Trichorzins HA and MA, antibiotic peptides from Trichoderma harzianum. I. Fermentation, isolation and biological properties.

Trichorzins HA and MA, original 18-residue peptides, were isolated from two strains of the widespread soil fungus Trichoderma harzianum which have been shown to exhibit antibiotic activity against phytopathogenic fungi. These linear peptides belonging to the peptaibol class are biosynthesized as a complex of closely related analogues. Nine major pure peptides, six trichorzins HA and three trichorzins MA, were isolated by reversed-phase HPLC. The isolated peptides exhibited antibacterial activity against S. aureus and increased the membrane permeability of egg phosphatidylcholine/cholesterol (7/3) liposomes, as measured by monitoring leakage kinetics of a fluorescent probe. Structure-activity relationships were deduced from the antibiotic and membrane-modifying properties.