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Combretastatin A‐4 (CA4) is a potent anti‐mitotic and vascular disrupting agent. Organic chemists have been working to optimize the synthesis of CA4 for the past 3 decades, with methods requiring hazardous solvents and harsh reaction conditions. Here, we report the synthesis of CA4 and a variety of stilbenes in an aqueous Wittig system. Potassium carbonate or lithium hydroxide were used as base in this Wittig reaction to give excellent yields of mixtures of E‐ and Z‐stilbenes. The synthesis of CA4 was achieved using tetrahydropyran (THP) or silyl protected phenolic aldehydes. The THP groups were removed using dilute acid whilst the silyl groups fortuitously fell off during work up.

In this paper, novel synthetic methods, including microwave O-alkylation, were used to produce several chrysin derivatives. These compounds were purified, characterised and tested on different cell lines and bacterial strains. From this family, 7-(2,4-dinitrophenoxy)-5-hydroxy-3-phenyl-4H-chromen-4-one (C3) was shown to be extremely active on bacterial strains methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae as well as having anticancer activity on a range of cancer cell lines with IC50 values less than 30 µM. Chrysin has been known for their anticancer and antimicrobial properties, and this study not only corroborates this but also shows that it is possible to synthesise new improved derivatives with therapeutic possibilities.

It is a challenge to select the right target to treat conditions without affecting non-diseased cells. Cancer belongs to the top 10 causes of death in the world and it remains difficult to treat. Amongst cancer emerging targets, silent information regulator 1 (SIRT1) – a histone deacetylase – has shown many roles in cancer, ageing and metabolism. Here we report novel SIRT1 ligands that bind and modulate the activity of SIRT1 within cells and enhance its enzymatic activity. We developed a modified aptamer capable of binding to and forming a complex with SIRT1. Our ligands are aptamers, they can be made of DNA or RNA oligonucleotides, their binding domain can recognise a target with very high affinity and specificity. We used the systematic evolution of ligands by exponential enrichment (SELEX) technique to develop circular and linear aptamers selectively binding to SIRT1. Cellular consequences of the interaction were monitored by fluorescence microscopy, cell viability assay, stability and enzymatic assays. Our results indicate that from our pool of aptamers, circular AC3 penetrates cancerous cells and is recruited to modulate the SIRT1 activity. This modulation of SIRT1 resulted in anticancer activity on different cancer cell lines. Furthermore, this modified aptamer showed no toxicity on one non-cancerous cell line and was stable in human plasma. We have demonstrated that aptamers are efficient tools for localisation of internal cell targets, and in this particular case, anticancer activity through modulation of SIRT1.

© 2016, Science Reviews 2000 Ltd. All rights reserved.There are over 2.6 million users of e-cigarettes in the United Kingdom alone as they have been promoted as a safer alternative to traditional cigarettes. The addition of flavours and aromas has also proven to be popular with younger generations. In this review, we survey the range of studies in the short timeframe since e-cigarettes reached the market to draw attention to the health associated risks and benefits of their introduction. We complement this review with a case study reporting on the composition of selected e-cigarette refills with particular emphasis on the toxicological activity of its components on lung cells.

Childhood bone cancer though rare, has very limited treatment choices, with poor survival rates and often involving amputation. We have developed a novel molecule, 2', 4'-dihydroxy-dithion-dibenzoyl-methane and tested it on hepatic, colon, lung and osteoblasts cancer cell lines. Thionylation of 2', 4'- dihydroxydibenzoylmethane led to selective targeting of bone cancer cells, stopping their growth and leading to their death without affecting non-cancerous cells within the bone marrow or other non-malignant cells.

A series of combretastatin derivatives were designed and synthesised by a two-step stereoselective synthesis by use of Wittig olefination followed by Suzuki cross-coupling. Interestingly, all new compounds (2a-2i) showed potent cell-based antiproliferative activities in nanomolar concentrations. Among the compounds, 2a, 2b and 2e were the most active across three cancer cell lines. In addition, these compounds inhibited the polymerisation of tubulin in vitro more efficiently than CA-4. They caused cell cycle arrest in G2/M phase further confirming their ability to inhibit tubulin polymerisation.

In this study, we describe a microwave-based click chemistry method used to prepare a family of novel bis-flavone dimers. The substituted 7-hydroxy and 4’-hydroxy flavonoids were linked through a triazole ring. The compounds were easily synthesized and purified in high yields. The bisflavonoids were tested on different cell lines including HCT116, HepG2, MCF7 and MOLT-4. Several analogues showed to have anticancer activity with IC50 values in the range of 20-60 μM. Flavonoids are known for their anticancer properties and this method provides the basis for new medicinal structures.

Virtual Screening is an increasingly attractive way to discover new small molecules with potential medicinal value. We introduce a novel strategy that integrates use of the molecular docking software Surflex with experimental validation by the method of competition dialysis. This integrated approach was used to identify ligands that selectively bind to the triplex DNA poly(dA)-[poly(dT)](2). A library containing approximately 2 million ligands was virtually screened to identify compounds with chemical and structural similarity to a known triplex intercalator, the napthylquinoline MHQ-12. Further molecular docking studies using compounds with high structural similarity resulted in two compounds that were then demonstrated by competition dialysis to have a superior affinity and selectivity for the triplex nucleic acid than MHQ-12. One of the compounds has a different chemical backbone than MHQ-12, which demonstrates the ability of this strategy to 'scaffold hop' and to identify small molecules with novel binding properties. Biophysical characterization of these compounds by circular dichroism and thermal denaturation studies confirmed their binding mode and selectivity. These studies provide a proof-of-principle for our integrated screening strategy, and suggest that this platform may be extended to discover new compounds that target therapeutically relevant nucleic acid morphologies.

