neurofibrillary tangles (NFT) and senile plaques, respectively, characterize this condition. In recent years, however, several studies have concluded that cell cycle re-entry is one of the key causes of neuronal death in the pathogenesis of Alzheimer's disease. The eukaryotic cell cycle is well-coordinated machinery that performs critical functions in cell replenishment, such as DNA replication, cell creation, repair, and the birth of new daughter cells from the mother cell. The complex interplay between the levels of various cyclins and cyclin-dependent kinases (CDKs) at different checkpoints is needed for cell cycle synchronization. CDKIs (cyclin-dependent kinase inhibitors) prevent cyclin degradation and CDK inactivation. Different external and internal factors regulate them differently, and they have different tissue expression and developmental functions. The checkpoints ensure that the previous step is completed correctly before starting the new cell cycle phase, and they protect against the transfer of defects to the daughter cells. Due to the development of more selective and potent ATP-competitive CDK inhibitors, CDK inhibitors appear to be on the verge of having a clinical impact. This avenue is likely to yield new and effective medicines for the treatment of cancer and other neurodegenerative diseases. These new methods for recognizing CDK inhibitors may be used to create non-ATP-competitive agents that target CDK4, CDK5, and other CDKs that have been recognized as important therapeutic targets in Alzheimer's disease treatment.

Nuclear dihydroxyacetone phosphate signals nutrient sufficiency and cell cycle phase to global histone acetylation

Global histone acetylation varies with changes in the nutrient and cell cycle phases; however, the mechanisms connecting these variations are not fully understood. Herein, we report that nutrient-related and cell-cycle-regulated nuclear acetate regulates global histone acetylation. Histone deacetylation-generated acetate accumulates in the nucleus and induces histone hyperacetylation. The nuclear acetate levels were controlled by glycolytic enzyme triosephosphate isomerase 1 (TPI1). Cyclin-dependent kinase 2 (CDK2), which is phosphorylated and activated by nutrient-activated mTORC1, phosphorylates TPI1 Ser 117 and promotes nuclear translocation of TPI1, decreases nuclear dihydroxyacetone phosphate (DHAP) and induces nuclear acetate accumulation because DHAP scavenges acetate via the formation of 1-acetyl-DHAP. CDK2 accumulates in the cytosol during the late G1/S phases. Inactivation or blockade of nuclear translocation of TPI1 abrogates nutrient-dependent and cell-cycle-dependent global histone acetylation, chromatin condensation, gene transcription and DNA replication. These results identify the mechanism of maintaining global histone acetylation by nutrient and cell cycle signals.

Small molecules in targeted cancer therapy: advances, challenges, and future perspectives

Due to the advantages in efficacy and safety compared with traditional chemotherapy drugs, targeted therapeutic drugs have become mainstream cancer treatments. Since the first tyrosine kinase inhibitor imatinib was approved to enter the market by the US Food and Drug Administration (FDA) in 2001, an increasing number of small-molecule targeted drugs have been developed for the treatment of malignancies. By December 2020, 89 small-molecule targeted antitumor drugs have been approved by the US FDA and the National Medical Products Administration (NMPA) of China. Despite great progress, small-molecule targeted anti-cancer drugs still face many challenges, such as a low response rate and drug resistance. To better promote the development of targeted anti-cancer drugs, we conducted a comprehensive review of small-molecule targeted anti-cancer drugs according to the target classification. We present all the approved drugs as well as important drug candidates in clinical trials for each target, discuss the current challenges, and provide insights and perspectives for the research and development of anti-cancer drugs.

Role of the base Cs2CO3 on the palladium-catalyzed intramolecular cyclization of two bromoindole derivatives to yield paullone-type products

