DETECTION OF ANTIBACTERIAL COMPOUND HIMANIMIDE B IN LIQUID CULTURES OF STEREUM HIRSUTUM BY HIGH-PERFORMANCE THIN-LAYER CHROMATOGRAPHY-BIOASSAY AND MASS SPECTROMETRY-BASED METHODS

Abstract

Higher fungi (Basidiomycetes) are known for releasing several bioactive compounds in liquid culture media. Some studies have reported a relevant antibacterial activity in extracts from the fungus Stereum hirsutum, however, the molecules responsible have still not been described. In the present work, an effect-directed analysis (EDA) using high-performance thin-layer chromatography (HPTLC) coupled to mass spectrometry (MS) was established to detect and identify antibacterial compounds in liquid culture of the Stereum hirsutum fungus. Bioactive molecules were separated on HPTLC silica gel 60 F₂₅₄ plates using a mobile phase composed of toluene and ethyl acetate (6.3 + 3.7 v/v), and the antibacterial compound was detected in situ on the plate by applying the Bacillus subtilis bioassay. By HPTLC/MS and liquid chromatography (LC)/MS, the antibacterial compound was identified as himanimide B, an N-hydroxylated maleimide derivative with potent antibacterial activity. To the best of our knowledge, himanimide B is reported for the first time as a secondary metabolite produced by liquid cultures of Stereum hirsutum.