Synthesis and biological evaluation of 3,4,6-triaryl-2-pyranones as a potential new class of anti-breast cancer agents

Design and synthesis of Meldrum's acid based 7-azaindole anchored 1,2,3-triazole hybrids as anticancer agents

A series of Meldrum's acid, 7-azaindole and 1,2,3-triazole hybrids were synthesized and evaluated for their in vitro anticancer activity against five different cancer cell lines viz. MCF-7 (breast cancer), HeLa (cervical cancer), DU-145 (prostate cancer), HepG2 (liver cancer) and K562 (myelogenous leukemia cell). Among the series, compound 6b containing a 4-methyl substitution showed potent activity against HeLa cell line. Cell cycle analysis revealed that compound 6b induced cell cycle arrest at the G2/M phase and induced apoptosis. Apoptotic activity was further confirmed by Hoechst staining and Annexin V-FITC assay. Compound 6b has been found to exhibit higher activity in all four cell lines, with IC50 values of 6.67 ± 0.39 μM, 4.44 ± 0.32 μM, 12.38 ± 0.51 μM and 9.97 ± 0.25 μM against MCF-7, HeLa, DU-145 and HepG2 cell lines respectively. Compounds 6m (9.68 ± 0.10 μM) and 6n (9.52 ± 0.38 μM), which have dimethoxy and trimethoxy substitutions, respectively, have demonstrated significant anticancer activity against HeLa cells compared to the other cells. The molecular docking study of ligand 6b against the crystal structure of EGFR and Mcl-1 scored notable binding energy values and displayed important interactions like H-bond, π-cation and other hydrophobic interactions.

Base- and sulfur-promoted oxidative lactonization of chalcone-acetate Michael adducts: access to pyran-2-ones

A cost-effective, practical, straightforward and scalable synthesis of α-pyrones via base- and sulfur-promoted annulation of phenylacetates and chalcones is reported. Generated in situ from the starting components by using dbu as a base catalyst, the Michael adducts underwent a smooth oxidative cyclization into 3,4,6-triaryl-2-pyranones upon heating with DABCO and sulfur in DMSO. Extension to malonate in place of phenylacetates led to 4,6-diaryl-2-pyranone-2-carboxylates.

Visible Light-Promoted Green and Sustainable Approach for One-Pot Synthesis of 4,4'-(Arylmethylene)bis(1H-pyrazol-5-ols), In Vitro Anticancer Activity, and Molecular Docking with Covid-19 Mpro

A visible light-promoted, efficient, green, and sustainable strategy has been adopted to unlatch a new pathway toward the synthesis of a library of medicinally important 4,4'-(arylmethylene)bis(1H-pyrazol-5-ols) moieties using substituted aromatic aldehydes and sterically hindered 3-methyl-1-phenyl-2-pyrazoline-5-one in excellent yield. This reaction shows high functional group tolerance and provides a cost-effective and catalyst-free protocol for the quick synthesis of biologically active compounds from readily available substrates. Synthesized compounds were characterized by spectroscopic techniques such as IR, 1HNMR, 13CNMR, and single-crystal XRD analysis. All the synthesized compounds were evaluated for their antiproliferative activities against a panel of five different human cancer cell lines and compared with Tamoxifen using MTT assay. Compound 3m exhibited maximum antiproliferative activity and was found to be more active as compared to Tamoxifen against both the MCF-7 and MDA-MB-231 cell lines with an IC50 of 5.45 and 9.47 μM, respectively. A molecular docking study with respect to COVID-19 main protease (Mpro) (PDB ID: 6LU7) has also been carried out which shows comparatively high binding affinity of compounds 3f and 3g (-8.3 and -8.8 Kcal/mole, respectively) than few reported drugs such as ritonavir, remdesivir, ribacvirin, favipiravir, hydroxychloroquine, chloroquine, and olsaltamivir. Hence, it reveals the possibility of these compounds to be used as effective COVID-19 inhibitors.

Design of new bis-triazolyl structure for identification of inhibitory activity on COVID-19 main protease by molecular docking approach

In the rapidly growing COVID-19 pandemic, designing of new drugs and evaluating their inhibitory action against main targets of corona virus could be an effective strategy to accelerate the drug discovery process and their efficacy towards corona virus disease. Herein, we design new bis-triazolyl probe for an investigation of inhibitory activity towards COVID-19 main protease by Molecular docking approach. The formulated compound has been thoroughly characterized by elemental analysis, NMR (¹H and ¹³C) and complete structure elucidation was achieved via X-ray crystallography. Docking study reveals that newly synthesized compound confers good inhibitory response to COVID-19 main protease as supported by calculated docking score and binding energy. Strong hydrogen bonding and hydrophobic interactions of the newly synthesized compound with several important amino acids of the main protease also helps to explain the potency of the compound to inhibit the main protease. We hope that the present study would help the researcher in the field of Medicinal chemistry and to develop potential drug against the novel corona virus.

