Cytotoxic Indole-Diterpenoids from the Marine-Derived Fungus Penicillium sp. KFD28.

Four new indole-diterpenoids, named penerpenes K-N ( 1 - 4 ), along with twelve known ones ( 5 - 16 ), were isolated from the fermentation broth produced by adding L-tryptophan to the culture medium of the marine-derived fungus Penicillium sp. KFD28. The structures of the new compounds were elucidated extensively by 1D and 2D NMR, HRESIMS data spectroscopic analyses and ECD calculations. Compound 4 represents the second example of paxilline-type indole diterpene bearing a 1,3-dioxepane ring. Three compounds ( 4 , 9, and 15 ) were cytotoxic to cancer cell lines, of which compound 9 was the most active and showed cytotoxic activity against the human liver cancer cell line BeL-7402 with an IC ₅₀ value of 5.3 μM. Moreover, six compounds ( 5 , 7 , 10 , 12 , 14 , and 15 ) showed antibacterial activities against Staphylococcus aureus ATCC 6538 and Bacillus subtilis ATCC 6633.