chick-heart-invasion-assay-for-testing-invasiveness-cancer-cells

Chick Heart Invasion Assay for Testing the Invasiveness of Cancer Cells and the Activity of Potentially Anti-invasive Compounds

The goal of the chick heart assay is to offer a relevant organ culture method to study tumor invasion in three dimensions. The assay can distinguish ...

During the synthesis of tricyclic phosphonopyrrolidines via intramolecular Diels-Alder reactions of 1-acylamino(furan-2-yl)methyl phosphonates, two isomers are formed in most cases. The presence of a short three-atom tether together with spectroscopic data, including difference NOE, revealed that the cycloaddition occurred exo, but the phosphonate substituent on the tether had an exo or endo orientation. This was confirmed via X-ray analysis. A thermodynamic preference for the product with the phosphonate function in the endo position was observed experimentally and was confirmed theoretically. Density functional theory methods and several high-level post Hartree-Fock procedures were used to rationalize the observed isomer ratio of the IMDAF-reactions. This was done for two different types of reagents: with the activating carbonyl group in the tether or as a substituent on the tether. For the first type of molecules there is a large steric hindrance of the bulky tether substituents that disfavors the exo-isomer. In the latter case, there was a very small energy difference between the transition states causing a mixture of epimers being formed.

Synthesis of tricyclic phosphonopyrrolidines via IMDAF: experimental and theoretical investigation of the observed stereoselectivity.

Phosphonylated azaheterocycles are an important class of compounds with high biological potential as conformationally restricted bioisosteres of amino acids. Therefore, it is of interest to synthesize conformationally constrained amino phosphonates. We wanted to investigate possible routes via ring opening of alpha-amino phosphonates with an oxanorbornene skeleton, as these can be synthesized with high stereoselectivity. This was achieved using different Lewis acids, leading to a range of products. The reaction with TiCl(4) and FeCl(3) was modelled at a DFT level of theory to get insight in the pathways towards the corresponding products. To ease the work up, the Fe(iii) catalyst was coated on montmorillonite clay, but this accelerated aromatization after ring opening. Quenching the FeCl(3) catalyzed reaction mixture on celite caused complete aromatization.

Experimental and computational study of the ring opening of tricyclic oxanorbornenes to polyhydro isoindole phosphonates.

Synthesis of β-, γ-, δ-, ..., ω-halogenated ketones and aldehydes.

In this study, the transglucosylation potential of six sucrose phosphorylase (SP) enzymes has been compared using eighty putative acceptors from different structural classes. To increase the solubility of hydrophobic acceptors, the addition of various co-solvents was first evaluated. All enzymes were found to retain at least 50% of their activity in 25% dimethylsulfoxide, with the enzymes from Bifidobacterium adolescentis and Streptococcus mutans being the most stable. Screening of the enzymes' specificity then revealed that the vast majority of acceptors are transglucosylated very slowly by SP, at a rate that is comparable to the contaminating hydrolytic reaction. The enzyme from S. mutans displayed the narrowest acceptor specificity and the one from Leuconostoc mesenteroides NRRL B1355 the broadest. However, high activity could only be detected on l-sorbose and l-arabinose, besides the native acceptors d-fructose and phosphate. Improving the affinity for alternative acceptors by means of enzyme engineering will, therefore, be a major challenge for the commercial exploitation of the transglucosylation potential of sucrose phosphorylase.

Transglucosylation potential of six sucrose phosphorylases toward different classes of acceptors.

A versatile and efficient method to synthesize tetrasubstituted imidazoles via a one-pot modified Debus-Radziszewski reaction and their subsequent transformation into the corresponding imidazolium ionic liquids is reported. The tetrasubstituted imidazoles were also synthesized by means of a continuous flow process. This straightforward synthetic procedure allows for a fast and selective synthesis of tetrasubstituted imidazoles on a large scale. The completely substituted imidazolium dicyanamide and bis(trifluoromethylsulfonyl)imide salts were obtained via a metathesis reaction of the imidazolium iodide salts. The melting points and viscosities are of the same order of magnitude as for their non-substituted analogues. In addition to the superior chemical stability of these novel ionic liquids, which allows them to be applied in strong alkaline media, the improved thermal and electrochemical stabilities of these compounds compared with conventional imidazolium ionic liquids is also demonstrated by thermogravimetrical analysis (TGA) and cyclic voltammetry (CV). Although increased substitution of the ionic liquids does not further increase thermal stability, a definite increase in cathodic stability is observable.

Continuous synthesis of peralkylated imidazoles and their transformation into ionic liquids with improved (electro)chemical stabilities.

In order to get a clearer view on the active geometry of anti-invasive chalcones, we have prepared a number of isoxazoles and related substances as conformationally restrained mimics of 1,3-diarylpropenones, and also of (Z)-stilbenes. In vitro anti-invasive activity data for 3,5-isoxazoles and 4,5-isoxazoles, together with an in silico geometrical comparison, point towards an active conformation for chalcones more resembling their s-trans geometry than the s-cis counterpart.