Reactions for the palladium-catalyzed intramolecular cyclization of the o-bromoindole and the o-bromo-N-methyl-indole derivatives in the presence and absence of base (Cs₂CO₃) were explored through DFT calculations. For the base-free reactions, the palladium atom firstly interacts with the aromatic rings of the indole molecule to yield a stable adduct. Once this adduct has been formed, reaction proceeds readily to the oxidative addition intermediate that arises from the insertion of the metal atom into the C-Br bond of the organic fragment. Further steps leading to the paullone (or dimethyl paullone) product, mainly those involving the metalation and deprotonation of the inserted intermediate, are not energetically viable for these reactions. When the effect of the base on the metalation-deprotonation steps is modeled by replacing the bromide ion with CO₃^2- in the metal-inserted structure, a feasible pathway connecting the oxidative addition intermediate with the paullone-type product was located for each of the investigated reactions. The results emerging from this study suggest that palladium can insert into the C-Br bond of the indole derivatives to yield the oxidative addition intermediate (without participation of the base). However, the metalation and deprotonation steps that evolve to the paullone-type product take place via a concerted action involving both the metal and the base. Metalation and deprotonation steps that evolve to the paullone-type product take place via a concerted action involving both the metal and the base.

Palladium-mediated C–O bond activation of benzopyrone in 4-oxo-4H-chromone-3-carbaldehyde-4(N)-substituted thiosemicarbazone: synthesis, structure, nucleic acid/albumin interaction, DNA cleavage, antioxidant and cytotoxic studies

Palladium ion-mediated C–O activation at the C2 carbon of the benzopyrone moiety of 3-formylchromone-4(N)-substituted thiosemicarbazone (HL1–4) has been observed in square-planar palladium(ii) complexes.

Synthesis and Clinical Development of Palbociclib: An overview

Breast cancer is the second most commonly identified cancer in women in the United States after skin cancer. The past few years have seen a substantial increase in breast cancer awareness campaigns and active research in fields of diagnosis and targeted therapy. These factors have led to a better mechanistic understanding of the disease, detection at earlier stages and more personalized approach to treatment, ultimately causing a crucial increase in the survival rates after detection. However, with the advances in treatment, cases of patients developing primary resistance and acquired resistance are increasing. Most of the breast cancers which develop resistance to therapy are ER+ and are typically treated with tamoxifen and fulvestrant. These drugs either lower the levels of estrogen or inhibit the receptors for estrogen and prevent the tumor from spreading. Around one third of women treated with these drugs develop resistance to them, lowering their chances of survival. This has directed to the search of newer drug therapies to target advanced breast cancer and resistance. One of these efforts has resulted in the development of Palbociclib, a first in class inhibitor of cyclin dependent kinases 4 and 6 (CDK4 and CDK6), which was granted accelerated approval from FDA for combination therapy in postmenopausal women with ER+, HER2- metastatic breast cancer. This review is focused on the various aspects of "Palbociclib" including its synthesis, molecular modeling studies and efficacy and safety profile with clinical trials data.

Inhibitors of Cyclin-Dependent Kinase 1/2 for Anticancer Treatment

BACKGROUND

The cell cycle is regulated by cyclin-dependent kinases (CDKs) and their cognate cyclins, along with their endogenous inhibitors (CDKIs). CDKs act as central regulators in this process. Different CDKs play relevant roles in different phases. Among all CDKs, CDK1 is indispensible, which can drive all events that are required in the cell cycle in the absence of interphase CDKs (CDK2, CDK3, CDK4 and CDK6). So, CDK1 is an attractive target for anticancer drug development.

METHODS

CDK1 and CDK2 have 89.19% similar residues and 74.32% identical residues, their structures especially the ATP-binding sites are of great similarity. So, it is difficult to inhibit CDK1 and CDK2 individually. In this review, recent advances about CDK1/2 inhibitors were summarized. The chemical structures of different classes of CDK1/2 inhibitors and their structure activity are presented.

RESULTS

19 kinds of CDK1/2 or CDK1 inhibitors with different scaffolds, including CDK2 allosteric inhibitors, were summarized. Some inhibitors are nature derived, for example, phenanthrene derivatives, nortopsentin derivatives, variolin B derivatives and meridians.

CONCLUSION

Nature products, especially marine ones are potential resources for CDK1 inhibitors development. The findings of CDK2 allosteric inhibitors open an avenue to the discovery of novel selective CDK1 or other CDKs allosteric inhibitors.

