Ophiobolin-Type Sesterterpenoids from the Mangrove Endophytic Fungus Aspergillus 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 Mo 2 (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 IC 50 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 IC 50 value of 19 μM.