Inverse γ‐Turn‐Inspired Peptide: Synthesis and Analysis of Segetalin A Indole Hemi­aminal

Abstract

Substitution of a peptide bond for an imine transforms the irreversible macrocyclization of peptides into a reversible process. The inherent cyclization tendency of a linear peptide is then analyzable through the equilibrium between the aldehyde and the imine by virtue of the higher reactivity of the corresponding linear peptide aldehyde. The tryptophan

Hydroxyapatite catalyzed hydrothermal liquefaction transforms food waste from an environmental liability to renewable fuel

“…Figure 3 C shows a zoomed in portion of the GC×GC chromatogram showing a series of alkyl phenols (cresols), with between one and four carbons present as side chains, shown in Figure 3 B. The cresols and indoles form from reactions of carbohydrates with one another ( Sad et al., 2008 ) or with amino acids ( Lamping et al., 2015 ; Meshram et al., 2013 ). Unlike the parent compounds, which are expected to be water soluble, these molecules possess log( K ow ) values >10, consistent with biocrude forming molecules.…”

Natural cyclic polypeptides as vital phytochemical constituents from seeds of selected medicinal plants

“…The tryptophan side chain of segetalin A aldehyde afforded a 12‐membered cyclic indole hemiaminal instead of the 18‐membered macrocyclic imine. [ 78 ]…”

Comparison of Two Reagents for Thionations

“…Segetaline A is a cyclohexapeptide (-Gly-Val-Pro-Val-Trp-Ala)-with estrogen-like activity that has been isolated from the seeds of Vaccaria segetalis. 38 Thionation with Lawesson's reagent (3) gave two products, A1 (Gly-thionated) and A2 (Gly-Ala-dithionated), which indicated that a clear selectively for the small (and less hindered) amino acids. The products A1 and A2 did not show any improved activity.…”