Antimicrobial Activity of Depsidones and Macrocyclic Peptides Isolated from Marine Sponge-Derived Fungus Aspergillus nidulans M256.

Chemical study on marine sponge-derivated fungus Aspergillus nidulans resulted in the isolation of seven depsidones (1-7) and two macrocyclic peptides (8 and 9). Their chemical structures were elucidated by extensive analyses of HRESIMS and NMR spectral data, as well as comparison with the literature. Compound 1 was an undescribed depsidone. All compounds exhibited significant antimicrobial activity (MICs: 2-128 µg/mL) towards at least one of seven microbial strains, including Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, and Candida albicans. Of these, chlorinated depsidones (1-3, and 5) displayed potential antimicrobial activity. Nidulin (2) possessed good activity against tested strains except for S. enterica with MIC values in range of 2-16 µg/mL. Interestingly, undescribed depsidone 1 was selectively bioactive on the Gram-positive bacteria (MICs: 2-4 µg/mL) and yeast (MIC: 8 µg/mL) but inactivity on the Gram-negative bacteria (MICs: >256 µg/mL). Macrocyclic peptides, 8 and 9, displayed modest activity against E. faecalis strain with MIC values of 32 and 128 µg/mL, respectively.

Anti-Inflammatory Properties of Longifuran A, a New Benzofuran from the Stems of Amomum longiligulare.

In this study, the following compounds were isolated from the dichloromethane fraction of the stems of Amomum longiligulare and then characterized: a new benzofuran, namely, longifuran A (1); five other phenolic compounds, namely, 4-methoxycinnamic acid (2), 2,5-dimethoxyphenol (3), eudesmic acid (4), 1,7-bis(4-hydroxyphenyl)-1,4,6-heptatrien-3-one (5), and 4,4'-dihydroxychalcone (6); and two triterpenoids, namely, 24-methylcycloartan-3ß-ol (7) and 24-methylencycloartan-3ß-ol (8). They were evaluated in terms of their inhibitory effects on NO production in LPS-stimulated RAW 264.7 macrophages. Results indicated that 1 and 5 exhibited promising inhibitory activities against NO generation with IC50 of 10.47±1.02 µM and 8.51±1.14 µM, respectively. Enzymatic assays demonstrated that they remarkably suppressed the secretion of two pro-inflammatory cytokines (i. e., IL-6 and TNF-α). They also dose-dependently inhibited the expression of inducible nitric oxide synthase and cyclooxygenase-2, two important enzymes modulating inflammation. Therefore, 1 and 5 could be targets for the development of new anti-inflammatory therapeutics.