(±)-Meliviticines A and B: Rearranged prenylated acetophenone derivatives from Melicope viticina and their antimicrobial activity

Two new prenylated acetophenone derivatives racemates, meliviticines A ( 1 ) and B ( 2 ) with unprecedented rearranged skeletons, were isolated from Melicope viticina . Subsequent chiral resolution led to the separation of two pairs of enantiomers, (±)-meliviticines A ( 1a / 1b ) and (±)-meliviticines B ( 2a / 2b ). Their structures including absolute configurations were elucidated by extensive spectroscopic data, electronic circular dichroism analysis, and X-ray crystallography. A plausible biosynthetic pathway of 1 and 2 , involving ring cleavage and rearrangement of the prenylated acetophenone backbone was proposed. All the isolates showed moderate antimicrobial activities with MIC values of 25–50 μ g/mL against several bacterial and fungal strains.