Catherine Auvin-Guette

Structural elucidation of trikoningins KA and KB, peptaibols from Trichoderma koningii

A Trichoderma koningii strain collected in Uruguay produced two antibiotic membrane-active peptidic groups, the trikoningins KA and KB, from which the main components KA V, KB I and KB II were purified. The peptide sequences were elucidated by FAB mass spectrometry and high-field NMR experiments. KA V was a nonadecapeptaibol, whereas KB I and KB II were two 11-residue lipopeptaibols. They all displayed antibiotic activity against Staphylococcus aureus. Their membrane-modifying properties were examined by following the leakage of liposome-entrapped carboxyfluorescein. KA V induced similar permeability modifications to those exhibited by known 19-residue peptaibols, while the KB I and KB II activities were weaker.

Pohlianins A, B and C, cyclic peptides from the laxes of Jatropha pohliana ssp. molissima

Abstract From the EtOAc extract of the latex of Jatropha pohliana (Euphorbiaceae), two cyclic heptapeptides, pohlianins A (1) and B (2) and one cyclic octapeptide, pohlianin C (3) were isolated by a multi-step chromatography procedure, including HPLC. Their structure were elucidated by chemical degradation, mass spectrometry, homonuclear and heteronuclear NMR experiments. Conformational analysis of these peptides was made by using NMR experiments and distance geometry calculations. Their antimalarial activities were examined.

Mahafacyclin A, a cyclic heptapeptide from Jatropha mahafalensis exhibiting β-bulge conformation

Abstract The structure of mahafacyclin A ( 1 ), a cyclic heptapeptide isolated from Jatropha mahafalensis latex was elucidated by a combination of chemical degradation, LSIMS data and 2D NMR experiments. Mahafacyclin A solution conformation was shown to have β-bulge characteristics.

Z-Gln(Trt)-Aib-Aib-Aib-OMe synthesis using UNCA and BOP/PyBroP coupling methods

Abstract The steric hindered Aib-Aib-Aib tripeptide was synthesized in mild conditions, using PyBroP for the coupling of two Aib and Fmoc-Aib-NCA for the generation of the tripeptide, which was obtained with an excellent yield in THF. The coupling of Gln was carried out in the presence of BOP.

Isolation, structure and synthesis of mahafacyclin B, a cyclic heptapeptide from the latex of Jatropha mahafalensis

Mahafacyclin B is a cyclic heptapeptide with antimalarial activity isolated from the latex of Jatropha mahafalensis. The structure is elucidated by chemical degradation, tandem mass spectrometry, homo- and heteronuclear NMR experiments, and confirmed by synthesis.

Isolation, structure and synthesis of chevalierins A, B and C, cyclic peptides from the latex of Jatropha chevalieri

From the EtOAc extract of the latex of Jatropha chevalieri (Euphorbiaceae), two cyclooctapeptides, chevalierins A (1) and B (2), and a cyclononapeptide, chevalierin C (3), were isolated by a multi-step chromatography procedure, including HPLC. Their structures were elucidated by chemical degradation, mass spectrometry, homonuclear and heteronuclear NMR experiments and confirmed from their synthesis. Their antimalarial activities were examined.