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Main observation and conclusion: The new racemic and dimeric indole alkaloids with the characteristic cyclopenta[b]indole backbone, (+)‐ and (–)‐spondomine (1a/1b), were isolated from a cultured sponge Tedania anhelans. A semi‐synthesis was employed to obtain 1a/1b and the other four stereoisomers 1c—1f. Their structures were determined by spectroscopic analysis, single‐crystal X‐ray, and quantum chemical calculations. Six stereoisomers differ in bioactivity according to their absolute configurations. Especially, (+)‐spondomine (1a) displayed cytotoxicity against the K562 cell line and exhibited stronger Wnt and HIF1 dual signaling inhibitory activity at 5 μmol/L than the positive control, which offers an exciting starting point for further investigations. All stereoisomers significantly promoted angiogenesis and showed moderate anti‐inflammation in zebrafish. A quantum chemical calculation and deuteration experiment were applied to unveil the reaction mechanism which guides the synthesis of the target compounds. [ABSTRACT FROM AUTHOR]

• Ten new polyketides (1–10) were isolated the deep-sea-derived fungus Aspergillus ochraceus. • Their absolute configurations were determined by modified Mosher's method, ICD experiments, and ECD calculations. • All the new isolates possess aspyrone nucleus. • Plausible biosynthetic pathways for 1–11 and 16 – 18 was outlined. Ten new C 9 polyketides (asperochratides A–J, 1 – 10) and 14 known miscellaneous compounds (11 – 24) were isolated from the deep-sea-derived fungus Aspergillus ochraceus. Structures of the new compounds were elucidated by extensive spectroscopic analyses, modified Mosher's method, Mo 2 (OAc) 4 induced circular dichroism (ICD) experiments, and ECD calculations. Structurally, compounds 1 – 11 and 16 – 18 share the same polyketide origin of the skeleton and belong to aspyrone co-metabolites. All isolates were tested for cytotoxic, anti-food allergic, anti-H1N1 virus, anti-microbe, and anti-inflammatory activities in vitro. Results showed that compounds 5 – 8 and 13 – 17 exerted significant cytotoxic effects on BV-2 cell line, and compound 16 showed the potential of anti-inflammatory activities. [ABSTRACT FROM AUTHOR]