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

Abstract

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.