Microascones, Decahydrofluorene-Class Alkaloids from the Marine-Derived Fungus Microascus sp. SCSIO 41821.

Eight new decahydrofluorene-class alkaloids, microascones A and B (1 and 2), 2,3-epoxyphomapyrrolidone C (3), 14,16-epiascomylactam B (4), 24-hydroxyphomapyrrolidone A (5), and microascones C-E (6-8), along with five known analogs (9-13) were isolated from the marine-derived fungus Microascus sp. SCSIO 41821. Compounds 1 and 2 have an unprecedented complex macrocyclic alkaloid skeleton with a 6/5/6/5/6/5/13 polycyclic system. Their structures and absolute configurations were determined by spectroscopic analysis, quantum chemical calculations of ECD spectra, and 13C NMR chemical shifts. Compounds 10-13 showed selective enzyme inhibitory activity against PTPSig, PTP1B, and CDC25B, and 4, 9, and 10 exhibited strong antibacterial activity against seven tested pathogens. Their structure-bioactivity relationship was discussed, and a plausible biosynthetic pathway for 1-8 was also proposed.

Mauritone A, a new polyketide from a fungal-bacterial symbiont Aspergillus spelaeus GXIMD 04541/Sphingomonas echinoides GXIMD 04532.

A new polyketide, mauritone A (1) with six known polyketides curvulone B (2), curvularin (3), 12-oxocurvularin (4), (10E,15S)-10,11-dehydrocurvularin (5), (11R,15S)-11-hydroxycurvularin (6), and (11S,15S)-11-hydroxycurvularin (7) were isolated from the fungal-bacterial symbiont Aspergillus spelaeus GXIMD 04541/Sphingomonas echinoides GXIMD 04532 derived from Mauritia arabica. Their structures were elucidated by extensive spectral analysis. All compounds (1-7) were evaluated for their anti-inflammatory effects. The inhibitory effects of 4, 5, and 7 on nitric oxide (NO) production were found to be significant, with IC50 values of 5.5 ± 0.26, 2.0 ± 0.31, and 8.3 ± 0.62 µM, respectively, surpassing that of the positive control quercetin (10.6 ± 0.64 µM). Compounds 3 and 6 exhibited moderate inhibition of NO, with IC50 values of 18.6 ± 0.53 and 12.7 ± 0.45 µM, respectively.