A novel Cu(II) distorted cubane complex containing Cu4O4 core as the first tetranuclear catalyst for temperature dependent oxidation of 3,5-di-tert-butyl catechol and in interaction with DNA & protein (BSA)

The tri-dentate Schiff base ligand 3-(2-hydroxyethylimino)-1-phenylbut-1-en-1-ol (L) produced the tetra-nuclear Cu(II) distorted cubane complex which contain Cu₄O₄ core, upon reaction with Cu(II)acetate.H₂O. The complex was structurally characterized by X-ray crystallography and found that, in this tetrameric and tetra-nuclear distorted cubane structure, each two-fold deprotonated Schiff base ligand coordinated to a Cu(II) center with their alcoholic oxygens and imine nitrogens and formed six and five-membered chelate rings. At the same time, each ligand bridged to a neighboring Cu(II) atom by its alcoholic oxygen, thus the metal centers became penta-coordinated. The copper(II) complex with μ-ɳ²-hydroxo bridges and Cu….Cu distance about 3 Å was structurally similar to the active site of natural catechol oxidase enzyme and exhibited excellent catecholase activity in aerobic oxidation of 3,5-di-tert-butyl catechol to its o-quinone. The kinetics and mechanism of the oxidation of 3, 5-DTBCH₂ catalyzed by [CuL]₄ complex, were studied at four different temperatures from 283 to 313K by UV-Vis spectroscopy. Interaction of [CuL]₄ complex with FS-DNA was investigated by UV-Vis and fluorescence spectroscopy, viscosity measurements, cyclic voltammetry (CV), circular dichroism (CD) and agarose gel electrophoresis. The main mode of binding of the complexes with DNA was intercalation. The interaction between [CuL]₄ complex and bovine serum albumin (BSA) was studied by UV-Vis, fluorescence and synchronous fluorescence spectroscopic techniques. The results indicated a high binding affinity of the complex to BSA. In vitro anticancer activity of the complex was evaluated against A549, Jurkat and Ragi cell lines by MTT assay. The complex was remarkably active against the cell lines and can be a good candidate for an anticancer drug. Theoretical docking studies were performed to further investigate the DNA and BSA binding interactions.

Discovery of novel cyclin-dependent kinase (CDK) and histone deacetylase (HDAC) dual inhibitors with potent in vitro and in vivo anticancer activity

In the current study, we reported a series of novel 1-H-pyrazole-3-carboxamide-based inhibitors targeting histone deacetylase (HDAC) and cyclin-dependent kinase (CDK). The representative compounds N-(4-((2-aminophenyl)carbamoyl)benzyl)-4-(2,6-dichlorobenzamido)-1H-pyrazole-3-carboxamide (7c) and N-(4-(2-((2-aminophenyl)amino)-2-oxoethyl)phenyl)-4-(2,6-dichlorobenzamido)-1H-pyrazole-3-carboxamide (14a) with potent antiproliferative activities towards five solid cancer cell lines, showed excellent inhibitory activities against HDAC2 (IC₅₀ = 0.25 and 0.24 nM respectively) and CDK2 (IC₅₀ = 0.30 and 0.56 nM respectively). In addition, compounds 7c and 14a significantly inhibited the migration of A375 and H460 cells. Further studies revealed that compounds 7c and 14a could arrest cell cycle in G2/M phase and promote apoptosis in A375, HCT116, H460 and Hela cells, which was associated with increasing the intracellular reactive oxygen species (ROS) levels. More importantly, compound 7c possessed favorable pharmacokinetic properties with the intraperitoneal bioavailability of 63.6% in ICR mice, and potent in vivo antitumor efficacy in the HCT116 xenograft model. Our study demonstrated that compound 7c provides a promising strategy for the treatment of malignant tumors.

o-Vanillin Derived Schiff Bases and Their Organotin(IV) Compounds: Synthesis, Structural Characterisation, In-Silico Studies and Cytotoxicity

