Probing Indole Diketopiperazine-Based Hybrids as Environmental-Induced Products from <i>Aspergillus</i> sp. EGF 15-0-3
Xia Wei, Jun‐Cheng Su, Jinshan Hu, Xixin He, Shuangjun Lin, Dongmei Zhang, Wen‐Cai Ye, Minfeng Chen, Hou‐Wen Lin, Cui‐Xian Zhang
Abstract
Comprehensive analyses of the metabolite spectra of Aspergillus sp. EGF 15-0-3 under different culture conditions revealed the presence of unique environmental-induced metabolites exclusively from the rice medium. Subsequent target isolation afforded four unprecedented indole diketopiperazine-based hybrids with a pyrano[3′,2′:7,8]isochromeno[4,3-b]pyrazino[2,1-i]indole core (1 and 2) or a spiro[piperazine-2,2′-pyrano[3,4,5-de]chromene] scaffold (3 and 4). Putative biosynthetic pathways for 1–4, with Diels–Alder cycloadditions as key steps, were proposed. 1–4 exhibited selective cytotoxicities among several human cancer cells.