New isoindolinone derivatives isolated from the fruiting bodies of the basidiomycete Hericium coralloides

Preparative high-performance liquid chromatography (HPLC) purification of the ethyl acetate extract derived from dried basidiomes of the European mushroom Hericium coralloides led to the identification of two previously undescribed isoindolinone derivatives named corallocins D and E (1-2). The structures of the compounds were elucidated based on HR-ESI-MS (high-resolution electron spray ionization mass spectrometry), interpretation of 1D and 2D NMR spectra, electronic circular dichroism (ECD) experiments, and comparisons with published and theoretical data. The metabolites were tested for their cytotoxic and antimicrobial effects in vitro where weak to moderate biological effects were observed against HeLa cells (KB 3.1), Mucor hiemalis and Bacillus subtilis.