Two novel anticancer compounds with minimum cardiotoxic property

BACKGROUND

Although two novel synthesized compounds with tri-aryl structures; 3-(4-chlorophenyl)-5-(4-fluorophenyl)-4-phenyl-4,5-dihydro-1,2,4-oxadiazole (A) and 3,5-bis-(4-chlorophenyl)-4-phenyl-4,5-dihydro-1,2,4-oxadiazole (B) have been previously demonstrated to possess remarkable anti-breast cancer activity, their cardiotoxicity remains a major concern due to their mechanism of action. To address this concern, we assessed the ability of these compounds to cause toxicity towards H9c2 cardiomyocytes as an in vitro model of cardiotoxicity.

METHODS

Cytotoxic activity of both compounds was explored in vitro on H9c2 cells using MTT assay. Annexin V/PI method, intracellular ROS determination and mitochondrial membrane potential assay were applied to elucidate the mechanism of action of the cell death.

RESULTS

MTT assay revealed a concentration- and time-dependent cardiotoxicity. Findings of apoptosis by double staining with annexin V and propidium iodide divulged no cell death including apoptosis and necrosis at the concentration that were effective to inhibit cancer cells proliferation (10 μM) at 24 and 48 h. Furthermore, flow cytometric measurement of membrane potential and ROS determination using DCFH-DA verified the safe concentration of the compounds against H9c2 cells with no cardiotoxic effect. However, the higher concentration of the compounds could induce cell death through ROS-mediated mitochondrial dysfunction.

CONCLUSIONS

Altogether, the results represented two novel chemical molecules possessing anti-breast cancer activity with minimum cardiac side effect.

Design, synthesis and anticancer activity of naphthoquinone derivatives

Basis on molecular docking and pharmacophore analysis of naphthoquinone moiety, a total of 23 compounds were designed and synthesised. With the help of reverse targets searching, anti-cancer activity was preliminarily evaluated, most of them are effective against some tumour cells, especially compound 12: 1-(5,8-dihydroxy-1,4-dioxo-1,4-dihydronaphthalen-2-yl)-4-methylpent-3-en-1-yl-4-oxo-4-((4-phenoxyphenyl)amino) butanoate whose IC₅₀ against SGC-7901 was 4.1 ± 2.6 μM. Meanwhile the anticancer mechanism of compound 12 had been investigated by AnnexinV/PI staining, immunofluorescence, Western blot assay and molecular docking. The results indicated that this compound might induce cell apoptosis and cell autophagy through regulating the PI3K signal pathway.

Design, synthesis and biological evaluation of a novel tubulin inhibitor SKLB0565 targeting the colchicine binding site

A series of 3-(((9H-purin-6-yl) amino) methyl) pyridin-2(1H)-one derivatives were designed, synthesized and confirmed as tubulin polymerization inhibitors. All compounds were evaluated for their anti-proliferative activities on three colorectal carcinoma (CRC) cell lines. Among these compounds, SKLB0565 displayed noteworthy potency against eight CRC cell lines with IC₅₀ values ranging from 0.012 μM and 0.081 μM. Besides, SKLB0565 inhibited tubulin polymerization, caused G2/M phase cell cycle arrest, depolarized mitochondria and induced cell apoptosis in CRC cells. Furthermore, SKLB0565 suppressed cell migration and disrupted the capillary tube formation of human umbilical vein endothelial cells (HUVECs). Our data clarified that SKLB0565 is a promising anti-tubulin agent for CRC therapy which is worthy of further evaluation.

The Azoles in Pharmacochemistry: Perspectives on the Synthesis of New Compounds and Chemoinformatic Contributions

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Due to their versatile biological activity, Azoles are widely studied in pharmacochemistry. It is possible to use them in many applications and in studies aimed at discovering antiparasitic, antineoplastic, antiviral, antimicrobial compounds; and in the production of materials for treatment of varied pathologies. Based on their biological activity, our review presents several studies that involve this class of organic compounds. A bibliographic survey of this type can effectively contribute to pharmaceutical sciences, stimulating the discovery of new compounds, and structural improvements to biological profiles of interest. In this review, articles are discussed involving the synthesis of new compounds and chemoinformatic contributions. Current applications of azoles in both the pharmaceutical and agri-business sectors are well known, yet as this research highlights, azole compounds can also bring important contributions to the fight against many diseases. Among the heterocyclics, azoles are increasingly studied by research groups around the world for application against tuberculosis, HIV, fungal and bacterial infections; and against parasites such as leishmaniasis and trypanosomiasis. Our hope is that this work will help arouse the interest of research groups planning to develop new bioactives to fight against these and other diseases.

