Ascandinines A–D, Indole Diterpenoids, from the Sponge-Derived Fungus <i>Aspergillus candidus</i> HDN15-152
Guoliang Zhou, Chunxiao Sun, Xuewen Hou, Qian Che, Guojian Zhang, Qianqun Gu, Chenguang Liu, Tianjiao Zhu, Dehai Li
Abstract
Four new indole diterpenoids, ascandinines A–D (1–4), were isolated from an Antarctic sponge-derived fungus Aspergillus candidus HDN15-152. Their structures, including absolute configurations, were established based on NMR data, computational calculations, and biosynthetic considerations. Ascandinine A (1) possesses an unprecedented 2-oxabicyclo[2.2.2]octan-3-ol motif embedded in a pentacyclic ring system, while compounds 2–4 represent a rare type of indole diterpenoid featuring the 6/5/5/6/6/6/6-fused ring system. Compound 3 displayed anti-influenza virus A (H1N1) activity with an IC50 value of 26 μM, while compound 4 showed cytotoxicity against HL-60 cells with an IC50 value of 7.8 μM.