A theoretical and experimental NMR study of (+)-biotin methyl ester

Novel Benzo[B]Furans with Anti-Microtubule Activity Upregulate Expression of Apoptotic Genes and Arrest Leukemia Cells in G2/M Phase

BACKGROUND

Novel derivatives of benzo[b]furan were found to be highly toxic towards human chronic myelogenous (K562), acute myelogenous (HL-60) and acute lymphoblastic (MOLT-4) leukemia cells.

OBJECTIVE

The objective was the characterization of the biological activity of novel benzofurans (influence on apoptosis, mitogen-activated protein kinases and on the cell cycle). Cellular protein(s) targeted by test benzofurans and mechanism of action were identified.

METHODS

The methods utilized in the study were chemical synthesis, fluorescence assays, flow cytometry, gene expression by DNA microarray and real-time RT-PCR, western blotting, cytotoxicity assays, pull-down assay, mass spectroscopy, in vitro polymerization of tubulin, molecular docking.

RESULTS

1,1'-[3-(bromomethyl)-5,6- dimethoxy-1-benzofuran-2,7-diyldiethanone (1) and methyl 4-bromo-6- (dibromoacetyl)-5-hydroxy-2-methyl-1-benzofuran-3-carboxylate (2) induced apoptosis in K562 and MOLT-4 cells. The profiling of gene expression revealed that 1 and 2 increased the expression of proapoptotic genes involved in both receptor (TNFRSF 10A, TNFRSF 10B, CASP8) and mitochondrial (BAX, BID, NOXA, APAF1) pathways of apoptosis. Test benzo[b]furans activated c-Jun N-terminal kinase (JNK) and p38 kinase in K562 cells. Tubulin was identified as a protein target for benzo[b]furans in pull-down experiments with biotinylated 2. Test benzo[b]furans inhibited polymerization of tubulin monomers in vitro, decreased the level of cellular microtubules and arrested cells in a G2/M phase. Molecular docking suggests that benzo[b]furans 1 and 2 bind to tubulin via colchicine binding pocket and the complex is stabilized mainly by hydrophobic interactions.

CONCLUSION

Novel benzo[b]furans with anti-microtubule activity were identified. They induce apoptosis in cancer cells and cause G2/M cell cycle arrest. Biological activity of 1 and 2 makes them potential lead compounds for development as anticancer drugs.

A theoretical and experimental study of the NMR spectra of 4,5,6,7-tetrafluorobenzazoles with special stress on PCM calculations of chemical shifts

The chemical shifts and several (19)F-(19)F, (13)C-(19) F and (1)H-(19)F spin-spin coupling constants (SSCSs) of eight 4,5,6,7-tetraflurobenzazoles (three benzimidazoles, three benzimidazolinones and two indazoles) have been determined. The chemical shifts were discussed using gauge including atomic orbital-density functional theory calculations taking into account solvent effects (polarizable continuum model) and, for the solid state, hydrogen bonds (clusters up to three molecules).

Molecular recognition studies on naphthyridine derivatives

The association constants K_b of three hosts I–III designed to have both enhanced hydrogen bonding donor strength and conformational preorganization with biotin analogues 1–5 are reported. ¹H-NMR titrations under two different concentration conditions have been employed to determine the association constants K_b. A statistical analysis using a presence absence matrix has been applied to calculate the different contributions. Hydrogen bond interactions make naphthyridine derivatives II and III potent binders and effective receptors for (+)-biotin methyl ester (1), due to the complex stabilization by additional hydrogen bonds.