Two Novel Tri-Aryl Derivatives Attenuate the Invasion-Promoting Effects of Stromal Mesenchymal Stem Cells on Breast Cancer

Background:

The concept of Epithelial-Mesenchymal Transition (EMT) to promote carcinoma progression has been recognized as a venue for research on novel anticancer drugs. Triaryl template-based structures are one of the pivotal structural features found in a number of compounds with a wide variety of biological properties including anti-breast cancer. Among the various factors triggering EMT program, cyclooxygenase-2 (COX-2), NF-κB as well as the transforming growth factor-beta (TGF-β) have been widely investigated.

Objective:

Here, we aim to investigate the effect of two novel compounds A and B possessing triaryl structures, which interact with both COX-2 and TGF-β active sites and suppress NF-κB activation, on EMT in a co-culture system with breast cancer and stromal cells.

Methods:

MDA-MB-231 and bone-marrow mesenchymal stem (BM-MS) cells were co-cultured in a trans-well plate. Migration, matrigel-based invasion and colony formation in soft agar assays along with Real- time PCR and Western blot analysis were performed to examine the effect of compounds A and B on the invasive properties of MDA-MB-231 cells after 72 hours of co-culturing with BM-MSCs. In addition, TGF-beta interaction was investigated by Localized Surface Plasmon Resonance (LSPR).

Results:

BM-MSCs enhanced migration, invasion and anchorage-independent growth of the co-cultured MDAMB- 231 cells. A reduction in E-cadherin level concomitant with an increase in vimentin and N-cadherin levels following the co-culture implied EMT as the underlying process. Compounds A and B inhibited invasion and anchorage-independent growth of breast cancer cells co-cultured with BM-MSCs at 10µM. The observed inhibitory effects along with an increase in E-cadherin and a reduction in vimentin and ZEB2 levels suggest that the anti-invasive properties of compounds A and B might proceed through the blockade of stromal cell-induced EMT, mediated by their interaction with TGF-beta.

Conclusion:

These findings introduce compounds A and B as novel promising agents, which prevent EMT in invasive breast cancer cells.

Synthesis and biological evaluation of 1-benzyl-N-(2-(phenylamino)pyridin-3-yl)-1H-1,2,3-triazole-4-carboxamides as antimitotic agents

A library of 1-benzyl-N-(2-(phenylamino)pyridin-3-yl)-1H-1,2,3-triazole-4-carboxamides (7a-al) have been designed, synthesized and screened for their anti-proliferative activity against some selected human cancer cell lines namely DU-145, A-549, MCF-7 and HeLa. Most of them have shown promising cytotoxicity against lung cancer cell line (A549), amongst them 7f was found to be the most potent anti-proliferative congener. Furthermore, 7f exhibited comparable tubulin polymerization inhibition (IC₅₀ value 2.04 µM) to the standard E7010 (IC₅₀ value 2.15 µM). Moreover, flow cytometric analysis revealed that this compound induced apoptosis via cell cycle arrest at G₂/M phase in A549 cells. Induction of apoptosis was further observed by examining the mitochondrial membrane potential and was also confirmed by Hoechst staining as well as Annexin V-FITC assays. Furthermore, molecular docking studies indicated that compound 7f binds to the colchicine binding site of the β-tubulin. Thus, 7f exhibits anti-proliferative properties by inhibiting the tubulin polymerization through the binding at the colchicine active site and by induction of apoptosis.

Imidazopyridine linked triazoles as tubulin inhibitors, effectively triggering apoptosis in lung cancer cell line

A library of new imidazopyridine linked triazole hybrid conjugates (8a-r) were designed, synthesized and evaluated for their cytotoxicity against four cancer cell lines namely, human lung (A549), human prostate (DU-145), human colon (HCT-116) and breast (MDA-MB 231) cancer. These conjugates exhibited good to moderate activity against the tested human cancer cell lines. Two of the conjugates (8g and 8j) showed significant antitumor activity against human lung cancer cell line (A549) with IC₅₀ values of 0.51 µM and 0.63 µM respectively. Flow cytometry analysis revealed that these conjugates arrested the cell cycle at G₂/M phase in human lung cancer cell line (A549). Immune-histochemistry and tubulin polymerization assay suggest inhibition of tubulin. Hoechst staining, annexin V and DNA fragmentation by tunnel assay suggested that these compounds induce cell death by apoptosis. Overall, the current study demonstrates that the synthesis of imidazopyridine linked triazole conjugates as promising anticancer agents causing G₂/M arrest and apoptotic-inducing ability.

Synthesis and biological evaluation of Schizandrin derivatives as potential anti-cancer agents

A new series of Schizandrin (1) derivatives were synthesized utilizing the C-9 position of the Schizandrin core and evaluated for their cytotoxic activities against HeLa (cervical cancer), A549 (lung cancer), MCF-7 (breast cancer) and DU-145 (prostate cancer) cell lines. Among the synthesized series, 4e, 4f, 4g and 5 showed potent activities against tested cell lines. More significantly, compound 5 exhibited most potent cytotoxic activity against DU-145 with an IC₅₀ value of 1.38 μM which is comparable to the standard agent, doxorubicin. Further, flow cytometry analysis indicated that 5 arrested cells in G2/M phase and consequently leading to apoptosis. Molecular docking analysis showed that 5 occupied the colchicine binding pocket of tubulin. Overall, the present study demonstrates that 5, as a mitotic-agent.

