Base-mediated 1,3-dipolar cycloaddition of pyridinium bromides with bromoallyl sulfones: a facile access to indolizine scaffolds.

An expedient and transition-metal-free synthetic strategy has been developed for the construction of substituted indolizines from a unique combination of pyridinium salts and 2-bromoallyl sulfones. This approach does not compromise with the diverse substitutions on both the pyridinium salts and 2-bromoallyl sulfones. Wide substrate scope, operational simplicity, milder reaction conditions and good to moderate yields are the merits associated with the current approach. Moreover, this method provides two products which are amenable for the generation of a library of key indolizine building blocks.

Synthesis of Combretastatin-A4 Carboxamidest that Mimic Sulfonyl Piperazines by a Molecular Hybridization Approach: in†vitro Cytotoxicity Evaluation and Inhibition of Tubulin Polymerization.

Molecular hybridization approach is a promising structural modification tool to design new chemical entities (NCEs) by mimicking two different pharmacophoric units into one scaffold to enhance the biological properties. With this aim, combretastatin-A4 acids were integrated with sulfonyl piperazine scaffolds as a one molecular platform and evaluated for their in vitro antiproliferative activity against a panel of human cancer lines cell lines namely, lung (A549), mouse melanoma (B16F10), breast (MDA MB-231and MCF-7) and colon (HCT-15) by MTT assay. Amongst which the compound (E)-3-(4-Chlorophenyl)-1-(4-((4-chlorophenyl)sulfonyl)piperazin-1-yl)-2-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (5 ab) displayed significant IC50 values in the range of 0.36 to 7.08 µm against the selected cancer cell lines. Moreover, 5 ab was found to be the most potent member of this series with IC50 0.36±0.02 µm. Further investigations revealed that the compound 5 ab displayed significant inhibition of tubulin assembly with IC50 5.24±0.06 µm and molecular docking studies also disclosed the binding of 5 ab effectively in CA4 binding space at the colchicine binding site. The flow cytometric analysis demonstrated that the compound 5 ab caused cell cycle arrest at G2/M phase in A549 cells. Compound 5 ab induced apoptosis in A549 cells which was further evaluated by different staining assays such as DAPI and AO which undoubtedly speculated, the induction of apoptosis. To study the anti-migration with 5 ab, cell migration/scratch wound assay was performed and the extent of apoptosis was studied by Annexin-V, including mitochondrial potential by JC-1 staining.

Pyrazolo-benzothiazole hybrids: Synthesis, anticancer properties and evaluation of antiangiogenic activity using in vitro VEGFR-2 kinase and in vivo transgenic zebrafish model.

A series of new pyrazolo-benzothiazole hybrids (7-26) were synthesised and screened for their cytotoxic activity towards several cancer cell lines [colon (HT-29), prostate (PC-3), lung (A549), glioblastoma (U87MG)] and normal human embryonic kidney cell line (Hek-293T). Compounds 8, 9, 13, 14, 18, 19, 23, and 24 displayed significant activity, with compound 14 being particularly potent towards all the tested cancer cell lines with IC50 values in the range 3.17-6.77 µM, even better than reference drug axitinib (4.88-21.7 µM). Compound 14 also showed the strongest growth inhibition in 3D multicellular spheroids of PC-3 and U87MG cells. The mechanism of cellular toxicity in PC-3 cells was found to be cell cycle arrest and apoptosis induction through depolarisation of mitochondrial membrane potential, increased ROS production and subsequent DNA damage. Further, compound 14 displayed significant in vitro (VEGFR-2 inhibition) and in vivo [transgenic zebrafish Tg(flila:EGFP) model] antiangiogenic properties. Overall, these results provide strong evidence that compound 14 could be considered for a lead candidate in anticancer and antiangiogenic drug discovery.

Synthesis and in vitro cytotoxicity evaluation of ß-carboline-combretastatin carboxamides as apoptosis inducing agents: DNA intercalation and topoisomerase-II inhibition.

