Study of Biological Activities and ADMET-Related Properties of Salicylanilide-Based Peptidomimetics.

A series of eleven benzylated intermediates and eleven target compounds derived from salicylanilide were tested against Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212 as reference strains and against three clinical isolates of methicillin-resistant S. aureus (MRSA) and three isolates of vancomycin-resistant E. faecalis. In addition, the compounds were evaluated against Mycobacterium tuberculosis H37Ra and M. smegmatis ATCC 700084. The in vitro cytotoxicity of the compounds was assessed using the human monocytic leukemia cell line THP-1. The lipophilicity of the prepared compounds was experimentally determined and correlated with biological activity. The benzylated intermediates were found to be completely biologically inactive. Of the final eleven compounds, according to the number of amide groups in the molecule, eight are diamides, and three are triamides that were inactive. 5-Chloro-2-hydroxy-N-[(2S)- 4-(methylsulfanyl)-1-oxo-1-{[4-(trifluoromethyl)phenyl]amino}butan-2-yl]benzamide (3e) and 5-chloro-2-hydroxy-N-[(2S)-(4-methyl-1-oxo-1-{[4-(trifluoromethyl)phenyl]amino)pentan-2-yl)benzamide (3f) showed the broadest spectrum of activity against all tested species/isolates comparable to the used standards (ampicillin and isoniazid). Six diamides showed high antistaphylococcal activity with MICs ranging from 0.070 to 8.95 µM. Three diamides showed anti-enterococcal activity with MICs ranging from 4.66 to 35.8 µM, and the activities of 3f and 3e against M. tuberculosis and M. smegmatis were MICs of 18.7 and 35.8 µM, respectively. All the active compounds were microbicidal. It was observed that the connecting linker between the chlorsalicylic and 4-CF3-anilide cores must be substituted with a bulky and/or lipophilic chain such as isopropyl, isobutyl, or thiabutyl chain. Anticancer activity on THP-1 cells IC50 ranged from 1.4 to >10 µM and increased with increasing lipophilicity.

Novel Sulfonamide-Based Carbamates as Selective Inhibitors of BChE.

A series of 14 target benzyl [2-(arylsulfamoyl)-1-substituted-ethyl]carbamates was prepared by multi-step synthesis and characterized. All the final compounds were tested for their ability to inhibit acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in vitro, and the selectivity index (SI) was determined. Except for three compounds, all compounds showed strong preferential inhibition of BChE, and nine compounds were even more active than the clinically used rivastigmine. Benzyl {(2S)-1-[(2-methoxybenzyl)sulfamoyl]-4-methylpentan-2-yl}carbamate (5k), benzyl {(2S)-1-[(4-chlorobenzyl)sulfamoyl]-4-methylpentan-2-yl}carbamate (5j), and benzyl [(2S)-1-(benzylsulfamoyl)-4-methylpentan-2-yl]carbamate (5c) showed the highest BChE inhibition (IC50 = 4.33, 6.57, and 8.52 µM, respectively), indicating that derivatives 5c and 5j had approximately 5-fold higher inhibitory activity against BChE than rivastigmine, and 5k was even 9-fold more effective than rivastigmine. In addition, the selectivity index of 5c and 5j was approx. 10 and that of 5k was even 34. The process of carbamylation and reactivation of BChE was studied for the most active derivatives 5k, 5j. The detailed information about the mode of binding of these compounds to the active site of both BChE and AChE was obtained in a molecular modeling study. In this study, combined techniques (docking, molecular dynamic simulations, and QTAIM (quantum theory of atoms in molecules) calculations) were employed.

Novel modified leucine and phenylalanine dipeptides modulate viability and attachment of cancer cells.

Here, we describe the synthesis and biological characterization of 32 novel phenylalanine and leucine dipeptides modified on both the N and C termini by salicylic acid and aromatic or alicyclic amines, respectively. All compounds displayed antiproliferative activity in the tested cancer cell lines and eight of the compounds exhibited single digit micromolar GI50 values. Treated cells rapidly detached from surface of tissue culture dishes and we found that focal adhesion kinase (FAK), p130CAS and paxillin, which are important regulators of cell adhesion, were dephosphorylated at Y397, Y410 and Y118, respectively. The most potent compound reduced proliferation in the HCT-116 cell line in a dose-dependent manner, as shown by a decrease in 5-bromo-2'-deoxyuridine incorporation into DNA. Furthermore, this compound increased the levels of several apoptotic markers, including activated caspases, and increased site-specific poly-(ADP-ribose)polymerase (PARP) cleavage.

Synthesis and antiproteasomal activity of novel O-benzyl salicylamide-based inhibitors built from leucine and phenylalanine.

Inhibition of protein degradation is one of strategies for suppression of uncontrolled proliferation of cancer cells. Proteolytic degradation in cells is mainly ensured by proteasome and its inhibition by bortezomib showed benefit in clinical use for the treatment of multiple myeloma. We report here the library of antiproteasomal O-benzyl salicylamides built from leucine and phenylalanine. Prepared compounds displayed antiproliferative activity on K562, CEM and U266 cancer cell lines, ranging from high micromolar to submicromolar GI50 values. The most potent compounds (series 4 and 6) were further assayed for their inhibition of chymotrypsin-like protease activity of the 26S proteasome in U266 cells. The majority of compounds inhibited the proteasome in mid-nanomolar concentrations (IC50 ranging from 57 to 197 nM) and it correlated with cellular potency. In a cell based assay involving green fluorescence protein (GFP) fused to a short degron that is rapidly degraded by a proteasome the compounds induced accumulation of GFP, visualised and quantified by live-cell imaging. Levels of polyubiquitinated proteins in U266 cells treated by compound 4m were also analyzed by immunoblotting, revealing a typical high molecular mass smear of ubiquitin conjugates. Finally, apoptotic cell death in treated U266 cells was detected biochemically by measuring the activity of caspases 3 and 7 in lysates and by immunoblotting of caspase 7, its substrate poly(ADP-ribose)polymerase, and Mcl-1, which all together showed changes typical for apoptosis. All these observations were in agreement with expected cellular mechanism of action and confirmed proteasome targeting by prepared O-benzyl salicylamides.