Synthesis and biological evaluation of imidazo[2,1-b]thiazole-benzimidazole conjugates as microtubule-targeting agents

A series of imidazo[2,1-b]thiazole-benzimidazole conjugates were synthesized and evaluated for their antiproliferative activity against four human cancer cell lines i.e.; HeLa (cervical), A549 (lung), MCF-7 (breast) and DU-145 (prostate) along with normal HEK-293 cell line. Amongst them, conjugate 6d displayed significant cytotoxicity against human lung cancer cell line, A549 with IC₅₀ value 1.08 µM. Further, cell cycle analysis revealed that this compound arrested the cell cycle at G2/M phase in A549 cells. Furthermore, the tubulin polymerization assay results suggest that this conjugate (6d) exhibits significant inhibitory effect on the tubulin assembly with an IC50 value of 1.68 µM. Moreover, the apoptotic inducing properties of compound 6d was confirmed by Hoechst staining, measurement of mitochondrial membrane potential (ΔΨm) and annexin V-FITC assay. Further, molecular docking studies revealed that compound 6d occupied the colchicine binding site.

2-aryl benzimidazole conjugate induced apoptosis in human breast cancer MCF-7 cells through caspase independent pathway

Apoptosis is a representative form of programmed cell death, which has been assumed to be critical for cancer prevention. Thus, any agent that can induce apoptosis may be useful for cancer treatment and apoptosis induction is arguably the most potent defense against cancer promotion. In our previous studies, 2-aryl benzimidazole conjugates were synthesized and evaluated for their antiproliferative activity and one of the new molecule (2f) was considered as a potential lead. This lead molecule showed significant antiproliferative activity against human breast cancer cell line, MCF-7. The results of the present study revealed that this compound arrested the cell cycle at G2/M phase. Topoisomerase II inhibition assay and Western blot analysis suggested that this compound effectively inhibits topoisomerase II activity which leads to apoptotic cell death. Apoptosis induction in MCF-7 cells was further confirmed by loss of mitochondrial membrane potential (∆Ψm), release of cytochrome c from mitochondria, an increase in the level of apoptosis inducing factor (AIF), generation of reactive oxygen species (ROS), up regulation of proapoptotic protein Bax and down regulation of anti apoptotic protein Bcl-2. Apoptosis assay using Annexin V-FITC assay also suggested that this compound induced cell death by apoptosis. However, compound 2f induced apoptosis could not be reversed by Z-VAD-FMK (a pan-caspase inhibitor) demonstrated that the 2f induced apoptosis was caspase independent. Further, 2f treatment did not activate caspase-7 and caspase-9 activity, suggesting that this compound induced apoptosis in breast cancer cells via a caspase independent pathway. Most importantly, this compound was less toxic towards non-tumorigenic breast epithelial cells, MCF-10A. Furthermore, docking studies also support the potentiality of this molecule to bind to the DNA topoisomerase II.

Synthesis of imidazo-thiadiazole linked indolinone conjugates and evaluated their microtubule network disrupting and apoptosis inducing ability

A series of imidazo[2,1-b][1,3,4]thiadiazole linked indolinone conjugates were synthesized and investigated for antiproliferative activity in different human cancer cell lines by changing various substitutions at indolinone and phenyl ring systems. Among them conjugates 7, 14 and 15 were exhibited potent antiproliferative activity with GI₅₀ values from 0.13 to 3.8 μΜ and evaluated for cell cycle analysis, tubulin polymerization assay and apoptosis. Treatment with 7, 14 and 15 were resulted in accumulation of cells in G2/M phase, inhibition of tubulin assembly, disruption of microtubule network. Inhibition of tubulin polymerization was further supported by Western blot analysis. In addition, the conjugates (7, 14 and 15) also showed apoptosis in HeLa cell line, detailed biological studies such as Hoechst 33,258 staining, DNA fragmentation and caspase-3 assays suggested that these compounds induce cell death by apoptosis. Docking studies revealed that these compounds (7, 14 and 15) bind with αAsn101, αThr179, αSer178, βCys241, βLys254 and βLys352 in the colchicine-binding site of the tubulin.

