Some new oxime ethers of types 7 and 8, in which the methyleneaminoxy group, C=N-O, of oxiconazole 6 is in an inverted atomic sequence, were synthesized and tested for their antifungal activities. Among them, the type 7 compounds, such as the N-ethoxy-morpholino-substituted derivatives 7l-o (Table 1), showed good antifungal properties against the Candida strains tested, with minimum inhibitory concentration (MIC) values similar to those of the reference drug 6. A remarkable result was obtained with these types of azoles, which had shown a cidal character against Candida albicans, while the reference drug oxiconazole was only fungistatic in the same tests. This fact may be seen from a comparison of the MIC values with those of the minimum fungicidal concentration (MFC) values for most of the type 7 compounds assayed that have shown differences between the MIC and the MFC, which are lower than three double diluitions. A simple molecular modeling of the P450 14-alpha-sterol demethylase from C. albicans (Candida P450DM) was built in order to understand how the structural differences between type 7 compounds and oxiconazole 6 can induce different antifungal profiles. The results of this work seem to confirm that it is possible to reverse the atomic sequence of the methyleneaminoxy group, C=N-O, of 6, obtaining new imidazoles possessing good antifungal properties.

Transthyretin (TTR) is one of thirty non-homologous proteins whose misfolding, dissociation, aggregation, and deposition is linked to human amyloid diseases. Previous studies have identified that TTR amyloidogenesis can be inhibited through stabilization of the native tetramer state by small molecule binding to the thyroid hormone sites of TTR. We have evaluated a new series of β-aminoxypropionic acids (compounds 5–21), with a single aromatic moiety (aryl or fluorenyl) linked through a flexible oxime tether to a carboxylic acid. These compounds are structurally distinct from the native ligand thyroxine and typical halogenated biaryl NSAID-like inhibitors to avoid off-target hormonal or anti-inflammatory activity. Based on an in vitro fibril formation assay, five of these compounds showed significant inhibition of TTR amyloidogenesis, with two fluorenyl compounds displaying inhibitor efficacy comparable to the well-known TTR inhibitor diflunisal. Fluorenyl 15 is the most potent compound in this series and importantly does not show off-target anti-inflammatory activity. Crystal structures of the TTR∶inhibitor complexes, in agreement with molecular docking studies, revealed that the aromatic moiety, linked to the sp2-hybridized oxime carbon, specifically directed the ligand in either a forward or reverse binding mode. Compared to the aryl family members, the bulkier fluorenyl analogs achieved more extensive interactions with the binding pockets of TTR and demonstrated better inhibitory activity in the fibril formation assay. Preliminary optimization efforts are described that focused on replacement of the C-terminal acid in both the aryl and fluorenyl series (compounds 22–32). The compounds presented here constitute a new class of TTR inhibitors that may hold promise in treating amyloid diseases associated with TTR misfolding.

Salicylaldoximes possess a hydrogen-bonded pseudocyclic A' ring in place of the typical phenolic A ring that is characteristic of most estrogen receptor (ER) ligands. Monoaryl-substituted salicylaldoximes were obtained by replacing the phenol moiety (ring A) of the ERbeta pharmacophore with the pseudocycle A' ring, which has previously been shown to behave as a bioequivalent of phenols in nonselective ER ligands. In this series, small substituents (CH 3, CN, Cl) were introduced into the central phenyl scaffold. An efficient sequential halogen-selective double cross-coupling reaction was developed for the synthesis of the methyl-substituted ER ligand. The measured ERbeta affinity proved to be very sensitive to the effect of central core substituents. The binding affinities of the compounds herein reported were in good agreement with the results of computational docking analysis. The chloro-substituted derivative showed the highest beta affinity and selectivity, and it also proved to be an ERbeta partial agonist with an EC 50 of 11 nM.