Design, synthesis and biological evaluation of 1, 4-dihydro indeno[1,2- c ] pyrazole linked oxindole analogues as potential anticancer agents targeting tubulin and inducing p53 dependent apoptosis

An Insight into the Structure-activity Relationship of Benzimidazole and Pyrazole Derivatives as Anticancer Agents

INTRODUCTION

Cancer is a leading cause of death worldwide, driving the urgent need for new and effective treatments. Benzimidazole and pyrazole derivatives have gained attention for their potential as anticancer agents due to their diverse biological activities. The development of resistance in cancer cells, toxicity concerns, and inconsistent efficacy across different types of cancer are a few of the challenges. To overcome these challenges, optimisation of these nuclei using the structure-activity relationships is necessary.

OBJECTIVES

This review aimed to examine various benzimidazole, pyrazole, and their hybrid derivatives by focusing on their structure-activity relationships (SAR) as anticancer agents. Results of the most potent and least potent benzimidazole, pyrazole compounds, and their hybrid derivatives published by researchers were compiled.

METHODS

The findings of different researchers working on benzimidazole and pyrazole nuclei were reviewed and analysed for different targets and cell lines. Moreover, substitutions on different positions of pyrazole, benzimidazole, and their hybrid were summarised to derive an optimised pharmacophore.

RESULTS

Based on our analysis of existing studies, we anticipate that this review will guide researchers in creating potent pyrazole, benzimidazole, and hybrid derivatives crucial for combating cancer effectively.

CONCLUSION

Structure-Activity Relationship (SAR) studies can help in developing pyrazolebenzimidazole hybrids that are more powerful and selective in targeting specific aspects of cancer.

Indole Compounds in Oncology: Therapeutic Potential and Mechanistic Insights

Cancer remains a formidable global health challenge, with current treatment modalities such as chemotherapy, radiotherapy, surgery, and targeted therapy often hindered by low efficacy and adverse side effects. The indole scaffold, a prominent heterocyclic structure, has emerged as a promising candidate in the fight against cancer. This review consolidates recent advancements in developing natural and synthetic indolyl analogs, highlighting their antiproliferative activities against various cancer types over the past five years. These analogs are categorized based on their efficacy against common cancer types, supported by biochemical assays demonstrating their antiproliferative properties. In this review, emphasis is placed on elucidating the mechanisms of action of these compounds. Given the limitations of conventional cancer therapies, developing targeted therapeutics with enhanced selectivity and reduced side effects remains a critical focus in oncological research.

Inherent efficacies of pyrazole-based derivatives for cancer therapy: the interface between experiment and in silico

There has been an increasing trend in the design of novel pyrazole derivatives for desired biological applications. For a cost-effective strategy, scientists have implemented various computational drug design tools to go hand in hand with experiments for the design and discovery of potentially effective pyrazole-based therapeutics. This review highlights the milestones of pyrazole-containing inhibitors and the use of molecular modeling techniques in conjunction with experimental studies to provide a view of the binding mechanism of these compounds. The review focuses on the established targets that play a key role in cancer therapy, including proteins involved in tubulin polymerization, carbonic anhydrase and tyrosine kinase. Overall, using both experimental and computational methods in drug design represents a promising approach to cancer therapy.

Recent Advances in the Development of Pyrazole Derivatives as Anticancer Agents

Pyrazole derivatives, as a class of heterocyclic compounds, possess unique chemical structures that confer them with a broad spectrum of pharmacological activities. They have been extensively explored for designing potent and selective anticancer agents. In recent years, numerous pyrazole derivatives have been synthesized and evaluated for their anticancer potential against various cancer cell lines. Structure-activity relationship studies have shown that appropriate substitution on different positions of the pyrazole ring can significantly enhance anticancer efficacy and tumor selectivity. It is noteworthy that many pyrazole derivatives have demonstrated multiple mechanisms of anticancer action by interacting with various targets including tubulin, EGFR, CDK, BTK, and DNA. Therefore, this review summarizes the current understanding on the structural features of pyrazole derivatives and their structure-activity relationships with different targets, aiming to facilitate the development of potential pyrazole-based anticancer drugs. We focus on the latest research advances in anticancer activities of pyrazole compounds reported from 2018 to present.