Six new organotin(IV) compounds of Schiff bases derived from S-R-dithiocarbazate [R = benzyl (B), 2- or 4-methylbenzyl (2M and 4M, respectively)] condensed with 2-hydroxy-3-methoxybenzaldehyde (oVa) were synthesised and characterised by elemental analysis, various spectroscopic techniques including infrared, UV-vis, multinuclear (¹H, ¹³C, ¹¹⁹Sn) NMR and mass spectrometry, and single crystal X-ray diffraction. The organotin(IV) compounds were synthesised from the reaction of Ph₂SnCl₂ or Me₂SnCl₂ with the Schiff bases (S2MoVaH/S4MoVaH/SBoVaH) to form a total of six new organotin(IV) compounds that had a general formula of [R₂Sn(L)] (where L = Schiff base; R = Ph or Me). The molecular geometries of Me₂Sn(S2MoVa), Me₂Sn(S4MoVa) and Me₂Sn(SBoVa) were established by X-ray crystallography and verified using density functional theory calculations. Interestingly, each experimental structure contained two independent but chemically similar molecules in the crystallographic asymmetric unit. The coordination geometry for each molecule was defined by thiolate-sulphur, phenoxide-oxygen and imine-nitrogen atoms derived from a dinegative, tridentate dithiocarbazate ligand with the remaining positions occupied by the methyl-carbon atoms of the organo groups. In each case, the resulting five-coordinate C₂NOS geometry was almost exactly intermediate between ideal trigonal-bipyramidal and square-pyramidal geometries. The cytotoxic activities of the Schiff bases and organotin(IV) compounds were investigated against EJ-28 and RT-112 (bladder), HT29 (colon), U87 and SJ-G2 (glioblastoma), MCF-7 (breast) A2780 (ovarian), H460 (lung), A431 (skin), DU145 (prostate), BE2-C (neuroblastoma) and MIA (pancreatic) cancer cell lines and one normal breast cell line (MCF-10A). Diphenyltin(IV) compounds exhibited greater potency than either the Schiff bases or the respective dimethyltin(IV) compounds. Mechanistic studies on the action of these compounds against bladder cancer cells revealed that they induced the production of reactive oxygen species (ROS). The bladder cancer cells were apoptotic after 24 h post-treatment with the diphenyltin(IV) compounds. The interactions of the organotin(IV) compounds with calf thymus DNA (CT-DNA) were experimentally explored using UV-vis absorption spectroscopy. This study revealed that the organotin(IV) compounds have strong DNA binding affinity, verified via molecular docking simulations, which suggests that these organotin(IV) compounds interact with DNA via groove-binding interactions.

Alkoxyallene-based syntheses of preussin and its analogs and their cytotoxicity

Short syntheses of oxa-preussin, racemic preussin and (-)-preussin are reported. Starting from a racemic 3-nonyl-substituted methoxyallene derivative, its lithiation and addition to phenylethanal provided the corresponding allenyl alcohol that was converted into two diastereomeric dihydrofuran derivatives by silver nitrate-catalyzed 5-endo-trig cyclization. The acid hydrolysis of the enol ether moiety gave heterocyclic ketones and subsequent highly stereoselective reductions with l-selectride furnished 2-benzyl-5-nonylfuran-3-ol derivatives in good overall yield. The major all-cis-diastereomer has the skeleton and relative configuration of preussin and is hence called oxa-preussin. An analogous sequence with the same allene, but an N-sulfonyl imine as the electrophile, finally led to racemic preussin. The stereoselectivities of the individual steps are discussed in detail. With an enantiopure 2-benzyl-5-nonylpyrrolidin-3-one intermediate the preparation of (-)-preussin with an enantiomeric ratio of >95 : 5 could be accomplished in a few steps. The sign of the optical rotation of this product finally proved the absolute configurations of its precursors and demonstrated that our chiral auxiliary-based route led to the antipode of the natural product. The cytotoxicity of several of the prepared heterocycles against MCF-7 tumor cells was investigated and five compounds, including racemic and enantiopure (-)-preussin, were identified as highly cytotoxic with IC50 values in the range of 3-6 μM.

Pyrimidine-based pyrazoles as cyclin-dependent kinase 2 inhibitors: Design, synthesis, and biological evaluation

A series of new pyrimidine-pyrazole hybrid molecules were designed as inhibitors of cyclin-dependent kinase 2. Designed compounds were docked using Glide and the compounds showing good score values and encouraging interactions with the residues were selected for synthesis. They were then evaluated using CDK2-CyclinA2 enzyme inhibition by a luminescent ADP detection assay. We show that of the 26 compounds synthesized and evaluated, at least 5 compounds were found to be highly potent (IC₅₀  < 20 nm); which can be further optimized to have selectivity over other kinase isoforms.

