Biologically active secondary metabolites from fungi. 12.(1) oidiolactones A-F, labdane diterpene derivatives isolated from oidiodendron truncata

Two known (1 and 2) and four new (3-6) diterpenes named oidiolactones A-F, respectively, and the antibiotic cladosporin were isolated from the fungus Oidiodendron truncata. The structure determination was mainly based on 1D and 2D NMR spectroscopy. The structures of compound 4, displaying an equilibrium between open-chain and cyclized form, and of cladosporin were confirmed by X-ray analysis.

Herbarulide, a ketodivinyllactone steroid with an unprecedented homo-6-oxaergostane skeleton from the endophytic fungus pleospora herbarum1

The novel ketodivinyllactonic steroid, herbarulide (1), deviating from the brassinosteroids in the position of the oxygen, was isolated from the endophytic fungus Pleospora herbarum. The structure was determined by extensive NMR studies, including particularly HMQC and HMBC experiments.

Geniculol, a new biologically active diterpene from the endophytic fungus geniculosporium sp.1

An endophytic fungus of the genus Geniculosporium was isolated from Teucrium scorodonia. The EtOAc extract of this isolate exhibited antialgal activities, as well as demonstrating an interesting profile during chemical screening. After mass cultivation of this fungus, in an optimized agar medium, two of the compounds responsible for the observed biological activity were isolated, the new diterpene geniculol (1), and the known fungal metabolite cytochalasin F (2). Geniculol is an unprecedented and irregular diterpenoid. For 1 and 2 complete 1H and 13C NMR data are reported. Both metabolites exhibit algacidal properties. Additionally, cytochalasin F was shown to be an inhibitor of photosynthesis, suggesting an ecological function in the plant-symbiont relationship for this secondary metabolite.