Switchable synthesis of natural-product-like lawsones and indenopyrazoles through regioselective ring-expansion of indantrione

Lawsones and indenopyrazoles are the prevalent structural motifs and building blocks in pharmaceuticals and bioactive molecules, but their synthesis has always remained challenging as no comprehensive protocol has been outlined to date. Herein, a metal-free, ring-expansion reaction of indantrione with diazomethanes, generated in situ from the N-tosylhydrazones, has been developed for the synthesis of lawsone and indenopyrazole derivatives in acetonitrile and alcohol solvents, respectively. It provides these valuable lawsone and pyrazole skeletons in good yields and high levels of diastereoselectivity from simple and readily available starting materials. DFT calculations were used to explore the mechanism in different solutions. The synthetic application example also showed the prospects of this method for the preparation of valuable compounds.

Two Important Anticancer Mechanisms of Natural and Synthetic Chalcones

ATP-binding cassette subfamily G and tubulin pharmacological mechanisms decrease the effectiveness of anticancer drugs by modulating drug absorption and by creating tubulin assembly through polymerization. A series of natural and synthetic chalcones have been reported to have very good anticancer activity, with a half-maximal inhibitory concentration lower than 1 µM. By modulation, it is observed in case of the first mechanism that methoxy substituents on the aromatic cycle of acetophenone residue and substitution of phenyl nucleus by a heterocycle and by methoxy or hydroxyl groups have a positive impact. To inhibit tubulin, compounds bind to colchicine binding site. Presence of methoxy groups, amino groups or heterocyclic substituents increase activity.

Naturally derived indole alkaloids targeting regulated cell death (RCD) for cancer therapy: from molecular mechanisms to potential therapeutic targets

Regulated cell death (RCD) is a critical and active process that is controlled by specific signal transduction pathways and can be regulated by genetic signals or drug interventions. Meanwhile, RCD is closely related to the occurrence and therapy of multiple human cancers. Generally, RCD subroutines are the key signals of tumorigenesis, which are contributed to our better understanding of cancer pathogenesis and therapeutics. Indole alkaloids derived from natural sources are well defined for their outstanding biological and pharmacological properties, like vincristine, vinblastine, staurosporine, indirubin, and 3,3′-diindolylmethane, which are currently used in the clinic or under clinical assessment. Moreover, such compounds play a significant role in discovering novel anticancer agents. Thus, here we systemically summarized recent advances in indole alkaloids as anticancer agents by targeting different RCD subroutines, including the classical apoptosis and autophagic cell death signaling pathways as well as the crucial signaling pathways of other RCD subroutines, such as ferroptosis, mitotic catastrophe, necroptosis, and anoikis, in cancer. Moreover, we further discussed the cross talk between different RCD subroutines mediated by indole alkaloids and the combined strategies of multiple agents (e.g., 3,10-dibromofascaplysin combined with olaparib) to exhibit therapeutic potential against various cancers by regulating RCD subroutines. In short, the information provided in this review on the regulation of cell death by indole alkaloids against different targets is expected to be beneficial for the design of novel molecules with greater targeting and biological properties, thereby facilitating the development of new strategies for cancer therapy.

A close look into the biological and synthetic aspects of fused pyrazole derivatives

The fusion of pyrazole scaffold with other skeletons creates a class of attractive molecules, demonstrating significant biological and chemical potentiality in the development of medicinal chemistry. Over the past few decades, numerous biologically active molecules featuring fused pyrazole moieties have been excavated and synthesized, some of which represented by sildenafil have been marketed as drugs, and the biological importance together with chemical synthesis strategies of fused pyrazole compounds, including structural modification based on lead compounds, have been steadily progressing. In this review, we focused our attention on the biological importance of fused pyrazoles and highlighted recent progress in the synthesis of this framework over the past 10 years. What' s more, the limitations, challenges, and future prospects were proposed, wishing to provide references for the development of pyrazole fused frameworks in the field of medicinal chemistry. Contents.