Click chemistry-assisted synthesis of triazolo linked podophyllotoxin conjugates as tubulin polymerization inhibitors

A series of new triazolo linked 4β-amidopodophyllotoxin conjugates (9a-l) were synthesized using click chemistry and evaluated for their antitumor activity against four human cancer cell lines. Among them, two compounds (9c and 9j) showed significant anticancer activity with IC50 values of 0.9 and 0.07 μM, respectively. Biological studies are conducted into the cell-cycle distribution of these conjugates inducing G2/M-phase arrest, apart from an increase in the levels of caspase-3 proteins, followed by apoptotic cell death. A tubulin polymerization assay analysis showed that these compounds effectively inhibit microtubule assembly in HeLa cells and, moreover, Hoechst 33258 and Immunohistochemistry staining suggest that these compounds induce cell death by apoptosis. The docking studies showed that compounds 9c and 9j interact and bind efficiently with the tubulin protein at the colchicine site.

The first total synthesis of anemarchalconyn and anemarcoumarin A

Anemarchalconyn (1) and anemarcoumarin A (2), the natural bioactive compounds isolated from the rhizomes of Anemarrhena asphodeloides Bunge (Liliaceae), were first totally synthesized using easily available materials in short, convenient routes with overall yields of 32 and 48%.

Novel menadione hybrids: Synthesis, anticancer activity, and cell-based studies

A series of novel menadione-based triazole hybrids were designed and synthesized by employing copper-catalyzed azide-alkyne cycloaddition (CuAAC). All the synthesized hybrids were characterized by their spectral data (¹ H NMR, ¹³ C NMR, IR, and HRMS). The synthesized compounds were evaluated for their anticancer activity against five selected cancer cell lines including lung (A549), prostate (DU-145), cervical (Hela), breast (MCF-7), and mouse melanoma (B-16) using MTT assay. The screening results showed that majority of the synthesized compounds displayed significant anticancer activity. Among the tested compounds, the triazoles 5 and 6 exhibited potent activity against all cell lines. In particular, compound 6 showed higher potency than the standard tamoxifen and parent menadione against MCF-7 cell line. Flow cytometric analysis revealed that compound 6 arrested cell cycle at G0/G1 phase and induced apoptotic cell death which was further confirmed by Hoechst staining, measurement of mitochondrial membrane potential (ΔΨm) and Annexin-V-FITC assay. Thus, compound 6 can be considered as lead molecule for further development as potent anticancer therapeutic agent.

Design, Synthesis, and in vitro and in vivo Evaluations of (Z)-3,4,5-Trimethoxystyrylbenzenesulfonamides/sulfonates as Highly Potent Tubulin Polymerization Inhibitors

Newer therapeutics can be developed in drug discovery by adopting the strategy of scaffold hopping of the privileged scaffolds from known bioactive compounds. This strategy has been widely employed in drug-discovery processes. Structure-based docking studies illustrate the basic underlying concepts and reveal that interactions of the sulfonamide group and hydrophobic interactions are crucial. On the basis of this strategy, over 60 synthetic analogues were synthesized and evaluated for their cytotoxicity against the NCI panel of 60 human cancer cell lines; the majority of these compounds exhibited promising cytotoxicity with GI₅₀ values ranging between 18 and 50 nm. Among these compounds, (Z)-N-[2,3-dimethoxy-5-(3,4,5-trimethoxystyryl)phenyl]-4-methoxybenzenesulfonamide (7 a) and (Z)-N-[2-hydroxy-3-methoxy-6-(3,4,5-trimethoxystyryl)phenyl]-4-methoxybenzenesulfonamide (9 a) were found to be potent. Similar results were obtained against three human cancer cell lines with IC₅₀ values ranging between 0.04 and 3.0 μm. Studies aimed at elucidating the mechanism of action of these new analogues revealed that they inhibited the in vitro polymerization of tubulin and disorganized the assembly of microtubules in HeLa and MCF-7cancer cells. Lead compounds 7 a and 9 a displayed notable in vivo antitumor activity in a HeLa tumor xenograft model. Our studies have resulted in the identification of a scaffold that can target tubulin polymerization, which should have significant potential toward the development of new antitumor drugs.

Medicinal attributes of 1,2,3-triazoles: Current developments

1,2,3-Triazoles are important five-membered heterocyclic scaffold due to their extensive biological activities. This framework can be readily obtained in good to excellent yields on the multigram scale through click chemistry via reaction of aryl/alkyl halides, alkynes and NaN₃ under ambient conditions. It has been an emerging area of interest for many researchers throughout the globe owing to its immense pharmacological scope. The present work aims to summarize the current approaches adopted for the synthesis of the 1,2,3-triazole and medicinal significance of these architectures as a lead structure for the discovery of drug molecules such as COX-1/COX-2 inhibitors (celecoxib, pyrazofurin), HIV protease inhibitors, CB1 cannabinoid receptor antagonist and much more which are in the pipeline of clinical trials. The emphasis has been given on the major advancements in the medicinal prospectus of this pharmacophore for the period during 2008-2016.

A one-pot, metal-free approach to bicyclic 2-pyridones

A practical one-pot process based on two-fold intramolecular cyclizations provides a more expedient entry into a variety of bicyclic 2-pyridones.