The indenoisoquinolines represent a class of non-camptothecin topoisomerase I (Top1) inhibitors that exert cytotoxicity by trapping the covalent complex formed between DNA and Top1 during relaxation of DNA supercoils. As an ongoing evaluation of Top1 inhibition and anticancer activity, indenoisoquinolines were linked via their lactam side chains to provide polyamines end-capped with intercalating motifs. The resulting bisindenoisoquinolines were evaluated for cytotoxicity in the National Cancer Institute's human cancer cell screen and for Top1 inhibition. Preliminary findings suggested that the 2-3-2 and 3-3-3 linkers, referring to the number of carbons between nitrogen atoms, were optimal for both potent Top1 inhibition and cytotoxicity. Using optimized linkers, bisindenoisoquinolines were synthesized with nitro and methoxy substituents on the aromatic rings. The biological results for substituted compounds revealed a disagreement between the structure-activity relationships of monomeric indenoisoquinolines and bisindenoisoquinolines as Top1 inhibitors, but cytotoxicity was maintained for both series of compounds.

Flavonoids have been shown to have a wide variety of biological activities and proven to be good scaffolds for the design of DNA-binding agents as anticancer therapeutics.In structure-activity relationship studies, flavonoid derivatives were designed and synthesised through various organic synthesis protocols, resulting in novel or previously described molecules. These were studied by UV-Vis absorbance and fluorescence spectroscopy as well as competition dialysis for their binding to DNA isoforms. Their cytotoxic potential was assessed using MTS assays on MCF-7 breast cancer and CCRFCEM leukaemia cell lines.Introduction of moieties such as chloride, nitrogen, acetoxy and methoxy groups did not help to improve binding affinity, but introduction of tertiary amines improved the binding 1,000-fold due to an improved interaction of the compound with the nucleic acid; replacement of oxygen by sulphur increased the binding 7-fold, possibly because sulphur being less electronegative than oxygen would allow the electrons of the molecule to interact more strongly with the nucleic acid. Inhibition of growth by 50% (IG(50)) values were moderate in breast and leukaemia cancer cell lines possibly due to the flavonoids interacting with other cellular components besides the nucleic acids.

The effects of substitution of O6-methylguanine on the structure and stability of a human telomere quadruplex was studied by circular dichroism, thermal denaturation, analytical ultracentrifugation, and molecular dynamics simulations. The results show that, while quadruplex structures can form containing the modified base, they are much less stable than the normal unmodified structure. The extent of destabilization is critically dependent on the exact position of the modified base within the quadruplex structure.

Circular dichroism (CD) is a useful technique for an assessment of DNA-binding mode, being a more accessible, low-resolution complement to NMR and X-ray diffraction methods. Ligand-DNA interactions can be studied by virtue of the interpretation of induced ligand CD signals resulting from the coupling of electric transition moments of the ligand and DNA bases within the asymmetric DNA environment. This protocol outlines methods to determine the binding mode and affinity of ligand-DNA interactions and takes approximately 7.5 h.

G-quadrplex DNA can exist in a rich variety of structural forms, ranging from unimolecular folded structures containing diverse types of loops and strand oreintations, to bimolecular dimeric structures, and finally to tetramolecular parallel-stranded structures. These diverse structures present numerous potential small molecule binding sites with distinctive properties. There is mounting evidence for important functional roles for G-quadruplex structures in biology. G-quadruplexes may participate in the maintainance of telomeres, in transcriptional regulation and, in mRNA, may act to modulate translation. G-quadruplexes thus represent an attractive target for new small-molecule therapeutic agents. Competition dialysis provides a useful tool for the discovery of small molecules that selectively recognize the unique structural features of G-quadruplexes. The principles and practice of the competition dialysis experiment are described here.

A series of fluorenone-carboxamide compounds was analyzed with regard to DNA binding properties by UV spectroscopy and competition dialysis methods. The morpholino derivative 10 provided interesting results in terms of affinity and specificity toward the DNA G-tetraplex structures. Interactions against this target were evaluated by a comparative molecular modeling study in agreement with the experimental data, proposing a model for the rational design of new agents with potent and selective DNA tetraplex binding properties.

Competition dialysis is a powerful new tool for the discovery of ligands that bind to nucleic acids with structural- or sequence-selectivity. The method is based on firm thermodynamic principles and is simple to implement. In the competition dialysis experiment, an array of nucleic acid structures and sequences is dialyzed against a common test ligand solution. After equilibration, the amount of ligand bound to each structure or sequence is determined by absorbance or fluorescence measurements. Since all structures and sequences are in equilibrium with the same free ligand concentration, the amount bound is directly proportional to the ligand binding affinity. Competition dialysis thus provides a direct and quantitative measure of selectivity, and unambiguously identifies which of the samples within the array are preferred by a particular ligand. We describe here the third generation implementation of the method, in which competition dialysis was adapted for use in a 96-well plate format. In this format, we have been able to greatly expand the array of nucleic acid structures studied, and now can routinely study the interactions of a ligand of interest with 46 different structures and sequences.