Patricia A. Ragazzon

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.

We report novel SIRT1 ligands that bind and modulate the activity of SIRT1 within cells and enhance its enzymatic activity. From a pool of aptamers we identify circular AC3 as having anticancer activity.

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.

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 developed a novel molecule, 2’, 4’-dihydroxy-dithion-dibenzoyl-methane and tested it on hepatic, colon, lung and osteoblast 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.

The interactions of small molecules with nucleic acids are of considerable interest for the design of novel anticancer compounds. The physical properties and sequence specificity observed in the interactions between a group of flavonoids with proven antitumour activity and various nucleic acid structures are summarised. UV and fluorescence spectroscopy, together with competition dialysis, were used to assess the affinity of the drugs for the nucleic acid structures in the presence or absence of different metal ions. The effect of these compounds on breast and leukaemia cancer cell lines was evaluated using MTS and COMET assays and flow cytometry. The flavonoids studied are weak duplex DNA-binding ligands and the binding of flavonoids to DNA is affected by metal ions. Baicalein and quercetin display stronger affinity for triplex and quadruplex than for double-stranded DNA and offer interesting scaffolds for the design of novel, high order DNA-binding agents.

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.

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 ∼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 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.