It is over 50 years since the discovery of microtubules, and they have become one of the most important drug targets for anti-cancer therapies. Microtubules are predominantly composed of the protein tubulin, which contains a number of different binding sites for small-molecule drugs. There is continued interest in drug development for compounds targeting the colchicine-binding site of tubulin, termed colchicine-binding site inhibitors (CBSIs). This review highlights CBSIs discovered through diverse sources: from natural compounds, rational design, serendipitously and via high-throughput screening. We provide an update on CBSIs reported in the past three years and discuss the clinical status of CBSIs. It is likely that efforts will continue to develop CBSIs for a diverse set of cancers, and this review provides a timely update on recent developments.

The synthesis and antiproliferative activity of a new series of rigid analogues of combretastatin A-4 are described which contain the 1,4-diaryl-2-azetidinone (β-lactam) ring system in place of the usual ethylene bridge present in the natural combretastatin stilbene products. These novel compounds are also

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Epoxy resin monomers, including diglycidyl ethers of bisphenol A and F (DGEBA and DGEBF), are extensively used as building blocks for thermosetting polymers. However, they are known to cause widespread contact allergy. This research describes a number of alternative epoxy resin monomers, designed with the aim of reducing the skin sensitizing potency whilst maintaining the ability to form thermosetting polymers. The compounds were designed, synthesized, assessed for skin sensitizing potency using the in vivo murine local lymph node assay, and tested for technical applicability using thermogravimetric analysis and differential scanning calorimetry. All the novel epoxy resin monomers had decreased skin sensitization potencies compared to DGEBA and DGEBF. With respect to EC3 values, which is the estimated concentration of a substance required to induce a 3-fold increase in sensitization compared to a control, the best of the new monomers had a value approximately 2.5 times higher than those of DGEBA and DGEBF. The diepoxides were reacted with triethylenetetramine and four out of the six novel monomers gave polymers with a thermal stability comparable to that obtained with DGEBA and DGEBF. The new epoxy resin monomers have the potential to replace DGEBA and DGEBF, leading to a decreased incidence of contact allergy due to epoxy resins, decreased healthcare costs, and an increased quality of life for those handling thermosetting materials.

A series of azetidin-2-ones substituted at positions 1, 3 and 4 of the azetidinone ring scaffold were synthesised and evaluated for antiproliferative, cytotoxic and tubulin-binding activity. In these compounds, the cis double bond of the vascular targeting agent combretastatin A-4 is replaced with the azetidinone ring in order to enhance the antiproliferative effects displayed by combretastatin A-4 and prevent the cis/trans isomerisation that is associated with inactivation of combretastatin A-4. The series of azetidinones was synthetically accessible via the Staudinger and Reformatsky reactions. Of a diverse range of heterocyclic derivatives, 3-(2-thienyl) analogue 28 and 3-(3-thienyl) analogue 29 displayed the highest potency in human MCF-7 breast cancer cells with IC(50) values of 7 nM and 10nM, respectively, comparable to combretastatin A-4. Compounds from this series also exhibited potent activity in MDA-MB-231 breast cancer cells and in the NCI60 cell line panel. No significant toxicity was observed in normal murine breast epithelial cells. The presence of larger, bulkier groups at the 3-position, for example, 3-naphthyl derivative 21 and 3-benzothienyl derivative 26, resulted in relatively lower antiproliferative activity in the micromolar range. Tubulin-binding studies of 28 (IC(50)=1.37 μM) confirmed that the molecular target of this series of compounds is tubulin. These novel 3-(thienyl) β-lactam antiproliferative agents are useful scaffolds for the development of tubulin-targeting drugs.

The concept of a single chemical entity with desirable activity at more than one biological target is an attractive one. Increasingly, multiple complex biochemical pathways are implicated in a variety of diseases including cancer. Successful treatment of these conditions often depends on pharmaceutical intervention at multiple pathways, with a combination of different drugs. Designed multiple ligands (DMLs) are drugs which act at multiple biomolecular targets. Numerous terms have been used to describe such ligands, including multiple-target directed ligands, heterodimers, promiscuous drugs and pan-agonists. However, although there are many reported examples of multiple-targeting anti-cancer agents, no review of these has been presented to date. A huge variety of biological signalling-pathways, proteins and enzymes are currently targeted and implicated in the pathogenesis of cancer. This review will provide an overview of reported designed multiple ligands for cancer and an exploration of the advantages and drawbacks of such compounds. The review also provides brief commentaries on the biological processes and proteins that are currently targeted in cancer therapy and the potential for dual or triple targeting of these with designed multiple ligands.

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Diglycidyl ethers of bisphenol A (DGEBA) and bisphenol F (DGEBF) are widely used as components in epoxy resin thermosetting products. They are known to cause occupational and non-occupational allergic contact dermatitis. The aim of this study is to investigate analogues of DGEBF with regard to contact allergy and cytotoxicity. A comprehensive knowledge of the structural features that contribute to the allergenic and cytotoxic effects of DGEBF will guide the development of future novel epoxy resin systems with reduced health hazards for those coming into contact with them. It was found that the allergenic effects of DGEBF were dependent on its terminal epoxide groups. In contrast, it was found that the cytotoxicity in monolayer cell culture was not only dependent on the presence of epoxide groups, but also on other structural features.