Quadristerols A-G: Seven undescribed ergosterols from Aspergillus quadrilineata.

Quadristerols A-G, seven undescribed ergosterols, were obtained from Aspergillus quadrilineata. Their structures and absolute configurations were determined based on HRESIMS, NMR, quantum-chemical calculations, and single-crystal X-ray diffraction analyses. Quadristerols A-G featured ergosterol skeletons with different attachments; quadristerols A-C were three diastereoisomers possessing a 2-hydroxy-propionyloxy group at C-6, and quadristerols D-G were two pairs of epimers with a 2,3-butanediol group at C-6. All of these compounds were evaluated for their immunosuppressive activities in vitro. Quadristerols B and C showed excellent inhibitory effects against concanavalin A-induced T lymphocyte proliferation with IC values of 7.43 and 3.95 μM, respectively, and quadristerols D and E strongly inhibited lipopolysaccharide-induced B lymphocyte proliferation with IC values of 10.96 and 7.47 μM, respectively.