A Review of the Recent Developments of Molecular Hybrids Targeting Tubulin Polymerization

Microtubules are cylindrical protein polymers formed from αβ-tubulin heterodimers in the cytoplasm of eukaryotic cells. Microtubule disturbance may cause cell cycle arrest in the G2/M phase, and anomalous mitotic spindles will form. Microtubules are an important target for cancer drug action because of their critical role in mitosis. Several microtubule-targeting agents with vast therapeutic advantages have been developed, but they often lead to multidrug resistance and adverse side effects. Thus, single-target therapy has drawbacks in the effective control of tubulin polymerization. Molecular hybridization, based on the amalgamation of two or more pharmacophores of bioactive conjugates to engender a single molecular structure with enhanced pharmacokinetics and biological activity, compared to their parent molecules, has recently become a promising approach in drug development. The practical application of combined active scaffolds targeting tubulin polymerization inhibitors has been corroborated in the past few years. Meanwhile, different designs and syntheses of novel anti-tubulin hybrids have been broadly studied, illustrated, and detailed in the literature. This review describes various molecular hybrids with their reported structural-activity relationships (SARs) where it is possible in an effort to generate efficacious tubulin polymerization inhibitors. The aim is to create a platform on which new active scaffolds can be modeled for improved tubulin polymerization inhibitory potency and hence, the development of new therapeutic agents against cancer.

Contribution of Knoevenagel Condensation Products towards Development of Anticancer Agents: An Updated Review

Knoevenagel condensation is an entrenched, prevailing, prominent arsenal following greener principles in the generation of α, β-unsaturated ketones/carboxylic acids by involving carbonyl functionalities and active methylenes. This reaction has proved to be a major driving force in many multicomponent reactions indicating the prolific utility towards the development of biologically fascinating molecules. This eminent reaction was acclimatised on different pharmacophoric aldehydes (benzimidazole, β-carboline, phenanthrene, indole, imidazothiadiazole, pyrazole etc.) and active methylenes (oxindole, barbituric acid, Meldrum's acid, thiazolidinedione etc.) to generate the library of chemical compounds. Their potential was also explicit to understand the significance of functionalities involved, which thereby evoke further developments in drug discovery. Furthermore, most of these reaction products exhibited remarkable anticancer activity in nanomolar to micromolar ranges by targeting different cancer targets like DNA, microtubules, Topo-I/II, and kinases (PIM, PARP, NMP, p300/CBP) etc. This review underscores the efficiency of the Knoevenagel condensation explored in the past six-year to generate molecules of pharmacological interest, predominantly towards cancer. The present review also provides the aspects of structure-activity relationships, mode of action and docking study with possible interaction with the target protein.

Indole derivatives as tubulin polymerization inhibitors for the development of promising anticancer agents

The α- and β-tubulins are the major polypeptide components of microtubules (MTs), which are attractive targets for anticancer drug development. Indole derivatives display a variety of biological activities including antitumor activity. In recent years, a great number of indole derivatives as tubulin polymerization inhibitors have sprung up, which encourages medicinal chemists to pursue promising inhibitors with improved antitumor activities, excellent physicochemical, pharmacokinetic and pharmacodynamic properties. In this review, the recent progress from 2010 to present in the development of indole derivatives as tubulin polymerization inhibitors was summarized and reviewed, which would provide useful clues and inspirations for further design of outstanding tubulin polymerization inhibitors.

