Mangrove-associated fungi are important sources for the discovery of new bioactive natural products. Three new isocoumarins (1–3) and one new pyrone derivative (4) were isolated from the ethyl acetate extract of the fermentation broth of the mangrove endophytic fungus Phomopsis sp. DHS-11. Nuclear magnetic resonance (NMR) spectroscopy (one-dimensional and two-dimensional) and mass spectrometry were used to determine the structures of these new compounds. The absolute configurations for the new isocoumarins 1–3 were determined by comparing their experimental and calculated electronic circular dichroism (ECD) spectra, while the configuration for the new pyrone-derivative 4 was tentatively solved by comparison of its ¹³C NMR data with reported data. In the biological activity test, compounds 1 and 3 showed cytotoxic activity against HeLa cells with IC₅₀ values of 11.49 ± 1.64 µM and 8.70 ± 0.94 µM, respectively. The initial structure and activity relationship (SAR) analysis revealed that the length of the side chain at C-3 for isocoumarin-type compounds 1–3 could affect the cytotoxicity against HeLa cells. Compound 4 exhibited cytotoxic activities against human hepatoma cells HepG2 with an IC₅₀ value of 34.10 ± 2.92 µM. All compounds have no immunosuppressive activity.

Aquisinenins G–I (1–3), three new 2-(2-phenylethyl)chromone-sesquiterpene hybrids, were isolated from the ethanol extract of Hainan agarwood derived from Aquilaria sinensis. Spectroscopic techniques, such as ¹D and ²D NMR and HRESIMS, were used to determine their structures. Experimental and computed ECD data were compared to confirm their absolute configurations. Compounds 1–3 are uncommon dimeric derivatives of 2-(2-phenylethyl)chromone-sesquiterpene, characterized by the fusion of 5,6,7,8-tetrahydro-2-(2-phenylethyl)chromone with agarofuran or agarospirane-type sesquiterpene units by an ester linkage. Compound 1 inhibited nitric oxide production in lipopolysaccharide-stimulated RAW264.7 cells, showing an IC₅₀ value of 22.31 ± 0.42 μM. The neuroprotective effects of compounds 1 and 3 against H₂O₂-induced apoptosis were assessed in human neuroblastoma SH-SY5Y cells. Compound 1 demonstrated cytotoxicity with IC₅₀ values of 72.37 ± 0.20 μM against K562 and 61.47 ± 0.22 μM against BEL-7402, while compounds 2 and 3 showed cytotoxicity across all five tested human cancer cell lines.

Cembranoid diterpenes are characteristic compounds of soft corals with diverse structures and significant activities, making them an important source of drug lead compounds. In this paper, five new cembranoid diterpenes, meijicrassolins A–E (1–5), were isolated from the soft coral Sarcophyton crassocaule, along with five previously reported compounds (6–10). The structures and absolute configuration for new compounds 1–5 were assigned by extensive spectroscopic analysis, single-crystal X-ray crystallography, quantum mechanical nuclear magnetic resonance (QM-NMR), and time-dependent density functional theory/electronic circular dichroism (TDDFT/ECD) calculations. Compounds 3, 4, and 9 showed moderate inhibition of nitric oxide generation in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Overall, our research results have enriched the library of secondary metabolites from soft corals, providing more molecular entities for subsequent research and development of related compounds.