Ophiobolin-Type Sesterterpenoids from the Mangrove Endophytic Fungus <i>Aspergillus</i> sp. ZJ-68

Eleven new ophiobolin-type sesterterpenoids, asperophiobolins A–K (1–11), along with 12 known analogues (12–23) were isolated from the cultures of the mangrove endophytic fungus Aspergillus sp. ZJ-68. The structures of the new compounds were elucidated through spectroscopic analyses, and their absolute configurations were assigned by a combination of Mo2(AcO)4-induced electronic circular dichroism spectra and quantum chemical calculations. Asperophiobolins A–D (1–4) represent the first examples possessing a five-membered lactam unit between C-5 and C-21 in ophiobolin derivatives. In the bioactivity assays, compounds 8–10 and 14–17 exhibited inhibitory effects on lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophage cells with IC50 values ranging from 9.6 to 25 μM, and compound 8 was found to show comparable inhibition of Mycobacterium tuberculosis protein tyrosine phosphatase B with an IC50 value of 19 μM.