Clonorosins A ( 1 ) and B ( 2 ), two novel indole alkaloids featuring unprecedented 6/5/6/6/5 and 6/5/5 cores, together with seven known indole-linked 2,5-diketopiperazine alkaloids ( 3 - 9 ), were isolated from the soil-derived fungusClonostachys roseaYRS-06. The new structures were proposed through HR-MS, NMR, and ECD spectroscopic data. They were established by comparing the calculated NMR, ECD, and specific rotation data with the experimental. To assist in determining the absolute configuration of the chiral carbon in the side chain of 2,5-diketopiperazine derivatives, flexible analogues 3i - 3iv were synthesized and analyzed. 1 was active againstFusarium oxysporumwith an MIC value of 50 μg/mL. 7 and 8 showed excellent activity against human HeLa and HepG2 cells with IC50values of 0.12-0.60 μM. © 2021 American Chemical Society and American Society of Pharmacognosy