Bis(μ-chloro) bridged 1D CuI and CuII coordination polymer complex and mononuclear CuII complex: Synthesis, crystal structure and biological properties

A novel one-dimensional coordination polymer containing Cu(I)Cu(II) core with chloro bridge on Cu(I) and ligand bridge on Cu(II) ions (1) and a mononuclear Cu(II) complex (2) have been synthesized from the reactions of 3- and 4-methoxy-3-quinolin-3-ylimino-methyl-2-phenol with [CuCl₂(PPh₃)₂]. The ligands and the complexes have been characterized by spectral and analytical methods. In addition, the structures of both the ligands and the copper complexes were confirmed by single crystal X-ray diffraction studies. In both complexes, the phenolic oxygen and azomethine nitrogen atom of the ligand coordinate to the copper ions in a monobasic bidentate manner resulting in an approximately square planar geometry around the copper ion. In the polymeric complex, the N atom of the quinoline ring is coordinated to Cu(I) in addition to the phenolic oxygen and azomethine nitrogen atom coordinating to Cu(II) ion, thus bridging Cu(I) and Cu(II) ions in the complex. The interactions of the compounds with calf thymus DNA (CT-DNA) have been followed by absorption and emission titration methods, which revealed that the compounds interact with CT-DNA through intercalation. Further, the interactions of the compounds with bovine serum albumin (BSA) were also investigated using UV-visible, fluorescence spectroscopic methods. The results indicated that complex 1 exhibited a stronger binding to CT-DNA and BSA than the free ligands and complex 2. In addition, the in vitro cytotoxicity experiment showed that complexes 1 and 2 exhibit potent cytotoxic properties against PANC-1and Hela cells. Moreover, while complex 1 showed prominent cytotoxic activity against both PANC-1 and Hela cells with IC₅₀ of 17.91 and 11.67 μM, complex 2 showed moderate cytotoxic activities with IC₅₀ of 25.13 and 16.41 μM in PANC-1 and Hela cells. Further, apoptosis was confirmed by fluorescence image using EB/AO reagent.

Effect of electrostatic polarization and bridging water on CDK2–ligand binding affinities calculated using a highly efficient interaction entropy method

A new highly efficient interaction entropy (IE) method combined with the polarized protein-specific charge (PPC) force field is employed to investigate the interaction mechanism of CDK2–ligand binding and the effect of the bridging water.

Synthesis of two potential anticancer copper(ii) complex drugs: their crystal structure, human serum albumin/DNA binding and anticancer mechanism

Two potential anticancer copper(ii) complex drugs showed better activity than cisplatin against HeLa cells, and efficiently bonded with DNA/HSA.

Synthesis and crystal structure of new monometallic Ni(ii) and Co(ii) complexes with an asymmetrical aroylhydrazone: effects of the complexes on DNA/protein binding property, molecular docking, and in vitro anticancer activity

Cytotoxic nickel and cobalt complexes containing asymmetrical aroylhydrazone were synthesized and their interactions with HS–DNA and BSA protein were investigated, which was supported by molecular docking studies.

Synthesis of (E)-oxindolylidene acetate using tandem palladium-catalyzed Heck and alkoxycarbonylation reactions

Tandem reactions use consecutive reaction steps to efficiently synthesize compounds of high molecular complexity. This paper presents a tandem Pd-catalyzed Heck and alkoxycarbonylation reaction for the stereoselective synthesis of (E)-oxindolylidene acetates. The mechanism underlying the Pd-catalyzed tandem reaction involves the syn-carbopalladation of ynamides followed by alkoxycarbonylation with CO and alcohol. This method makes it possible to obtain the desired (E)-configuration of oxindolylidene acetates exclusively. We evaluated the scope of the reaction by applying optimal reaction conditions to the facile synthesis of a library of (E)-oxindolylidene acetates. The resulting (E)-oxindolylidene acetates exhibited potent anticancer activities against a variety of human cancer cell lines. The anticancer activities of some (E)-oxindolylidene acetates were even superior to those of known CDK inhibitors indirubin-3'-oxime and roscovitine.