To explore a new set of cytotoxic agents, ß-carboline-combretastatin carboxamide conjugates were designed, synthesized and evaluated for their in vitro cytotoxicity potential, DNA binding affinity and Topoisomerase-II (topo-II) inhibition activity. Among the designed hybrids, 10v and 10af have shown significant cytotoxic effect against A549 (lung cancer) cell line having IC50 value 1.01 µM and 1.17 µM respectively. Further, it was speculated that treatment with compound 10v may induce apoptosis among A549 cells, which was supported by Hoechst staining, DCFDA, Annexin V-FITC and morphological assays. Flow cytometric analysis revealed that the hybrid 10v arrests A549 cells in G2/M phase of cell cycle in a dose dependent manner. Amongst the active hybrids, most potent hybrid 10v was tested for DNA topo-II inhibition activity. Moreover, to further support the biological activity and to infer the mode of interaction between ligands and DNA, spectroscopy and molecular docking studies were carried out. The docking and spectroscopy results showed that the ligands exhibited an intercalative mode of binding with DNA and could efficiently bind to DNA and form topo-II ternary complex. Based on these experiments, the hybrids 10v and 10af were identified as proficient new scaffolds which need to be developed as hit molecules for therapeutic interest.

Transition metal-free one-pot synthesis of substituted pyrroles by employing aza-Wittig reaction.

A mild and metal-free one-pot synthetic strategy has been developed for the construction of substituted pyrroles by employing aza-Wittig reaction from a unique and unexplored combination of chromones and phenacyl azides. This method does not compromise the diverse substitutions on both the phenacyl azides and chromones. The merits of this method are wide substrate scope, easy functionalization, short reaction time, operationally simple, and higher yields. Moreover, this method is amenable for the generation of a library of key pyrrole building blocks.

Design and synthesis of C3-tethered 1,2,3-triazolo-ß-carboline derivatives: Anticancer activity, DNA-binding ability, viscosity and molecular modeling studies.

A series of new DNA-interactive C3-tethered 1,2,3-triazolo-ß-carboline derivatives have been synthesized via 'click' reaction and evaluated for their in vitro cytotoxicity as well as DNA binding affinity. Interestingly, these hybrids have displayed potent in vitro cytotoxicity in comparison to Harmine against the HT-29 (colon cancer) and HGC-27 (gastric cancer) cell lines. The compounds 7f, 7k, 7n and 7s appear to be more effective against the HGC-27 cell line, among which compound 7f showed the highest cytotoxicity (5.44 ± 0.58, IC50 µM). The compounds 7e and 7f appear to be more active against the HT-29 cell line, among which compound 7f exhibited the highest cytotoxicity (3.67 ± 0.62, IC50 µM). To gain more insight into the DNA-binding ability, spectroscopic techniques such as UV-Visible, fluorescence and circular dichroism studies were performed. Viscosity measurements and molecular docking studies substantiate that these compounds indeed bind to DNA via the minor groove.

DNA-binding affinity and anticancer activity of ß-carboline-chalcone conjugates as potential DNA intercalators: Molecular modelling and synthesis.

A new series of DNA-interactive ß-carboline-chalcone conjugates have been synthesized and evaluated for their in vitro cytotoxicity and DNA-binding affinity. It has been observed that most of these new hybrids have shown potent cytotoxic activities on A-549 (lung adenocarcinoma) cell lines with IC50 values lower than 10 µM. The hybrid 7b is more effective against some of the selected cancer cell lines with IC50 values less than 50 µM. In addition, compounds 7e, 7k, 7p-u has displayed significant elevation in ΔTm of DNA in comparison to Adriamycin, suggesting significant interaction and remarkable DNA stabilization. The DNA intercalation of these new hybrids has been investigated by fluorescence titration, DNA viscosity measurements, molecular docking as well as molecular dynamics and the results are in agreement with the thermal denaturation studies.