Antifungal and Antimicroalgal Trichothecene Sesquiterpenes from the Marine Algicolous Fungus Trichoderma brevicompactum A‑DL-9‑2

Eight new trichothecene derivatives,
trichodermarins G-N (1–8), and two
new cuparene derivatives,
trichocuparins A (9) and B (10), as well
as six known trichothecenes (11–16) were isolated from the fungal strain Trichoderma
brevicompactum A-DL-9-2 obtained from the inner tissue
of the marine red alga Chondria tenuissima. The structures and relative configurations of 1–10 were assigned by NMR and MS data, and the absolute configurations
of 1, 2, and 9 were established
by X-ray diffraction. Compound 8 features an aminosugar
unit bond to the trichothecene framework for the first time, while 9 and 10 represent the first occurrence of cuparene
sesquiterpenes in Trichoderma. All the isolates were
assayed for growth inhibition of five phytopathogenic fungi (Botrytis cinerea, Cochliobolus miyabeanus, Fusarium oxysporum f. sp. cucumerium, Fusarium oxysporum f. sp. niveum, and Phomopsis asparagi) and four marine phytoplankton species (Amphidinium
carterae, Heterocapsa circularisquama, Heterosigma akashiwo, and Prorocentrum donghaiense). Several of them exhibited
significant inhibitory activities against the fungi and phytoplankton
tested of which trichodermin (12) showed the highest
antifungal and antimicroalgal activities with MIC and IC50 values being 4.0 and 0.82 μg/mL, respectively.