A New Series of Indeno[1,2-c]pyrazoles as EGFR TK Inhibitors for NSCLC Therapy

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death throughout the world. Due to the shortcomings of traditional chemotherapy, targeted therapies have come into prominence for the management of NSCLC. In particular, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) therapy has emerged as a first-line therapy for NSCLC patients with EGFR-activating mutations. In this context, new indenopyrazoles, which were prepared by an efficient microwave-assisted method, were subjected to in silico and in vitro assays to evaluate their potency as EGFR TK-targeted anti-NSCLC agents. Compound 4 was the most promising antitumor agent towards A549 human lung adenocarcinoma cells, with an IC₅₀ value of 6.13 µM compared to erlotinib (IC₅₀ = 19.67 µM). Based on its low cytotoxicity to peripheral blood mononuclear cells (PBMCs), it can be concluded that compound 4 exerts selective antitumor action. This compound also inhibited EGFR TK with an IC₅₀ value of 17.58 µM compared to erlotinib (IC₅₀ = 0.04 µM) and induced apoptosis (56.30%). Taking into account in silico and in vitro data, compound 4 stands out as a potential EGFR TKI for the treatment of NSCLC.

Oxindole and its derivatives: A review on recent progress in biological activities

Oxindole has been shown to be a pharmacologically advantageous scaffold having many biological properties that are relevant to medicinal chemistry. The simplicity and widespread occurrence of this scaffold in plant-based alkaloids have further reinforced oxindole's merit in the domain of novel drug discovery. First extracted from Uncaria tomentosa, commonly the known as cat claw's plant which was found abundantly in the Amazon rainforest, molecules with the oxindole moiety have been shown to be common in a wide variety of compounds extracted from plant sources. The role of oxindole as a chemical scaffold for fabricating and designing biological drugs agents can be ascribed to its ability to be modified by a number of chemical groups to generate novel biological functions. This review is aimed at providing a description of the general chemistry based on existing corresponding structure-activity relationships (SARs) and compile all recent developmentary studies on oxindole-derived compounds as a successful pharmaceutical agent. A substantial group of oxindole derivatives are chiefly being tested as anticancer agents, however, a several oxindole derivatives have been shown to possesses antimicrobial, α-glucosidase inhibitory, antiviral, antileishmanial, antitubercular, antioxidative, tyrosinase inhibitory, PAK4 inhibitory, antirheumatoid arthritis and intraocular pressure reducing activities, to name a few. In this review we show the potential value of developing newer oxindole derivatives with an improved range of pharmacological implications as well as identifying drugs possessing oxindole core, that are showing and serving increased efficacy in clinical practice.

New indenopyrazole linked oxadiazole conjugates as anti-pancreatic cancer agents: Design, synthesis, in silico studies including 3D-QSAR analysis

To continue the quest of newer anticancer agents, herein a novel class of 1,4-Dihydroindenopyrazole linked oxadiazole conjugates 9(a-r) was designed, synthesized and experimented for their anti-proliferative activities against four different cancer cell lines (human) such as MDA MB-231 (breast), PANC-1 (pancreatic), MCF-7 (breast), and Caco-2 (Colorectal) by using MTT assay. Among the series compound 9h and 9 m demonstrated significant potency against the PANC-1 (human pancreatic cancer cells) with IC₅₀ value 7.4 μM and 4.3 μM respectively. While compound 9 m was found to be equipotent to standard Gomitabine (IC₅₀ = 4.2 μM). The detailed biological assays revealed S phase cell cycle arrest and their ability to propagate apoptosis by activating caspase 3 and 9 enzymes which was confirmed by Annexin-FITC assay and caspase assay. Moreover, docking study suggested their binding modes and interactions with caspase-3. In addition, in silico studies revealed that they exhibit good pharmacokinetics and drug likeliness properties. Furthermore, 3D-QSAR was carried out to achieve a pharmacophoric model with CoMFA (q² = 0.631, r² = 0.977) and CoMSIA (q² = 0.686, r² = 0.954) on PANC-1 cancer cells which were established, generated and validated to be reliable models for further design and optimization of newer molecules with enhanced anticancer activity.

