Chondrosterins A–E, Triquinane-Type Sesquiterpenoids from Soft Coral-Associated Fungus Chondrostereum sp.

Abstract

The marine fungus Chondrostereum sp. was collected from a soft coral Sarcophyton tortuosum from the South China Sea. This fungus was cultured in potato dextrose broth medium and the culture broth was extracted with EtOAc. Five new triquinane-type sesquiterpenoids, chondrosterins A–E ( 1– 5), and the known sesquiterpenoid hirsutanol C ( 6), were isolated. The structures were elucidated mainly on the basis of NMR, MS, and X-ray single-crystal diffraction data. Chondrosterin A ( 1) showed significant cytotoxic activities against cancer lines A549, CNE2, and LoVo with IC ₅₀ values of 2.45, 4.95, and 5.47 μM, respectively.