Confluenines A–F, N-oxidized l-isoleucine derivatives from the edible mushroom Albatrellus confluens

Abstract

The phytochemical study of the fruiting bodies of Albatrellus confluens afforded three pairs of new N-Oxidized l-Isoleucine derivatives epimers, confluenines A–F (1–6). The structures of these compounds were deduced using spectroscopic techniques, and the absolute configurations of the compounds were assigned by comparison between experimental and theoretical NMR and ECD data, respectively. Putative biosynthetic pathways toward the oxime, hydroxamate moieties and epimers were discussed. Compounds 5 and 6 exhibited weak antimicrobial activities against Staphylococcus aureus with MIC90 values at 29.3 μg/mL and 56.7 μg/mL, respectively.