In silico studies on potential MCF-7 inhibitors: a combination of pharmacophore and 3D-QSAR modeling, virtual screening, molecular docking, and pharmacokinetic analysis

Gallic acid and its derivatives exhibit a diverse range of biological applications, including anti-cancer activity. In this work, a data-set of forty-six molecules containing the galloyl moiety, and known to show anticarcinogenic activity against the MCF-7 human cancer cell line, have been chosen for pharmacophore modeling and 3D-Quantitative Structure Activity Relationship (3D-QSAR) studies. A tree-based partitioning algorithm has been used to find common pharmacophore hypotheses. The QSAR model was generated for three, four, and five featured hypotheses with increasing PLS factors and analyzed. Results for five featured hypotheses with three acceptors and two aromatic rings were the best out of all the possible combinations. On analyzing the results, the most robust (R²= .8990) hypothesis with a good predictive power (Q²= .7049) was found to be AAARR.35. A good external validation (R² = .6109) was also obtained. In order to design new MCF-7 inhibitors, the QSAR model was further utilized in pharmacophore-based virtual screening of a large database. The predicted IC₅₀ values of the identified potential MCF-7 inhibitors were found to lie in the micromolar range. Molecular docking into the colchicine domain of tubulin was performed in order to examine one of the probable mechanisms. This revealed various interactions between the ligand and the active site protein residues. The present study is expected to provide an effective guide for methodical development of potent MCF-7 inhibitors.

Synthesis and biological evaluation of imidazo[1,5-a]pyridine-benzimidazole hybrids as inhibitors of both tubulin polymerization and PI3K/Akt pathway

A series of imidazo[1,5-a]pyridine-benzimidazole hybrids (5a–aa) were prepared and evaluated for their cytotoxic activity against a panel of sixty human tumor cell lines. Among them compounds 5d and 5l showed significant cytotoxic activity with GI50 values ranging from 1.06 to 14.9 μM and 0.43 to 7.73 μM, respectively. Flow cytometric analysis revealed that these compounds arrest the cell cycle at G2/M phase and induced cell death by apoptosis. The tubulin polymerization assay (IC50 of 5d is 3.25 μM and 5l is 1.71 μM) and immunofluorescence analysis showed that these compounds effectively inhibited the microtubule assembly in human breast cancer cells (MCF-7). Further, the apoptotic effects of compounds were confirmed by Hoechst staining, mitochondrial membrane potential, cytochrome c release, ROS generation, caspase 9 activation and DNA fragmentation analysis. After treatment with these compounds for 48 h, p-PTEN and p-AKT levels were markedly decreased. Moreover, these compounds did not significantly inhibit the normal human embryonic kidney cells, HEK-293. The molecular docking simulations predicted the binding interactions of 5d and 5l with colchicine binding site of the tubulin, which is in compliance with the antiproliferative activity data.

Design and synthesis of imidazo[2,1-b]thiazole-chalcone conjugates: microtubule-destabilizing agents

A series of chalcone conjugates featuring the imidazo[2,1-b]thiazole scaffold was designed, synthesized, and evaluated for their cytotoxic activity against five human cancer cell lines (MCF-7, A549, HeLa, DU-145 and HT-29). These new hybrid molecules have shown promising cytotoxic activity with IC50 values ranging from 0.64 to 30.9 μM. Among them, (E)-3-(6-(4-fluorophenyl)-2,3-bis(4-methoxyphenyl)imidazo[2,1-b]thiazol-5-yl)-1-(pyridin-2-yl)prop-2-en-1-one (11 x) showed potent antiproliferative activity with IC50 values ranging from 0.64 to 1.44 μM in all tested cell lines. To investigate the mechanism of action, the detailed biological aspects of this promising conjugate (11 x) were carried out on the A549 lung cancer cell line. The tubulin polymerization assay and immunofluoresence analysis results suggest that this conjugate effectively inhibits microtubule assembly in A549 cells. Flow cytometric analysis revealed that this conjugate induces cell-cycle arrest in the G2/M phase and leads to apoptotic cell death. This was further confirmed by Hoechst staining, activation of caspase-3, DNA fragmentation analysis, and Annexin V-FITC assay. Moreover, molecular docking studies indicated that this conjugate (11 x) interacts and binds efficiently with the tubulin protein.