Exploration of the SAR of anti-invasive chalcones: synthesis and biological evaluation of conformationally restricted analogues.

Over the past few years, isoindoles have found wide application in materials science. Isoindole containing BODIPY dyes are highly fluorescent materials and have been extensively used in various fields of science. Phthalocyanines, metal containing cyclic tetramers of isoindole, form coordination complexes with most elements of the periodic table. These complexes are intensely coloured and are used as pigments and dyes. However, isoindoles are relatively unstable 10π-heteroaromatic systems and few synthetic methods provide these compounds in good yields. This tutorial review will give an overview of the reported synthetic methods towards isoindoles and related heteroaromatic systems over a time span of approximately 10 years (2000 to current), including the applications where they have been reported. The importance of the field will be illustrated and factors influencing product stability will be discussed.

Synthesis of isoindoles and related iso-condensed heteroaromatic pyrroles.

In our ongoing exploration of the structure-activity landscape of anti-invasive chalcones, we have prepared and evaluated a number of structurally related (E)- and (Z)-stilbenes. These molecules exhibited an extraordinary high in vitro potency in the chick heart invasion assay, being active up to 10nmolL(-1), a concentration level a 100-fold lower than the lowest effective doses that have been reported for natural analogues. Furthermore, they possess an interesting pharmacological profile in silico.

Design, synthesis and structure-activity relationships of some novel, highly potent anti-invasive (E)- and (Z)-stilbenes.

In our ongoing search for new anti-invasive chemotypes, we have made an excursion from previously reported potent 1,3-diarylpropenones (chalcones) to congeners bearing longer linkers between the aromatic moieties. Nine 1,ω-diarylalkenones, including curcumin and bisdemethoxycurcumin, were evaluated in the chick heart invasion assay. Unfortunately, these compounds proved less potent and more toxic than earlier evaluated chemotypes. In the 1,3-diarylpenta-2,4-dien-1-one series, fluoro and/or trimethoxy substitution caused an increase in potency. This agrees with observations made earlier for the chalcone class.

Further studies on anti-invasive chemotypes: An excursion from chalcones to curcuminoids.

Awareness of the impact of microbiota in both health and disease is growing. Using a new in vitro oral mucosa co-culture model, we recently showed a clear inhibition of epithelial wound healing in the presence of an oral microbial community. In this paper, we have used the same model in combination with specific oral microbial species to obtain a better insight into the role of the oral microbiota in wound healing. Monocultures of Klebsiella oxytoca and Lactobacillus salivarius significantly inhibited wound healing with ~20%, whereas Streptococcus mitis and S. oralis enhanced the healing process with ~15% in 24 h. Yet, neither S. oralis or S. mitis were able to counteract the inhibitory effects from K. oxytoca on wound healing. Other tested microbial species had no effect on wound healing. Apart from this species-dependency, the inhibitory effect on wound healing depended on a microbial threshold concentration. Further mechanistic experiments with K. oxytoca excluded different microbial factors and hypothesized that quorum sensing molecules might play a role in the inter-kingdom signalling during wound healing. These results are important for the development of new strategies for the management of (infected) wounds and ulcerations.

Article	Year
Synthesis of tricyclic phosphonopyrrolidines via IMDAF: experimental and theoretical investigation of the observed stereoselectivity. The Journal of organic chemistry\| PubMed ID: 18785707	2008
Experimental and computational study of the ring opening of tricyclic oxanorbornenes to polyhydro isoindole phosphonates. Organic & biomolecular chemistry\| PubMed ID: 20544085	2010
Synthesis of β-, γ-, δ-, ..., ω-halogenated ketones and aldehydes. Chemical reviews\| PubMed ID: 20590147	2010
Transglucosylation potential of six sucrose phosphorylases toward different classes of acceptors. Carbohydrate research\| PubMed ID: 21798524	2011
Continuous synthesis of peralkylated imidazoles and their transformation into ionic liquids with improved (electro)chemical stabilities. Chemphyschem : a European journal of chemical physics and physical chemistry\| PubMed ID: 22730073	2012
Exploration of the SAR of anti-invasive chalcones: synthesis and biological evaluation of conformationally restricted analogues. Bioorganic & medicinal chemistry\| PubMed ID: 22743088	2012
Synthesis of isoindoles and related iso-condensed heteroaromatic pyrroles. Chemical Society reviews\| PubMed ID: 22782188	2012
Design, synthesis and structure-activity relationships of some novel, highly potent anti-invasive (E)- and (Z)-stilbenes. Bioorganic & medicinal chemistry\| PubMed ID: 23867387	2013
Further studies on anti-invasive chemotypes: An excursion from chalcones to curcuminoids. Bioorganic & medicinal chemistry letters\| PubMed ID: 25666820	2015
Microbial inhibition of oral epithelial wound recovery: potential role for quorum sensing molecules? AMB Express\| PubMed ID: 25995981	2015

Bart I. Roman

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