In the course of our continuing investigation of bioactive secondary metabolites from marine-derived fungal strains, a racemate of a novel diphenolic derivative named (±)-tylopilusin D (1) along with ten previously known secondary metabolites (2-11) were isolated from a marine-derived fungal strain Aspergillus sp. SF-5929. Their structures were elucidated mainly by analysis of NMR and MS data. In addition, the inhibitory effects of the isolated compounds against protein tyrosine phosphatase 1B (PTP1B) activity were evaluated, and compounds 1, 2, and 5-7 inhibited PTP1B activity with IC50 values ranging from 3.3 to 8.1 µM. Kinetics studies suggested that compounds 1, 2, and 5 had noncompetitive inhibitory effects against PTP1B.
Keywords: Aspergillus sp.; Marine-derived fungus; PTP1B inhibitors; diphenolic derivative.