Synthesis and biological evaluation of 1,2,3-triazole linked aminocombretastatin conjugates as mitochondrial mediated apoptosis inducers

A series of 1,2,3-triazole linked aminocombretastatin conjugates were synthesized and evaluated for cytotoxicity, inhibition of tubulin polymerization and apoptosis inducing ability. Most of the conjugates exhibited significant anticancer activity against some representative human cancer cell lines and two of the conjugates 6d and 7c displayed potent cytotoxicity with IC50 values of 53 nM and 44 nM against A549 human lung cancer respectively, and were comparable to combretastatin A-4 (CA-4). SAR studies revealed that 1-benzyl substituted triazole moiety with an amide linkage at 3-position of B-ring of the combretastatin subunit are more active compared to 2-position. G2/M cell cycle arrest was induced by these conjugates 6d and 7c and the tubulin polymerization assay (IC50 of 1.16 μM and 0.95 μM for 6d and 7c, respectively) as well as immunofluorescence analysis showed that these conjugates effectively inhibit microtubule assembly at both molecular and cellular levels in A549 cells. Colchicine competitive binding assay suggested that these conjugates bind at the colchicine binding site of tubulin as also observed from the docking studies. Further, mitochondrial membrane potential, ROS generation, caspase-3 activation assay, Hoechst staining and DNA fragmentation analysis revealed that these conjugates induce cell death by apoptosis.

DABCO catalyzed cross-Rauhut-Currier/transesterification reactions of activated alkenes with phenyl acrylates: scope and mechanistic insight

DABCO catalyzed the cross-Rauhut-Currier/transesterification reaction of α-cyano-α,β-unsaturated ketones and aryl acrylates was discovered. The reaction rate law was determined by an integral method under pseudo-first-order reaction conditions, which assisted in proposing the mechanism of cross-Rauhut-Currier reaction promoted by Brønsted acid and establishing the rate-determining step.

Synthesis and anticancer activity of heteroaromatic linked 4β-amido podophyllotoxins as apoptotic inducing agents

A series of different heteroaromatic linked 4β-amidopodophyllotoxin conjugates (16a-i, 17a-i and 18a-d) were synthesized and evaluated for anticancer activity against five human cancer cell lines. Among the series, one of the compound 17g showed significant antiproliferative activity in A549 (lung cancer) cell line. Flow cytometric analysis showed that 17g arrested the cell cycle in the G2/M phase leading to caspase-3 dependent apoptotic cell death. Further, Hoechst 33258 staining and DNA fragmentation assay also suggests that 17g induces cell death by apoptosis.

In vitro anti-breast cancer activity of ethanolic extract of Wrightia tomentosa: role of pro-apoptotic effects of oleanolic acid and urosolic acid

ETHNOPHARMACOLOGICAL RELEVANCE

Wrightia tomentosa Roem. & Schult. (Apocynaceae) is known in the traditional medicine for anti-cancer activity along with other broad indications like snake and scorpion bites, renal complications, menstrual disorders etc. However, the anti-cancer activity of this plant or its constituents has never been studied systematically in any cancer types so far.

AIM OF THE STUDY

To evaluate the anti-cancer activities of the ethanolic extract of W. tomentosa and identified constituent active molecule(s) against breast cancer.

MATERIAL AND METHODS

Powdered leaves of W. tomentosa were extracted with ethanol. The ethanolic extract, subsequent hexane fractions and fraction F-4 of W. tomentosa were tested for its anti-proliferative and pro-apoptotic effects in breast cancer cells MCF-7 and MDA-MB-231.

RESULTS

The ethanolic extract, subsequent hexane fractions and fraction F-4 of W. tomentosa inhibited the proliferation of human breast cancer cell lines, MCF-7 and MDA-MB-231. The fraction F-4 obtained from hexane fraction inhibited proliferation of MCF-7 and MDA-MB-231 cells in concentration and time dependent manner with IC₅₀ of 50 μg/ml and 30 μg/ml for 24 h, 28 μg/ml and 22 μg/ml for 48 h and 25 μg/ml and 20 μg/ml for 72 h respectively. The fraction F-4 induced G1 cell cycle arrest, reactive oxygen species (ROS) generation, loss of mitochondrial membrane potential and subsequent apoptosis. Apoptosis is indicated in terms of increased Bax/Bcl-2 ratio, enhanced Annexin-V positivity, caspase 8 activation and DNA fragmentation. The active molecule isolated from fraction F-4, oleanolic acid and urosolic acid inhibited cell proliferation of MCF-7 and MDA-MB-231 cells at IC₅₀ value of 7.5 μM and 7.0 μM respectively, whereas there is devoid of significant cell inhibiting activity in non-cancer originated cells, HEK-293. In both MCF-7 and MDA-MB-231, oleanolic acid and urosolic acid induced cell cycle arrest and apoptosis as indicated by significant increase in Annexin-V positive apoptotic cell counts.

CONCLUSION

Our results suggest that W. tomentosa extracts has significant anti-cancer activity against breast cancer cells due to induction of apoptosis pathway. Olenolic and urosolic acid are important constituent molecules in the extract responsible for anti-cancer activity of W. tomentosa.

