Undescribed alkaloids, peptides and polyketides from marine sediment-derived fungus Aspergillus terreus PPS1.

Abstract

The chemical investigation of the marine sediment-derived fungus Aspergillus terreus PPS1 led to the isolation and identification of seven previously undescribed secondary metabolites, including three alkaloids, asperspiroids A, B (1, 2) and astepyrazinol C (3), two lumazine peptides, terrelumamides C, D (5, 6), and two polyketides, scytalols E, F (8, 9), together with two known compounds. The structures of these undescribed compounds were elucidated by comprehensive spectroscopic analysis of NMR and HRESIMS data, and the absolute configurations were determined using ECD calculations, modified Mosher's method, and Marfey's analysis. Notably, asperspiroids A, B (1, 2) were uncommon alkaloids characterized by a rare 6/5/6 indole spirocyclolactone structure found naturally. The isolated compounds were assessed for their potential antibacterial, cytotoxic and anti-inflammatory activities. Astepyrazinol C (3) and its analog astepyrazinol B (4) demonstrated significant inhibition activity against LPS-induced NO production in RAW264.7 macrophages, with inhibition rates of 37.4% and 64.6%, respectively, at a concentration of 20 μM.