New palbociclib analogues modified at the terminal piperazine ring and their anticancer activities

A series of new palbociclib analogs by extensive functionalization of the tail piperazine ring with various carbamates and amides have been synthesized. All the palbociclib derivatives were evaluated for their cytotoxic activities against MCF-7 cell line. From the anti-proliferation activity results, two of the tested compounds (compounds 4d and 4e) showed significant cytotoxic effects. And compounds 4d and 4e exhibited potent anticancer activities in MDA-MB-453 and MDA-MB-231 cells. Among these derivatives compound 4e was found to possess cytotoxicity that is better than standard drug palbociclib. Moreover, compound 4e demonstrated robust tumor growth inhibition in vivo model.

Design strategies, structure activity relationship and mechanistic insights for purines as kinase inhibitors

Kinases control a diverse set of cellular processes comprising of reversible phosphorylation of proteins. Protein kinases play a pivotal role in human tumor cell proliferation, migration and survival of neoplasia. In the recent past, purine based molecules have emerged as significantly potent kinase inhibitors. In view of their promising potential for the inhibition of kinases, this review article focuses on purines which have progressed as kinase inhibitors during the last five years. A detailed account of the design strategies employed for the synthesis of purine analogs exerting inhibitory effects on diverse kinases has been presented. Apart from presenting the design strategies, the article also highlights the structure activity relationship along with mechanistic insights revealed during the biological evaluation of the purine analogs for kinase inhibition. The interactions with the amino acid residues responsible for kinase inhibitory potential of purine based molecules have also been discussed. In this assemblage, purine based protein kinase inhibitors patented in the past have also been summarized in the tabular form. This compilation will be of great interest for the researchers working in the area of protein kinase inhibitors.

Mixed-ligand copper(ii)-phenolate complexes: structure and studies on DNA/protein binding profiles, DNA cleavage, molecular docking and cytotoxicity

Copper(ii) complexes with simple and mixed ligands, [Cu(L)(ClO₄)] and [Cu(L)(diimine)]ClO₄ were synthesized and characterized by elemental analysis, UV-vis, FT-IR, electrospray ionization-mass spectrometry (ESI-MS) and electrochemical studies.

CDK5 knockdown prevents hippocampal degeneration and cognitive dysfunction produced by cerebral ischemia

Acute ischemic stroke is a cerebrovascular accident and it is the most common cause of physical disabilities around the globe. Patients may present with repeated ictuses, experiencing mental consequences, such as depression and cognitive disorders. Cyclin-dependent kinase 5 (CDK5) is a kinase that is involved in neurotransmission and plasticity, but its dysregulation contributes to cognitive disorders and dementia. Gene therapy targeting CDK5 was administered to the right hippocampus of ischemic rats during transient cerebral middle artery occlusion. Physiologic parameters (blood pressure, pH, pO2, and pCO2) were measured. The CDK5 downregulation resulted in neurologic and motor improvement during the first week after ischemia. Cyclin-dependent kinase 5 RNA interference (RNAi) prevented dysfunctions in learning, memory, and reversal learning at 1 month after ischemia. These observations were supported by the prevention of neuronal loss, the reduction of microtubule-associated protein 2 (MAP2) immunoreactivity, and a decrease in astroglial and microglia hyperreactivities and tauopathy. Additionally, CDK5 silencing led to an increase in the expression of brain-derived neurotrophic factor (BDNF), its Tropomyosin Receptor kinase B (TRKB) receptor, and activation of cyclic AMP response element-binding protein (CREB) and extracellular signal-regulated kinase (ERK), which are important targets in neuronal plasticity. Together, our findings suggest that gene therapy based on CDK5 silencing prevents cerebral ischemia-induced neurodegeneration and motor and cognitive deficits.

Sampling of conformational ensemble for virtual screening using molecular dynamics simulations and normal mode analysis

Aim: Molecular dynamics simulations and normal mode analysis are well-established approaches to generate receptor conformational ensembles (RCEs) for ligand docking and virtual screening. Here, we report new fast molecular dynamics-based and normal mode analysis-based protocols combined with conformational pocket classifications to efficiently generate RCEs. Materials & Methods: We assessed our protocols on two well-characterized protein targets showing local active site flexibility, dihydrofolate reductase and large collective movements, CDK2. The performance of the RCEs was validated by distinguishing known ligands of dihydrofolate reductase and CDK2 among a dataset of diverse chemical decoys. Results & discussion: Our results show that different simulation protocols can be efficient for generation of RCEs depending on different kind of protein flexibility.[Formula: see text]