Macoligophones A-I, prenylated acetophenone dimers and monomers from Maclurodendron oligophlebium

Chemical investigation of the bark of Maclurodendron oligophlebium resulted in the isolation of three prenylated acetophenone (PAP) dimers (1-3) and seventeen monomers (4-20). Among them, macoligophones A-I (1, 2, and 4-10) are previously undescribed. Utilizing chiral column, compounds 1-7 were separated into their individual enantiomers. Compound (-)-3 represents an undescribed levorotatory form of a known PAP dimer, acrotrione. Structurally, compounds 1 and 2 contain an unusual oxidized xanthene moiety featured by an uncommon enol substituent. Compound 8 incorporates a unique highly modified coumarin core, representing the second PAP bearing a C₇ side chain. Their structures were determined using a combination of spectroscopic analyses, X-ray crystallography, and quantum chemical ECD calculations. Furthermore, both pairs of dimeric PAP enantiomers, (+)-/(-)-1 and (+)-/(-)-2, displayed moderate antiplasmodial activity against chloroquine-resistant Plasmodium falciparum Dd2 strain. This study not only extends the structural repertoire of this important class of aromatic compounds, but also provides a noteworthy source of inspiration for the discovery of antimalaria drugs.