RESUMEN
Polyether ionophores are complex natural products capable of transporting cations across biological membranes. Many polyether ionophores possess potent antimicrobial activity and a few selected compounds have the ability to target aggressive cancer cells. Nevertheless, ionophore function is believed to be associated with idiosyncratic cellular toxicity and, consequently, human clinical development has not been pursued. Here, we demonstrate that structurally novel polyether ionophores can be efficiently constructed by recycling components of highly abundant polyethers to afford analogues with enhanced antibacterial selectivity compared to a panel of natural polyether ionophores. We used classic degradation reactions of the natural polyethers lasalocid and monensin and combined the resulting fragments with building blocks provided by total synthesis, including halogen-functionalized tetronic acids as cation-binding groups. Our results suggest that structural optimization of polyether ionophores is possible and that this area represents a potential opportunity for future methodological innovation.
Asunto(s)
Antibacterianos/síntesis química , Éteres/química , Ionóforos/química , Aldehídos/química , Antibacterianos/química , Antibacterianos/farmacología , Línea Celular , Supervivencia Celular/efectos de los fármacos , Cristalografía por Rayos X , Furanos/síntesis química , Furanos/química , Humanos , Ionóforos/síntesis química , Ionóforos/farmacología , Lasalocido/síntesis química , Lasalocido/química , Conformación Molecular , Monensina/síntesis química , Monensina/química , Oxidación-ReducciónRESUMEN
Seven Mannich base derivatives of polyether antibiotic Lasalocid acid (2a-2g) were synthesized and screened for their antiproliferative activity against various human cancer cell lines. A novel chemoselective one-pot synthesis of these Mannich bases was developed. Compounds 2a-2c and 2g with sterically smaller dialkylamine substituent, displayed potent antiproliferative activity (IC50: 3.2-7.3 µM), and demonstrated higher than twofold selectivity for specific type of cancer. The nature of Mannich base substituent on C-2 atom at the aromatic ring may be critical in the search for selectivity towards a particular cancer cell.
Asunto(s)
Antibacterianos/síntesis química , Antibacterianos/farmacología , Antineoplásicos/síntesis química , Antineoplásicos/farmacología , Lasalocido/análogos & derivados , Lasalocido/farmacología , Bases de Mannich/química , Antibacterianos/química , Antineoplásicos/química , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Células HT29 , Humanos , Lasalocido/síntesis química , Lasalocido/química , Células MCF-7 , Conformación Molecular , Relación Estructura-ActividadRESUMEN
The polyether antibiotic Lasalocid acid has been converted to its Mannich base derivative by a chemoselective one-pot reaction with formaldehyde and morpholine through the decarboxylation process. Spectroscopic studies of the structure of this new derivative have shown that in this ortho-phenol Mannich base the O-Hâ¯N intarmolecular hydrogen bond is present. The compound forms complexes with Li(+), Na(+) and K(+) cations of exclusively 1:1 stoichiometry. The structures of these complexes have been studied and visualized by semi-empirical calculation based on results of spectrometric and spectroscopic investigation. It is demonstrated that in contrast to Lasalocid acid the novel Mannich type derivative forms preferential complexes with Li(+) cation.