Recent Progress on Anticancer Agents Incorporating Pyrazole Scaffold

The search of new anticancer agents is considered as a dynamic field of medicinal chemistry. In recent years, the synthesis of compounds with anticancer potential has increased and a large number of structurally varied compounds displaying potent anticancer activities have been published. Pyrazole is an important biologically active scaffold that possessed nearly all types of biological activities. The aim of this review is to collate literature work reported by researchers to provide an overview on in vivo and in vitro anticancer activities of pyrazole based derivatives among the diverse biological activities displayed by them and also presents recent efforts made on this heterocyclic moiety regarding anticancer activities. This review has been driven from the increasing number of publications, on this issue, which have been reported in the literature since the ending of the 20th century (from 1995-to date).

Cinnamide derived pyrimidine-benzimidazole hybrids as tubulin inhibitors: Synthesis, in silico and cell growth inhibition studies

An approach in modern medicinal chemistry to discover novel bioactive compounds is by mimicking diverse complementary pharmacophores. In extension of this strategy, a new class of piperazine-linked cinnamide derivatives of benzimidazole-pyrimidine hybrids have been designed and synthesized. Their in vitro cytotoxicity profiles were explored on selected human cancer cell lines. Specifically, structural comparison of target hybrids with tubulin-DAMA-colchicine and tubulin-nocodazole complexes has exposed a deep position of benzimidazole ring into the αT5 loop. All the synthesized compounds were demonstrated modest to interesting cytotoxicity against different cancer cell lines. The utmost cytotoxicity has shown with an amine linker of benzimidazole-pyrimidine series, with specificity toward A549 (lung cancer) cell line. The most potent compound in this series was 18i, which inhibited cancer cell growth at micromolar concentrations ranging 2.21-7.29 µM. Flow cytometry studies disclosed that 18i inhibited the cells in G2/M phase of cell cycle. The potent antitumor activity of 18i resulted from enhanced microtubule disruption at a similar level as nocodazole on β-tubulin antibody, explored using immunofluorescence staining. The most active compound 18i also inhibited tubulin polymerization with an IC₅₀ of 5.72 ± 0.51 µM. In vitro biological analysis of 18i presented apoptosis induction on A549 cells with triggering of ROS generation and loss of mitochondrial membrane potential, resulting in DNA injury. In addition, 18i displayed impairment in cellular migration and inhibited the colony formation. Notably, the safety profile of most potent compound 18i was revealed by screening against normal human pulmonary epithelial cells (L132: IC₅₀: 69.25 ± 5.95 μM). The detailed binding interactions of 18i with tubulin was investigated by employing molecular docking, superimposition and free energy analyses. Thus remarks made in this study established that pyrimidine-benzimidazole hybrids as a new class of tubulin polymerization inhibitors with significant anticancer activity.

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

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

Design, synthesis and screening of benzimidazole containing compounds with methoxylated aryl radicals as cytotoxic molecules on (HCT-116) colon cancer cells

A novel series of benzimidazole derivatives with methoxylated aryl groups was designed and synthesized as molecules with potential cytotoxic activity. In vitro cytotoxic activity over HCT-116 cells showed that N-(benzimidazothiazolone)acetamides 11a, 11b and 11c were found to be the most cytotoxic compounds compared camptothecin (CPT). The tested compounds had a dual topoisomerase I-β (Topo I-β) and tubulin inhibiting activities when compared to CPT and Podophyllotoxin (Podo) where, compounds l0a, l0b, 11a and 11b exhibited a potent inhibitory activity on Topo I-β enzyme in nano-molar concentration, on the other hand, compounds 12b and 13b exhibited the best inhibitory activity β-tubulin polymerization. Results of the cell cycle analysis as well as the results of annexin-V on HCT-116 cells showed that benzimidazothiazoles 12b and 13b had a pro-apoptotic activity higher than CPT by 1.33- and 1.30-folds, respectively. Moreover, the concentration of p53, Bax/Bcl-2 ratio and caspase 3/7 increased in compounds l0b, 11b, l2b, 13b, especially, compounds 11b and 13b exhibited an increased level of these mediators than CPT. Finally, compound 11b regulated the radiosensitizing activity of the HCT-116 cells by modulating the chromosomal instability.

