Antifungal and Antimicroalgal Trichothecene Sesquiterpenes from the Marine Algicolous Fungus A-DL-9-2.

Eight new trichothecene derivatives, trichodermarins G-N (-), and two new cuparene derivatives, trichocuparins A () and B (), as well as six known trichothecenes (- were isolated from the fungal strain A-DL-9-2 obtained from the inner tissue of the marine red alga . The structures and relative configurations of - were assigned by NMR and MS data, and the absolute configurations of , , and were established by X-ray diffraction. Compound features an aminosugar unit bond to the trichothecene framework for the first time, while and represent the first occurrence of cuparene sesquiterpenes in . All the isolates were assayed for growth inhibition of five phytopathogenic fungi (, , f. sp. , f. sp. , and ) and four marine phytoplankton species (, , , and ). Several of them exhibited significant inhibitory activities against the fungi and phytoplankton tested of which trichodermin () showed the highest antifungal and antimicroalgal activities with MIC and IC values being 4.0 and 0.82 μg/mL, respectively.