文摘
Six new spiroindole alkaloids (1鈥?b>6) and two new spiroditerpenoids (7 and 8) were isolated from an EtOAc extract of Aspergillus duricaulis culture media together with five known compounds. The structures of the isolated compounds were elucidated by analysis of NMR and MS data, and the absolute configurations of compounds 1鈥?b>8 were confirmed by CD spectroscopic methods. All isolated compounds were evaluated for their inhibition of beta-amyloid (A尾) aggregate-induced toxicity in PC12 cells and A尾 aggregation. Compounds 8鈥?b>11 efficiently protected PC12 cells against A尾 aggregate-induced toxicity, but only compound 9 inhibited A尾 aggregation. On the other hand, compounds 4 and 5 exhibited moderate inhibitory effects on A尾 aggregation, but did not protect the cells from A尾 aggregate-induced toxicity. Preincubating A尾 monomers with compounds 4 and 5 rescued PC12 cells against A尾 aggregate-induced toxicity by reducing neurotoxic A尾 aggregates. Compound 9 inhibited both A尾 aggregate-induced toxicity and A尾 aggregation.