Aculeanoids A-D, the second 17-nor fusicoccane diterpenoids with immunosuppressive activity from Aspergillus aculeatus.

Chemical investigation on the secondary metabolites of Aspergillus aculeatus led to the identification of ten modified fusicoccane-type diterpenoids aculeanoids A-J (1-10). Their structures and absolute configurations were characterized by comprehensive spectroscopic analysis, DP4+ analysis, Mo2(OAc)4-induced ECD, single-crystal X-ray diffractions, and ECD calculations. Compounds 1-4 belong to a rare class of 17-nor fusicoccane diterpenoids, with only one previously reported example. Biologically, compounds 6, 7, and 10 exhibited significant immunosuppressive activities against con A-induced T cell proliferation with IC50 values ranging from 2.44 to 5.26 μM and LPS-induced B cell proliferation with IC50 values ranging from 4.18 to 5.78 μM, which provided more possibilities with the treatment of organ transplantation and various autoimmune diseases.