14-Residue peptaibol velutibol A from Trichoderma velutinum: its structural and cytotoxic evaluation

Isolation, Characterization, and Bioherbicidal Potential of the 16-Residue Peptaibols from Emericellopsis sp. XJ1056

Eco-friendly bioherbicides are urgently needed for managing the problematic weed Amaranthus retroflexus. A mass spectrometry- and bioassay-guided screening approach was employed to identify phytotoxic secondary metabolites from fungi for the development of such bioherbicides. This effort led to the discovery of six phytotoxic 16-residue peptaibols, including five new compounds (2-6) and a known congener (1), from Emericellopsis sp. XJ1056. Their planar structures were elucidated through the analysis of tandem mass and NMR spectroscopic data. The absolute configurations of the chiral amino acids were determined by advanced Marfey's method and chiral-phase liquid chromatography-mass spectrometry (LC-MS) analysis. Bioinformatic analysis and targeted gene disruption identified the biosynthetic gene cluster for these peptaibols. Compounds 1 and 2 significantly inhibited the radicle growth of A. retroflexus seedlings, and 1 demonstrated potent postemergence herbicidal activity against A. retroflexus while exhibiting minimal toxicity to Sorghum bicolor. Structure-activity relationship analysis underscored the importance of trans-4-hydroxy-l-prolines at both the 10th and 13th positions for the herbicidal activities of these peptaibols.

Thirteen new peptaibols with antimicrobial activities from Trichoderma sp

From the fungus Trichoderma sp., we isolated seven novel 18-residue peptaibols, neoatroviridins E-K (1-7), and six new 14-residue peptaibols, harzianins NPDG J-O (8-13). Additionally, four previously characterized 18-residue peptaibols neoatroviridins A-D (14-17) were also identified. The structural configurations of the newly identified peptaibols (1-13) were determined by comprehensive nuclear magnetic resonance (NMR) and high-resolution electrospray ionization tandem mass spectrometry (HR-ESI-MS/MS) data. Their absolute configurations were further determined using Marfey's method. Notably, compounds 12 and 13 represent the first 14-residue peptaibols containing an acidic amino acid residue. In antimicrobial assessments, all 18-residue peptaibols (1-7, 14-17) exhibited moderate inhibitory activities against Staphylococcus aureus 209P, with minimum inhibitory concentration (MIC) values ranging from 8-32 μg·mL-1. Moreover, compound 9 exhibited moderate inhibitory effect on Candida albicans FIM709, with a MIC value of 16 μg·mL-1.

18-Residue Peptaibols Produced by the Sponge-Derived Trichoderma sp. GXIMD 01001

Seven new 18-residue peptaibols, trichorzins A-G (1-7), were isolated from the sponge-derived fungus Trichoderma sp. GXIMD 01001. Their structures and configurations were characterized by a comprehensive interpretation of the NMR spectroscopic data, MS/MS fragmentation, Marfey's method, and ECD analysis. The general sequences of trichorzins A-G are as follows: Ac-Aib¹-Ala/Ser²-Ala³-Aib/Iva⁴-Iva⁵-Gln⁶-Aib/Iva⁷-Val/allo-Ile⁸-Aib⁹-Gly¹⁰-Leu¹¹-Aib¹²-Pro¹³-Leu¹⁴-Aib¹⁵-Aib¹⁶-Gln¹⁷-Trpol/Pheol¹⁸. The obtained compounds were assessed for their potential antiproliferative and antimicrobial activities. All obtained compounds did not show potent antibacterial activity but exhibited significant cytotoxicity, with the lowest IC₅₀ values at 0.46-4.7 μM against four human carcinoma cell lines.

Eleven-Residue Peptaibols Isolated from Trichoderma Longibrachiatum Rifai DMG-3-1-1 and Their Structure-Activity Relationship

Total 23 eleven-residue peptaibols, including five reported ones (1-5) in our previous work, were isolated from the fungus Trichoderma longibrachiatum Rifai DMG-3-1-1, which was obtained from the mushroom Clitocybe nebularis (Batsch) P. Kumm. The structures of the 13 new peptaibols (6-10 and 12-19) were determined by their NMR and MALDI-MS/MS data, their absolute structures were further determined by Marfey's analyses and their ECD data. Careful comparison of the structures of 1-23 showed that only seven residues varied including the 2nd (Gln 2 /Asn 2 ), 3rd (Ile 3 /Val 3 ), 4th (Ile 4 /Val 4 ), 6th (Pro 6 /Hyp 6 ), 8 th (Pro 6 /Hyp 6 ), 10th (Pro 10 /Hyp 10 ) and 11th (Leuol 11 /Ileol 11 /Valol 11 ) residues. Comparison of the IC 50 s against the three tested cell lines of 1-23 indicated that 2nd, 3rd and 4th amino acid residues affected their cytotoxicities powerfully. Compounds 2, 5, 9, 11, 21 and 22 showed moderate antibacterial activities against Staphylococcus aureus MRSA T144, which also showed stronger cytotoxicities against BV2 and MCF-7 cells.

Exploring Peptaibol's Profile, Antifungal, and Antitumor Activity of Emericellipsin A of Emericellopsis Species from Soda and Saline Soils

Features of the biochemical adaptations of alkaliphilic fungi to exist in extreme environments could promote the production of active antibiotic compounds with the potential to control microorganisms, causing infections associated with health care. Thirty-eight alkaliphilic and alkalitolerant Emericellopsis strains (E. alkalina, E. cf. maritima, E. cf. terricola, Emericellopsis sp.) isolated from different saline soda soils and belonging to marine, terrestrial, and soda soil ecological clades were investigated for emericellipsin A (EmiA) biosynthesis, an antifungal peptaibol previously described for Emericellopsis alkalina. The analysis of the Emericellopsis sp. strains belonging to marine and terrestrial clades from chloride soils revealed another novel form with a mass of 1032.7 Da, defined by MALDI-TOF Ms/Ms spectrometers, as the EmiA lacked a hydroxyl (dEmiA). EmiA displayed strong inhibitory effects on cell proliferation and viability of HCT 116 cells in a dose- and time-dependent manners and induced apoptosis.

Total Synthesis and Conformational Analysis of Naturally Occurring Lipovelutibols along with Lead Optimization of Lipovelutibol D

Four lipopeptaibols, namely, lipovelutibols A-D, were recently isolated from psychrotrophic fungus Trichoderma velutinum and reported to have significant cytotoxic activity against HL-60, MDA-MD-231, A549, and LS180 cancer cell lines. In the present study, these peptides were synthesized in a solution using a segment condensation approach. The conformational analysis of these peptides carried out using CD spectrophotometry revealed the formation of 310-helix, and the NMR-VT experiments showed intramolecular hydrogen bonding for NH-5, NH-6, and NH-7. Lipovelutibol D showed potent cytotoxic activity and was chosen for lead optimization. It involved N- and C-terminal truncation, N- and C-terminal modification, random deletion, l/d configuration replacement, and other synthetic analogues. These were tested against various breast cancer cell lines. The C-terminal aldehyde analogue resulting from lead optimization of lipovelutibol D was found to have almost twofold enhanced cytotoxicity against MDA-MB-231 breast cancer cell lines.