Antioxidative Indole Diketopiperazine Alkaloids from Endophytic Fungi Aspergillus sp. JXC‐5

Abstract

Three previously undescribed indole diketopiperazine alkaloids and seventeen known compounds were characterized from Aspergillus sp. JXC‐5 by solid fermentation. Their structures were elucidated by spectroscopic methods and HRESIMS, and the absolute configurations were further confirmed by electronic circular dichroism (ECD), induced CD spectra and ML_J_DP4 methods. In the in vitro bioassays, Compound 5 exhibits potent DPPH and ABTS·+ free radicals radical scavenging activities with IC50 values of 19.54 ± 0.39 μM and 26.39 ± 0.09 μM respectively. Compounds 10‐12, 14 and 15 exhibited potent ABTS·+ free radicals radical scavenging activity.