Synthesis by diastereomeric resolution, biochemical evaluation and molecular modelling of chiral 3-hydroxyl b-lactam microtubule-targeting agents for the treatment of triple negative breast and chemoresistant colorectal cancers.

The synthesis and biochemical activity of a series of chiral trans 3-hydroxyl ß-lactams targeting tubulin is described. Synthesis of the series of enantiopure ß-lactams was achieved using chiral derivatising reagent N-Boc-l-proline. The absolute configuration was determined as 3S,4S for (+) enantiomer 4EN1 and 3R,4R for (-) enantiomer 4EN2. Antiproliferative studies identified chiral 3S,4S b-lactams with subnanomolar IC50 values across a range of cancer cell lines, improving potency with respect to the corresponding racemates. Fluoro-substituted (+)-(3S,4S)-4-(3-fluoro-4-methoxyphenyl)-3-hydroxy-1-(3,4,5-trimethoxyphenyl)azetidin-2-one (27EN1) was determined as the lead eutomer with dual antiproliferative activity in triple negative breast cancer cells (TNBC), and combretastatin A-4 resistant HT-29 colorectal cancer cells. IC50 values were in the range of 0.26-0.7 nM across four cell lines. Tubulin polymerisation assays, confocal microscopy and molecular modelling studies indicated that 3S,4S eutomers are microtubule destabilisers, while 3R,4R distomers have lower potency as microtubule destabilisers. 27EN1 demonstrated anti-mitotic and pro-apoptotic activity in MDA-MB-231 and HT-29 cells in addition to selective toxicity toward MCF-7 breast cancer versus non-tumorigenic MCF-10-2A cells. The related 3S,4S ß-lactam eutomer 4EN1 downregulated expression of key cell survival anti-apoptotic proteins Bcl-2 and Mcl-1 in MDA-MB-231 cells while 27EN1 downregulated Mcl-1 in HT-29 cells. Chiral ß-lactam 27EN1 will be further developed for treatment of TNBC and CA-4 resistant colorectal cancers.

A scoping review of non-professional medication practices and medication safety outcomes during public health emergencies.

OBJECTIVES: Public health emergencies (PHE) can disrupt personal medication practices and increase the risk of medication-related harm and other negative medication-related outcomes. Our aim was to examine the extent and nature of published research on this topic to guide future research and practice. STUDY DESIGN: Scoping review. METHODS: Standard electronic databases were searched. PRISMA-ScR guidelines were followed. Extracted data were organised in response to review questions and narrative accounts developed. RESULTS: A total of 129 studies were included, conducted across 32 countries, mostly in the USA (n = 42). Sixty-eight (53%) reported on infectious events, 49 (39%) climatological or ecological events and the remainder a mixture of terrorism, war or other disasters. The studies described several medication safety outcomes (medication-related harm, adherence, supply) and adaptive medication practices (self-altering prescribed medications, sharing medications and changing healthcare providers). Challenges to maintaining routine medication practices during a PHE included transport, finance, quarantine and knowledge-related issues. Twenty-eight studies (22%) examined health inequalities pertaining to adverse medication-related outcomes, with findings suggesting that gender, age, ethnicity, educational and socio-economic status may be related to inequalities. Research gaps identified included carers', children's and minority communities' experiences and intervention studies. CONCLUSIONS: There is considerable evidence of disruptions to routine personal medication practices during PHEs and of medication-related harm and other negative outcomes. Maintaining medication supply for the management of chronic conditions is a universal problem across all emergency types. Research is needed to address these disruptions, particularly amongst people who experience health inequalities who may need additional support.

Application of 2D EXSY and qNMR Spectroscopy for Diastereomeric Excess Determination Following Chiral Resolution of ß-Lactams.

