An indole diketopiperazine alkaloid and a bisabolane sesquiterpenoid with unprecedented skeletons from Aspergillus fumigatus. Issue 10 (23rd February 2023) - Jiang, Yaqin
Abstract : Fumitryprostatin A, an indole diketopiperazine alkaloid with a tricyclic 5/6/5 skeleton and fuminoid A, a sesquiterpenoid with a bicyclo[3.2.1]octane ring, were isolated Aspergillus fumigatus . Fumitryprostatin A exhibited moderate cytotoxic activity with an IC50 of 14.6 μM. Abstract : Fumitryprostatin A (1 ), the first example of an indole diketopiperazine alkaloid with a tricyclic 5/6/5 skeleton characterized by a dipyrrolo[1, 2- a :1′, 2′- d ]pyrazine-5, 10-dione ring system decorated with a prenylated indole moiety, and fuminoid A (2 ), a sesquiterpenoid with a bicyclo[3.2.1]octane ring featuring a novel carbon skeleton via the transformation of the methyl, were isolated from the fungus Aspergillus fumigatus along with six known diketopiperazine alkaloids. The structure with the absolute configuration of 1 was determined based on spectroscopic analyses and X-ray crystallographic analysis, while the configuration of 2 was assigned tentatively by 13 C NMR data with DP4+ probability analyses and ECD calculations. A plausible biosynthetic pathway for 1 was proposed starting from l -Trp and l -Pro via normal indole diketopiperazine. Compound 1 exhibited moderate cytotoxic activity with an IC50 value of 14.6 μM, while compound 8 exhibited moderate immunosuppressive activity in vitro .