Sesquiterpenes and Cyclodepsipeptides from Marine-Derived Fungus Trichoderma longibrachiatum and Their Antagonistic Activities against Soil-borne Pathogens.

Soil-borne pathogens, including phytopathogenic fungi and root-knot nematodes, could synergistically invade vegetable roots and result in serious economic losses. The genus of Trichoderma has been proven to be a promising reservoir of biocontrol agents in agriculture. In this study, the search for antagonistic metabolites from a marine-derived fungus, Trichoderma longibrachiatum, obtained two structural series of sesquiterpenes 1-6 and cyclodepsipeptides 7-9. Notably, the novel 1 was a rare norsesquiterpene characterized by an unprecedented tricyclic-6/5/5-[4.3.1.01,6]-decane skeleton. Their structures were elucidated by extensive spectroscopic analyses, while the absolute configuration of novel 1 was determined by the comparison of experimental and calculated ECD spectra. The novel 1 and known 2 and 3 showed significant antifungal activities against Colletotrichum lagrnarium with MIC values of 8, 16, and 16 µg/mL respectively, even better than those of the commonly used synthetic fungicide carbendazim with 32 µg/mL. They also exhibited antifungal potential against carbendazim-resistant Botrytis cinerea. Cyclodepsipeptides 7-9 showed moderate nematicidal activities against the southern root-knot nematode (Meloidogyne incognita). This study constitutes the first report on the antagonistic effects of metabolites from T. Longibrachiatum against soil-borne pathogens, also highlighting the integrated antagonistic potential of marine-derived T. Longibrachiatum as a biocontrol agent.

Cyclodepsipeptides and Sesquiterpenes from Marine-Derived Fungus Trichothecium roseum and Their Biological Functions.

On the basis of the 'one strain, many compounds' (OSMAC) strategy, chemical investigation of the marine-derived fungus Trichothecium roseum resulted in the isolation of trichomide cyclodepsipeptides (compounds 1⁻4) from PDB medium, and destruxin cyclodepsipeptides (compounds 5⁻7) and cyclonerodiol sesquiterpenes (compounds 8⁻10) from rice medium. The structures and absolute configurations of novel (compounds 1, 8, and 9) and known compounds were elucidated by extensive spectroscopic analyses, X-ray crystallographic analysis, and ECD calculations. All isolated compounds were evaluated for cytotoxic, nematicidal, and antifungal activities, as well as brine shrimp lethality. The novel compound 1 exhibited significant cytotoxic activities against the human cancer cell lines MCF-7, SW480, and HL-60, with IC50 values of 0.079, 0.107, and 0.149 µM, respectively. In addition, it also showed significant brine shrimp lethality, with an LD50 value of 0.48 µM, and moderate nematicidal activity against Heterodera avenae, with an LC50 value of 94.9 µg/mL. This study constitutes the first report on the cytotoxic and nematicidal potential of trichomide cyclodepsipeptides.