Specific targeting of insulin-like growth factor 1 receptor signaling in human estrogen dependent breast cancer cell by a novel tyrosine-based benzoxazepine derivative

The present study sought to investigate the in vitro and in vivo effects of a tyrosine-based benzoxazepine, 4-[4-(toluene-4-sulfonyl)-2,3,4,5-tetrahydro-benzo[f][1,4]oxazepin-3-ylmethyl]-phenol) [THBP] in human breast cancer cells, with a focus on determining its molecular target. THBP had growth inhibitory effect on MCF-7 and MDA-MD-231 cells. At IC(50) value (∼20 μM), THBP resulted in G1 arrest, decrease in cyclin D1 levels and induction of apoptosis of MCF-7 cells. Mechanistically, activation of caspase 8 contributes critically to the induction of apoptotic cell death as copresence of selective inhibition of caspase 8 effectively abrogates the cytotoxic effect of THBP in MCF-7 cells. Further, THBP increased pro-apoptotic protein, Bax; decreased anti-apoptotic protein, Bcl-2; and decreased mitochondrial membrane potential in MCF-7 cells, indicating involvement of an intrinsic pathway of apoptosis following caspase 8 activation. Out of the various growth factors/hormones, THBP selectively abrogated increased viability of MCF-7 cells by insulin-like growth factor 1 (IGF-1). Molecular docking studies revealed that THBP occupied the ATP binding pocket of IGF-1 receptor (IGF-1R). Accordingly THBP was found to inhibit IGF-1-induced phosphorylation of IGF-1R and insulin receptor substrate-1 (IRS-1) without inhibiting insulin signaling in MCF-7 cells. In athymic nude mice, compared with vehicle, THBP treatment significantly reduced the growth of MCF-7 xenograft tumors through inhibition of cancer cell proliferation as well as promotion of cell death that correlated with reduced phospho-IGF-1R levels. We suggest that interfering with the IGF-1R signaling by the benzoxazepine THBP offers a novel and selective therapeutic strategy for estrogen receptor-positive, postmenopausal breast cancer patients.

Synthesis and anticancer activity of oxindole derived imidazo[1,5-a]pyrazines

A series of oxindole derivatives of imidazo[1,5-a]pyrazines were prepared and confirmed by 1H NMR, mass and HRMS data. These compounds were evaluated for their anticancer activity against a panel of 52 human tumor cell lines derived from nine different cancer types: leukemia, lung, colon, CNS, melanoma, ovarian, renal, prostate and breast. Among them compound 7l showed significant anticancer activity with GI50 values ranging from 1.54 to 13.0 μM. Cell cycle arrest was observed in G0/G1 phase upon treatment of A549 cells with 6.5 μM (IC50) concentration of compound 7l and induced apoptosis. This was confirmed by Annexin V-FITC as well as DNA fragmentation analysis and interestingly this compound (7l) did not affect the normal cells.

Blueberry anthocyanins and pyruvic acid adducts: anticancer properties in breast cancer cell lines

The purpose of this study was to investigate the anticancer properties of an anthocyanin-pyruvic acid adduct extract, which is being developed aiming to be further applied in the food industry. An anthocyanin extract from blueberry (extract I) and an anthocyanin-pyruvic acid adduct extract (extract II) were tested on two breast cancer cell lines (MDA-MB-231 and MCF7). Proliferation was assessed by SRB assay and ³H-thymidine incorporation. Caspase-3 activity was determined in the presence of both extracts. Their capacity as chemoattractants and their invasive potential were also assayed. In both cell lines, extracts I and II significantly reduced cell proliferation at 250 μg/mL, after 24 h of cell incubation. Caspase-3 activity was not altered by the extracts (250 μg/mL) in either cell line, with the exception of extract II in MCF-7, which increased its activity, probably explaining its effects on cell proliferation. Both extracts (250 μg/mL) demonstrated significant antiinvasive potential in both cell lines. Furthermore, they did not demonstrate any capacity for chemotaxis. In conclusion, blueberry anthocyanins and the respective anthocyanin-pyruvic acid adducts demonstrated anticancer properties by inhibiting cancer cell proliferation and by acting as cell antiinvasive factors and chemoinhibitors. The anthocyanin-pyruvic acid adduct extract showed a more pronounced effect in MDA-MB-231, suggesting an effect independent of estrogen receptors.

In-vitro antiproliferative activity of benzopyranone derivatives in comparison with standard chemotherapeutic drugs

The cytotoxic activities of five new benzopyranone derivatives containing basic amino side chain are described. Their cytotoxicities against ER(+) MCF-7 and ER(-) MDA-MB-231 human breast cancer cell lines, and Ishikawa human endometrial cell line were determined after 72 h drug exposure employing CellTiter-Glo assay at concentrations ranging from 0.01-1.0 × 10(5) nM. The antiproliferative activities of these compounds were compared to tamoxifen (TAM), 4-hydroxytamoxifen (4-OHT, active metabolite of tamoxifen), and raloxifene (RAL). In-vitro results indicated that compounds 9, 10, 12, and 13 were more potent than TAM against the human breast cancer cell lines with IC(50)  < 20 µM. The in-silico structure-activity relationships of these compounds and their binding mode within the estrogen receptor (ER) binding site using AutoDock vina are discussed.