Sesquiterpene-α-amino acid quaternary ammonium hybrids from Stereum complicatum (Steraceae)

Abstract Five sesquiterpene-α-amino acid quaternary ammonium hybrids and the sesquiterpene core with no amino acid moiety linked were isolated from the n-butanol partition of the Stereum complicatum fungal culture grown on potato dextrose broth. Chemical structures were unambiguously elucidated by high resolution electrospray ionization mass spectrometry (HR-ESI-MS) in positive ion mode and NMR experiments and were identified as sterostrein Q and stereumamides A - E. The isolation and structure elucidation of these hybrid compounds is reported herein for the first time from S. complicatum. The phytotoxic, antifungal and antibacterial activities of these compounds were evaluated, but no significant activity was found. The HR-ESI-MS fragmentation pattern of the sesquiterpene-α-amino acid quaternary ammonium hybrid metabolites and its chemotaxonomic implication are discussed.