Eurotiumins A⁻E, Five New Alkaloids from the Marine-Derived Fungus sp. SCSIO F452.

Three new prenylated indole 2,5-diketopiperazine alkaloids (⁻) with nine known ones (⁻), one new indole alkaloid (), and one new bis-benzyl pyrimidine derivative () were isolated and characterized from the marine-derived fungus sp. SCSIO F452. and , occurring as a pair of diastereomers, both presented a hexahydropyrrolo[2,3-]indole skeleton. Their chemical structures, including absolute configurations, were elucidated by 1D and 2D NMR, HRESIMS, quantum chemical calculations of electronic circular dichroism, and single crystal X-ray diffraction experiments. Most isolated compounds were screened for antioxidative potency. Compounds , , , , , , and showed significant radical scavenging activities against DPPH with IC values of 13, 19, 4, 3, 24, 13, and 18 µM, respectively. Five new compounds were evaluated for cytotoxic activities.