ABSTRACT
Described are mechanistic studies of two Sanguinamide B (San B) derivatives. These compounds were identified as eukaryotic ribosomal inhibitors. Two biotinylated San B derivatives were synthesized and used to capture protein targets in a pull-down assay. LC/MS/MS analysis of the San B-captured targets identified several proteins that comprise eukaryotic ribosomal subunits. The translation inhibitory effect of San B was confirmed using an in vitro translation assay. Moreover, an evaluation of cell death mechanisms is reported.
Subject(s)
Oxazoles/chemical synthesis , Peptides, Cyclic/chemical synthesis , Ribosomes/drug effects , Thiazoles/chemical synthesis , Apoptosis/drug effects , Humans , Molecular Structure , Nuclear Magnetic Resonance, Biomolecular , Oxazoles/chemistry , Oxazoles/pharmacology , Peptides, Cyclic/chemistry , Peptides, Cyclic/pharmacology , Proteins/metabolism , Ribosomes/metabolism , Thiazoles/chemistry , Thiazoles/pharmacologyABSTRACT
Herein we report the first total synthesis of the natural product Urkuthaplestatin A (Ustat A) utilizing a convergent synthetic strategy. The characterization and biological activity match those of the previously published natural product. Interestingly, several intermediates, including the linear and serine cyclized precursors, show a 100-fold decrease in cytotoxicity, with IC50's in the low micromolar range. These data indicate that the rigidity and the consecutive aromatic heterocyclic system are responsible for the biological activity.
Subject(s)
Biological Products/chemical synthesis , Leucine/analogs & derivatives , Serine/chemistry , Thiazoles/chemistry , Thiazoles/chemical synthesis , Inhibitory Concentration 50 , Leucine/chemical synthesis , Leucine/chemistry , Molecular Structure , StereoisomerismABSTRACT
We report the first synthesis of sanguinamide B analogues. Substituting N-methylated (N-Me) amino acids, glycine (Gly), and L- or D-phenylalanine (Phe) into the backbone of sanguinamide B showed that only l- and d-Phe residues controlled the macrocycle conformation. The N-methylated and glycine analogues all had multiple conformations, whereas the L- and D-Phe derivatives only had a single conformation. Testing of all conformer analogues showed that inclusion of an L- or D-Phe was a superior design element than incorporating the N-Me moiety that is often utilized to control macrocyclic conformation. Finally, we show that there is an ideal Phe residue (in this case L-Phe) for generating compounds that have the greatest inhibitory effect on bacterial motility. Our data support the hypothesis that the macrocyclic conformation is dictated by the benzyl moiety requiring a "pseudoequatorial" position, and all other energy considerations are secondary.
