41839-95-6

Upstream product

• 1054661-52-7 C₇₀H₁₁₀N₁₂O₁₅ 

Downstream Products

• 113-73-5 Gramicidin S 

Relevant academic research and scientific papers

Photopharmacological Control of Cyclic Antimicrobial Peptides

Gramicidin S is a naturally occurring antimicrobial cyclic peptide. Herein, we present a series of cyclic peptides based on gramicidin S that contain an azobenzene photoswitch to reversibly control secondary structure and, hence, antimicrobial activity. 1H NMR spectroscopy and density functional theory calculations revealed a β-sheet/β-turn secondary structure for the cis configuration of each peptide, and an ill-defined conformation for all associated trans structures. The cis-enriched and trans-enriched photostationary states (PSSs) for peptides 1–3 were assayed against Staphylococcus aureus to reveal a clear relationship between well-defined secondary structure, amphiphilicity and optimal antimicrobial activity. Most notably, peptides 2 a and 2 b exhibited a fourfold difference in antimicrobial activity in the cis-enriched PSS over the trans-enriched equivalent. This photopharmacological approach allows antimicrobial activity to be regulated through photochemical control of the azobenzene photoswitch, thereby opening new avenues in the design and synthesis of future antibiotics.

Development of Therapeutic Gramicidin S Analogues Bearing Plastic β,γ-Diamino Acids

Gramicidin S (GS), one of the most widely investigated antimicrobial peptides (AMPs), is known for its robust antimicrobial activity. However, it is restricted to topical application due to undesired hemolytic activity. With the aim of obtaining nontoxic GS analogues, we describe herein a molecular approach in which the native GS β-turn region is replaced by synthetic β,γ-diamino acids (β,γ-DiAAs). Four β,γ-DiAA diastereomers were employed to mimic the β-turn structure to afford GS analogues GS3–6, which exhibit diminished hemolytic activity. A comparative structural study demonstrates that the (βR,γS)-DiAA is the most-stable β-turn mimic. To further improve the therapeutic index (e. g., high antibacterial activity and low hemolytic activity) and to extend the molecular diversity, GS5 and GS6 were used as structural scaffolds to introduce additional hydrophobic or hydrophilic groups. We show that GS6K, GS6F and GS display comparable antibacterial activity, and GS6K and GS6F have significantly decreased toxicity. Moreover, antibacterial mechanism studies suggest that GS6K kills bacteria mainly through the disruption of the membrane.

Rapid, Traceless, AgI-Promoted Macrocyclization of Peptides Possessing an N-Terminal Thioamide

Peptide macrocyclization is often a slow process, plagued by epimerization and cyclodimerization. Herein, we describe a new method for peptide macrocyclization employing the AgI-promoted transformation of peptide thioamides. The AgI has a dual function: chemoselectively activating the thioamide and tethering the N-terminal thioamide to the C-terminal carboxylate. Extrusion of Ag2S generates an isoimide intermediate, which undergoes acyl transfer to generate the native cyclic peptide, resulting in a rapid, traceless macrocylization process. Cyclic peptides are furnished in high yields within 1 hour, free of epimerization and cyclodimerization.

Peptoid oligomers, pharmaceutical compositions and methods of using the same

Novel peptoid oligomers are disclosed that have a formula represented by the following formula I: The peptoids demonstrate antimicrobial activity and may be prepared as pharmaceutical compositions and used for the prevention or treatment of a variety of c

CYCLIC PEPTOID OLIGOMERS, PHARMACEUTICAL COMPOSITIONS AND METHODS OF USING THE SAME

Novel peptoid oligomers are disclosed that have a formula represented by the following formula I: wherein R1 and n are as described herein. The peptoids demonstrate antimicrobial and antimalarial activity and may be prepared as pharmaceutical compositions and used for the prevention or treatment of a variety of conditions in mammals including humans where microbial or malarial infection is involved. The present cyclic peptoids are particularly valuable as their effect is rapid, broad in spectrum and mostly indifferent to resistance provoked by standard antibiotics.

A practical synthesis of gramicidin S and sugar amino acid containing analogues

A practical gram-scale and high-yielding synthesis of the antimicrobial peptide gramicidin S is presented. An Fmoc-based solid-phase peptide synthesis protocol is employed for the generation of the linear decapeptide precursor, which is cyclized in solution to afford the target compound. The versatility of our method is demonstrated by the construction of eight gramicidin S analogues (15a-h) having nonproteinogenic sugar amino acid residues (4-7) incorporated in the turn regions.

Photoinduced electron transfer on ?2-sheet cyclic peptides

Gramicidin S analogues that contain a single pyrenyl group and a single p-nitrophenyl group at different positions were synthesized. Photoinduced electron transfer (ET) from an excited pyrenyl group located at the fourth position to a nitrophenyl group located at five different positions was investigated on the ?2-sheet chains of the cyclic peptides. The observed ET rate constants displayed a complex dependence on the number of spacer units or on the edge-to-edge distance between the two aromatic groups. The ET rate constants, however, showed a reasonable linear relationship with the equivalent ??-distances calculated from the Beratan-Onuchic tunneling pathway model, if through-hydrogen-bond ET was taken into account. The results support the applicability of the tunneling pathway model on both helix and ?2-sheet model peptides.