Skeleton-Rearranged Prenylated Acetophenone Dimers With Anti-Renal Fibrosis Activity From Maclurodendron...

Five novel pairs of dimeric prenylated acetophenone (PAP) enantiomers, (+)- and (-)-macluphlebones A-E, were isolated from an ethanolic extract of the bark of Maclurodendron oligophlebium, a plant of ethnopharmacological importance. Their structures were elucidated by comprehensive spectroscopic analyses, single-crystal x-ray diffraction, and quantum chemical nuclear magnetic resonance (NMR) and electronic circular dichroism (ECD) calculations. Among them, macluphlebones A-C feature three unprecedented carbon skeletons, each possessing a highly oxygenated cyclopenta[b]chromene core, while macluphlebones C-E represent the first examples of PAPs containing a primary enamine group. Putative biosynthetic pathways involving skeletal rearrangement and degradation processes are proposed to account for the formation of these unique scaffolds. Biologically, some isolates exhibited significant, dose-dependent anti-renal fibrosis effects at noncytotoxic concentrations, underscoring their potential value in antifibrotic drug research.