Selective complexation of divalent cations by a cyclic α,ß-peptoid hexamer: a spectroscopic and computational study.

We describe the qualitative and quantitative analysis of the complexation properties towards cations of a cyclic peptoid hexamer composed of alternating α- and ß-peptoid monomers, which bear exclusively chiral (S)-phenylethyl side chains (spe) that have no noticeable chelating properties. The binding of a series of monovalent and divalent cations was assessed by 1H NMR, circular dichroism, fluorescence and molecular modelling. In contrast to previous studies on cations binding by 18-membered α-cyclopeptoid hexamers, the 21-membered cyclopeptoid cP1 did not complex monovalent cations (Na+, K+, Ag+) but showed selectivity for divalent cations (Ca2+, Ba2+, Sr2+ and Mg2+). Hexacoordinated C-3 symmetrical complexes were demonstrated for divalent cations with ionic radii around 1 Å (Ca2+ and Ba2+), while 5-coordination is preferred for divalent cations with larger (Ba2+) or smaller ionic radii (Mg2+).

Effect of proteases against biofilms of Staphylococcus aureus and Staphylococcus epidermidis.

UNLABELLED: Biofilms play a key role in bacterial resistance against antibacterial agents-an issue that causes multiple problems in medical fields, particularly with Staphylococcus biofilms that colonize medical indwelling devices. The literature reports several anti-biofilm strategies that have been applied in medicine. Disrupting the biofilm formation process creates new sites open to colonization by treatment-generated planktonic bacteria, so efforts have turned to focus on strategies to prevent and control the initial Staphylococci adhesion. Here, we investigated the preventive activities of three commercial proteases (Flavourzyme, Neutrase and Alcalase) against biofilm formation by two Staphylococcus strains. Some proteolytic extracts revealed interesting results with Staphylococcus epidermidis and Staphylococcus aureus aureus biofilms. SIGNIFICANCE AND IMPACT OF THE STUDY: Three proteases were tested against Staphylococcus aureus and Staphylococcus epidermidis biofilms in standard conditions. The Flavourzyme containing a mix of Aspergillus orizae endo- and exoproteases demonstrated significant efficacy against Staph. epidermidis biofilm formation. These results could prove valuable in the effort to develop simple anti-biofilm methods.

Antioxidant Activities of Peptoid-Grafted Chitosan Films.

The aim of this study was to investigate the possibility of immobilizing peptoid on chitosan film in order to generate new active material. Chitosan films have been grafted for the first time with short-length peptoid oligomers displaying antioxidant activities. The antioxidant activity of the selected peptoids was initially investigated with the DPPH assay and hydroxyl radical procedure. The metal chelating capacity of peptoids was also evaluated prior to their covalent attachment to chitosan. The benefit of chitosan functionalization with respect to its intrinsic antioxidant properties was finally evaluated in the present study. Interestingly, an increase of up to 90 % of the antioxidant activity of chitosan was observed.

Correction: Weak backbone CHO[double bond, length as m-dash]C and side chain tButBu London interactions help promote helix folding of achiral NtBu peptoids.

Correction for 'Weak backbone CHO[double bond, length as m-dash]C and side chain tButBu London interactions help promote helix folding of achiral NtBu peptoids' by G. Angelici et al., Chem. Commun., 2016, 52, 4573-4576.

Weak backbone CH···O=C and side chain tBu···tBu London interactions help promote helix folding of achiral NtBu peptoids.

The synthesis of all-cis amide (NtBu)-glycine oligomers up to 15 residues long by a blockwise coupling approach is reported. The structure and dynamical behavior of these peptoids have been studied by X-ray crystallography, NMR and molecular modeling. Analyses reveal that the folding of these oligomers is driven by weak CH···O=C hydrogen bonding along the peptoid backbone and London interaction between tBu···tBu side-chains.

Multivalent thioglycopeptoids via photoclick chemistry: potent affinities towards LecA and BC2L-A lectins.

Solution-phase synthesis of linear and cyclic ß- and α,ß-peptoids was coupled to photo-induced thiol-ene coupling reaction to readily access multivalent thioglycoclusters. A tetrameric cyclic ß-peptoid scaffold displaying 1-thio-ß-d-galactose or 1-thio-α-d-mannose has revealed by ITC experiments efficient binding potency for bacterial lectins LecA and BC2L-A, respectively.

The tert-butyl side chain: a powerful means to lock peptoid amide bonds in the cis conformation.

The very simple sterically hindered tert-butyl side chain exerts complete control over the peptoid amide geometry which only exists in the cis conformation. It is exemplified in NtBu glycine homo-oligomers and in linear oligopeptoids designed with an alternating cis-trans backbone amide pattern.

1,6-anhydro-2, 3-di-O-benzyl-5C-[(R)-ethoxycarbonyl(hydroxy)methyl]-beta-L-altrofur ano se.

The crystal structure of the title compound, C(24)H(28)O(8), has been determined. The conformation of the furanose ring can be described as 58% ideal envelope (O)E conformer and 42% ideal twisted (O)T(1) conformer. The 1,3-dioxane ring adopts a chair conformation with the anhydro-O atom pointing upwards. Both phenyl rings are quasi-perpendicular to the mean plane of the furanose ring. The hydrogen bonding is intermolecular and consists of infinite chains parallel to the a axis.

Synthesis and biological testings as inhibitors of HMGCoA reductase of the seco-acid of tuckolide and its C-7 epimer.

The seco-acid of the natural macrolactone, tuckolide (decarestrictin D) and the C-7 epimer have been prepared in enantiomerically pure form from D-gluconolactone and poly(3-hydroxy butyric acid). The key steps are Horner Emmons olefination and stereoselective reduction of the resulting enone to provide both epimers at C-7. None of the seco-acids inhibit microsomal HMGCoA reductase of pea or rat liver. It may be concluded that the cholesterol biosynthesis inhibiting effect of tuckolide is unlikely to proceed via HMGCoA reductase inhibition.