Pinglin Li

1. Terpenoids, with over 80,000 characterised members, constitute the most chemically and structurally diverse class of natural products (Christianson 2017). Attributable largely to the distinctive...

Four new cembranes, sinublimies A–D (1–4), were identified from Chinese soft coral Sinularia sublimis, along with three structurally related known metabolites (5–7). Notably, sinublimie A (1) is a new cembrane-based diterpene, possessing an undescribed 6/10/7 tricyclic ring system. Sinublimie C (3) is a cembrane with two rare five-membered oxygen-containing rings. The structural elucidation of these compounds relied upon extensive spectroscopic characterization, complemented by DP4+ probability analyses and ECD analysis. Bioactivity screening revealed that compounds 1 and 2 demonstrated moderate anti-inflammatory activity when tested in zebrafish models.

Marine fungus-derived natural products are an important source of new drugs and lead compounds. In this study, guided by the Global Natural Products Social (GNPS) molecular networking strategy, four new cyclohexenone derivatives, aspergiflones A–D ( 1 – 4 ), together with three known analogues ( 5 – 7 ), were isolated from the coral-derived fungus Aspergillus flavus. The structures of these compounds were elucidated through extensive spectroscopic analyses, comparison with literature data, hydrolysis reactions, quantum chemical calculations, and TDDFT-ECD calculations. Structurally, aspergiflone A ( 1 ) is a novel cyclohexenone dimer featuring an unprecedented skeleton in which two cyclohexenone units are connected at C-15 via a C−C single bond. Compound 1 exhibited potent antibacterial activity against Escherichia coli . Mechanism studies revealed that compound 1 disrupts bacterial cell morphology, increases cell membrane permeability, and decreases intracellular K ⁺ ion levels. Additionally, transcriptome analysis revealed that the differentially expressed genes (DEGs) were mainly associated with cellular process regulation, stimulus response, catalytic, and binding functions. Several pathways were also significantly affected in Escherichia coli , including ABC transporters, cofactor biosynthesis, energy metabolism, and arginine biosynthesis. The finding indicated that aspergiflone A has considerable potential in food safety. Graphical abstract

The first systematic chemical investigation on Sinularia mollis resulted in the isolation and identification of 36 seven-membered cembranolides, including 14 new compounds named sinumollolides A–N (1–14) and 22 known analogs (15–36) by HSQC-based small molecule accurate recognition technology (SMART). Their structures were characterized by spectroscopic methods (1D/2D NMR and UV), HRESIMS, quantum chemical calculations (DP4+ analysis and ECD calculations), and X-ray diffraction analysis. In zebrafish assays, compounds 1, 2, 4, and 5 exhibited anti-inflammatory activity at 20 μM by inhibiting the number of macrophages around the neuromasts, with inhibition rates ranging from 30.4% to 45.6%. Moreover, the two most bioactive and less toxic compounds, 1 and 5, featuring a 14-membered macrocyclic lactone scaffold with several hydroxyl groups and a seven-membered α, β-unsaturated lactone moiety, can inhibit inflammation by suppressing the secretion of inflammatory cytokines at 10 μM in LPS-stimulated BV-2 cells.

Combining biosynthetic gene cluster analysis with the OSMAC strategy, fractionation of the fermentation extract of Aspergillus templicola from the sponge Agelas sp. led to the isolation of four novel cytochalasins, colachalasins J–M (1–4), a novel cyclic pentapeptide, avellanin P (5), together with five known compounds (6–10). The structures of 1–9 were elucidated using spectroscopic data, single crystal X-ray diffraction, and Marfey’s analysis. Compound 2 exhibited potent anti-inflammatory activity in zebrafish assays. Additionally, Compounds 4 and 6 showed modest cytotoxicity against several human cancer cell lines with IC₅₀ values ranging from 2.6 to 11.2 μm.

A detailed chemical study of the culture of a coral-derived fungus Penicillium chrysogenum resulted in the isolation and identification of four new aromatic heterocycles chrysoquinazolinones A–B (1–2) and chrysobenzothiazoles A–B (3–4), along with a new sorbicillinoid 4-carboxylsorbicillin (5). Chrysoquinazolinones A–B (1–2) combine a quinazolinone fragment with a bicyclo[2.2.2]octane or a pyrrolidone moiety, respectively, demonstrating the unexpected structures of marine natural products. Chrysobenzothiazoles A–B (3–4) possess a benzothiazole system and are the second isolation of this class of skeleton compounds from marine organisms. The existence of the pair of enantiomers (±3) was deduced by chiral HPLC analysis. Their structures and absolute configurations were elucidated by detailed spectroscopic analysis, comparison with the literature data, single-crystal X-ray crystallographic analysis and TDDFT-ECD calculations. Compound 5 exhibited moderate cytotoxicity against K562 and NCI-H446 cell lines, with IC₅₀ values of 15.00 μM and 16.87 μM, respectively.