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Diversity-oriented synthesis is aiming to increase the chemical diversity of the target natural products for extensive biological activity evaluation. Indole ring is an important functional group in a large number of drugs and other biologically active agents, and indole-containing natural products have been frequently isolated from marine sources in recent years. In this paper, a series of indole-containing marine natural hyrtioreticulin derivatives, including 19 new ones, were designed, synthesized via a key Pictet-Spengler reaction, and evaluated for their inflammation related activity. Compound 13b displayed the most promising activity by inhibiting TNF-α cytokine release with inhibitory rate of 92% at a concentration of 20 μM. A preliminary structure-activity relationship analysis was also discussed. This research may give an insight for the discovery of marine indole alkaloid derived anti-inflammatory drug leads.

A new diterpenoid with an unusual capnosane skeleton, sinuhumilol A (1), alone with twelve known diverse compounds (2–13), were isolated from the South China Sea soft coral Sinularia humilis. Their structures and stereochemistry were elucidated by extensive spectroscopic analysis, quantum chemical calculations, and/or by the comparison of the spectroscopic data with those reported in the literature. In bioassay, compound 11 exhibited interesting specific cytotoxicity against the human colon adenocarcinoma cell line HT-29 with IC50 value of 12.5 µM.

A new bis-γ-pyrone polypropionate, 4,16-di-epi-onchidiol (1), along with three known related compounds (2–4) were isolated from the marine pulmonate mollusk Onchidium sp. The structure of compound 1 was elucidated by extensive spectroscopic analysis and by comparison the NMR data with its stereoisomers 2–4, whereas its absolute configuration was determined by the combination of X-ray diffraction analysis and TDDFT-ECD calculation. In bioassay, the isolated compounds exhibited broad cytotoxicity against several cancer cell lines with IC50 values ranging from 24.6 to 88.5μM.