Liposomes encapsulated iridium(III) polypyridyl complexes enhance anticancer activity in vitro and in vivo

Three iridium(III) complexes [Ir(ppy)₂(CPIP)](PF₆) (Ir-1, ppy = 2-phenylpyridine, CPIP = 2-(4-chlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline), [Ir(ppy)₂(DCPIP)](PF₆) (Ir-2, DCPIP = 2-(3,4-dichlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline) and [Ir(ppy)₂(TCPIP)](PF₆) (Ir-3, TCPIP = 2,3,5-trichlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline) were synthesized and characterized. The complexes Ir-1, Ir-2 and Ir-3 were encapsulated in liposomes to form Ir-1-Lipo, Ir-2-Lipo and Ir-3-Lipo. Morphology, size distribution, and zeta potential of liposomes were examined by transmission electron microscopy (TEM) and Zetasizer. The cytotoxic activity in vitro of Ir-1, Ir-2 and Ir-3 against cancer A549, HTC-116, HepG2, BEL-7402, Eca-109, B16, HeLa SGC-7901 and normal NIH3T3 cells was evaluated by 3-(4,5-dimethylthiazole-2-yl)-2,5-biphenyl tetrazolium bromide (MTT) method. Ir-2 and Ir-3 show no cytotoxic activity against the selected cancer cells, and Ir-1 displays moderate cytotoxic effect on the cell growth in A549 cells. However, Ir-1, Ir-2 and Ir-3 were encapsulated in liposomes, the cytotoxic activity was greatly enhanced. In particular, Ir-1-Lipo and Ir-2-Lipo can effectively inhibit the cell growth in A549 cells with a low IC₅₀ value of 3.1 ± 0.3 and 1.2 ± 0.4 μM. The apoptosis was assayed by flow cytometry. Ir-1, Ir-2 and Ir-3 reveal weak apoptotic effect, whereas Ir-1-Lipo, Ir-2-Lipo and Ir-3-Lipo induce an apoptotic percentage of 55.6%, 69.3% and 16.7% in A549 cells, respectively. Specially, in the assay of antitumor activity in vivo, the inhibiting percentage of tumor growth induced by Ir-2 is 27.65%, while inhibiting percentage of tumor growth caused by Ir-2-Lipo is 57.45%. Obviously, the liposomes can enhance anticancer activity in vitro and in vivo compared with the complexes. The results show that the iridium(III) complexes encapsulated liposomes induce apoptosis in A549 cells through ROS-mediated lysosome-mitochondria dysfunction pathway and target the microtubules.

Design, synthesis, and antimicrobial evaluation of 1,4-dihydroindeno[1,2-c]pyrazole tethered carbohydrazide hybrids: exploring their in silico ADMET, ergosterol inhibition and ROS inducing potential

A series of new 1,4-dihydroindeno[1,2-c]pyrazole tethered carbohydrazide hybrids (5a-u) were designed, synthesized and evaluated for their antimicrobial activity. Compounds 5d, 5g, 5j, 5k and 5q demonstrated significant activity against the entire panel of test pathogens. Further, compounds 5d and 5g exhibited significant anti-Candida activity. These potential hybrids (5d and 5g) also exhibited promising ergosterol biosynthesis inhibition against Candida albicans, which was further validated through molecular docking studies. Furthermore, compounds 5d and 5g caused intracellular ROS accumulation in C. albicans MTCC 3017 and were non-toxic to normal human lung cell line MRC5. In silico studies revealed that they demonstrated drug likeness and an appreciable pharmacokinetic profile. Overall, the findings demonstrate that 5d and 5g may be considered as promising leads for further development of new antifungal drugs.

