Sesquiterpenoids from culture of the fungus Stereum complicatum (Steraceae): structural diversity, antifungal and phytotoxic activities

Herein, we describe the isolation and identification of four new and three known sesquiterpenes from the culture broth of the fungus Stereum complicatum. Chemical structures were elucidated based on HR-DART-MS, 1D and 2D NMR experiments. Compounds were identified as sterostrein X (1), sterostrein Y (2), hirsutenol G (3), sterpurol C (4), sterostrein H (5), sterostrein P (6) and sterostrein Q (7). The phytotoxicity of 1-7 was assayed against Lacuica sativa, Agrostis stolonifera and Lemna paucicostata. Compounds showed slight or no activity against L. sativa, whereas 5 and 6 were the most active against A. stolonifera. Moreover, 5 was the only compound that was phytotoxic to L. paucicostata (IC50 46.2 mu M). Compounds 2 and 5 slightly inhibited growth of B. cinerea and C. fragariae at 100 mM and C. acutatum at 50 mM, while 5 inhibited C. acutatum at 20 mM. Compound 6 was slightly active against all fungi at 20 mM.