Trans-ß-lactam isomers have garnered much attention as anti-cancer microtubule targeting agents. Currently available synthetic methods are available for the preparation of enantiopure ß-lactams and favour isomeric cis/trans ß-lactam mixtures. Indirect chiral resolution offers the opportunity for isolation of exclusively enantiopure trans-ß-lactams. In this study, liquid chromatography chiral resolution of ß-lactams derivatized as diastereomer mixtures with a panel of N-protected amino acids is explored, where N-(Boc)-L-proline served as the optimal chiral derivatising reagent. High-performance liquid chromatography failed to adequately determine diastereomeric excess (de) of resolved diastereomers. Variable temperature, 1 H NMR and 2D EXSY spectroscopic analyses of proline-derivatised diastereomers were successfully employed to characterise equilibrating rotamers of resolved diastereomers and determine their de. Integration of resolved resonances corresponding to H3 and H4 of the ß-lactam ring served as a quantitative qNMR tool for the calculation of de following resolution.

Synthesis, Characterisation and Mechanism of Action of Anticancer 3-Fluoroazetidin-2-ones.

The stilbene combretastatin A-4 (CA-4) is a potent microtubule-disrupting agent interacting at the colchicine-binding site of tubulin. In the present work, the synthesis, characterisation and mechanism of action of a series of 3-fluoro and 3,3-difluoro substituted ß-lactams as analogues of the tubulin-targeting agent CA-4 are described. The synthesis was achieved by a convenient microwave-assisted Reformatsky reaction and is the first report of 3-fluoro and 3,3-difluoro ß-lactams as CA-4 analogues. The ß-lactam compounds 3-fluoro-4-(3-hydroxy-4-methoxyphenyl)-1-(3,4,5-trimethoxy phenyl)azetidin-2-one 32 and 3-fluoro-4-(3-fluoro-4-methoxyphenyl)-1-(3,4,5-trimethoxyphenyl)azetidin-2-one) 33 exhibited potent activity in MCF-7 human breast cancer cells with IC50 values of 0.075 µM and 0.095 µM, respectively, and demonstrated low toxicity in non-cancerous cells. Compound 32 also demonstrated significant antiproliferative activity at nanomolar concentrations in the triple-negative breast cancer cell line Hs578T (IC50 0.033 µM), together with potency in the invasive isogenic subclone Hs578Ts(i)8 (IC50 = 0.065 µM), while 33 was also effective in MDA-MB-231 cells (IC50 0.620 µM). Mechanistic studies demonstrated that 33 inhibited tubulin polymerisation, induced apoptosis in MCF-7 cells, and induced a downregulation in the expression of anti-apoptotic Bcl2 and survivin with corresponding upregulation in the expression of pro-apoptotic Bax. In silico studies indicated the interaction of the compounds with the colchicine-binding site, demonstrating the potential for further developing novel cancer therapeutics as microtubule-targeting agents.

Correction: McLoughlin, E.C.; O'Boyle, N.M. Colchicine-Binding Site Inhibitors from Chemistry to Clinic: A Review. Pharmaceuticals 2020, 13, 8.

We, the authors, wish to make the following corrections to our paper[...].

Colchicine-Binding Site Inhibitors from Chemistry to Clinic: A Review.

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.

Potent Quinoline-Containing Combretastatin A-4 Analogues: Design, Synthesis, Antiproliferative, and Anti-Tubulin Activity.

A novel series of quinoline derivatives of combretastatin A-4 incorporating rigid hydrazone and a cyclic oxadiazole linkers were synthesized and have demonstrated potent tubulin polymerization inhibitory properties. Many of these novel derivatives have shown significant antiproliferative activities in the submicromolar range. The most potent compound, 19h, demonstrated superior IC50 values ranging from 0.02 to 0.04 µM against four cancer cell lines while maintaining low cytotoxicity in MCF-10A non-cancer cells, thereby suggesting 19h's selectivity towards proliferating cancer cells. In addition to tubulin polymerization inhibition, 19h caused cell cycle arrest in MCF-7 cells at the G2/M phase and induced apoptosis. Collectively, these findings indicate that 19h holds potential for further investigation as a potent chemotherapeutic agent targeting tubulin.