Synthesis and biological evaluation of novel indenopyrazole derivatives

A series of novel indenopyrazole derivatives 2a-j and 3a-j were synthesized from the reaction of 1-(4-(hydroxy(1-oxo-1,3-dihydro-2 H-inden-2-ylidene)methyl)phenyl)-3-phenylurea derivatives 1a-j with hydrazine and phenylhydrazine, respectively. The obtained novel indenopyrazoles ( 2a-j and 3a-j) were evaluated for anticancer activity against HeLa and C6 cell lines. Antiproliferative activity was determined by the BrdU proliferation ELISA assay; 2a, 2b, 2d, 2h, and 3h were found to be the most active compounds. The compounds were also screened for antimicrobial activity, and all compounds showed moderate activity against used microorganisms.

Cink4T, a quinazolinone-based dual inhibitor of Cdk4 and tubulin polymerization, identified via ligand-based virtual screening, for efficient anticancer therapy

Inhibition of cyclin dependent kinase 4 (Cdk4) prevents cancer cells from entering the early G₀/G₁ phase of the cell division cycle whereas inhibiting tubulin polymerization blocks cancer cells' ability to undergo mitosis (M) late in the cell cycle. We had reported earlier that two non-planar and relatively non-toxic fascaplysin derivatives, an indole and a tryptoline, inhibit Cdk4 with IC₅₀ values of 6.2 and 10 μM, respectively. Serendipitously, we had also found that they inhibited tubulin polymerization. The molecules were efficacious in mouse tumor models. We have now identified Cink4T in a 59-compound quinazolinone library, designed on the basis of ligand-based virtual screening, as a compound that inhibits Cdk4 and tubulin. Its IC₅₀ value for Cdk4 inhibition is 0.47 μM and >50 μM for inhibition of Cdk1, Cdk2, Cdk6, Cdk9. Cink4T inhibits tubulin polymerization with an IC₅₀ of 0.6 μM. Molecular modelling studies on Cink4T with Cdk4 and tubulin crystal structures lend support to these observations. Cancer cell cycle analyses confirm that Cink4T blocks cells at both G₀/G₁ and M phases as it should if it were to inhibit both Cdk4 and tubulin polymerization. Our results show, for the very first time, that virtual screening can be used to design novel inhibitors that can potently block two crucial phases of the cell division cycle.

Toll-like receptor 9 activation by CpG oligodeoxynucleotide 7909 enhances the radiosensitivity of A549 lung cancer cells via the p53 signaling pathway

Unmethylated cytosine-phosphorothioate-guanine (CpG)-containing oligodeoxynucleotides (ODNs) are synthetic DNA sequences that mimic bacterial DNA, and are known to serve as ligands for Toll-like receptor 9 (TLR9). The interaction between a CpG ODNs with TLR9 activates the complex downstream cascade that contributes to exerting its function. In the present study, the results of clonogenic assays demonstrated that the activation of TLR9 by CpG ODNs significantly increased the radiosensitivity of A549 lung cancer cells, with a sensitivity enhancement ratio (SER) of 1.28. When the expression of TLR9 was effectively silenced, CpG ODNs used alone were identified to produce SERs as low as 1.01. Flow cytometry demonstrated that the interaction between TLR9 and CpG ODN 7909 alone did not significantly affect the rate of apoptosis, but may significantly enhance the radiation-induced apoptosis of A549 cells. Western blot analysis revealed that TLR9 activation by CpG ODN 7909 increased the levels of mitogen-activated protein kinase 14, cellular tumor antigen p53, B-cell lymphoma 2 associated X protein and genome polyprotein, and decreased Bcl-2 expression levels, whereas these effects were not observed in CpG ODN 7909-treated cells in which TLR9 was knocked down. These results suggest that CpG ODN 7909 may enhance radiosensitivity through TLR9 activation, and partially via the p53 pathway in A549 lung cancer cells.

Bromide-catalyzed electrochemical trifluoromethylation/cyclization of N-arylacrylamides with low catalyst loading

An electro-generated trifluoromethyl radical mediated by a bromide ion is efficiently applied to the trifluoromethylarylation/cyclization of N-arylacrylamides.