Peniandranoids A–E: Meroterpenoids with Antiviral and Immunosuppressive Activity from a Penicillium sp.

Peniandranoids A–E (1–5), five new meroterpenoids, together with three known analogues (6–8), were isolated from the fermentation of a soil-derived fungus, Penicillium sp.sb62. Their structures including absolute configurations were determined by extensive spectroscopic analysis, and the absolute configurations of compounds 1 and 5 were further elucidated by single-crystal X-ray diffraction. Peniandranoids A–E belong to a rare class of andrastin-type meroterpenoids incorporating an extra polyketide unit (a C₁₀ polyketide unit for 1 and 2, a C₉ polyketide unit for 3 and 4, and a furancarboxylic acid unit for 5). Compounds 1 and 6 exhibited favorable inhibitory activities against influenza virus A (H1N1) with EC₅₀ values of 19 and 14 μg/mL, respectively. Compounds 3–8 exhibited potent immunosuppressive activities against concanavalin A-induced T cell proliferation with EC₅₀ values ranging from 4.3 to 27 μM and lipopolysaccharide-induced B cell proliferation with EC₅₀ values ranging from 7.5 to 23 μM, respectively.