Penicillactonin and preaustinoid C, lactone-containing metabolites from a hot spring sediment Penicillium sp

Phytochemical investigation of Penicillium sp. RO-11 strain, collected from the sediments of a hydrothermal spring located in the southwestern area of Saudi Arabia, afforded, along with previously isolated compounds, the undescribed polyketides penicillactonin (1), penipyranicin D (4) and isopyrenulin B (5) and the undescribed meroterpenoid preaustinoid C (7). The structures of these compounds were elucidated based on data from mass spectrometry, 1D and 2D NMR, and comparison between experimental and calculated ECD spectra. Penicillactonin and preaustinoid C bring unprecedented structural features, for which a biosynthetic rationale is proposed, further extending the chemodiversity associated to Penicillium fungi. Preaustinoid C showed significant activity against LPS-induced NO production and selective effect on IL-2 and IFN-γ gene regulation in activated Jurkat cells.