STRUCTURAL ASSIGNMENT OF THE PEPTIDE ANTIBIOTIC LP237-F8, A METABOLITE OF TOLYPOCLADIUM GEODES

Antibiotic LP237-F8 is the main cytotoxic metabolite isolated from the liquid cultures of the fungus Tolypocladium geodes. Complete H-1 and C-13 NMR resonance assignments and sequencing of the peptide was achie ved by extensive high-field 2D NMR spectroscopy. The N- and C-terminal s of LP237-F8 are protected with a capryloyl unit and the amino alcoho l leucinol, respectively. This linear peptide is a new member of the p eptaibol class of natural products, containing the unusual amino acids cl-aminoisobutyric acid (Aib) and alpha-amino-alpha-ethyl-n-pentanoic acid (alpha-ethylnorvaline, alpha-EtNor).