Pentadecaibins I-V: 15-Residue Peptaibols Produced by a Marine-Derived Trichoderma sp. of the Harzianum Clade.

In the course of investigations on peptaibol chemodiversity from marine-derived Trichoderma spp., five new 15-residue peptaibols named pentadecaibins I-V (1-5) were isolated from the solid culture of the strain Trichoderma sp. MMS1255 belonging to the T. harzianum species complex. Phylogenetic analyses allowed precise positioning of the strain close to T. lentiforme lineage inside the Harzianum clade. Peptaibol sequences were elucidated on the basis of their MS/MS fragmentation and extensive 2D NMR experiments. Amino acid configurations were determined by Marfey's analyses. The pentadecaibins are based on the sequences Ac-Aib1-Gly2-Ala3-Leu4-Aib/Iva5-Gln6-Aib/Iva7-Val/Leu8-Aib9-Ala10-Aib11-Aib12-Aib13-Gln14-Pheol15. Characteristic of the pentadecaibin sequences is the lack of the Aib-Pro motif commonly present in peptaibols produced by Trichoderma spp. Genome sequencing of Trichoderma sp. MMS1255 allowed the detection of a 15-module NRPS-encoding gene closely associated with pentadecaibin biosynthesis. Pentadecaibins were assessed for their potential antiproliferative and antimicrobial activities.

Phenolic Profiling of Flax Highlights Contrasting Patterns in Winter and Spring Varieties.

Flax (Linum usitatissimum) is a plant grown in temperate regions either for its fiber or for its seeds, which are rich in the essential fatty acid omega-3. It is also well known as a source of medicinal compounds. The chemical composition of its leaves is currently poorly described. In order to fill this gap, we have conducted a comprehensive analysis of flax leaf metabolome. The exploration of the metabolome allowed the characterization of compounds isolated for the first time in flax leaves. These molecules were isolated by preparative HPLC and then characterized by NMR, LC-MS and standard analysis. This work extended our picture of C-glycosyl-flavonoids and coniferyl alcohol derivatives accumulated in flax. The follow-up of the content of these different metabolites via UPLC-MS revealed significant accumulation differences in spring and winter flax leaves. In particular, two methylated C-glycosylflavonoids (swertisin and swertiajaponin) were the most abundant phenolic compounds in winter flax whereas they were not detected in spring flax. This result suggests that these 2 compounds are involved in cold stress tolerance in flax.

Development and validation of LC-MS methods for peptaibol quantification in fungal extracts according to their lengths.

Some terrestrial Trichoderma sp. strains are already used as biological control agents (BCAs). They all produce peptaibols, small antimicrobial peptides which are supposed to play a role in the anti-phytopathogenic activity of Trichoderma sp. Trichoderma strains producing high amounts of peptaibols could represent new potential BCAs. In this context, marine-derived Trichoderma strains from the marine fungal strain collection of the "Mer, Molécules, Santé" (MMS) laboratory were investigated for their peptaibol production. Previously, the quantification of peptaibols was performed using alamethicin, as standard (20-amino acid residues peptaibol). In this study, the development and validation of quantification LC/ESI-TI-MS methods using different standards of peptaibols (11-, 14- and 20-amino acid residues) was performed in order to quantify all of them, in a single analysis, in Trichoderma crude extracts according to their chain length. The developed and validated methods were used to study the peptaibol production kinetic of a marine-derived Trichoderma strain, i.e., Trichoderma longibrachiatum (MMS 151). The results showed the optimal culture time at the 9th day with concentrations reaching 1.4±0.2% and 2.3±0.4% of the fungal biomass respectively for 11- and 20-residue peptaibols. Then, the different peptaibol subgroups produced by 13 Trichoderma strains were quantified. According to their 18-, 19- and 20-residue peptaibol production, three strains referenced as MMS 1541, MMS 639 and MMS 151 seemed to be good candidates as potential new biological control agents with respective production of 0.4, 0.4 and 2.1%.

Unprecedented 17-residue peptaibiotics produced by marine-derived Trichoderma atroviride.

In the course of investigations on marine-derived toxigenic fungi, five strains of Trichoderma atroviride were studied for their production of peptaibiotics. While these five strains were found to produce classical 19-residue peptaibols, three of them exhibited unusual peptidic sodium-adduct [M + 2 Na](2+) ion peaks at m/z between 824 and 854. The sequencing of these peptides led to two series of unprecedented 17-residue peptaibiotics based on the model Ac-XXX-Ala-Ala-XXX-XXX-Gln-Aib-Aib-Aib-Ala/Ser-Lxx-Aib-Pro-XXX-Aib-Lxx-[C(129) ]. The C-terminus of these new peptides was common to all of them, and its elemental formula C5 H9 N2 O2 was established by HR-MS. It could correspond to the cyclized form of N(δ) -hydroxyornithine which has already been observed at the C-terminus of various peptidic siderophores. The comparison of the sequences of 17- and 19-residue peptides showed similarities for positions 1-16. This observation seems to indicate a common biosynthesis pathway. Both new 17-residue peptaibiotics and 19-residue peptaibols exhibited weak in vitro cytotoxicities against KB cells.